Add all the plugins I currently use

64 files changed, 8841 insertions, 0 deletions

diff --git a/start/cmp/COMMIT b/start/cmp/COMMIT
new file mode 100644
index 0000000..c5798ea
--- /dev/null
+++ b/start/cmp/COMMIT
@@ -0,0 +1 @@
+cd694b8944eb1ae98f1d0e01cf837e66b15c2857
\ No newline at end of file
diff --git a/start/cmp/COMMIT-LSP b/start/cmp/COMMIT-LSP
new file mode 100644
index 0000000..d5d6e67
--- /dev/null
+++ b/start/cmp/COMMIT-LSP
@@ -0,0 +1 @@
+affe808a5c56b71630f17aa7c38e15c59fd648a8
\ No newline at end of file
diff --git a/start/cmp/LICENSE b/start/cmp/LICENSE
new file mode 100644
index 0000000..ae725ef
--- /dev/null
+++ b/start/cmp/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 hrsh7th
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/start/cmp/after/plugin/cmp_nvim_lsp.lua b/start/cmp/after/plugin/cmp_nvim_lsp.lua
new file mode 100644
index 0000000..6d566fa
--- /dev/null
+++ b/start/cmp/after/plugin/cmp_nvim_lsp.lua
@@ -0,0 +1 @@
+require('cmp_nvim_lsp').setup()
diff --git a/start/cmp/autoload/cmp.vim b/start/cmp/autoload/cmp.vim
new file mode 100644
index 0000000..43b8cc2
--- /dev/null
+++ b/start/cmp/autoload/cmp.vim
@@ -0,0 +1,64 @@
+let s:bridge_id = 0
+let s:sources = {}
+
+"
+" cmp#register_source
+"
+function! cmp#register_source(name, source) abort
+  let l:methods = []
+  for l:method in ['is_available', 'get_debug_name', 'get_trigger_characters', 'get_keyword_pattern', 'complete', 'execute', 'resolve']
+    if has_key(a:source, l:method) && type(a:source[l:method]) == v:t_func
+      call add(l:methods, l:method)
+    endif
+  endfor
+
+  let s:bridge_id += 1
+  let a:source.bridge_id = s:bridge_id
+  let a:source.id = luaeval('require("cmp").register_source(_A[1], require("cmp.vim_source").new(_A[2], _A[3]))', [a:name, s:bridge_id, l:methods])
+  let s:sources[s:bridge_id] = a:source
+  return a:source.id
+endfunction
+
+"
+" cmp#unregister_source
+"
+function! cmp#unregister_source(id) abort
+  if has_key(s:sources, a:id)
+    unlet s:sources[a:id]
+  endif
+  call luaeval('require("cmp").unregister_source(_A)', a:id)
+endfunction
+
+"
+" cmp#_method
+"
+function! cmp#_method(bridge_id, method, args) abort
+  try
+    let l:source = s:sources[a:bridge_id]
+    if a:method ==# 'is_available'
+      return l:source[a:method]()
+    elseif a:method ==# 'get_debug_name'
+      return l:source[a:method]()
+    elseif a:method ==# 'get_keyword_pattern'
+      return l:source[a:method](a:args[0])
+    elseif a:method ==# 'get_trigger_characters'
+      return l:source[a:method](a:args[0])
+    elseif a:method ==# 'complete'
+      return l:source[a:method](a:args[0], s:callback(a:args[1]))
+    elseif a:method ==# 'resolve'
+      return l:source[a:method](a:args[0], s:callback(a:args[1]))
+    elseif a:method ==# 'execute'
+      return l:source[a:method](a:args[0], s:callback(a:args[1]))
+    endif
+  catch /.*/
+    echomsg string({ 'exception': v:exception, 'throwpoint': v:throwpoint })
+  endtry
+  return v:null
+endfunction
+
+"
+" s:callback
+"
+function! s:callback(id) abort
+  return { ... -> luaeval('require("cmp.vim_source").on_callback(_A[1], _A[2])', [a:id, a:000]) }
+endfunction
diff --git a/start/cmp/doc/cmp-nvim-lsp.txt b/start/cmp/doc/cmp-nvim-lsp.txt
new file mode 100644
index 0000000..28e3700
--- /dev/null
+++ b/start/cmp/doc/cmp-nvim-lsp.txt
@@ -0,0 +1,29 @@
+*cmp-nvim-lsp*
+
+==============================================================================
+CONTENTS                                                 *cmp-nvim-lsp-contents*
+
+FAQ                                                           |cmp-nvim-lsp-faq|
+
+
+
+==============================================================================
+FAQ                                                           *cmp-nvim-lsp-faq*
+
+How to disable specific LSP server's cmpletion?~
+
+  You can disable specific LSP server's cmpletion by adding the following
+
+>
+  require('lspconfig')[%YOUR_LSP_SERVER%].setup {
+    on_attach = function(client)
+      client.server_capabilities.completionProvider = false
+    end
+  }
+<
+
+
+
+==============================================================================
+ vim:tw=78:ts=2:et:ft=help:norl:
+
diff --git a/start/cmp/doc/cmp.txt b/start/cmp/doc/cmp.txt
new file mode 100644
index 0000000..e54f66e
--- /dev/null
+++ b/start/cmp/doc/cmp.txt
@@ -0,0 +1,806 @@
+*nvim-cmp* *cmp*
+
+A completion plugin for neovim coded in Lua.
+
+==============================================================================
+CONTENTS                                                          *cmp-contents*
+
+Abstract                                                          |cmp-abstract|
+Concept                                                            |cmp-concept|
+Usage                                                                |cmp-usage|
+Function                                                          |cmp-function|
+Mapping                                                            |cmp-mapping|
+Command                                                            |cmp-command|
+Highlight                                                        |cmp-highlight|
+Autocmd                                                            |cmp-autocmd|
+Config                                                              |cmp-config|
+Config Helper                                                |cmp-config-helper|
+Develop                                                            |cmp-develop|
+FAQ                                                                    |cmp-faq|
+==============================================================================
+Abstract                                                          *cmp-abstract*
+
+This is nvim-cmp's document.
+
+1. This help file uses the type definition notation like `{lsp,cmp,vim}.*`
+  - You can find it in `../lua/cmp/types/init.lua`.
+2. Advanced configuration is described on the wiki.
+  - https://github.com/hrsh7th/nvim-cmp/wiki
+
+==============================================================================
+Concept                                                            *cmp-concept*
+
+- Full support for LSP completion related capabilities
+- Powerful customization abilities via Lua functions
+- Smart handling of key mapping
+- No flicker
+
+==============================================================================
+Usage                                                                *cmp-usage*
+
+Recommended configuration is written below.
+  NOTE:
+    1. You must provide `snippet.expand` function.
+    2. `cmp.setup.cmdline` won't work if you use `native` completion menu.
+    3. You can disable the `default` options via specifying `cmp.config.disable` value.
+>
+  call plug#begin(s:plug_dir)
+  Plug 'neovim/nvim-lspconfig'
+  Plug 'hrsh7th/cmp-nvim-lsp'
+  Plug 'hrsh7th/cmp-buffer'
+  Plug 'hrsh7th/cmp-path'
+  Plug 'hrsh7th/cmp-cmdline'
+  Plug 'hrsh7th/nvim-cmp'
+
+  " For vsnip users.
+  Plug 'hrsh7th/cmp-vsnip'
+  Plug 'hrsh7th/vim-vsnip'
+
+  " For luasnip users.
+  " Plug 'L3MON4D3/LuaSnip'
+  " Plug 'saadparwaiz1/cmp_luasnip'
+
+  " For snippy users.
+  " Plug 'dcampos/nvim-snippy'
+  " Plug 'dcampos/cmp-snippy'
+
+  " For ultisnips users.
+  " Plug 'SirVer/ultisnips'
+  " Plug 'quangnguyen30192/cmp-nvim-ultisnips'
+
+  call plug#end()
+
+  set completeopt=menu,menuone,noselect
+
+  lua <<EOF
+    local cmp = require'cmp'
+
+    -- Global setup.
+    cmp.setup({
+      snippet = {
+        expand = function(args)
+          vim.fn["vsnip#anonymous"](args.body) -- For `vsnip` users.
+          -- require('luasnip').lsp_expand(args.body) -- For `luasnip` users.
+          -- require'snippy'.expand_snippet(args.body) -- For `snippy` users.
+          -- vim.fn["UltiSnips#Anon"](args.body) -- For `ultisnips` users.
+        end,
+      },
+      window = {
+        -- completion = cmp.config.window.bordered(),
+        -- documentation = cmp.config.window.bordered(),
+      },
+      mapping = cmp.mapping.preset.insert({
+        ['<C-d>'] = cmp.mapping.scroll_docs(-4),
+        ['<C-f>'] = cmp.mapping.scroll_docs(4),
+        ['<C-Space>'] = cmp.mapping.complete(),
+        ['<CR>'] = cmp.mapping.confirm({ select = true }),
+      }),
+      sources = cmp.config.sources({
+        { name = 'nvim_lsp' },
+        { name = 'vsnip' }, -- For vsnip users.
+        -- { name = 'luasnip' }, -- For luasnip users.
+        -- { name = 'snippy' }, -- For snippy users.
+        -- { name = 'ultisnips' }, -- For ultisnips users.
+      }, {
+        { name = 'buffer' },
+      })
+    })
+
+    -- `/` cmdline setup.
+    cmp.setup.cmdline('/', {
+      mapping = cmp.mapping.preset.cmdline(),
+      sources = {
+        { name = 'buffer' }
+      }
+    })
+
+    -- `:` cmdline setup.
+    cmp.setup.cmdline(':', {
+      mapping = cmp.mapping.preset.cmdline(),
+      sources = cmp.config.sources({
+        { name = 'path' }
+      }, {
+        { name = 'cmdline' }
+      })
+    })
+
+    -- Setup lspconfig.
+    local capabilities = require('cmp_nvim_lsp').update_capabilities(vim.lsp.protocol.make_client_capabilities())
+    require('lspconfig')[%YOUR_LSP_SERVER%].setup {
+      capabilities = capabilities
+    }
+  EOF
+<
+==============================================================================
+Function                                                          *cmp-function*
+
+NOTE: `<Cmd>lua require('cmp').complete()<CR>` can be used to call these functions in mapping.
+
+*cmp.setup* (config: cmp.ConfigSchema)
+  Setup global configuration. See configuration options.
+
+*cmp.setup.filetype* (filetype: string, config: cmp.ConfigSchema)
+  Setup filetype-specific configuration.
+
+*cmp.setup.buffer* (config: cmp.ConfigSchema)
+  Setup configuration for the current buffer.
+
+*cmp.setup.cmdline* (cmdtype: string, config: cmp.ConfigSchema)
+  Setup cmdline configuration for the specific type of cmd.
+  See |getcmdtype()|
+  NOTE: nvim-cmp does not support the `=` cmd type.
+
+*cmp.visible* ()
+  Return boolean showing whether the completion menu is visible or not.
+
+*cmp.get_entries* ()
+  Return all current entries.
+
+*cmp.get_selected_entry* ()
+  Return current selected entry (contains preselected).
+
+*cmp.get_active_entry* ()
+  Return current selected entry (without preselected).
+
+*cmp.close* ()
+  Close the completion menu.
+
+*cmp.abort* ()
+  Closes the completion menu and restore the current line to the state when it was started current completion.
+
+*cmp.select_next_item* (option: { behavior = cmp.SelectBehavior })
+  Select next item.
+
+*cmp.select_prev_item* (option: { behavior = cmp.SelectBehavior })*
+  Select previous item.
+
+*cmp.scroll_docs* (delta: number)
+  Scroll docs if visible.
+
+*cmp.complete* (option: { reason = cmp.ContextReason, config = cmp.ConfigSchema })
+  Invoke completion.
+
+  The following configurations defines the key mapping to show completion only for vsnip snippets.
+>
+  cmp.setup {
+    mapping = {
+      ['<C-s>'] = cmp.mapping.complete({
+        config = {
+          sources = {
+            { name = 'vsnip' }
+          }
+        }
+      })
+    }
+  }
+< >
+  inoremap <C-S> <Cmd>lua require('cmp').complete({ config = { sources = { { name = 'vsnip' } } } })<CR>
+<
+  NOTE: `config` in that case means a temporary setting, but `config.mapping` remains permanent.
+
+*cmp.complete_common_string* ()
+  Complete common string (reminds shell completion behavior).
+>
+  cmp.setup {
+    mapping = {
+      ['<C-l>'] = cmp.mapping(function(fallback)
+        if cmp.visible() then
+          return cmp.complete_common_string()
+        end
+        fallback()
+      end, { 'i', 'c' }),
+    }
+  }
+<
+*cmp.confirm* (option: cmp.ConfirmOption, callback: function)
+  Accepts current selected completion item.
+  If you didn't select any item and `{ select = true }` is specified for
+  this, nvim-cmp would automatically select the first item.
+
+*cmp.event:on* ('%EVENT_NAME%, callback)
+  Subscribe to nvim-cmp's event. Events are listed below.
+
+  - `complete_done`: emit after current completion is done.
+  - `confirm_done`: emit after confirmation is done.
+
+==============================================================================
+Mapping                                                            *cmp-mapping*
+
+Nvim-cmp's mapping mechanism is complex but flexible and user-friendly.
+
+You can specify the mapping function that receives the `fallback` function as argument.
+The `fallback` function can be used to call an existing mapping.
+
+For example, typical pair-wise plugin automatically defines the mappings for `<CR>` and `(`.
+Nvim-cmp might overwrite it via specified mapping.
+But you can use existing mapping via invoking the `fallback` function.
+>
+  cmp.setup {
+    mapping = {
+      ['<CR>'] = function(fallback)
+        if cmp.visible() then
+          cmp.confirm()
+        else
+          fallback() -- If you use vim-endwise, this fallback will behave as vim-endwise.
+        end
+      end
+    }
+  }
+< >
+  cmp.setup {
+    mapping = {
+      ['<Tab>'] = function(fallback)
+        if cmp.visible() then
+          cmp.select_next_item()
+        else
+          fallback()
+        end
+      end
+    }
+  }
+<
+
+And you can specify the mapping modes.
+>
+  cmp.setup {
+    mapping = {
+      ['<CR>'] = cmp.mapping(your_mapping_function, { 'i', 'c' })
+    }
+  }
+<
+And you can specify different mappings for different modes using the same key.
+>
+  cmp.setup {
+    mapping = {
+      ['<CR>'] = cmp.mapping({
+        i = your_mapping_function_a,
+        c = your_mapping_function_b,
+      })
+    }
+  }
+<
+You can also use built-in mapping helpers.
+
+  *cmp.mapping.close* ()
+    Same as |cmp.close|.
+
+  *cmp.mapping.abort* ()
+    Same as |cmp.abort|.
+
+  *cmp.mapping.select_next_item* (option: { behavior = cmp.SelectBehavior })
+    Same as |cmp.select_next_item|.
+
+  *cmp.mapping.select_prev_item* (option: { behavior = cmp.SelectBehavior })
+    Same as |cmp.select_prev_item|.
+
+  *cmp.mapping.scroll_docs* (delta: number)
+    Same as |cmp.scroll_docs|.
+
+  *cmp.mapping.complete* (option: cmp.CompleteParams)
+    Same as |cmp.complete|.
+
+  *cmp.mapping.complete_common_string* ()
+    Same as |cmp.complete_common_string|.
+
+  *cmp.mapping.confirm* (option: cmp.ConfirmOption)
+    Same as |cmp.confirm|.
+
+Built-in mapping helpers are only available as a configuration option.
+If you want to call nvim-cmp features directly, please use |cmp-function| instead.
+
+==============================================================================
+Command                                                            *cmp-command*
+
+*CmpStatus*
+  Describes statuses and states of sources.
+  Sometimes `unknown` source will be printed but it isn't problem.
+  For that reason `cmp-nvim-lsp` registered on the InsertEnter autocmd will
+  have `unknown` status.
+
+==============================================================================
+Highlight                                                        *cmp-highlight*
+
+*CmpItemAbbr*
+  Highlights unmatched characters of each completion field.
+
+*CmpItemAbbrDeprecated*
+  Highlights unmatched characters of each deprecated completion field.
+
+*CmpItemAbbrMatch*
+  Highlights matched characters of each completion field. Matched characters
+  must form a substring of a field which share a starting position.
+
+*CmpItemAbbrMatchFuzzy*
+  Highlights fuzzy-matched characters of each completion field.
+
+*CmpItemKind*
+  Highlights kind of the field.
+
+NOTE: `kind` is a symbol after each completion option.
+
+*CmpItemKind%KIND_NAME%*
+  Highlights kind of the field for specific `lsp.CompletionItemKind`.
+  If you only want to overwrite the `method` kind's highlight group, you can do this:
+>
+    highlight CmpItemKindMethod guibg=NONE guifg=Orange
+<
+*CmpItemMenu*
+  The menu field's highlight group.
+
+==============================================================================
+Autocmd                                                            *cmp-autocmd*
+
+You can create custom autocommands for certain nvim-cmp events by defining
+autocommands for the User event with the following patterns:
+
+*CmpReady*
+  Invoked when nvim-cmp gets sourced from `plugin/cmp.lua`.
+
+==============================================================================
+Config                                                              *cmp-config*
+
+You can use the following options via `cmp.setup { ... }` .
+
+                                                            *cmp-config.enabled*
+enabled~
+  `boolean | fun(): boolean`
+  Toggles the plugin on and off.
+
+                                                          *cmp-config.preselect*
+preselect~
+  `cmp.PreselectMode`
+
+  1. `cmp.PreselectMode.Item`
+    nvim-cmp will pre-select the item that the source specified.
+  2. `cmp.PreselectMode.None`
+    nvim-cmp wouldn't pre-select any items.
+
+                                                            *cmp-config.mapping*
+mapping~
+  `table<string, fun(fallback: function)`
+  See |cmp-mapping| section.
+
+                                                     *cmp-config.snippet.expand*
+snippet.expand~
+  `fun(option: cmp.SnippetExpansionParams)`
+  The snippet expansion function. That's how cmp interacts with snippet engine.
+
+                                          *cmp-config.completion.keyword_length*
+completion.keyword_length~
+  `number`
+  The number of characters needed to trigger auto-completion.
+
+                                         *cmp-config.completion.keyword_pattern*
+completion.keyword_pattern~
+  `string`
+  The default keyword pattern.
+
+                                            *cmp-config.completion.autocomplete*
+completion.autocomplete~
+  `cmp.TriggerEvent[] | false`
+  The event to trigger autocompletion. If false specified, than completion is
+  only invoked manually.
+
+                                             *cmp-config.completion.completeopt*
+completion.completeopt~
+  `string`
+  The vim's completeopt-like setting. See 'completeopt'.
+  Besically, you don't need to change this.
+
+                                 *cmp-config.confirmation.get_commit_characters*
+confirmation.get_commit_characters~
+  `fun(commit_characters:string[]):string[]`
+  You can append or exclude commitCharacters via this configuration option function.
+  The commitCharacters is defined by LSP spec.
+
+                                                  *cmp-config.formatting.fields*
+formatting.fields~
+  `cmp.ItemField[]`
+  The array of completion fields to specify their order.
+
+                                                  *cmp-config.formatting.format*
+formatting.format~
+  `fun(entry: cmp.Entry, vim_item: vim.CompletedItem): vim.CompletedItem`
+  The function used to customize the completion menu appearance. See
+  |complete-items|. This value can also be used to modify `dup` property.
+  NOTE: The `vim.CompletedItem` can have special properties `abbr_hl_group`,
+  `kind_hl_group` and `menu_hl_group`.
+
+                                   *cmp-config.matching.disallow_fuzzy_matching*
+matching.disallow_fuzzy_matching~
+  `boolean`
+  Whether to allow fuzzy matching.
+
+                                 *cmp-config.matching.disallow_partial_matching*
+matching.disallow_partial_matching~
+  `boolean`
+  Whether to allow partial matching.
+
+                                *cmp-config.matching.disallow_prefix_unmatching*
+matching.disallow_prefix_unmatching~
+  `boolean`
+  Whether to allow prefix unmatching.
+
+                                            *cmp-config.sorting.priority_weight*
+sorting.priority_weight~
+  `number`
+  Each item's original priority (given by its corresponding source) will be
+  increased by `#sources - (source_index - 1)` and multiplied by `priority_weight`.
+  That is, the final priority is calculated by the following formula:
+>
+  final_score = orig_score + ((#sources - (source_index - 1)) * sorting.priority_weight)
+<
+                                                *cmp-config.sorting.comparators*
+sorting.comparators~
+  `(fun(entry1: cmp.Entry, entry2: cmp.Entry): boolean | nil)[]`
+  The function to customize the sorting behavior.
+  You can use built-in comparators via `cmp.config.compare.*`.
+
+                                                            *cmp-config.sources*
+sources~
+  `cmp.SourceConfig[]`
+  List of the sources and their configurations to use.
+  Order of the sources matters for sorting order.
+
+                                                    *cmp-config.sources[n].name*
+sources[n].name~
+  `string`
+  The source name.
+
+                                                  *cmp-config.sources[n].option*
+sources[n].option~
+  `table`
+  The specific options defined by the source itself.
+
+                                          *cmp-config.sources[n].keyword_length*
+sources[n].keyword_length~
+  `number`
+  The source specific keyword length to trigger auto completion.
+
+                                         *cmp-config.sources[n].keyword_pattern*
+sources[n].keyword_pattern~
+  `number`
+  The source specific keyword pattern.
+
+                                      *cmp-config.sources[n].trigger_characters*
+sources[n].trigger_characters~
+  `string[]`
+  The source specific keyword pattern.
+
+                                                *cmp-config.sources[n].priority*
+sources[n].priority~
+  `number`
+  The source specific priority value.
+
+                                          *cmp-config.sources[n].max_item_count*
+sources[n].max_item_count~
+  `number`
+  The source specific item count.
+
+                                             *cmp-config.sources[n].group_index*
+sources[n].group_index~
+  `number`
+  The source group index.
+
+  For instance, you can specify the `buffer`'s source `group_index` to bigger number
+  if you don't want to see the buffer source items when nvim-lsp source is available.
+>
+    cmp.setup {
+      sources = {
+        { name = 'nvim_lsp', group_index = 1 },
+        { name = 'buffer', group_index = 2 },
+      }
+    }
+<
+  You can specify this via the built-in configuration helper like this.
+>
+    cmp.setup {
+      sources = cmp.config.sources({
+        { name = 'nvim_lsp' },
+      }, {
+        { name = 'buffer' },
+      })
+    }
+<
+                                                               *cmp-config.view*
+view~
+  `{ entries: cmp.EntriesConfig|string }`
+  Specify the view class to customize appearance.
+  Currently available configuration options are:
+
+                           *cmp-config.window.{completion,documentation}.border*
+window.{completion,documentation}.border~
+  `string | string[] | nil`
+  Border characters used for the completion popup menu when |experimental.native_menu| is disabled.
+  See |nvim_open_win|.
+
+                     *cmp-config.window.{completion,documentation}.winhighlight*
+window.{completion,documentation}.winhighlight~
+  `string | cmp.WinhighlightConfig`
+  Specify the window's winhighlight option.
+  See |nvim_open_win|.
+
+                           *cmp-config.window.{completion,documentation}.zindex*
+window.{completion,documentation}.zindex~
+  `number`
+  The completion window's zindex.
+  See |nvim_open_win|.
+
+                                     *cmp-config.window.documentation.max_width*
+window.documentation.max_width~
+  `number`
+  The documentation window's max width.
+
+                                    *cmp-config.window.documentation.max_height*
+window.documentation.max_height~
+  `number`
+  The documentation window's max height.
+
+                                            *cmp-config.experimental.ghost_text*
+experimental.ghost_text~
+  `boolean | { hl_group = string }`
+  Whether to enable the ghost_text feature.
+
+==============================================================================
+Config Helper                                                *cmp-config-helper*
+
+You can use the following configuration helpers:
+
+cmp.config.compare~
+
+  TBD
+
+cmp.config.context~
+
+  The `cmp.config.context` can be used for context-aware completion toggling.
+>
+    cmp.setup {
+      enabled = function()
+        -- disable completion if the cursor is `Comment` syntax group.
+        return not cmp.config.context.in_syntax_group('Comment')
+      end
+    }
+<
+  *cmp.config.context.in_syntax_group* (group)
+    You can specify the vim's built-in syntax group.
+    If you use tree-sitter, you should use `cmp.config.context.in_treesitter_capture` instead.
+
+  *cmp.config.context.in_treesitter_capture* (capture)
+    You can specify the treesitter capture name.
+    If you don't use `nvim-treesitter`, this helper doesn't work correctly.
+
+cmp.config.mapping~
+
+  See |cmp-mapping|
+
+cmp.config.sources~
+
+  *cmp.config.sources* (...sources)
+    You can specify multiple source arrays. The sources are grouped in the
+    order you specify, and the groups are displayed as a fallback, like chain
+    completion.
+>
+    cmp.setup {
+      sources = cmp.config.sources({
+        { name = 'nvim_lsp' },
+      }, {
+        { name = 'buffer' },
+      })
+    }
+<
+cmp.config.window~
+
+  *cmp.config.window.bordered* (option)
+    Make window `bordered`.
+    The option is described in `cmp.ConfigSchema`.
+>
+    cmp.setup {
+      window = {
+        completion = cmp.config.window.bordered(),
+        documentation = cmp.config.window.bordered(),
+      }
+    }
+<
+==============================================================================
+Develop                                                            *cmp-develop*
+
+Create custom source~
+
+NOTE:
+  1. The `complete` method is required. Others can be omitted.
+  2. The `callback` argument must always be called.
+  3. You can use only `require('cmp')` in custom source.
+  4. If LSP spec was changed, nvim-cmp would follow it without any announcement.
+  5. You should read ./lua/cmp/types and https://microsoft.github.io/language-server-protocol/specifications/specification-current.
+  6. Please add `nvim-cmp` topic for github repo.
+
+You can create custom source like the following example.
+
+>
+  local source = {}
+
+  ---Return this source is available in current context or not. (Optional)
+  ---@return boolean
+  function source:is_available()
+    return true
+  end
+
+  ---Return the debug name of this source. (Optional)
+  ---@return string
+  function source:get_debug_name()
+    return 'debug name'
+  end
+
+  ---Return keyword pattern for triggering completion. (Optional)
+  ---If this is ommited, nvim-cmp will use default keyword pattern. See |cmp-config.completion.keyword_pattern|
+  ---@return string
+  function source:get_keyword_pattern()
+    return [[\k\+]]
+  end
+
+  ---Return trigger characters for triggering completion. (Optional)
+  function source:get_trigger_characters()
+    return { '.' }
+  end
+
+  ---Invoke completion. (Required)
+  ---@param params cmp.SourceCompletionApiParams
+  ---@param callback fun(response: lsp.CompletionResponse|nil)
+  function source:complete(params, callback)
+    callback({
+      { label = 'January' },
+      { label = 'February' },
+      { label = 'March' },
+      { label = 'April' },
+      { label = 'May' },
+      { label = 'June' },
+      { label = 'July' },
+      { label = 'August' },
+      { label = 'September' },
+      { label = 'October' },
+      { label = 'November' },
+      { label = 'December' },
+    })
+  end
+
+  ---Resolve completion item. (Optional)
+  ---@param completion_item lsp.CompletionItem
+  ---@param callback fun(completion_item: lsp.CompletionItem|nil)
+  function source:resolve(completion_item, callback)
+    callback(completion_item)
+  end
+
+  ---Execute command after item was accepted.
+  ---@param completion_item lsp.CompletionItem
+  ---@param callback fun(completion_item: lsp.CompletionItem|nil)
+  function source:execute(completion_item, callback)
+    callback(completion_item)
+  end
+
+  ---Register custom source to nvim-cmp.
+  require('cmp').register_source('month', source.new())
+<
+==============================================================================
+FAQ                                                                    *cmp-faq*
+
+Why does cmp automatically select a particular item? ~
+How to disable the preselect feature? ~
+
+  Nvim-cmp respects LSP(Language Server Protocol) specification.
+  The LSP spec defines the `preselect` feature for completion.
+
+  You can disable the `preselect` feature like the following.
+>
+  cmp.setup {
+    preselect = cmp.PreselectMode.None
+  }
+<
+
+Why nvim-cmp confirm item automatically?~
+How to disable commitCharacters?~
+
+  You can disable commitCharacters feature (that defined in LSP spec).
+>
+  cmp.setup {
+    confirmation = {
+      get_commit_characters = function(commit_characters)
+        return {}
+      end
+    }
+  }
+<
+
+
+How to disable auto-completion?~
+How to use nvim-cmp as like omnifunc?~
+
+  You can disable auto-completion like this.
+>
+  cmp.setup {
+    ...
+    completion = {
+      autocomplete = false
+    }
+    ...
+  }
+<
+  And you can invoke completion manually.
+>
+  inoremap <C-x><C-o> <Cmd>lua require('cmp').complete()<CR>
+<
+
+How to disable nvim-cmp on the specific buffer?~
+How to setup on the specific buffer?~
+
+  You can setup buffer specific configuration like this.
+>
+  cmp.setup.filetype({ 'markdown', 'help' }, {
+    sources = {
+      { name = 'path' },
+      { name = 'buffer' },
+    }
+  })
+<
+
+How to disable documentation window?~
+
+  You can use the following config.
+>
+  cmp.setup.filetype({ 'markdown', 'help' }, {
+    window = {
+      documentation = cmp.config.disable
+    }
+  })
+<
+
+How to integrate with copilot.vim?~
+
+  Copilot.vim and nvim-cmp both have a `key-mapping fallback` mechanism.
+  Therefore, you should manage those plugins by yourself.
+
+  Fortunately, the copilot.vim has the feature that disables the fallback mechanism.
+>
+  let g:copilot_no_tab_map = v:true
+  imap <expr> <Plug>(vimrc:copilot-dummy-map) copilot#Accept("\<Tab>")
+<
+  You can manage copilot.vim's accept feature with nvim-cmp' key-mapping configuration.
+>
+  cmp.setup {
+    mapping = {
+      ['<C-g>'] = cmp.mapping(function(fallback)
+        vim.api.nvim_feedkeys(vim.fn['copilot#Accept'](vim.api.nvim_replace_termcodes('<Tab>', true, true, true)), 'n', true)
+      end)
+    },
+    experimental = {
+      ghost_text = false -- this feature conflict with copilot.vim's preview.
+    }
+  }
+<
+
+
+How to customize menu appearance?~
+
+  You can see nvim-cmp wiki (https://github.com/hrsh7th/nvim-cmp/wiki).
+
+==============================================================================
+ vim:tw=78:ts=2:et:ft=help:norl:
diff --git a/start/cmp/lua/cmp/config.lua b/start/cmp/lua/cmp/config.lua
new file mode 100644
index 0000000..42e9a43
--- /dev/null
+++ b/start/cmp/lua/cmp/config.lua
@@ -0,0 +1,229 @@
+local mapping = require('cmp.config.mapping')
+local cache = require('cmp.utils.cache')
+local keymap = require('cmp.utils.keymap')
+local misc = require('cmp.utils.misc')
+local api = require('cmp.utils.api')
+
+---@class cmp.Config
+---@field public g cmp.ConfigSchema
+local config = {}
+
+---@type cmp.Cache
+config.cache = cache.new()
+
+---@type cmp.ConfigSchema
+config.global = require('cmp.config.default')()
+
+---@type table<number, cmp.ConfigSchema>
+config.buffers = {}
+
+---@type table<string, cmp.ConfigSchema>
+config.filetypes = {}
+
+---@type table<string, cmp.ConfigSchema>
+config.cmdline = {}
+
+---@type cmp.ConfigSchema
+config.onetime = {}
+
+---Set configuration for global.
+---@param c cmp.ConfigSchema
+config.set_global = function(c)
+  config.global = config.normalize(misc.merge(c, config.global))
+  config.global.revision = config.global.revision or 1
+  config.global.revision = config.global.revision + 1
+end
+
+---Set configuration for buffer
+---@param c cmp.ConfigSchema
+---@param bufnr number|nil
+config.set_buffer = function(c, bufnr)
+  local revision = (config.buffers[bufnr] or {}).revision or 1
+  config.buffers[bufnr] = c or {}
+  config.buffers[bufnr].revision = revision + 1
+end
+
+---Set configuration for filetype
+---@param c cmp.ConfigSchema
+---@param filetypes string[]|string
+config.set_filetype = function(c, filetypes)
+  for _, filetype in ipairs(type(filetypes) == 'table' and filetypes or { filetypes }) do
+    local revision = (config.filetypes[filetype] or {}).revision or 1
+    config.filetypes[filetype] = c or {}
+    config.filetypes[filetype].revision = revision + 1
+  end
+end
+
+---Set configuration for cmdline
+---@param c cmp.ConfigSchema
+---@param cmdtype string
+config.set_cmdline = function(c, cmdtype)
+  local revision = (config.cmdline[cmdtype] or {}).revision or 1
+  config.cmdline[cmdtype] = c or {}
+  config.cmdline[cmdtype].revision = revision + 1
+end
+
+---Set configuration as oneshot completion.
+---@param c cmp.ConfigSchema
+config.set_onetime = function(c)
+  local revision = (config.onetime or {}).revision or 1
+  config.onetime = c or {}
+  config.onetime.revision = revision + 1
+end
+
+---@return cmp.ConfigSchema
+config.get = function()
+  local global_config = config.global
+  if config.onetime.sources then
+    local onetime_config = config.onetime
+    return config.cache:ensure({
+      'get',
+      'onetime',
+      global_config.revision or 0,
+      onetime_config.revision or 0,
+    }, function()
+      local c = {}
+      c = misc.merge(c, config.normalize(onetime_config))
+      c = misc.merge(c, config.normalize(global_config))
+      return c
+    end)
+  elseif api.is_cmdline_mode() then
+    local cmdtype = vim.fn.getcmdtype()
+    local cmdline_config = config.cmdline[cmdtype] or { revision = 1, sources = {} }
+    return config.cache:ensure({
+      'get',
+      'cmdline',
+      global_config.revision or 0,
+      cmdtype,
+      cmdline_config.revision or 0,
+    }, function()
+      local c = {}
+      c = misc.merge(c, config.normalize(cmdline_config))
+      c = misc.merge(c, config.normalize(global_config))
+      return c
+    end)
+  else
+    local bufnr = vim.api.nvim_get_current_buf()
+    local filetype = vim.api.nvim_buf_get_option(bufnr, 'filetype')
+    local buffer_config = config.buffers[bufnr] or { revision = 1 }
+    local filetype_config = config.filetypes[filetype] or { revision = 1 }
+    return config.cache:ensure({
+      'get',
+      'default',
+      global_config.revision or 0,
+      filetype,
+      filetype_config.revision or 0,
+      bufnr,
+      buffer_config.revision or 0,
+    }, function()
+      local c = {}
+      c = misc.merge(config.normalize(c), config.normalize(buffer_config))
+      c = misc.merge(config.normalize(c), config.normalize(filetype_config))
+      c = misc.merge(config.normalize(c), config.normalize(global_config))
+      return c
+    end)
+  end
+end
+
+---Return cmp is enabled or not.
+config.enabled = function()
+  local enabled = config.get().enabled
+  if type(enabled) == 'function' then
+    enabled = enabled()
+  end
+  return enabled and api.is_suitable_mode()
+end
+
+---Return source config
+---@param name string
+---@return cmp.SourceConfig
+config.get_source_config = function(name)
+  local c = config.get()
+  for _, s in ipairs(c.sources) do
+    if s.name == name then
+      return s
+    end
+  end
+  return nil
+end
+
+---Return the current menu is native or not.
+config.is_native_menu = function()
+  local c = config.get()
+  if c.experimental and c.experimental.native_menu then
+    return true
+  end
+  if c.view and c.view.entries then
+    return c.view.entries == 'native' or c.view.entries.name == 'native'
+  end
+  return false
+end
+
+---Normalize mapping key
+---@param c any
+---@return cmp.ConfigSchema
+config.normalize = function(c)
+  -- make sure c is not 'nil'
+  c = c == nil and {} or c
+
+  -- Normalize mapping.
+  if c.mapping then
+    local normalized = {}
+    for k, v in pairs(c.mapping) do
+      normalized[keymap.normalize(k)] = mapping(v, { 'i' })
+    end
+    c.mapping = normalized
+  end
+
+  -- Notice experimental.native_menu.
+  if c.experimental and c.experimental.native_menu then
+    vim.api.nvim_echo({
+      { '[nvim-cmp] ', 'Normal' },
+      { 'experimental.native_menu', 'WarningMsg' },
+      { ' is deprecated.\n', 'Normal' },
+      { '[nvim-cmp] Please use ', 'Normal' },
+      { 'view.entries = "native"', 'WarningMsg' },
+      { ' instead.', 'Normal' },
+    }, true, {})
+
+    c.view = c.view or {}
+    c.view.entries = c.view.entries or 'native'
+  end
+
+  -- Notice documentation.
+  if c.documentation ~= nil then
+    vim.api.nvim_echo({
+      { '[nvim-cmp] ', 'Normal' },
+      { 'documentation', 'WarningMsg' },
+      { ' is deprecated.\n', 'Normal' },
+      { '[nvim-cmp] Please use ', 'Normal' },
+      { 'window.documentation = cmp.config.window.bordered()', 'WarningMsg' },
+      { ' instead.', 'Normal' },
+    }, true, {})
+    c.window = c.window or {}
+    c.window.documentation = c.documentation
+  end
+
+  -- Notice sources.[n].opts
+  if c.sources then
+    for _, s in ipairs(c.sources) do
+      if s.opts and not s.option then
+        s.option = s.opts
+        s.opts = nil
+        vim.api.nvim_echo({
+          { '[nvim-cmp] ', 'Normal' },
+          { 'sources[number].opts', 'WarningMsg' },
+          { ' is deprecated.\n', 'Normal' },
+          { '[nvim-cmp] Please use ', 'Normal' },
+          { 'sources[number].option', 'WarningMsg' },
+          { ' instead.', 'Normal' },
+        }, true, {})
+      end
+      s.option = s.option or {}
+    end
+  end
+
+  return c
+end
+
+return config
diff --git a/start/cmp/lua/cmp/config/compare.lua b/start/cmp/lua/cmp/config/compare.lua
new file mode 100644
index 0000000..4b4fadc
--- /dev/null
+++ b/start/cmp/lua/cmp/config/compare.lua
@@ -0,0 +1,234 @@
+local types = require('cmp.types')
+local cache = require('cmp.utils.cache')
+local misc = require('cmp.utils.misc')
+
+local compare = {}
+
+-- offset
+compare.offset = function(entry1, entry2)
+  local diff = entry1:get_offset() - entry2:get_offset()
+  if diff < 0 then
+    return true
+  elseif diff > 0 then
+    return false
+  end
+end
+
+-- exact
+compare.exact = function(entry1, entry2)
+  if entry1.exact ~= entry2.exact then
+    return entry1.exact
+  end
+end
+
+-- score
+compare.score = function(entry1, entry2)
+  local diff = entry2.score - entry1.score
+  if diff < 0 then
+    return true
+  elseif diff > 0 then
+    return false
+  end
+end
+
+-- recently_used
+compare.recently_used = setmetatable({
+  records = {},
+  add_entry = function(self, e)
+    self.records[e.completion_item.label] = vim.loop.now()
+  end,
+}, {
+  __call = function(self, entry1, entry2)
+    local t1 = self.records[entry1.completion_item.label] or -1
+    local t2 = self.records[entry2.completion_item.label] or -1
+    if t1 ~= t2 then
+      return t1 > t2
+    end
+  end,
+})
+
+-- kind
+compare.kind = function(entry1, entry2)
+  local kind1 = entry1:get_kind()
+  kind1 = kind1 == types.lsp.CompletionItemKind.Text and 100 or kind1
+  local kind2 = entry2:get_kind()
+  kind2 = kind2 == types.lsp.CompletionItemKind.Text and 100 or kind2
+  if kind1 ~= kind2 then
+    if kind1 == types.lsp.CompletionItemKind.Snippet then
+      return true
+    end
+    if kind2 == types.lsp.CompletionItemKind.Snippet then
+      return false
+    end
+    local diff = kind1 - kind2
+    if diff < 0 then
+      return true
+    elseif diff > 0 then
+      return false
+    end
+  end
+end
+
+-- sortText
+compare.sort_text = function(entry1, entry2)
+  if misc.safe(entry1.completion_item.sortText) and misc.safe(entry2.completion_item.sortText) then
+    local diff = vim.stricmp(entry1.completion_item.sortText, entry2.completion_item.sortText)
+    if diff < 0 then
+      return true
+    elseif diff > 0 then
+      return false
+    end
+  end
+end
+
+-- length
+compare.length = function(entry1, entry2)
+  local diff = #entry1.completion_item.label - #entry2.completion_item.label
+  if diff < 0 then
+    return true
+  elseif diff > 0 then
+    return false
+  end
+end
+
+-- order
+compare.order = function(entry1, entry2)
+  local diff = entry1.id - entry2.id
+  if diff < 0 then
+    return true
+  elseif diff > 0 then
+    return false
+  end
+end
+
+-- locality
+compare.locality = setmetatable({
+  lines_count = 10,
+  lines_cache = cache.new(),
+  locality_map = {},
+  update = function(self)
+    local config = require('cmp').get_config()
+    if not vim.tbl_contains(config.sorting.comparators, compare.scopes) then
+      return
+    end
+
+    local win, buf = vim.api.nvim_get_current_win(), vim.api.nvim_get_current_buf()
+    local cursor_row = vim.api.nvim_win_get_cursor(win)[1] - 1
+    local max = vim.api.nvim_buf_line_count(buf)
+
+    if self.lines_cache:get('buf') ~= buf then
+      self.lines_cache:clear()
+      self.lines_cache:set('buf', buf)
+    end
+
+    self.locality_map = {}
+    for i = math.max(0, cursor_row - self.lines_count), math.min(max, cursor_row + self.lines_count) do
+      local is_above = i < cursor_row
+      local buffer = vim.api.nvim_buf_get_lines(buf, i, i + 1, false)[1] or ''
+      local locality_map = self.lines_cache:ensure({ 'line', buffer }, function()
+        local locality_map = {}
+        local regexp = vim.regex(config.completion.keyword_pattern)
+        while buffer ~= '' do
+          local s, e = regexp:match_str(buffer)
+          if s and e then
+            local w = string.sub(buffer, s + 1, e)
+            local d = math.abs(i - cursor_row) - (is_above and 0.1 or 0)
+            locality_map[w] = math.min(locality_map[w] or math.huge, d)
+            buffer = string.sub(buffer, e + 1)
+          else
+            break
+          end
+        end
+        return locality_map
+      end)
+      for w, d in pairs(locality_map) do
+        self.locality_map[w] = math.min(self.locality_map[w] or d, math.abs(i - cursor_row))
+      end
+    end
+  end,
+}, {
+  __call = function(self, entry1, entry2)
+    local local1 = self.locality_map[entry1:get_word()]
+    local local2 = self.locality_map[entry2:get_word()]
+    if local1 ~= local2 then
+      if local1 == nil then
+        return false
+      end
+      if local2 == nil then
+        return true
+      end
+      return local1 < local2
+    end
+  end,
+})
+
+-- scopes
+compare.scopes = setmetatable({
+  scopes_map = {},
+  update = function(self)
+    local config = require('cmp').get_config()
+    if not vim.tbl_contains(config.sorting.comparators, compare.scopes) then
+      return
+    end
+
+    local ok, locals = pcall(require, 'nvim-treesitter.locals')
+    if ok then
+      local win, buf = vim.api.nvim_get_current_win(), vim.api.nvim_get_current_buf()
+      local cursor_row = vim.api.nvim_win_get_cursor(win)[1] - 1
+
+      -- Cursor scope.
+      local cursor_scope = nil
+      for _, scope in ipairs(locals.get_scopes(buf)) do
+        if scope:start() <= cursor_row and cursor_row <= scope:end_() then
+          if not cursor_scope then
+            cursor_scope = scope
+          else
+            if cursor_scope:start() <= scope:start() and scope:end_() <= cursor_scope:end_() then
+              cursor_scope = scope
+            end
+          end
+        elseif cursor_scope and cursor_scope:end_() <= scope:start() then
+          break
+        end
+      end
+
+      -- Definitions.
+      local definitions = locals.get_definitions_lookup_table(buf)
+
+      -- Narrow definitions.
+      local depth = 0
+      for scope in locals.iter_scope_tree(cursor_scope, buf) do
+        local s, e = scope:start(), scope:end_()
+
+        -- Check scope's direct child.
+        for _, definition in pairs(definitions) do
+          if s <= definition.node:start() and definition.node:end_() <= e then
+            if scope:id() == locals.containing_scope(definition.node, buf):id() then
+              local text = vim.treesitter.query.get_node_text(definition.node, buf) or ''
+              if not self.scopes_map[text] then
+                self.scopes_map[text] = depth
+              end
+            end
+          end
+        end
+        depth = depth + 1
+      end
+    end
+  end,
+}, {
+  __call = function(self, entry1, entry2)
+    local local1 = self.scopes_map[entry1:get_word()]
+    local local2 = self.scopes_map[entry2:get_word()]
+    if local1 ~= local2 then
+      if local1 == nil then
+        return false
+      end
+      if local2 == nil then
+        return true
+      end
+      return local1 < local2
+    end
+  end,
+})
+
+return compare
diff --git a/start/cmp/lua/cmp/config/context.lua b/start/cmp/lua/cmp/config/context.lua
new file mode 100644
index 0000000..584f38a
--- /dev/null
+++ b/start/cmp/lua/cmp/config/context.lua
@@ -0,0 +1,65 @@
+local context = {}
+
+---Check if cursor is in syntax group
+---@param group string
+---@return boolean
+context.in_syntax_group = function(group)
+  local lnum, col = vim.fn.line('.'), math.min(vim.fn.col('.'), #vim.fn.getline('.'))
+  for _, syn_id in ipairs(vim.fn.synstack(lnum, col)) do
+    syn_id = vim.fn.synIDtrans(syn_id) -- Resolve :highlight links
+    if vim.fn.synIDattr(syn_id, 'name') == group then
+      return true
+    end
+  end
+  return false
+end
+
+---Check if cursor is in treesitter capture
+---@param capture string
+---@return boolean
+context.in_treesitter_capture = function(capture)
+  local highlighter = require('vim.treesitter.highlighter')
+  local ts_utils = require('nvim-treesitter.ts_utils')
+  local buf = vim.api.nvim_get_current_buf()
+
+  local row, col = unpack(vim.api.nvim_win_get_cursor(0))
+  row = row - 1
+  if vim.api.nvim_get_mode().mode == 'i' then
+    col = col - 1
+  end
+
+  local self = highlighter.active[buf]
+  if not self then
+    return false
+  end
+
+  local node_types = {}
+
+  self.tree:for_each_tree(function(tstree, tree)
+    if not tstree then
+      return
+    end
+
+    local root = tstree:root()
+    local root_start_row, _, root_end_row, _ = root:range()
+    if root_start_row > row or root_end_row < row then
+      return
+    end
+
+    local query = self:get_query(tree:lang())
+    if not query:query() then
+      return
+    end
+
+    local iter = query:query():iter_captures(root, self.bufnr, row, row + 1)
+    for _, node, _ in iter do
+      if ts_utils.is_in_node_range(node, row, col) then
+        table.insert(node_types, node:type())
+      end
+    end
+  end, true)
+
+  return vim.tbl_contains(node_types, capture)
+end
+
+return context
diff --git a/start/cmp/lua/cmp/config/default.lua b/start/cmp/lua/cmp/config/default.lua
new file mode 100644
index 0000000..dce5168
--- /dev/null
+++ b/start/cmp/lua/cmp/config/default.lua
@@ -0,0 +1,97 @@
+local compare = require('cmp.config.compare')
+local types = require('cmp.types')
+
+local WIDE_HEIGHT = 40
+
+---@return cmp.ConfigSchema
+return function()
+  return {
+    enabled = function()
+      local disabled = false
+      disabled = disabled or (vim.api.nvim_buf_get_option(0, 'buftype') == 'prompt')
+      disabled = disabled or (vim.fn.reg_recording() ~= '')
+      disabled = disabled or (vim.fn.reg_executing() ~= '')
+      return not disabled
+    end,
+
+    preselect = types.cmp.PreselectMode.Item,
+
+    mapping = {},
+
+    snippet = {
+      expand = function()
+        error('snippet engine is not configured.')
+      end,
+    },
+
+    completion = {
+      autocomplete = {
+        types.cmp.TriggerEvent.TextChanged,
+      },
+      completeopt = 'menu,menuone,noselect',
+      keyword_pattern = [[\%(-\?\d\+\%(\.\d\+\)\?\|\h\w*\%(-\w*\)*\)]],
+      keyword_length = 1,
+    },
+
+    formatting = {
+      fields = { 'abbr', 'kind', 'menu' },
+      format = function(_, vim_item)
+        return vim_item
+      end,
+    },
+
+    matching = {
+      disallow_fuzzy_matching = false,
+      disallow_partial_matching = false,
+      disallow_prefix_unmatching = false,
+    },
+
+    sorting = {
+      priority_weight = 2,
+      comparators = {
+        compare.offset,
+        compare.exact,
+        -- compare.scopes,
+        compare.score,
+        compare.recently_used,
+        compare.locality,
+        compare.kind,
+        compare.sort_text,
+        compare.length,
+        compare.order,
+      },
+    },
+
+    sources = {},
+
+    confirmation = {
+      default_behavior = types.cmp.ConfirmBehavior.Insert,
+      get_commit_characters = function(commit_characters)
+        return commit_characters
+      end,
+    },
+
+    event = {},
+
+    experimental = {
+      ghost_text = false,
+    },
+
+    view = {
+      entries = { name = 'custom', selection_order = 'top_down' },
+    },
+
+    window = {
+      completion = {
+        border = { '', '', '', '', '', '', '', '' },
+        winhighlight = 'Normal:Pmenu,FloatBorder:Pmenu,CursorLine:PmenuSel,Search:None',
+      },
+      documentation = {
+        max_height = math.floor(WIDE_HEIGHT * (WIDE_HEIGHT / vim.o.lines)),
+        max_width = math.floor((WIDE_HEIGHT * 2) * (vim.o.columns / (WIDE_HEIGHT * 2 * 16 / 9))),
+        border = { '', '', '', ' ', '', '', '', ' ' },
+        winhighlight = 'FloatBorder:NormalFloat',
+      },
+    },
+  }
+end
diff --git a/start/cmp/lua/cmp/config/mapping.lua b/start/cmp/lua/cmp/config/mapping.lua
new file mode 100644
index 0000000..c2028c8
--- /dev/null
+++ b/start/cmp/lua/cmp/config/mapping.lua
@@ -0,0 +1,172 @@
+local types = require('cmp.types')
+local misc = require('cmp.utils.misc')
+local feedkeys = require('cmp.utils.feedkeys')
+local keymap = require('cmp.utils.keymap')
+
+local mapping = setmetatable({}, {
+  __call = function(_, invoke, modes)
+    if type(invoke) == 'function' then
+      local map = {}
+      for _, mode in ipairs(modes or { 'i' }) do
+        map[mode] = invoke
+      end
+      return map
+    end
+    return invoke
+  end,
+})
+
+---Mapping preset configuration.
+mapping.preset = {}
+
+---Mapping preset insert-mode configuration.
+mapping.preset.insert = function(override)
+  return misc.merge(override or {}, {
+    ['<Down>'] = {
+      i = mapping.select_next_item({ behavior = types.cmp.SelectBehavior.Select }),
+    },
+    ['<Up>'] = {
+      i = mapping.select_prev_item({ behavior = types.cmp.SelectBehavior.Select }),
+    },
+    ['<C-n>'] = {
+      i = mapping.select_next_item({ behavior = types.cmp.SelectBehavior.Insert }),
+    },
+    ['<C-p>'] = {
+      i = mapping.select_prev_item({ behavior = types.cmp.SelectBehavior.Insert }),
+    },
+    ['<C-y>'] = {
+      i = mapping.confirm({ select = false }),
+    },
+    ['<C-e>'] = {
+      i = mapping.abort(),
+    },
+  })
+end
+
+---Mapping preset cmdline-mode configuration.
+mapping.preset.cmdline = function(override)
+  return misc.merge(override or {}, {
+    ['<Tab>'] = {
+      c = function()
+        local cmp = require('cmp')
+        if cmp.visible() then
+          cmp.select_next_item()
+        else
+          feedkeys.call(keymap.t('<C-z>'), 'n')
+        end
+      end,
+    },
+    ['<S-Tab>'] = {
+      c = function()
+        local cmp = require('cmp')
+        if cmp.visible() then
+          cmp.select_prev_item()
+        else
+          feedkeys.call(keymap.t('<C-z>'), 'n')
+        end
+      end,
+    },
+    ['<C-n>'] = {
+      c = function(fallback)
+        local cmp = require('cmp')
+        if cmp.visible() then
+          cmp.select_next_item()
+        else
+          fallback()
+        end
+      end,
+    },
+    ['<C-p>'] = {
+      c = function(fallback)
+        local cmp = require('cmp')
+        if cmp.visible() then
+          cmp.select_prev_item()
+        else
+          fallback()
+        end
+      end,
+    },
+    ['<C-e>'] = {
+      c = mapping.close(),
+    },
+  })
+end
+
+---Invoke completion
+---@param option cmp.CompleteParams
+mapping.complete = function(option)
+  return function(fallback)
+    if not require('cmp').complete(option) then
+      fallback()
+    end
+  end
+end
+
+---Complete common string.
+mapping.complete_common_string = function()
+  return function(fallback)
+    if not require('cmp').complete_common_string() then
+      fallback()
+    end
+  end
+end
+
+---Close current completion menu if it displayed.
+mapping.close = function()
+  return function(fallback)
+    if not require('cmp').close() then
+      fallback()
+    end
+  end
+end
+
+---Abort current completion menu if it displayed.
+mapping.abort = function()
+  return function(fallback)
+    if not require('cmp').abort() then
+      fallback()
+    end
+  end
+end
+
+---Scroll documentation window.
+mapping.scroll_docs = function(delta)
+  return function(fallback)
+    if not require('cmp').scroll_docs(delta) then
+      fallback()
+    end
+  end
+end
+
+---Select next completion item.
+mapping.select_next_item = function(option)
+  return function(fallback)
+    if not require('cmp').select_next_item(option) then
+      local release = require('cmp').core:suspend()
+      fallback()
+      vim.schedule(release)
+    end
+  end
+end
+
+---Select prev completion item.
+mapping.select_prev_item = function(option)
+  return function(fallback)
+    if not require('cmp').select_prev_item(option) then
+      local release = require('cmp').core:suspend()
+      fallback()
+      vim.schedule(release)
+    end
+  end
+end
+
+---Confirm selection
+mapping.confirm = function(option)
+  return function(fallback)
+    if not require('cmp').confirm(option) then
+      fallback()
+    end
+  end
+end
+
+return mapping
diff --git a/start/cmp/lua/cmp/config/sources.lua b/start/cmp/lua/cmp/config/sources.lua
new file mode 100644
index 0000000..cfb09c0
--- /dev/null
+++ b/start/cmp/lua/cmp/config/sources.lua
@@ -0,0 +1,10 @@
+return function(...)
+  local sources = {}
+  for i, group in ipairs({ ... }) do
+    for _, source in ipairs(group) do
+      source.group_index = i
+      table.insert(sources, source)
+    end
+  end
+  return sources
+end
diff --git a/start/cmp/lua/cmp/config/window.lua b/start/cmp/lua/cmp/config/window.lua
new file mode 100644
index 0000000..b6fec0f
--- /dev/null
+++ b/start/cmp/lua/cmp/config/window.lua
@@ -0,0 +1,12 @@
+local window = {}
+
+window.bordered = function(opts)
+  opts = opts or {}
+  return {
+    border = opts.border or 'rounded',
+    winhighlight = opts.winhighlight or 'Normal:Normal,FloatBorder:Normal,CursorLine:Visual,Search:None',
+    zindex = opts.zindex or 1001,
+  }
+end
+
+return window
diff --git a/start/cmp/lua/cmp/context.lua b/start/cmp/lua/cmp/context.lua
new file mode 100644
index 0000000..6188259
--- /dev/null
+++ b/start/cmp/lua/cmp/context.lua
@@ -0,0 +1,105 @@
+local misc = require('cmp.utils.misc')
+local pattern = require('cmp.utils.pattern')
+local types = require('cmp.types')
+local cache = require('cmp.utils.cache')
+local api = require('cmp.utils.api')
+
+---@class cmp.Context
+---@field public id string
+---@field public cache cmp.Cache
+---@field public prev_context cmp.Context
+---@field public option cmp.ContextOption
+---@field public filetype string
+---@field public time number
+---@field public bufnr number
+---@field public cursor vim.Position|lsp.Position
+---@field public cursor_line string
+---@field public cursor_after_line string
+---@field public cursor_before_line string
+local context = {}
+
+---Create new empty context
+---@return cmp.Context
+context.empty = function()
+  local ctx = context.new({}) -- dirty hack to prevent recursive call `context.empty`.
+  ctx.bufnr = -1
+  ctx.input = ''
+  ctx.cursor = {}
+  ctx.cursor.row = -1
+  ctx.cursor.col = -1
+  return ctx
+end
+
+---Create new context
+---@param prev_context cmp.Context
+---@param option cmp.ContextOption
+---@return cmp.Context
+context.new = function(prev_context, option)
+  option = option or {}
+
+  local self = setmetatable({}, { __index = context })
+  self.id = misc.id('cmp.context.new')
+  self.cache = cache.new()
+  self.prev_context = prev_context or context.empty()
+  self.option = option or { reason = types.cmp.ContextReason.None }
+  self.filetype = vim.api.nvim_buf_get_option(0, 'filetype')
+  self.time = vim.loop.now()
+  self.bufnr = vim.api.nvim_get_current_buf()
+
+  local cursor = api.get_cursor()
+  self.cursor_line = api.get_current_line()
+  self.cursor = {}
+  self.cursor.row = cursor[1]
+  self.cursor.col = cursor[2] + 1
+  self.cursor.line = self.cursor.row - 1
+  self.cursor.character = misc.to_utfindex(self.cursor_line, self.cursor.col)
+  self.cursor_before_line = string.sub(self.cursor_line, 1, self.cursor.col - 1)
+  self.cursor_after_line = string.sub(self.cursor_line, self.cursor.col)
+  return self
+end
+
+---Return context creation reason.
+---@return cmp.ContextReason
+context.get_reason = function(self)
+  return self.option.reason
+end
+
+---Get keyword pattern offset
+---@return number|nil
+context.get_offset = function(self, keyword_pattern)
+  return self.cache:ensure({ 'get_offset', keyword_pattern, self.cursor_before_line }, function()
+    return pattern.offset(keyword_pattern .. '\\m$', self.cursor_before_line) or self.cursor.col
+  end)
+end
+
+---Return if this context is changed from previous context or not.
+---@return boolean
+context.changed = function(self, ctx)
+  local curr = self
+
+  if curr.bufnr ~= ctx.bufnr then
+    return true
+  end
+  if curr.cursor.row ~= ctx.cursor.row then
+    return true
+  end
+  if curr.cursor.col ~= ctx.cursor.col then
+    return true
+  end
+  if curr:get_reason() == types.cmp.ContextReason.Manual then
+    return true
+  end
+
+  return false
+end
+
+---Shallow clone
+context.clone = function(self)
+  local cloned = {}
+  for k, v in pairs(self) do
+    cloned[k] = v
+  end
+  return cloned
+end
+
+return context
diff --git a/start/cmp/lua/cmp/context_spec.lua b/start/cmp/lua/cmp/context_spec.lua
new file mode 100644
index 0000000..976e194
--- /dev/null
+++ b/start/cmp/lua/cmp/context_spec.lua
@@ -0,0 +1,31 @@
+local spec = require('cmp.utils.spec')
+
+local context = require('cmp.context')
+
+describe('context', function()
+  before_each(spec.before)
+
+  describe('new', function()
+    it('middle of text', function()
+      vim.fn.setline('1', 'function! s:name() abort')
+      vim.bo.filetype = 'vim'
+      vim.fn.execute('normal! fm')
+      local ctx = context.new()
+      assert.are.equal(ctx.filetype, 'vim')
+      assert.are.equal(ctx.cursor.row, 1)
+      assert.are.equal(ctx.cursor.col, 15)
+      assert.are.equal(ctx.cursor_line, 'function! s:name() abort')
+    end)
+
+    it('tab indent', function()
+      vim.fn.setline('1', '\t\tab')
+      vim.bo.filetype = 'vim'
+      vim.fn.execute('normal! fb')
+      local ctx = context.new()
+      assert.are.equal(ctx.filetype, 'vim')
+      assert.are.equal(ctx.cursor.row, 1)
+      assert.are.equal(ctx.cursor.col, 4)
+      assert.are.equal(ctx.cursor_line, '\t\tab')
+    end)
+  end)
+end)
diff --git a/start/cmp/lua/cmp/core.lua b/start/cmp/lua/cmp/core.lua
new file mode 100644
index 0000000..08949a9
--- /dev/null
+++ b/start/cmp/lua/cmp/core.lua
@@ -0,0 +1,486 @@
+local debug = require('cmp.utils.debug')
+local str = require('cmp.utils.str')
+local char = require('cmp.utils.char')
+local pattern = require('cmp.utils.pattern')
+local feedkeys = require('cmp.utils.feedkeys')
+local async = require('cmp.utils.async')
+local keymap = require('cmp.utils.keymap')
+local context = require('cmp.context')
+local source = require('cmp.source')
+local view = require('cmp.view')
+local misc = require('cmp.utils.misc')
+local config = require('cmp.config')
+local types = require('cmp.types')
+local api = require('cmp.utils.api')
+local event = require('cmp.utils.event')
+
+local SOURCE_TIMEOUT = 500
+local DEBOUNCE_TIME = 80
+local THROTTLE_TIME = 40
+
+---@class cmp.Core
+---@field public suspending boolean
+---@field public view cmp.View
+---@field public sources cmp.Source[]
+---@field public context cmp.Context
+---@field public event cmp.Event
+local core = {}
+
+core.new = function()
+  local self = setmetatable({}, { __index = core })
+  self.suspending = false
+  self.sources = {}
+  self.context = context.new()
+  self.event = event.new()
+  self.view = view.new()
+  self.view.event:on('keymap', function(...)
+    self:on_keymap(...)
+  end)
+  self.view.event:on('complete_done', function(evt)
+    self.event:emit('complete_done', evt)
+  end)
+  return self
+end
+
+---Register source
+---@param s cmp.Source
+core.register_source = function(self, s)
+  self.sources[s.id] = s
+end
+
+---Unregister source
+---@param source_id string
+core.unregister_source = function(self, source_id)
+  self.sources[source_id] = nil
+end
+
+---Get new context
+---@param option cmp.ContextOption
+---@return cmp.Context
+core.get_context = function(self, option)
+  local prev = self.context:clone()
+  prev.prev_context = nil
+  local ctx = context.new(prev, option)
+  self:set_context(ctx)
+  return self.context
+end
+
+---Set new context
+---@param ctx cmp.Context
+core.set_context = function(self, ctx)
+  self.context = ctx
+end
+
+---Suspend completion
+core.suspend = function(self)
+  self.suspending = true
+  -- It's needed to avoid conflicting with autocmd debouncing.
+  return vim.schedule_wrap(function()
+    self.suspending = false
+  end)
+end
+
+---Get sources that sorted by priority
+---@param filter cmp.SourceStatus[]|fun(s: cmp.Source): boolean
+---@return cmp.Source[]
+core.get_sources = function(self, filter)
+  local f = function(s)
+    if type(filter) == 'table' then
+      return vim.tbl_contains(filter, s.status)
+    elseif type(filter) == 'function' then
+      return filter(s)
+    end
+    return true
+  end
+
+  local sources = {}
+  for _, c in pairs(config.get().sources) do
+    for _, s in pairs(self.sources) do
+      if c.name == s.name then
+        if s:is_available() and f(s) then
+          table.insert(sources, s)
+        end
+      end
+    end
+  end
+  return sources
+end
+
+---Keypress handler
+core.on_keymap = function(self, keys, fallback)
+  local mode = api.get_mode()
+  for key, mapping in pairs(config.get().mapping) do
+    if keymap.equals(key, keys) and mapping[mode] then
+      return mapping[mode](fallback)
+    end
+  end
+
+  --Commit character. NOTE: This has a lot of cmp specific implementation to make more user-friendly.
+  local chars = keymap.t(keys)
+  local e = self.view:get_active_entry()
+  if e and vim.tbl_contains(config.get().confirmation.get_commit_characters(e:get_commit_characters()), chars) then
+    local is_printable = char.is_printable(string.byte(chars, 1))
+    self:confirm(e, {
+      behavior = is_printable and 'insert' or 'replace',
+      commit_character = chars,
+    }, function()
+      local ctx = self:get_context()
+      local word = e:get_word()
+      if string.sub(ctx.cursor_before_line, -#word, ctx.cursor.col - 1) == word and is_printable then
+        fallback()
+      else
+        self:reset()
+      end
+    end)
+    return
+  end
+
+  fallback()
+end
+
+---Prepare completion
+core.prepare = function(self)
+  for keys, mapping in pairs(config.get().mapping) do
+    for mode in pairs(mapping) do
+      keymap.listen(mode, keys, function(...)
+        self:on_keymap(...)
+      end)
+    end
+  end
+end
+
+---Check auto-completion
+core.on_change = function(self, trigger_event)
+  local ignore = false
+  ignore = ignore or self.suspending
+  ignore = ignore or (vim.fn.pumvisible() == 1 and (vim.v.completed_item).word)
+  ignore = ignore or not self.view:ready()
+  if ignore then
+    self:get_context({ reason = types.cmp.ContextReason.Auto })
+    return
+  end
+  self:autoindent(trigger_event, function()
+    local ctx = self:get_context({ reason = types.cmp.ContextReason.Auto })
+    debug.log(('ctx: `%s`'):format(ctx.cursor_before_line))
+    if ctx:changed(ctx.prev_context) then
+      self.view:on_change()
+      debug.log('changed')
+
+      if vim.tbl_contains(config.get().completion.autocomplete or {}, trigger_event) then
+        self:complete(ctx)
+      else
+        self.filter.timeout = self.view:visible() and THROTTLE_TIME or 0
+        self:filter()
+      end
+    else
+      debug.log('unchanged')
+    end
+  end)
+end
+
+---Cursor moved.
+core.on_moved = function(self)
+  local ignore = false
+  ignore = ignore or self.suspending
+  ignore = ignore or (vim.fn.pumvisible() == 1 and (vim.v.completed_item).word)
+  ignore = ignore or not self.view:visible()
+  if ignore then
+    return
+  end
+  self:filter()
+end
+
+---Check autoindent
+---@param trigger_event cmp.TriggerEvent
+---@param callback function
+core.autoindent = function(self, trigger_event, callback)
+  if trigger_event ~= types.cmp.TriggerEvent.TextChanged then
+    return callback()
+  end
+  if not api.is_insert_mode() then
+    return callback()
+  end
+
+  -- Check prefix
+  local cursor_before_line = api.get_cursor_before_line()
+  local prefix = pattern.matchstr('[^[:blank:]]\\+$', cursor_before_line) or ''
+  if #prefix == 0 then
+    return callback()
+  end
+
+  -- Reset current completion if indentkeys matched.
+  for _, key in ipairs(vim.split(vim.bo.indentkeys, ',')) do
+    if vim.tbl_contains({ '=' .. prefix, '0=' .. prefix }, key) then
+      self:reset()
+      self:set_context(context.empty())
+      break
+    end
+  end
+
+  callback()
+end
+
+---Complete common string for current completed entries.
+core.complete_common_string = function(self)
+  if not self.view:visible() or self.view:get_active_entry() then
+    return false
+  end
+
+  config.set_onetime({
+    sources = config.get().sources,
+    matching = {
+      disallow_prefix_unmatching = true,
+      disallow_partial_matching = true,
+      disallow_fuzzy_matching = true,
+    },
+  })
+
+  self:filter()
+  self.filter:sync(1000)
+
+  config.set_onetime({})
+
+  local cursor = api.get_cursor()
+  local offset = self.view:get_offset()
+  local common_string
+  for _, e in ipairs(self.view:get_entries()) do
+    local vim_item = e:get_vim_item(offset)
+    if not common_string then
+      common_string = vim_item.word
+    else
+      common_string = str.get_common_string(common_string, vim_item.word)
+    end
+  end
+  if common_string and #common_string > (1 + cursor[2] - offset) then
+    feedkeys.call(keymap.backspace(string.sub(api.get_current_line(), offset, cursor[2])) .. common_string, 'n')
+    return true
+  end
+  return false
+end
+
+---Invoke completion
+---@param ctx cmp.Context
+core.complete = function(self, ctx)
+  if not api.is_suitable_mode() then
+    return
+  end
+
+  self:set_context(ctx)
+
+  -- Invoke completion sources.
+  local sources = self:get_sources()
+  for _, s in ipairs(sources) do
+    local callback
+    callback = (function(s_)
+      return function()
+        local new = context.new(ctx)
+        if s_.incomplete and new:changed(s_.context) then
+          s_:complete(new, callback)
+        else
+          if not self.view:get_active_entry() then
+            self.filter.stop()
+            self.filter.timeout = DEBOUNCE_TIME
+            self:filter()
+          end
+        end
+      end
+    end)(s)
+    s:complete(ctx, callback)
+  end
+
+  if not self.view:get_active_entry() then
+    self.filter.timeout = self.view:visible() and THROTTLE_TIME or 1
+    self:filter()
+  end
+end
+
+---Update completion menu
+core.filter = async.throttle(function(self)
+  self.filter.timeout = THROTTLE_TIME
+
+  -- Check invalid condition.
+  local ignore = false
+  ignore = ignore or not api.is_suitable_mode()
+  if ignore then
+    return
+  end
+
+  -- Check fetching sources.
+  local sources = {}
+  for _, s in ipairs(self:get_sources({ source.SourceStatus.FETCHING, source.SourceStatus.COMPLETED })) do
+    -- Reserve filter call for timeout.
+    if not s.incomplete and SOURCE_TIMEOUT > s:get_fetching_time() then
+      self.filter.timeout = SOURCE_TIMEOUT - s:get_fetching_time()
+      self:filter()
+      if #sources == 0 then
+        return
+      end
+    end
+    table.insert(sources, s)
+  end
+
+  local ctx = self:get_context()
+
+  -- Display completion results.
+  self.view:open(ctx, sources)
+
+  -- Check onetime config.
+  if #self:get_sources(function(s)
+    if s.status == source.SourceStatus.FETCHING then
+      return true
+    elseif #s:get_entries(ctx) > 0 then
+      return true
+    end
+    return false
+  end) == 0 then
+    config.set_onetime({})
+  end
+end, THROTTLE_TIME)
+
+---Confirm completion.
+---@param e cmp.Entry
+---@param option cmp.ConfirmOption
+---@param callback function
+core.confirm = function(self, e, option, callback)
+  if not (e and not e.confirmed) then
+    return callback()
+  end
+  e.confirmed = true
+
+  debug.log('entry.confirm', e:get_completion_item())
+
+  local release = self:suspend()
+
+  -- Close menus.
+  self.view:close()
+
+  feedkeys.call(keymap.indentkeys(), 'n')
+  feedkeys.call('', 'n', function()
+    local ctx = context.new()
+    local keys = {}
+    table.insert(keys, keymap.backspace(ctx.cursor.character - misc.to_utfindex(ctx.cursor_line, e:get_offset())))
+    table.insert(keys, e:get_word())
+    table.insert(keys, keymap.undobreak())
+    feedkeys.call(table.concat(keys, ''), 'in')
+  end)
+  feedkeys.call('', 'n', function()
+    local ctx = context.new()
+    if api.is_cmdline_mode() then
+      local keys = {}
+      table.insert(keys, keymap.backspace(ctx.cursor.character - misc.to_utfindex(ctx.cursor_line, e:get_offset())))
+      table.insert(keys, string.sub(e.context.cursor_before_line, e:get_offset()))
+      feedkeys.call(table.concat(keys, ''), 'in')
+    else
+      vim.api.nvim_buf_set_text(0, ctx.cursor.row - 1, e:get_offset() - 1, ctx.cursor.row - 1, ctx.cursor.col - 1, {
+        string.sub(e.context.cursor_before_line, e:get_offset()),
+      })
+      vim.api.nvim_win_set_cursor(0, { e.context.cursor.row, e.context.cursor.col - 1 })
+    end
+  end)
+  feedkeys.call('', 'n', function()
+    local ctx = context.new()
+    if #(misc.safe(e:get_completion_item().additionalTextEdits) or {}) == 0 then
+      e:resolve(function()
+        local new = context.new()
+        local text_edits = misc.safe(e:get_completion_item().additionalTextEdits) or {}
+        if #text_edits == 0 then
+          return
+        end
+
+        local has_cursor_line_text_edit = (function()
+          local minrow = math.min(ctx.cursor.row, new.cursor.row)
+          local maxrow = math.max(ctx.cursor.row, new.cursor.row)
+          for _, te in ipairs(text_edits) do
+            local srow = te.range.start.line + 1
+            local erow = te.range['end'].line + 1
+            if srow <= minrow and maxrow <= erow then
+              return true
+            end
+          end
+          return false
+        end)()
+        if has_cursor_line_text_edit then
+          return
+        end
+        vim.lsp.util.apply_text_edits(text_edits, ctx.bufnr, 'utf-16')
+      end)
+    else
+      vim.lsp.util.apply_text_edits(e:get_completion_item().additionalTextEdits, ctx.bufnr, 'utf-16')
+    end
+  end)
+  feedkeys.call('', 'n', function()
+    local ctx = context.new()
+    local completion_item = misc.copy(e:get_completion_item())
+    if not misc.safe(completion_item.textEdit) then
+      completion_item.textEdit = {}
+      completion_item.textEdit.newText = misc.safe(completion_item.insertText) or completion_item.word or completion_item.label
+    end
+    local behavior = option.behavior or config.get().confirmation.default_behavior
+    if behavior == types.cmp.ConfirmBehavior.Replace then
+      completion_item.textEdit.range = e:get_replace_range()
+    else
+      completion_item.textEdit.range = e:get_insert_range()
+    end
+
+    local diff_before = math.max(0, e.context.cursor.character - completion_item.textEdit.range.start.character)
+    local diff_after = math.max(0, completion_item.textEdit.range['end'].character - e.context.cursor.character)
+    local new_text = completion_item.textEdit.newText
+
+    if api.is_insert_mode() then
+      local is_snippet = completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet
+      completion_item.textEdit.range.start.line = ctx.cursor.line
+      completion_item.textEdit.range.start.character = ctx.cursor.character - diff_before
+      completion_item.textEdit.range['end'].line = ctx.cursor.line
+      completion_item.textEdit.range['end'].character = ctx.cursor.character + diff_after
+      if is_snippet then
+        completion_item.textEdit.newText = ''
+      end
+      vim.lsp.util.apply_text_edits({ completion_item.textEdit }, ctx.bufnr, 'utf-16')
+      local texts = vim.split(completion_item.textEdit.newText, '\n')
+      local position = completion_item.textEdit.range.start
+      position.line = position.line + (#texts - 1)
+      if #texts == 1 then
+        position.character = position.character + misc.to_utfindex(texts[1])
+      else
+        position.character = misc.to_utfindex(texts[#texts])
+      end
+      local pos = types.lsp.Position.to_vim(0, position)
+      vim.api.nvim_win_set_cursor(0, { pos.row, pos.col - 1 })
+      if is_snippet then
+        config.get().snippet.expand({
+          body = new_text,
+          insert_text_mode = completion_item.insertTextMode,
+        })
+      end
+    else
+      local keys = {}
+      table.insert(keys, string.rep(keymap.t('<BS>'), diff_before))
+      table.insert(keys, string.rep(keymap.t('<Del>'), diff_after))
+      table.insert(keys, new_text)
+      feedkeys.call(table.concat(keys, ''), 'in')
+    end
+  end)
+  feedkeys.call(keymap.indentkeys(vim.bo.indentkeys), 'n')
+  feedkeys.call('', 'n', function()
+    e:execute(vim.schedule_wrap(function()
+      release()
+      self.event:emit('confirm_done', {
+        entry = e,
+        commit_character = option.commit_character,
+      })
+      if callback then
+        callback()
+      end
+    end))
+  end)
+end
+
+---Reset current completion state
+core.reset = function(self)
+  for _, s in pairs(self.sources) do
+    s:reset()
+  end
+  self.context = context.empty()
+end
+
+return core
diff --git a/start/cmp/lua/cmp/core_spec.lua b/start/cmp/lua/cmp/core_spec.lua
new file mode 100644
index 0000000..c37090e
--- /dev/null
+++ b/start/cmp/lua/cmp/core_spec.lua
@@ -0,0 +1,158 @@
+local spec = require('cmp.utils.spec')
+local feedkeys = require('cmp.utils.feedkeys')
+local types = require('cmp.types')
+local core = require('cmp.core')
+local source = require('cmp.source')
+local keymap = require('cmp.utils.keymap')
+local api = require('cmp.utils.api')
+
+describe('cmp.core', function()
+  describe('confirm', function()
+    local confirm = function(request, filter, completion_item)
+      local c = core.new()
+      local s = source.new('spec', {
+        complete = function(_, _, callback)
+          callback({ completion_item })
+        end,
+      })
+      c:register_source(s)
+      feedkeys.call(request, 'n', function()
+        c:complete(c:get_context({ reason = types.cmp.ContextReason.Manual }))
+        vim.wait(5000, function()
+          return #c.sources[s.id].entries > 0
+        end)
+      end)
+      feedkeys.call(filter, 'n', function()
+        c:confirm(c.sources[s.id].entries[1], {})
+      end)
+      local state = {}
+      feedkeys.call('', 'x', function()
+        feedkeys.call('', 'n', function()
+          if api.is_cmdline_mode() then
+            state.buffer = { api.get_current_line() }
+          else
+            state.buffer = vim.api.nvim_buf_get_lines(0, 0, -1, false)
+          end
+          state.cursor = api.get_cursor()
+        end)
+      end)
+      return state
+    end
+
+    describe('insert-mode', function()
+      before_each(spec.before)
+
+      it('label', function()
+        local state = confirm('iA', 'IU', {
+          label = 'AIUEO',
+        })
+        assert.are.same(state.buffer, { 'AIUEO' })
+        assert.are.same(state.cursor, { 1, 5 })
+      end)
+
+      it('insertText', function()
+        local state = confirm('iA', 'IU', {
+          label = 'AIUEO',
+          insertText = '_AIUEO_',
+        })
+        assert.are.same(state.buffer, { '_AIUEO_' })
+        assert.are.same(state.cursor, { 1, 7 })
+      end)
+
+      it('textEdit', function()
+        local state = confirm(keymap.t('i***AEO***<Left><Left><Left><Left><Left>'), 'IU', {
+          label = 'AIUEO',
+          textEdit = {
+            range = {
+              start = {
+                line = 0,
+                character = 3,
+              },
+              ['end'] = {
+                line = 0,
+                character = 6,
+              },
+            },
+            newText = 'foo\nbar\nbaz',
+          },
+        })
+        assert.are.same(state.buffer, { '***foo', 'bar', 'baz***' })
+        assert.are.same(state.cursor, { 3, 3 })
+      end)
+
+      it('insertText & snippet', function()
+        local state = confirm('iA', 'IU', {
+          label = 'AIUEO',
+          insertText = 'AIUEO($0)',
+          insertTextFormat = types.lsp.InsertTextFormat.Snippet,
+        })
+        assert.are.same(state.buffer, { 'AIUEO()' })
+        assert.are.same(state.cursor, { 1, 6 })
+      end)
+
+      it('textEdit & snippet', function()
+        local state = confirm(keymap.t('i***AEO***<Left><Left><Left><Left><Left>'), 'IU', {
+          label = 'AIUEO',
+          insertTextFormat = types.lsp.InsertTextFormat.Snippet,
+          textEdit = {
+            range = {
+              start = {
+                line = 0,
+                character = 3,
+              },
+              ['end'] = {
+                line = 0,
+                character = 6,
+              },
+            },
+            newText = 'foo\nba$0r\nbaz',
+          },
+        })
+        assert.are.same(state.buffer, { '***foo', 'bar', 'baz***' })
+        assert.are.same(state.cursor, { 2, 2 })
+      end)
+    end)
+
+    describe('cmdline-mode', function()
+      before_each(spec.before)
+
+      it('label', function()
+        local state = confirm(':A', 'IU', {
+          label = 'AIUEO',
+        })
+        assert.are.same(state.buffer, { 'AIUEO' })
+        assert.are.same(state.cursor[2], 5)
+      end)
+
+      it('insertText', function()
+        local state = confirm(':A', 'IU', {
+          label = 'AIUEO',
+          insertText = '_AIUEO_',
+        })
+        assert.are.same(state.buffer, { '_AIUEO_' })
+        assert.are.same(state.cursor[2], 7)
+      end)
+
+      it('textEdit', function()
+        local state = confirm(keymap.t(':***AEO***<Left><Left><Left><Left><Left>'), 'IU', {
+          label = 'AIUEO',
+          textEdit = {
+            range = {
+              start = {
+                line = 0,
+                character = 3,
+              },
+              ['end'] = {
+                line = 0,
+                character = 6,
+              },
+            },
+            newText = 'foobarbaz',
+          },
+        })
+        assert.are.same(state.buffer, { '***foobarbaz***' })
+        assert.are.same(state.cursor[2], 12)
+      end)
+    end)
+  end)
+end)
diff --git a/start/cmp/lua/cmp/entry.lua b/start/cmp/lua/cmp/entry.lua
new file mode 100644
index 0000000..83c53a2
--- /dev/null
+++ b/start/cmp/lua/cmp/entry.lua
@@ -0,0 +1,468 @@
+local cache = require('cmp.utils.cache')
+local char = require('cmp.utils.char')
+local misc = require('cmp.utils.misc')
+local str = require('cmp.utils.str')
+local config = require('cmp.config')
+local types = require('cmp.types')
+local matcher = require('cmp.matcher')
+
+---@class cmp.Entry
+---@field public id number
+---@field public cache cmp.Cache
+---@field public match_cache cmp.Cache
+---@field public score number
+---@field public exact boolean
+---@field public matches table
+---@field public context cmp.Context
+---@field public source cmp.Source
+---@field public source_offset number
+---@field public source_insert_range lsp.Range
+---@field public source_replace_range lsp.Range
+---@field public completion_item lsp.CompletionItem
+---@field public resolved_completion_item lsp.CompletionItem|nil
+---@field public resolved_callbacks fun()[]
+---@field public resolving boolean
+---@field public confirmed boolean
+local entry = {}
+
+---Create new entry
+---@param ctx cmp.Context
+---@param source cmp.Source
+---@param completion_item lsp.CompletionItem
+---@return cmp.Entry
+entry.new = function(ctx, source, completion_item)
+  local self = setmetatable({}, { __index = entry })
+  self.id = misc.id('entry.new')
+  self.cache = cache.new()
+  self.match_cache = cache.new()
+  self.score = 0
+  self.exact = false
+  self.matches = {}
+  self.context = ctx
+  self.source = source
+  self.source_offset = source.request_offset
+  self.source_insert_range = source:get_default_insert_range()
+  self.source_replace_range = source:get_default_replace_range()
+  self.completion_item = completion_item
+  self.resolved_completion_item = nil
+  self.resolved_callbacks = {}
+  self.resolving = false
+  self.confirmed = false
+  return self
+end
+
+---Make offset value
+---@return number
+entry.get_offset = function(self)
+  return self.cache:ensure({ 'get_offset', self.resolved_completion_item and 1 or 0 }, function()
+    local offset = self.source_offset
+    if misc.safe(self:get_completion_item().textEdit) then
+      local range = misc.safe(self:get_completion_item().textEdit.insert) or misc.safe(self:get_completion_item().textEdit.range)
+      if range then
+        local c = misc.to_vimindex(self.context.cursor_line, range.start.character)
+        for idx = c, self.source_offset do
+          if not char.is_white(string.byte(self.context.cursor_line, idx)) then
+            offset = idx
+            break
+          end
+        end
+      end
+    else
+      -- NOTE
+      -- The VSCode does not implement this but it's useful if the server does not care about word patterns.
+      -- We should care about this performance.
+      local word = self:get_word()
+      for idx = self.source_offset - 1, self.source_offset - #word, -1 do
+        if char.is_semantic_index(self.context.cursor_line, idx) then
+          local c = string.byte(self.context.cursor_line, idx)
+          if char.is_white(c) then
+            break
+          end
+          local match = true
+          for i = 1, self.source_offset - idx do
+            local c1 = string.byte(word, i)
+            local c2 = string.byte(self.context.cursor_line, idx + i - 1)
+            if not c1 or not c2 or c1 ~= c2 then
+              match = false
+              break
+            end
+          end
+          if match then
+            offset = math.min(offset, idx)
+          end
+        end
+      end
+    end
+    return offset
+  end)
+end
+
+---Create word for vim.CompletedItem
+---NOTE: This method doesn't clear the cache after completionItem/resolve.
+---@return string
+entry.get_word = function(self)
+  return self.cache:ensure({ 'get_word' }, function()
+    --NOTE: This is nvim-cmp specific implementation.
+    if misc.safe(self:get_completion_item().word) then
+      return self:get_completion_item().word
+    end
+
+    local word
+    if misc.safe(self:get_completion_item().textEdit) and not misc.empty(self:get_completion_item().textEdit.newText) then
+      word = str.trim(self:get_completion_item().textEdit.newText)
+      if self:get_completion_item().insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+        word = vim.lsp.util.parse_snippet(word)
+      end
+      local overwrite = self:get_overwrite()
+      if 0 < overwrite[2] or self:get_completion_item().insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+        word = str.get_word(word, string.byte(self.context.cursor_after_line, 1), overwrite[1] or 0)
+      end
+    elseif not misc.empty(self:get_completion_item().insertText) then
+      word = str.trim(self:get_completion_item().insertText)
+      if self:get_completion_item().insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+        word = str.get_word(vim.lsp.util.parse_snippet(word))
+      end
+    else
+      word = str.trim(self:get_completion_item().label)
+    end
+    return str.oneline(word)
+  end)
+end
+
+---Get overwrite information
+---@return number, number
+entry.get_overwrite = function(self)
+  return self.cache:ensure({ 'get_overwrite', self.resolved_completion_item and 1 or 0 }, function()
+    if misc.safe(self:get_completion_item().textEdit) then
+      local r = misc.safe(self:get_completion_item().textEdit.insert) or misc.safe(self:get_completion_item().textEdit.range)
+      local s = misc.to_vimindex(self.context.cursor_line, r.start.character)
+      local e = misc.to_vimindex(self.context.cursor_line, r['end'].character)
+      local before = self.context.cursor.col - s
+      local after = e - self.context.cursor.col
+      return { before, after }
+    end
+    return { 0, 0 }
+  end)
+end
+
+---Create filter text
+---@return string
+entry.get_filter_text = function(self)
+  return self.cache:ensure({ 'get_filter_text', self.resolved_completion_item and 1 or 0 }, function()
+    local word
+    if misc.safe(self:get_completion_item().filterText) then
+      word = self:get_completion_item().filterText
+    else
+      word = str.trim(self:get_completion_item().label)
+    end
+    return word
+  end)
+end
+
+---Get LSP's insert text
+---@return string
+entry.get_insert_text = function(self)
+  return self.cache:ensure({ 'get_insert_text', self.resolved_completion_item and 1 or 0 }, function()
+    local word
+    if misc.safe(self:get_completion_item().textEdit) then
+      word = str.trim(self:get_completion_item().textEdit.newText)
+      if self:get_completion_item().insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+        word = str.remove_suffix(str.remove_suffix(word, '$0'), '${0}')
+      end
+    elseif misc.safe(self:get_completion_item().insertText) then
+      word = str.trim(self:get_completion_item().insertText)
+      if self:get_completion_item().insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+        word = str.remove_suffix(str.remove_suffix(word, '$0'), '${0}')
+      end
+    else
+      word = str.trim(self:get_completion_item().label)
+    end
+    return word
+  end)
+end
+
+---Return the item is deprecated or not.
+---@return boolean
+entry.is_deprecated = function(self)
+  return self:get_completion_item().deprecated or vim.tbl_contains(self:get_completion_item().tags or {}, types.lsp.CompletionItemTag.Deprecated)
+end
+
+---Return view information.
+---@param suggest_offset number
+---@param entries_buf number The buffer this entry will be rendered into.
+---@return { abbr: { text: string, bytes: number, width: number, hl_group: string }, kind: { text: string, bytes: number, width: number, hl_group: string }, menu: { text: string, bytes: number, width: number, hl_group: string } }
+entry.get_view = function(self, suggest_offset, entries_buf)
+  local item = self:get_vim_item(suggest_offset)
+  return self.cache:ensure({ 'get_view', self.resolved_completion_item and 1 or 0, entries_buf }, function()
+    local view = {}
+    -- The result of vim.fn.strdisplaywidth depends on which buffer it was
+    -- called in because it reads the values of the option 'tabstop' when
+    -- rendering <Tab> characters.
+    vim.api.nvim_buf_call(entries_buf, function()
+      view.abbr = {}
+      view.abbr.text = item.abbr or ''
+      view.abbr.bytes = #view.abbr.text
+      view.abbr.width = vim.fn.strdisplaywidth(view.abbr.text)
+      view.abbr.hl_group = item.abbr_hl_group or (self:is_deprecated() and 'CmpItemAbbrDeprecated' or 'CmpItemAbbr')
+      view.kind = {}
+      view.kind.text = item.kind or ''
+      view.kind.bytes = #view.kind.text
+      view.kind.width = vim.fn.strdisplaywidth(view.kind.text)
+      view.kind.hl_group = item.kind_hl_group or ('CmpItemKind' .. (types.lsp.CompletionItemKind[self:get_kind()] or ''))
+      view.menu = {}
+      view.menu.text = item.menu or ''
+      view.menu.bytes = #view.menu.text
+      view.menu.width = vim.fn.strdisplaywidth(view.menu.text)
+      view.menu.hl_group = item.menu_hl_group or 'CmpItemMenu'
+      view.dup = item.dup
+    end)
+    return view
+  end)
+end
+
+---Make vim.CompletedItem
+---@param suggest_offset number
+---@return vim.CompletedItem
+entry.get_vim_item = function(self, suggest_offset)
+  return self.cache:ensure({ 'get_vim_item', suggest_offset, self.resolved_completion_item and 1 or 0 }, function()
+    local completion_item = self:get_completion_item()
+    local word = self:get_word()
+    local abbr = str.oneline(completion_item.label)
+
+    -- ~ indicator
+    local is_snippet = false
+    if #(misc.safe(completion_item.additionalTextEdits) or {}) > 0 then
+      is_snippet = true
+    elseif completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+      is_snippet = self:get_insert_text() ~= word
+    elseif completion_item.kind == types.lsp.CompletionItemKind.Snippet then
+      is_snippet = true
+    end
+    if is_snippet then
+      abbr = abbr .. '~'
+    end
+
+    -- append delta text
+    if suggest_offset < self:get_offset() then
+      word = string.sub(self.context.cursor_before_line, suggest_offset, self:get_offset() - 1) .. word
+    end
+
+    -- labelDetails.
+    local menu = nil
+    if misc.safe(completion_item.labelDetails) then
+      menu = ''
+      if misc.safe(completion_item.labelDetails.detail) then
+        menu = menu .. completion_item.labelDetails.detail
+      end
+      if misc.safe(completion_item.labelDetails.description) then
+        menu = menu .. completion_item.labelDetails.description
+      end
+    end
+
+    -- remove duplicated string.
+    if self:get_offset() ~= self.context.cursor.col then
+      for i = 1, #word - 1 do
+        if str.has_prefix(self.context.cursor_after_line, string.sub(word, i, #word)) then
+          word = string.sub(word, 1, i - 1)
+          break
+        end
+      end
+    end
+
+    local vim_item = {
+      word = word,
+      abbr = abbr,
+      kind = types.lsp.CompletionItemKind[self:get_kind()] or types.lsp.CompletionItemKind[1],
+      menu = menu,
+      dup = self:get_completion_item().dup or 1,
+    }
+    if config.get().formatting.format then
+      vim_item = config.get().formatting.format(self, vim_item)
+    end
+    vim_item.word = str.oneline(vim_item.word or '')
+    vim_item.abbr = str.oneline(vim_item.abbr or '')
+    vim_item.kind = str.oneline(vim_item.kind or '')
+    vim_item.menu = str.oneline(vim_item.menu or '')
+    vim_item.equal = 1
+    vim_item.empty = 1
+
+    return vim_item
+  end)
+end
+
+---Get commit characters
+---@return string[]
+entry.get_commit_characters = function(self)
+  return misc.safe(self:get_completion_item().commitCharacters) or {}
+end
+
+---Return insert range
+---@return lsp.Range|nil
+entry.get_insert_range = function(self)
+  local insert_range
+  if misc.safe(self:get_completion_item().textEdit) then
+    if misc.safe(self:get_completion_item().textEdit.insert) then
+      insert_range = self:get_completion_item().textEdit.insert
+    else
+      insert_range = self:get_completion_item().textEdit.range
+    end
+  else
+    insert_range = {
+      start = {
+        line = self.context.cursor.row - 1,
+        character = math.min(misc.to_utfindex(self.context.cursor_line, self:get_offset()), self.source_insert_range.start.character),
+      },
+      ['end'] = self.source_insert_range['end'],
+    }
+  end
+  return insert_range
+end
+
+---Return replace range
+---@return lsp.Range|nil
+entry.get_replace_range = function(self)
+  return self.cache:ensure({ 'get_replace_range', self.resolved_completion_item and 1 or 0 }, function()
+    local replace_range
+    if misc.safe(self:get_completion_item().textEdit) and misc.safe(self:get_completion_item().textEdit.replace) then
+      replace_range = self:get_completion_item().textEdit.replace
+    else
+      replace_range = {
+        start = {
+          line = self.source_replace_range.start.line,
+          character = math.min(misc.to_utfindex(self.context.cursor_line, self:get_offset()), self.source_replace_range.start.character),
+        },
+        ['end'] = self.source_replace_range['end'],
+      }
+    end
+    return replace_range
+  end)
+end
+
+---Match line.
+---@param input string
+---@param matching_config cmp.MatchingConfig
+---@return { score: number, matches: table[] }
+entry.match = function(self, input, matching_config)
+  return self.match_cache:ensure({
+    input,
+    self.resolved_completion_item and 1 or 0,
+    matching_config.disallow_fuzzy_matching and 1 or 0,
+    matching_config.disallow_partial_matching and 1 or 0,
+    matching_config.disallow_prefix_unmatching and 1 or 0,
+  }, function()
+    local option = {
+      disallow_fuzzy_matching = matching_config.disallow_fuzzy_matching,
+      disallow_partial_matching = matching_config.disallow_partial_matching,
+      disallow_prefix_unmatching = matching_config.disallow_prefix_unmatching,
+      synonyms = {
+        self:get_word(),
+        self:get_completion_item().label,
+      },
+    }
+
+    local score, matches, _
+    score, matches = matcher.match(input, self:get_filter_text(), option)
+
+    -- Support the language server that doesn't respect VSCode's behaviors.
+    if score == 0 then
+      if misc.safe(self:get_completion_item().textEdit) and not misc.empty(self:get_completion_item().textEdit.newText) then
+        local diff = self.source_offset - self:get_offset()
+        if diff > 0 then
+          local prefix = string.sub(self.context.cursor_line, self:get_offset(), self:get_offset() + diff)
+          local accept = false
+          accept = accept or string.match(prefix, '^[^%a]+$')
+          accept = accept or string.find(self:get_completion_item().textEdit.newText, prefix, 1, true)
+          if accept then
+            score, matches = matcher.match(input, prefix .. self:get_filter_text(), option)
+          end
+        end
+      end
+    end
+
+    if self:get_filter_text() ~= self:get_completion_item().label then
+      _, matches = matcher.match(input, self:get_completion_item().label, { self:get_word() })
+    end
+
+    return { score = score, matches = matches }
+  end)
+end
+
+---Get resolved completion item if possible.
+---@return lsp.CompletionItem
+entry.get_completion_item = function(self)
+  return self.cache:ensure({ 'get_completion_item', self.resolved_completion_item and 1 or 0 }, function()
+    if self.resolved_completion_item then
+      local completion_item = misc.copy(self.completion_item)
+      for k, v in pairs(self.resolved_completion_item) do
+        completion_item[k] = v or completion_item[k]
+      end
+      return completion_item
+    end
+    return self.completion_item
+  end)
+end
+
+---Create documentation
+---@return string
+entry.get_documentation = function(self)
+  local item = self:get_completion_item()
+
+  local documents = {}
+
+  -- detail
+  if misc.safe(item.detail) and item.detail ~= '' then
+    local ft = self.context.filetype
+    local dot_index = string.find(ft, '%.')
+    if dot_index ~= nil then
+      ft = string.sub(ft, 0, dot_index - 1)
+    end
+    table.insert(documents, {
+      kind = types.lsp.MarkupKind.Markdown,
+      value = ('```%s\n%s\n```'):format(ft, str.trim(item.detail)),
+    })
+  end
+
+  if type(item.documentation) == 'string' and item.documentation ~= '' then
+    table.insert(documents, {
+      kind = types.lsp.MarkupKind.PlainText,
+      value = str.trim(item.documentation),
+    })
+  elseif type(item.documentation) == 'table' and item.documentation.value ~= '' then
+    table.insert(documents, item.documentation)
+  end
+
+  return vim.lsp.util.convert_input_to_markdown_lines(documents)
+end
+
+---Get completion item kind
+---@return lsp.CompletionItemKind
+entry.get_kind = function(self)
+  return misc.safe(self:get_completion_item().kind) or types.lsp.CompletionItemKind.Text
+end
+
+---Execute completion item's command.
+---@param callback fun()
+entry.execute = function(self, callback)
+  self.source:execute(self:get_completion_item(), callback)
+end
+
+---Resolve completion item.
+---@param callback fun()
+entry.resolve = function(self, callback)
+  if self.resolved_completion_item then
+    return callback()
+  end
+  table.insert(self.resolved_callbacks, callback)
+
+  if not self.resolving then
+    self.resolving = true
+    self.source:resolve(self.completion_item, function(completion_item)
+      self.resolved_completion_item = misc.safe(completion_item) or self.completion_item
+      for _, c in ipairs(self.resolved_callbacks) do
+        c()
+      end
+    end)
+  end
+end
+
+return entry
diff --git a/start/cmp/lua/cmp/entry_spec.lua b/start/cmp/lua/cmp/entry_spec.lua
new file mode 100644
index 0000000..d01125c
--- /dev/null
+++ b/start/cmp/lua/cmp/entry_spec.lua
@@ -0,0 +1,342 @@
+local spec = require('cmp.utils.spec')
+local source = require('cmp.source')
+local async = require('cmp.utils.async')
+
+local entry = require('cmp.entry')
+
+describe('entry', function()
+  before_each(spec.before)
+
+  it('one char', function()
+    local state = spec.state('@.', 1, 3)
+    state.input('@')
+    local e = entry.new(state.manual(), state.source(), {
+      label = '@',
+    })
+    assert.are.equal(e:get_offset(), 3)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, '@')
+  end)
+
+  it('word length (no fix)', function()
+    local state = spec.state('a.b', 1, 4)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      label = 'b',
+    })
+    assert.are.equal(e:get_offset(), 5)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, 'b')
+  end)
+
+  it('word length (fix)', function()
+    local state = spec.state('a.b', 1, 4)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      label = 'b.',
+    })
+    assert.are.equal(e:get_offset(), 3)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, 'b.')
+  end)
+
+  it('semantic index (no fix)', function()
+    local state = spec.state('a.bc', 1, 5)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      label = 'c.',
+    })
+    assert.are.equal(e:get_offset(), 6)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, 'c.')
+  end)
+
+  it('semantic index (fix)', function()
+    local state = spec.state('a.bc', 1, 5)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      label = 'bc.',
+    })
+    assert.are.equal(e:get_offset(), 3)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, 'bc.')
+  end)
+
+  it('[vscode-html-language-server] 1', function()
+    local state = spec.state('    </>', 1, 7)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      label = '/div',
+      textEdit = {
+        range = {
+          start = {
+            line = 0,
+            character = 0,
+          },
+          ['end'] = {
+            line = 0,
+            character = 6,
+          },
+        },
+        newText = '  </div',
+      },
+    })
+    assert.are.equal(e:get_offset(), 5)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, '</div')
+  end)
+
+  it('[clangd] 1', function()
+    --NOTE: clangd does not return `.foo` as filterText but we should care about it.
+    --nvim-cmp does care it by special handling in entry.lua.
+    local state = spec.state('foo', 1, 4)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      insertText = '->foo',
+      label = ' foo',
+      textEdit = {
+        newText = '->foo',
+        range = {
+          start = {
+            character = 3,
+            line = 1,
+          },
+          ['end'] = {
+            character = 4,
+            line = 1,
+          },
+        },
+      },
+    })
+    assert.are.equal(e:get_vim_item(4).word, '->foo')
+    assert.are.equal(e:get_filter_text(), 'foo')
+  end)
+
+  it('[typescript-language-server] 1', function()
+    local state = spec.state('Promise.resolve()', 1, 18)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      label = 'catch',
+    })
+    -- The offset will be 18 in this situation because the server returns `[Symbol]` as candidate.
+    assert.are.equal(e:get_vim_item(18).word, '.catch')
+    assert.are.equal(e:get_filter_text(), 'catch')
+  end)
+
+  it('[typescript-language-server] 2', function()
+    local state = spec.state('Promise.resolve()', 1, 18)
+    state.input('.')
+    local e = entry.new(state.manual(), state.source(), {
+      filterText = '.Symbol',
+      label = 'Symbol',
+      textEdit = {
+        newText = '[Symbol]',
+        range = {
+          ['end'] = {
+            character = 18,
+            line = 0,
+          },
+          start = {
+            character = 17,
+            line = 0,
+          },
+        },
+      },
+    })
+    assert.are.equal(e:get_vim_item(18).word, '[Symbol]')
+    assert.are.equal(e:get_filter_text(), '.Symbol')
+  end)
+
+  it('[lua-language-server] 1', function()
+    local state = spec.state("local m = require'cmp.confi", 1, 28)
+    local e
+
+    -- press g
+    state.input('g')
+    e = entry.new(state.manual(), state.source(), {
+      insertTextFormat = 2,
+      label = 'cmp.config',
+      textEdit = {
+        newText = 'cmp.config',
+        range = {
+          ['end'] = {
+            character = 27,
+            line = 1,
+          },
+          start = {
+            character = 18,
+            line = 1,
+          },
+        },
+      },
+    })
+    assert.are.equal(e:get_vim_item(19).word, 'cmp.config')
+    assert.are.equal(e:get_filter_text(), 'cmp.config')
+
+    -- press '
+    state.input("'")
+    e = entry.new(state.manual(), state.source(), {
+      insertTextFormat = 2,
+      label = 'cmp.config',
+      textEdit = {
+        newText = 'cmp.config',
+        range = {
+          ['end'] = {
+            character = 27,
+            line = 1,
+          },
+          start = {
+            character = 18,
+            line = 1,
+          },
+        },
+      },
+    })
+    assert.are.equal(e:get_vim_item(19).word, 'cmp.config')
+    assert.are.equal(e:get_filter_text(), 'cmp.config')
+  end)
+
+  it('[lua-language-server] 2', function()
+    local state = spec.state("local m = require'cmp.confi", 1, 28)
+    local e
+
+    -- press g
+    state.input('g')
+    e = entry.new(state.manual(), state.source(), {
+      insertTextFormat = 2,
+      label = 'lua.cmp.config',
+      textEdit = {
+        newText = 'lua.cmp.config',
+        range = {
+          ['end'] = {
+            character = 27,
+            line = 1,
+          },
+          start = {
+            character = 18,
+            line = 1,
+          },
+        },
+      },
+    })
+    assert.are.equal(e:get_vim_item(19).word, 'lua.cmp.config')
+    assert.are.equal(e:get_filter_text(), 'lua.cmp.config')
+
+    -- press '
+    state.input("'")
+    e = entry.new(state.manual(), state.source(), {
+      insertTextFormat = 2,
+      label = 'lua.cmp.config',
+      textEdit = {
+        newText = 'lua.cmp.config',
+        range = {
+          ['end'] = {
+            character = 27,
+            line = 1,
+          },
+          start = {
+            character = 18,
+            line = 1,
+          },
+        },
+      },
+    })
+    assert.are.equal(e:get_vim_item(19).word, 'lua.cmp.config')
+    assert.are.equal(e:get_filter_text(), 'lua.cmp.config')
+  end)
+
+  it('[intelephense] 1', function()
+    local state = spec.state('\t\t', 1, 4)
+
+    -- press g
+    state.input('$')
+    local e = entry.new(state.manual(), state.source(), {
+      kind = 6,
+      label = '$this',
+      sortText = '$this',
+      textEdit = {
+        newText = '$this',
+        range = {
+          ['end'] = {
+            character = 3,
+            line = 1,
+          },
+          start = {
+            character = 2,
+            line = 1,
+          },
+        },
+      },
+    })
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, '$this')
+    assert.are.equal(e:get_filter_text(), '$this')
+  end)
+
+  it('[odin-language-server] 1', function()
+    local state = spec.state('\t\t', 1, 4)
+
+    -- press g
+    state.input('s')
+    local e = entry.new(state.manual(), state.source(), {
+      additionalTextEdits = {},
+      command = {
+        arguments = {},
+        command = '',
+        title = '',
+      },
+      deprecated = false,
+      detail = 'string',
+      documentation = '',
+      insertText = '',
+      insertTextFormat = 1,
+      kind = 14,
+      label = 'string',
+      tags = {},
+    })
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, 'string')
+  end)
+
+  it('[ansiblels] 1', function()
+    local item = {
+      detail = 'ansible.builtin',
+      filterText = 'blockinfile ansible.builtin.blockinfile',
+      kind = 7,
+      label = 'blockinfile',
+      sortText = '2_blockinfile',
+      textEdit = {
+        newText = '',
+        range = {
+          ['end'] = {
+            character = 7,
+            line = 15,
+          },
+          start = {
+            character = 6,
+            line = 15,
+          },
+        },
+      },
+    }
+    local s = source.new('dummy', {
+      resolve = function(_, _, callback)
+        item.textEdit.newText = 'modified'
+        callback(item)
+      end,
+    })
+    local e = entry.new(spec.state('', 1, 1).manual(), s, item)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, 'blockinfile')
+    async.sync(function(done)
+      e:resolve(done)
+    end, 100)
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, 'blockinfile')
+  end)
+
+  it('[#47] word should not contain \\n character', function()
+    local state = spec.state('', 1, 1)
+
+    -- press g
+    state.input('_')
+    local e = entry.new(state.manual(), state.source(), {
+      kind = 6,
+      label = '__init__',
+      insertTextFormat = 1,
+      insertText = '__init__(self) -> None:\n  pass',
+    })
+    assert.are.equal(e:get_vim_item(e:get_offset()).word, '__init__(self) -> None:')
+    assert.are.equal(e:get_filter_text(), '__init__')
+  end)
+end)
diff --git a/start/cmp/lua/cmp/init.lua b/start/cmp/lua/cmp/init.lua
new file mode 100644
index 0000000..06f5f41
--- /dev/null
+++ b/start/cmp/lua/cmp/init.lua
@@ -0,0 +1,336 @@
+local core = require('cmp.core')
+local source = require('cmp.source')
+local config = require('cmp.config')
+local feedkeys = require('cmp.utils.feedkeys')
+local autocmd = require('cmp.utils.autocmd')
+local keymap = require('cmp.utils.keymap')
+local misc = require('cmp.utils.misc')
+local async = require('cmp.utils.async')
+
+local cmp = {}
+
+cmp.core = core.new()
+
+---Expose types
+for k, v in pairs(require('cmp.types.cmp')) do
+  cmp[k] = v
+end
+cmp.lsp = require('cmp.types.lsp')
+cmp.vim = require('cmp.types.vim')
+
+---Expose event
+cmp.event = cmp.core.event
+
+---Export mapping for special case
+cmp.mapping = require('cmp.config.mapping')
+
+---Export default config presets
+cmp.config = {}
+cmp.config.disable = misc.none
+cmp.config.compare = require('cmp.config.compare')
+cmp.config.sources = require('cmp.config.sources')
+cmp.config.mapping = require('cmp.config.mapping')
+cmp.config.window = require('cmp.config.window')
+
+---Sync asynchronous process.
+cmp.sync = function(callback)
+  return function(...)
+    cmp.core.filter:sync(1000)
+    if callback then
+      return callback(...)
+    end
+  end
+end
+
+---Suspend completion.
+cmp.suspend = function()
+  return cmp.core:suspend()
+end
+
+---Register completion sources
+---@param name string
+---@param s cmp.Source
+---@return number
+cmp.register_source = function(name, s)
+  local src = source.new(name, s)
+  cmp.core:register_source(src)
+  return src.id
+end
+
+---Unregister completion source
+---@param id number
+cmp.unregister_source = function(id)
+  cmp.core:unregister_source(id)
+end
+
+---Get current configuration.
+---@return cmp.ConfigSchema
+cmp.get_config = function()
+  return require('cmp.config').get()
+end
+
+---Invoke completion manually
+---@param option cmp.CompleteParams
+cmp.complete = cmp.sync(function(option)
+  option = option or {}
+  config.set_onetime(option.config)
+  cmp.core:complete(cmp.core:get_context({ reason = option.reason or cmp.ContextReason.Manual }))
+  return true
+end)
+
+---Complete common string in current entries.
+cmp.complete_common_string = cmp.sync(function()
+  return cmp.core:complete_common_string()
+end)
+
+---Return view is visible or not.
+cmp.visible = cmp.sync(function()
+  return cmp.core.view:visible() or vim.fn.pumvisible() == 1
+end)
+
+---Get current selected entry or nil
+cmp.get_selected_entry = cmp.sync(function()
+  return cmp.core.view:get_selected_entry()
+end)
+
+---Get current active entry or nil
+cmp.get_active_entry = cmp.sync(function()
+  return cmp.core.view:get_active_entry()
+end)
+
+---Get current all entries
+cmp.get_entries = cmp.sync(function()
+  return cmp.core.view:get_entries()
+end)
+
+---Close current completion
+cmp.close = cmp.sync(function()
+  if cmp.core.view:visible() then
+    local release = cmp.core:suspend()
+    cmp.core.view:close()
+    cmp.core:reset()
+    vim.schedule(release)
+    return true
+  else
+    return false
+  end
+end)
+
+---Abort current completion
+cmp.abort = cmp.sync(function()
+  if cmp.core.view:visible() then
+    local release = cmp.core:suspend()
+    cmp.core.view:abort()
+    vim.schedule(release)
+    return true
+  else
+    return false
+  end
+end)
+
+---Select next item if possible
+cmp.select_next_item = cmp.sync(function(option)
+  option = option or {}
+
+  if cmp.core.view:visible() then
+    local release = cmp.core:suspend()
+    cmp.core.view:select_next_item(option)
+    vim.schedule(release)
+    return true
+  elseif vim.fn.pumvisible() == 1 then
+    -- Special handling for native pum. Required to facilitate key mapping processing.
+    if (option.behavior or cmp.SelectBehavior.Insert) == cmp.SelectBehavior.Insert then
+      feedkeys.call(keymap.t('<C-n>'), 'in')
+    else
+      feedkeys.call(keymap.t('<Down>'), 'in')
+    end
+    return true
+  end
+  return false
+end)
+
+---Select prev item if possible
+cmp.select_prev_item = cmp.sync(function(option)
+  option = option or {}
+
+  if cmp.core.view:visible() then
+    local release = cmp.core:suspend()
+    cmp.core.view:select_prev_item(option)
+    vim.schedule(release)
+    return true
+  elseif vim.fn.pumvisible() == 1 then
+    -- Special handling for native pum. Required to facilitate key mapping processing.
+    if (option.behavior or cmp.SelectBehavior.Insert) == cmp.SelectBehavior.Insert then
+      feedkeys.call(keymap.t('<C-p>'), 'in')
+    else
+      feedkeys.call(keymap.t('<Up>'), 'in')
+    end
+    return true
+  end
+  return false
+end)
+
+---Scrolling documentation window if possible
+cmp.scroll_docs = cmp.sync(function(delta)
+  if cmp.core.view:visible() then
+    cmp.core.view:scroll_docs(delta)
+    return true
+  else
+    return false
+  end
+end)
+
+---Confirm completion
+cmp.confirm = cmp.sync(function(option, callback)
+  option = option or {}
+  callback = callback or function() end
+
+  local e = cmp.core.view:get_selected_entry() or (option.select and cmp.core.view:get_first_entry() or nil)
+  if e then
+    cmp.core:confirm(e, {
+      behavior = option.behavior,
+    }, function()
+      callback()
+      cmp.core:complete(cmp.core:get_context({ reason = cmp.ContextReason.TriggerOnly }))
+    end)
+    return true
+  else
+    -- Special handling for native puma. Required to facilitate key mapping processing.
+    if vim.fn.complete_info({ 'selected' }).selected ~= -1 then
+      feedkeys.call(keymap.t('<C-y>'), 'in')
+      return true
+    end
+    return false
+  end
+end)
+
+---Show status
+cmp.status = function()
+  local kinds = {}
+  kinds.available = {}
+  kinds.unavailable = {}
+  kinds.installed = {}
+  kinds.invalid = {}
+  local names = {}
+  for _, s in pairs(cmp.core.sources) do
+    names[s.name] = true
+
+    if config.get_source_config(s.name) then
+      if s:is_available() then
+        table.insert(kinds.available, s:get_debug_name())
+      else
+        table.insert(kinds.unavailable, s:get_debug_name())
+      end
+    else
+      table.insert(kinds.installed, s:get_debug_name())
+    end
+  end
+  for _, s in ipairs(config.get().sources) do
+    if not names[s.name] then
+      table.insert(kinds.invalid, s.name)
+    end
+  end
+
+  if #kinds.available > 0 then
+    vim.api.nvim_echo({ { '\n', 'Normal' } }, false, {})
+    vim.api.nvim_echo({ { '# ready source names\n', 'Special' } }, false, {})
+    for _, name in ipairs(kinds.available) do
+      vim.api.nvim_echo({ { ('- %s\n'):format(name), 'Normal' } }, false, {})
+    end
+  end
+
+  if #kinds.unavailable > 0 then
+    vim.api.nvim_echo({ { '\n', 'Normal' } }, false, {})
+    vim.api.nvim_echo({ { '# unavailable source names\n', 'Comment' } }, false, {})
+    for _, name in ipairs(kinds.unavailable) do
+      vim.api.nvim_echo({ { ('- %s\n'):format(name), 'Normal' } }, false, {})
+    end
+  end
+
+  if #kinds.installed > 0 then
+    vim.api.nvim_echo({ { '\n', 'Normal' } }, false, {})
+    vim.api.nvim_echo({ { '# unused source names\n', 'WarningMsg' } }, false, {})
+    for _, name in ipairs(kinds.installed) do
+      vim.api.nvim_echo({ { ('- %s\n'):format(name), 'Normal' } }, false, {})
+    end
+  end
+
+  if #kinds.invalid > 0 then
+    vim.api.nvim_echo({ { '\n', 'Normal' } }, false, {})
+    vim.api.nvim_echo({ { '# unknown source names\n', 'ErrorMsg' } }, false, {})
+    for _, name in ipairs(kinds.invalid) do
+      vim.api.nvim_echo({ { ('- %s\n'):format(name), 'Normal' } }, false, {})
+    end
+  end
+end
+
+---@type cmp.Setup
+cmp.setup = setmetatable({
+  global = function(c)
+    config.set_global(c)
+  end,
+  filetype = function(filetype, c)
+    config.set_filetype(c, filetype)
+  end,
+  buffer = function(c)
+    config.set_buffer(c, vim.api.nvim_get_current_buf())
+  end,
+  cmdline = function(type, c)
+    config.set_cmdline(c, type)
+  end,
+}, {
+  __call = function(self, c)
+    self.global(c)
+  end,
+})
+
+-- In InsertEnter autocmd, vim will detects mode=normal unexpectedly.
+local on_insert_enter = function()
+  if config.enabled() then
+    cmp.config.compare.scopes:update()
+    cmp.config.compare.locality:update()
+    cmp.core:prepare()
+    cmp.core:on_change('InsertEnter')
+  end
+end
+autocmd.subscribe({ 'InsertEnter', 'CmdlineEnter' }, async.debounce_next_tick(on_insert_enter))
+
+-- async.throttle is needed for performance. The mapping `:<C-u>...<CR>` will fire `CmdlineChanged` for each character.
+local on_text_changed = function()
+  if config.enabled() then
+    cmp.core:on_change('TextChanged')
+  end
+end
+autocmd.subscribe({ 'TextChangedI', 'TextChangedP' }, on_text_changed)
+autocmd.subscribe('CmdlineChanged', async.debounce_next_tick(on_text_changed))
+
+autocmd.subscribe('CursorMovedI', function()
+  if config.enabled() then
+    cmp.core:on_moved()
+  else
+    cmp.core:reset()
+    cmp.core.view:close()
+  end
+end)
+
+-- If make this asynchronous, the completion menu will not close when the command output is displayed.
+autocmd.subscribe({ 'InsertLeave', 'CmdlineLeave' }, function()
+  cmp.core:reset()
+  cmp.core.view:close()
+end)
+
+cmp.event:on('complete_done', function(evt)
+  if evt.entry then
+    cmp.config.compare.recently_used:add_entry(evt.entry)
+  end
+  cmp.config.compare.scopes:update()
+  cmp.config.compare.locality:update()
+end)
+
+cmp.event:on('confirm_done', function(evt)
+  if evt.entry then
+    cmp.config.compare.recently_used:add_entry(evt.entry)
+  end
+end)
+
+return cmp
diff --git a/start/cmp/lua/cmp/matcher.lua b/start/cmp/lua/cmp/matcher.lua
new file mode 100644
index 0000000..7a22d9e
--- /dev/null
+++ b/start/cmp/lua/cmp/matcher.lua
@@ -0,0 +1,324 @@
+local char = require('cmp.utils.char')
+
+local matcher = {}
+
+matcher.WORD_BOUNDALY_ORDER_FACTOR = 10
+
+matcher.PREFIX_FACTOR = 8
+matcher.NOT_FUZZY_FACTOR = 6
+
+---@type function
+matcher.debug = function(...)
+  return ...
+end
+
+--- score
+--
+-- ### The score
+--
+--   The `score` is `matched char count` generally.
+--
+--   But cmp will fix the score with some of the below points so the actual score is not `matched char count`.
+--
+--   1. Word boundary order
+--
+--     cmp prefers the match that near by word-beggining.
+--
+--   2. Strict case
+--
+--     cmp prefers strict match than ignorecase match.
+--
+--
+-- ### Matching specs.
+--
+--   1. Prefix matching per word boundary
+--
+--     `bora`         -> `border-radius` # imaginary score: 4
+--      ^^~~              ^^     ~~
+--
+--   2. Try sequential match first
+--
+--     `woroff`       -> `word_offset`   # imaginary score: 6
+--      ^^^~~~            ^^^  ~~~
+--
+--     * The `woroff`'s second `o` should not match `word_offset`'s first `o`
+--
+--   3. Prefer early word boundary
+--
+--     `call`         -> `call`          # imaginary score: 4.1
+--      ^^^^              ^^^^
+--     `call`         -> `condition_all` # imaginary score: 4
+--      ^~~~              ^         ~~~
+--
+--   4. Prefer strict match
+--
+--     `Buffer`       -> `Buffer`        # imaginary score: 6.1
+--      ^^^^^^            ^^^^^^
+--     `buffer`       -> `Buffer`        # imaginary score: 6
+--      ^^^^^^            ^^^^^^
+--
+--   5. Use remaining characters for substring match
+--
+--     `fmodify`        -> `fnamemodify`   # imaginary score: 1
+--      ^~~~~~~             ^    ~~~~~~
+--
+--   6. Avoid unexpected match detection
+--
+--     `candlesingle` -> candle#accept#single
+--      ^^^^^^~~~~~~     ^^^^^^        ~~~~~~
+--      * The `accept`'s `a` should not match to `candle`'s `a`
+--
+--   7. Avoid false positive matching
+--
+--     `,` -> print,
+--                 ~
+--      * Typically, the middle match with symbol characters only is false positive. should be ignored.
+--
+--
+---Match entry
+---@param input string
+---@param word string
+---@param option { synonyms: string[], disallow_fuzzy_matching: boolean, disallow_partial_matching: boolean, disallow_prefix_unmatching: boolean }
+---@return number
+matcher.match = function(input, word, option)
+  option = option or {}
+
+  -- Empty input
+  if #input == 0 then
+    return matcher.PREFIX_FACTOR + matcher.NOT_FUZZY_FACTOR, {}
+  end
+
+  -- Ignore if input is long than word
+  if #input > #word then
+    return 0, {}
+  end
+
+  -- Check prefix matching.
+  if option.disallow_prefix_unmatching then
+    if not char.match(string.byte(input, 1), string.byte(word, 1)) then
+      return 0, {}
+    end
+  end
+
+  -- Gather matched regions
+  local matches = {}
+  local input_start_index = 1
+  local input_end_index = 1
+  local word_index = 1
+  local word_bound_index = 1
+  local no_symbol_match = false
+  while input_end_index <= #input and word_index <= #word do
+    local m = matcher.find_match_region(input, input_start_index, input_end_index, word, word_index)
+    if m and input_end_index <= m.input_match_end then
+      m.index = word_bound_index
+      input_start_index = m.input_match_start + 1
+      input_end_index = m.input_match_end + 1
+      no_symbol_match = no_symbol_match or m.no_symbol_match
+      word_index = char.get_next_semantic_index(word, m.word_match_end)
+      table.insert(matches, m)
+    else
+      word_index = char.get_next_semantic_index(word, word_index)
+    end
+    word_bound_index = word_bound_index + 1
+  end
+
+  -- Check partial matching.
+  if option.disallow_partial_matching and #matches > 1 then
+    return 0, {}
+  end
+
+  if #matches == 0 then
+    return 0, {}
+  end
+
+  matcher.debug(word, matches)
+
+  -- Add prefix bonus
+  local prefix = false
+  if matches[1].input_match_start == 1 and matches[1].word_match_start == 1 then
+    prefix = true
+  else
+    for _, synonym in ipairs(option.synonyms or {}) do
+      prefix = true
+      local o = 1
+      for i = matches[1].input_match_start, matches[1].input_match_end do
+        if not char.match(string.byte(synonym, o), string.byte(input, i)) then
+          prefix = false
+          break
+        end
+        o = o + 1
+      end
+      if prefix then
+        break
+      end
+    end
+  end
+
+  if no_symbol_match and not prefix then
+    return 0, {}
+  end
+
+  -- Compute prefix match score
+  local score = prefix and matcher.PREFIX_FACTOR or 0
+  local offset = prefix and matches[1].index - 1 or 0
+  local idx = 1
+  for _, m in ipairs(matches) do
+    local s = 0
+    for i = math.max(idx, m.input_match_start), m.input_match_end do
+      s = s + 1
+      idx = i
+    end
+    idx = idx + 1
+    if s > 0 then
+      s = s * (1 + m.strict_ratio)
+      s = s * (1 + math.max(0, matcher.WORD_BOUNDALY_ORDER_FACTOR - (m.index - offset)) / matcher.WORD_BOUNDALY_ORDER_FACTOR)
+      score = score + s
+    end
+  end
+
+  -- Check remaining input as fuzzy
+  if matches[#matches].input_match_end < #input then
+    if not option.disallow_fuzzy_matching then
+      if prefix and matcher.fuzzy(input, word, matches) then
+        return score, matches
+      end
+    end
+    return 0, {}
+  end
+
+  return score + matcher.NOT_FUZZY_FACTOR, matches
+end
+
+--- fuzzy
+matcher.fuzzy = function(input, word, matches)
+  local last_match = matches[#matches]
+
+  -- Lately specified middle of text.
+  local input_index = last_match.input_match_end + 1
+  for i = 1, #matches - 1 do
+    local curr_match = matches[i]
+    local next_match = matches[i + 1]
+    local word_offset = 0
+    local word_index = char.get_next_semantic_index(word, curr_match.word_match_end)
+    while word_offset + word_index < next_match.word_match_start and input_index <= #input do
+      if char.match(string.byte(word, word_index + word_offset), string.byte(input, input_index)) then
+        input_index = input_index + 1
+        word_offset = word_offset + 1
+      else
+        word_index = char.get_next_semantic_index(word, word_index + word_offset)
+        word_offset = 0
+      end
+    end
+  end
+
+  -- Remaining text fuzzy match.
+  local last_input_index = input_index
+  local matched = false
+  local word_offset = 0
+  local word_index = last_match.word_match_end + 1
+  local input_match_start = -1
+  local input_match_end = -1
+  local word_match_start = -1
+  local strict_count = 0
+  local match_count = 0
+  while word_offset + word_index <= #word and input_index <= #input do
+    local c1, c2 = string.byte(word, word_index + word_offset), string.byte(input, input_index)
+    if char.match(c1, c2) then
+      if not matched then
+        input_match_start = input_index
+        word_match_start = word_index + word_offset
+      end
+      matched = true
+      input_index = input_index + 1
+      strict_count = strict_count + (c1 == c2 and 1 or 0)
+      match_count = match_count + 1
+    elseif matched then
+      input_index = last_input_index
+      input_match_end = input_index - 1
+    end
+    word_offset = word_offset + 1
+  end
+  if input_index > #input then
+    table.insert(matches, {
+      input_match_start = input_match_start,
+      input_match_end = input_match_end,
+      word_match_start = word_match_start,
+      word_match_end = word_index + word_offset - 1,
+      strict_ratio = strict_count / match_count,
+      fuzzy = true,
+    })
+    return true
+  end
+  return false
+end
+
+--- find_match_region
+matcher.find_match_region = function(input, input_start_index, input_end_index, word, word_index)
+  -- determine input position ( woroff -> word_offset )
+  while input_start_index < input_end_index do
+    if char.match(string.byte(input, input_end_index), string.byte(word, word_index)) then
+      break
+    end
+    input_end_index = input_end_index - 1
+  end
+
+  -- Can't determine input position
+  if input_end_index < input_start_index then
+    return nil
+  end
+
+  local input_match_start = -1
+  local input_index = input_end_index
+  local word_offset = 0
+  local strict_count = 0
+  local match_count = 0
+  local no_symbol_match = false
+  while input_index <= #input and word_index + word_offset <= #word do
+    local c1 = string.byte(input, input_index)
+    local c2 = string.byte(word, word_index + word_offset)
+    if char.match(c1, c2) then
+      -- Match start.
+      if input_match_start == -1 then
+        input_match_start = input_index
+      end
+
+      strict_count = strict_count + (c1 == c2 and 1 or 0)
+      match_count = match_count + 1
+      word_offset = word_offset + 1
+      no_symbol_match = no_symbol_match or char.is_symbol(c1)
+    else
+      -- Match end (partial region)
+      if input_match_start ~= -1 then
+        return {
+          input_match_start = input_match_start,
+          input_match_end = input_index - 1,
+          word_match_start = word_index,
+          word_match_end = word_index + word_offset - 1,
+          strict_ratio = strict_count / match_count,
+          no_symbol_match = no_symbol_match,
+          fuzzy = false,
+        }
+      else
+        return nil
+      end
+    end
+    input_index = input_index + 1
+  end
+
+  -- Match end (whole region)
+  if input_match_start ~= -1 then
+    return {
+      input_match_start = input_match_start,
+      input_match_end = input_index - 1,
+      word_match_start = word_index,
+      word_match_end = word_index + word_offset - 1,
+      strict_ratio = strict_count / match_count,
+      no_symbol_match = no_symbol_match,
+      fuzzy = false,
+    }
+  end
+
+  return nil
+end
+
+return matcher
diff --git a/start/cmp/lua/cmp/matcher_spec.lua b/start/cmp/lua/cmp/matcher_spec.lua
new file mode 100644
index 0000000..c95dfc3
--- /dev/null
+++ b/start/cmp/lua/cmp/matcher_spec.lua
@@ -0,0 +1,64 @@
+local spec = require('cmp.utils.spec')
+
+local matcher = require('cmp.matcher')
+
+describe('matcher', function()
+  before_each(spec.before)
+
+  it('match', function()
+    assert.is.truthy(matcher.match('', 'a') >= 1)
+    assert.is.truthy(matcher.match('a', 'a') >= 1)
+    assert.is.truthy(matcher.match('ab', 'a') == 0)
+    assert.is.truthy(matcher.match('ab', 'ab') > matcher.match('ab', 'a_b'))
+    assert.is.truthy(matcher.match('ab', 'a_b_c') > matcher.match('ac', 'a_b_c'))
+
+    assert.is.truthy(matcher.match('bora', 'border-radius') >= 1)
+    assert.is.truthy(matcher.match('woroff', 'word_offset') >= 1)
+    assert.is.truthy(matcher.match('call', 'call') > matcher.match('call', 'condition_all'))
+    assert.is.truthy(matcher.match('Buffer', 'Buffer') > matcher.match('Buffer', 'buffer'))
+    assert.is.truthy(matcher.match('luacon', 'lua_context') > matcher.match('luacon', 'LuaContext'))
+    assert.is.truthy(matcher.match('fmodify', 'fnamemodify') >= 1)
+    assert.is.truthy(matcher.match('candlesingle', 'candle#accept#single') >= 1)
+
+    assert.is.truthy(matcher.match('vi', 'void#') >= 1)
+    assert.is.truthy(matcher.match('vo', 'void#') >= 1)
+    assert.is.truthy(matcher.match('var_', 'var_dump') >= 1)
+    assert.is.truthy(matcher.match('conso', 'console') > matcher.match('conso', 'ConstantSourceNode'))
+    assert.is.truthy(matcher.match('usela', 'useLayoutEffect') > matcher.match('usela', 'useDataLayer'))
+    assert.is.truthy(matcher.match('my_', 'my_awesome_variable') > matcher.match('my_', 'completion_matching_strategy_list'))
+    assert.is.truthy(matcher.match('2', '[[2021') >= 1)
+
+    assert.is.truthy(matcher.match(',', 'pri,') == 0)
+    assert.is.truthy(matcher.match('/', '/**') >= 1)
+
+    assert.is.truthy(matcher.match('true', 'v:true', { synonyms = { 'true' } }) == matcher.match('true', 'true'))
+    assert.is.truthy(matcher.match('g', 'get', { synonyms = { 'get' } }) > matcher.match('g', 'dein#get', { 'dein#get' }))
+  end)
+
+  it('disallow_fuzzy_matching', function()
+    assert.is.truthy(matcher.match('fmodify', 'fnamemodify', { disallow_fuzzy_matching = true }) == 0)
+    assert.is.truthy(matcher.match('fmodify', 'fnamemodify', { disallow_fuzzy_matching = false }) >= 1)
+  end)
+
+  it('disallow_partial_matching', function()
+    assert.is.truthy(matcher.match('fb', 'foo_bar', { disallow_partial_matching = true }) == 0)
+    assert.is.truthy(matcher.match('fb', 'foo_bar', { disallow_partial_matching = false }) >= 1)
+    assert.is.truthy(matcher.match('fb', 'fboo_bar', { disallow_partial_matching = true }) >= 1)
+    assert.is.truthy(matcher.match('fb', 'fboo_bar', { disallow_partial_matching = false }) >= 1)
+  end)
+
+  it('disallow_prefix_unmatching', function()
+    assert.is.truthy(matcher.match('bar', 'foo_bar', { disallow_prefix_unmatching = true }) == 0)
+    assert.is.truthy(matcher.match('bar', 'foo_bar', { disallow_prefix_unmatching = false }) >= 1)
+  end)
+
+  it('debug', function()
+    matcher.debug = function(...)
+      print(vim.inspect({ ... }))
+    end
+    -- print(vim.inspect({
+    --   a = matcher.match('true', 'v:true', { 'true' }),
+    --   b = matcher.match('true', 'true'),
+    -- }))
+  end)
+end)
diff --git a/start/cmp/lua/cmp/source.lua b/start/cmp/lua/cmp/source.lua
new file mode 100644
index 0000000..bee0634
--- /dev/null
+++ b/start/cmp/lua/cmp/source.lua
@@ -0,0 +1,365 @@
+local context = require('cmp.context')
+local config = require('cmp.config')
+local entry = require('cmp.entry')
+local debug = require('cmp.utils.debug')
+local misc = require('cmp.utils.misc')
+local cache = require('cmp.utils.cache')
+local types = require('cmp.types')
+local async = require('cmp.utils.async')
+local pattern = require('cmp.utils.pattern')
+local char = require('cmp.utils.char')
+
+---@class cmp.Source
+---@field public id number
+---@field public name string
+---@field public source any
+---@field public cache cmp.Cache
+---@field public revision number
+---@field public incomplete boolean
+---@field public is_triggered_by_symbol boolean
+---@field public entries cmp.Entry[]
+---@field public offset number
+---@field public request_offset number
+---@field public context cmp.Context
+---@field public completion_context lsp.CompletionContext|nil
+---@field public status cmp.SourceStatus
+---@field public complete_dedup function
+local source = {}
+
+---@alias cmp.SourceStatus 1 | 2 | 3
+source.SourceStatus = {}
+source.SourceStatus.WAITING = 1
+source.SourceStatus.FETCHING = 2
+source.SourceStatus.COMPLETED = 3
+
+---@return cmp.Source
+source.new = function(name, s)
+  local self = setmetatable({}, { __index = source })
+  self.id = misc.id('cmp.source.new')
+  self.name = name
+  self.source = s
+  self.cache = cache.new()
+  self.complete_dedup = async.dedup()
+  self.revision = 0
+  self:reset()
+  return self
+end
+
+---Reset current completion state
+---@return boolean
+source.reset = function(self)
+  self.cache:clear()
+  self.revision = self.revision + 1
+  self.context = context.empty()
+  self.is_triggered_by_symbol = false
+  self.incomplete = false
+  self.entries = {}
+  self.offset = -1
+  self.request_offset = -1
+  self.completion_context = nil
+  self.status = source.SourceStatus.WAITING
+  self.complete_dedup(function() end)
+end
+
+---Return source config
+---@return cmp.SourceConfig
+source.get_source_config = function(self)
+  return config.get_source_config(self.name) or {}
+end
+
+---Return matching config
+---@return cmp.MatchingConfig
+source.get_matching_config = function()
+  return config.get().matching
+end
+
+---Get fetching time
+source.get_fetching_time = function(self)
+  if self.status == source.SourceStatus.FETCHING then
+    return vim.loop.now() - self.context.time
+  end
+  return 100 * 1000 -- return pseudo time if source isn't fetching.
+end
+
+---Return filtered entries
+---@param ctx cmp.Context
+---@return cmp.Entry[]
+source.get_entries = function(self, ctx)
+  if self.offset == -1 then
+    return {}
+  end
+
+  local target_entries = (function()
+    local key = { 'get_entries', self.revision }
+    for i = ctx.cursor.col, self.offset, -1 do
+      key[3] = string.sub(ctx.cursor_before_line, 1, i)
+      local prev_entries = self.cache:get(key)
+      if prev_entries then
+        return prev_entries
+      end
+    end
+    return self.entries
+  end)()
+
+  local inputs = {}
+  local entries = {}
+  for _, e in ipairs(target_entries) do
+    local o = e:get_offset()
+    if not inputs[o] then
+      inputs[o] = string.sub(ctx.cursor_before_line, o)
+    end
+
+    local match = e:match(inputs[o], self:get_matching_config())
+    e.score = match.score
+    e.exact = false
+    if e.score >= 1 then
+      e.matches = match.matches
+      e.exact = e:get_filter_text() == inputs[o] or e:get_word() == inputs[o]
+      table.insert(entries, e)
+    end
+  end
+  self.cache:set({ 'get_entries', self.revision, ctx.cursor_before_line }, entries)
+
+  local max_item_count = self:get_source_config().max_item_count or 200
+  local limited_entries = {}
+  for _, e in ipairs(entries) do
+    table.insert(limited_entries, e)
+    if max_item_count and #limited_entries >= max_item_count then
+      break
+    end
+  end
+  return limited_entries
+end
+
+---Get default insert range
+---@return lsp.Range|nil
+source.get_default_insert_range = function(self)
+  if not self.context then
+    return nil
+  end
+
+  return self.cache:ensure({ 'get_default_insert_range', self.revision }, function()
+    return {
+      start = {
+        line = self.context.cursor.row - 1,
+        character = misc.to_utfindex(self.context.cursor_line, self.offset),
+      },
+      ['end'] = {
+        line = self.context.cursor.row - 1,
+        character = misc.to_utfindex(self.context.cursor_line, self.context.cursor.col),
+      },
+    }
+  end)
+end
+
+---Get default replace range
+---@return lsp.Range|nil
+source.get_default_replace_range = function(self)
+  if not self.context then
+    return nil
+  end
+
+  return self.cache:ensure({ 'get_default_replace_range', self.revision }, function()
+    local _, e = pattern.offset('^' .. '\\%(' .. self:get_keyword_pattern() .. '\\)', string.sub(self.context.cursor_line, self.offset))
+    return {
+      start = {
+        line = self.context.cursor.row - 1,
+        character = misc.to_utfindex(self.context.cursor_line, self.offset),
+      },
+      ['end'] = {
+        line = self.context.cursor.row - 1,
+        character = misc.to_utfindex(self.context.cursor_line, e and self.offset + e - 1 or self.context.cursor.col),
+      },
+    }
+  end)
+end
+
+---Return source name.
+source.get_debug_name = function(self)
+  local name = self.name
+  if self.source.get_debug_name then
+    name = self.source:get_debug_name()
+  end
+  return name
+end
+
+---Return the source is available or not.
+source.is_available = function(self)
+  if self.source.is_available then
+    return self.source:is_available()
+  end
+  return true
+end
+
+---Get trigger_characters
+---@return string[]
+source.get_trigger_characters = function(self)
+  local c = self:get_source_config()
+  if c.trigger_characters then
+    return c.trigger_characters
+  end
+
+  local trigger_characters = {}
+  if self.source.get_trigger_characters then
+    trigger_characters = self.source:get_trigger_characters(misc.copy(c)) or {}
+  end
+  if config.get().completion.get_trigger_characters then
+    return config.get().completion.get_trigger_characters(trigger_characters)
+  end
+  return trigger_characters
+end
+
+---Get keyword_pattern
+---@return string
+source.get_keyword_pattern = function(self)
+  local c = self:get_source_config()
+  if c.keyword_pattern then
+    return c.keyword_pattern
+  end
+  if self.source.get_keyword_pattern then
+    return self.source:get_keyword_pattern(misc.copy(c))
+  end
+  return config.get().completion.keyword_pattern
+end
+
+---Get keyword_length
+---@return number
+source.get_keyword_length = function(self)
+  local c = self:get_source_config()
+  if c.keyword_length then
+    return c.keyword_length
+  end
+  return config.get().completion.keyword_length or 1
+end
+
+---Invoke completion
+---@param ctx cmp.Context
+---@param callback function
+---@return boolean Return true if not trigger completion.
+source.complete = function(self, ctx, callback)
+  local offset = ctx:get_offset(self:get_keyword_pattern())
+
+  -- NOTE: This implementation is nvim-cmp specific.
+  -- We trigger new completion after core.confirm but we check only the symbol trigger_character in this case.
+  local before_char = string.sub(ctx.cursor_before_line, -1)
+  if ctx:get_reason() == types.cmp.ContextReason.TriggerOnly then
+    before_char = string.match(ctx.cursor_before_line, '(.)%s*$')
+    if not before_char or not char.is_symbol(string.byte(before_char)) then
+      before_char = ''
+    end
+  end
+
+  local completion_context
+  if ctx:get_reason() == types.cmp.ContextReason.Manual then
+    completion_context = {
+      triggerKind = types.lsp.CompletionTriggerKind.Invoked,
+    }
+  elseif vim.tbl_contains(self:get_trigger_characters(), before_char) then
+    completion_context = {
+      triggerKind = types.lsp.CompletionTriggerKind.TriggerCharacter,
+      triggerCharacter = before_char,
+    }
+  elseif ctx:get_reason() ~= types.cmp.ContextReason.TriggerOnly then
+    if self:get_keyword_length() <= (ctx.cursor.col - offset) then
+      if self.incomplete and self.context.cursor.col ~= ctx.cursor.col and self.status ~= source.SourceStatus.FETCHING then
+        completion_context = {
+          triggerKind = types.lsp.CompletionTriggerKind.TriggerForIncompleteCompletions,
+        }
+      elseif not vim.tbl_contains({ self.request_offset, self.offset }, offset) then
+        completion_context = {
+          triggerKind = types.lsp.CompletionTriggerKind.Invoked,
+        }
+      end
+    else
+      self:reset() -- Should clear current completion if the TriggerKind isn't TriggerCharacter or Manual and keyword length does not enough.
+    end
+  else
+    self:reset() -- Should clear current completion if ContextReason is TriggerOnly and the triggerCharacter isn't matched
+  end
+
+  -- Does not perform completions.
+  if not completion_context then
+    return
+  end
+
+  if completion_context.triggerKind == types.lsp.CompletionTriggerKind.TriggerCharacter then
+    self.is_triggered_by_symbol = char.is_symbol(string.byte(completion_context.triggerCharacter))
+  end
+
+  debug.log(self:get_debug_name(), 'request', offset, vim.inspect(completion_context))
+  local prev_status = self.status
+  self.status = source.SourceStatus.FETCHING
+  self.offset = offset
+  self.request_offset = offset
+  self.context = ctx
+  self.completion_context = completion_context
+  self.source:complete(
+    vim.tbl_extend('keep', misc.copy(self:get_source_config()), {
+      offset = self.offset,
+      context = ctx,
+      completion_context = completion_context,
+    }),
+    self.complete_dedup(vim.schedule_wrap(function(response)
+      response = response or {}
+
+      self.incomplete = response.isIncomplete or false
+
+      if #(response.items or response) > 0 then
+        debug.log(self:get_debug_name(), 'retrieve', #(response.items or response))
+        local old_offset = self.offset
+        local old_entries = self.entries
+
+        self.status = source.SourceStatus.COMPLETED
+        self.entries = {}
+        for i, item in ipairs(response.items or response) do
+          if (misc.safe(item) or {}).label then
+            local e = entry.new(ctx, self, item)
+            self.entries[i] = e
+            self.offset = math.min(self.offset, e:get_offset())
+          end
+        end
+        self.revision = self.revision + 1
+        if #self:get_entries(ctx) == 0 then
+          self.offset = old_offset
+          self.entries = old_entries
+          self.revision = self.revision + 1
+        end
+      else
+        -- The completion will be invoked when pressing <CR> if the trigger characters contain the <Space>.
+        -- If the server returns an empty response in such a case, should invoke the keyword completion on the next keypress.
+        if offset == ctx.cursor.col then
+          self:reset()
+        end
+        self.status = prev_status
+      end
+      callback()
+    end))
+  )
+  return true
+end
+
+---Resolve CompletionItem
+---@param item lsp.CompletionItem
+---@param callback fun(item: lsp.CompletionItem)
+source.resolve = function(self, item, callback)
+  if not self.source.resolve then
+    return callback(item)
+  end
+  self.source:resolve(item, function(resolved_item)
+    callback(resolved_item or item)
+  end)
+end
+
+---Execute command
+---@param item lsp.CompletionItem
+---@param callback fun()
+source.execute = function(self, item, callback)
+  if not self.source.execute then
+    return callback()
+  end
+  self.source:execute(item, function()
+    callback()
+  end)
+end
+
+return source
diff --git a/start/cmp/lua/cmp/source_spec.lua b/start/cmp/lua/cmp/source_spec.lua
new file mode 100644
index 0000000..339149f
--- /dev/null
+++ b/start/cmp/lua/cmp/source_spec.lua
@@ -0,0 +1,109 @@
+local config = require('cmp.config')
+local spec = require('cmp.utils.spec')
+
+local source = require('cmp.source')
+
+describe('source', function()
+  before_each(spec.before)
+
+  describe('keyword length', function()
+    it('not enough', function()
+      config.set_buffer({
+        completion = {
+          keyword_length = 3,
+        },
+      }, vim.api.nvim_get_current_buf())
+
+      local state = spec.state('', 1, 1)
+      local s = source.new('spec', {
+        complete = function(_, _, callback)
+          callback({ { label = 'spec' } })
+        end,
+      })
+      assert.is.truthy(not s:complete(state.input('a'), function() end))
+    end)
+
+    it('enough', function()
+      config.set_buffer({
+        completion = {
+          keyword_length = 3,
+        },
+      }, vim.api.nvim_get_current_buf())
+
+      local state = spec.state('', 1, 1)
+      local s = source.new('spec', {
+        complete = function(_, _, callback)
+          callback({ { label = 'spec' } })
+        end,
+      })
+      assert.is.truthy(s:complete(state.input('aiu'), function() end))
+    end)
+
+    it('enough -> not enough', function()
+      config.set_buffer({
+        completion = {
+          keyword_length = 3,
+        },
+      }, vim.api.nvim_get_current_buf())
+
+      local state = spec.state('', 1, 1)
+      local s = source.new('spec', {
+        complete = function(_, _, callback)
+          callback({ { label = 'spec' } })
+        end,
+      })
+      assert.is.truthy(s:complete(state.input('aiu'), function() end))
+      assert.is.truthy(not s:complete(state.backspace(), function() end))
+    end)
+
+    it('continue', function()
+      config.set_buffer({
+        completion = {
+          keyword_length = 3,
+        },
+      }, vim.api.nvim_get_current_buf())
+
+      local state = spec.state('', 1, 1)
+      local s = source.new('spec', {
+        complete = function(_, _, callback)
+          callback({ { label = 'spec' } })
+        end,
+      })
+      assert.is.truthy(s:complete(state.input('aiu'), function() end))
+      assert.is.truthy(not s:complete(state.input('eo'), function() end))
+    end)
+  end)
+
+  describe('isIncomplete', function()
+    it('isIncomplete=true', function()
+      local state = spec.state('', 1, 1)
+      local s = source.new('spec', {
+        complete = function(_, _, callback)
+          callback({
+            items = { { label = 'spec' } },
+            isIncomplete = true,
+          })
+        end,
+      })
+      vim.wait(100, function()
+        return s.status == source.SourceStatus.COMPLETED
+      end, 100, false)
+      assert.is.truthy(s:complete(state.input('s'), function() end))
+      vim.wait(100, function()
+        return s.status == source.SourceStatus.COMPLETED
+      end, 100, false)
+      assert.is.truthy(s:complete(state.input('p'), function() end))
+      vim.wait(100, function()
+        return s.status == source.SourceStatus.COMPLETED
+      end, 100, false)
+      assert.is.truthy(s:complete(state.input('e'), function() end))
+      vim.wait(100, function()
+        return s.status == source.SourceStatus.COMPLETED
+      end, 100, false)
+      assert.is.truthy(s:complete(state.input('c'), function() end))
+      vim.wait(100, function()
+        return s.status == source.SourceStatus.COMPLETED
+      end, 100, false)
+    end)
+  end)
+end)
diff --git a/start/cmp/lua/cmp/types/cmp.lua b/start/cmp/lua/cmp/types/cmp.lua
new file mode 100644
index 0000000..8759aca
--- /dev/null
+++ b/start/cmp/lua/cmp/types/cmp.lua
@@ -0,0 +1,166 @@
+local cmp = {}
+
+---@alias cmp.ConfirmBehavior 'insert' | 'replace'
+cmp.ConfirmBehavior = {
+  Insert = 'insert',
+  Replace = 'replace',
+}
+
+---@alias cmp.SelectBehavior 'insert' | 'select'
+cmp.SelectBehavior = {
+  Insert = 'insert',
+  Select = 'select',
+}
+
+---@alias cmp.ContextReason 'auto' | 'manual' 'triggerOnly' | 'none'
+cmp.ContextReason = {
+  Auto = 'auto',
+  Manual = 'manual',
+  TriggerOnly = 'triggerOnly',
+  None = 'none',
+}
+
+---@alias cmp.TriggerEvent 'InsertEnter' | 'TextChanged'
+cmp.TriggerEvent = {
+  InsertEnter = 'InsertEnter',
+  TextChanged = 'TextChanged',
+}
+
+---@alias cmp.PreselectMode 'item' | 'None'
+cmp.PreselectMode = {
+  Item = 'item',
+  None = 'none',
+}
+
+---@alias cmp.ItemField 'abbr' | 'kind' | 'menu'
+cmp.ItemField = {
+  Abbr = 'abbr',
+  Kind = 'kind',
+  Menu = 'menu',
+}
+
+---@class cmp.ContextOption
+---@field public reason cmp.ContextReason|nil
+
+---@class cmp.ConfirmOption
+---@field public behavior cmp.ConfirmBehavior
+---@field public commit_character? string
+
+---@class cmp.SelectOption
+---@field public behavior cmp.SelectBehavior
+
+---@class cmp.SnippetExpansionParams
+---@field public body string
+---@field public insert_text_mode number
+
+---@class cmp.CompleteParams
+---@field public reason? cmp.ContextReason
+---@field public config? cmp.ConfigSchema
+
+---@class cmp.Setup
+---@field public __call fun(c: cmp.ConfigSchema)
+---@field public buffer fun(c: cmp.ConfigSchema)
+---@field public global fun(c: cmp.ConfigSchema)
+---@field public cmdline fun(type: string, c: cmp.ConfigSchema)
+---@field public filetype fun(type: string|string[], c: cmp.ConfigSchema)
+
+---@class cmp.SourceApiParams: cmp.SourceConfig
+
+---@class cmp.SourceCompletionApiParams : cmp.SourceConfig
+---@field public offset number
+---@field public context cmp.Context
+---@field public completion_context lsp.CompletionContext
+
+---@class cmp.Mapping
+---@field public i nil|function(fallback: function): void
+---@field public c nil|function(fallback: function): void
+---@field public x nil|function(fallback: function): void
+---@field public s nil|function(fallback: function): void
+
+---@class cmp.ConfigSchema
+---@field private revision number
+---@field public enabled fun():boolean|boolean
+---@field public preselect cmp.PreselectMode
+---@field public completion cmp.CompletionConfig
+---@field public window cmp.WindowConfig|nil
+---@field public confirmation cmp.ConfirmationConfig
+---@field public matching cmp.MatchingConfig
+---@field public sorting cmp.SortingConfig
+---@field public formatting cmp.FormattingConfig
+---@field public snippet cmp.SnippetConfig
+---@field public mapping table<string, cmp.Mapping>
+---@field public sources cmp.SourceConfig[]
+---@field public view cmp.ViewConfig
+---@field public experimental cmp.ExperimentalConfig
+
+---@class cmp.WindowConfig
+---@field completion cmp.WindowConfig
+---@field documentation cmp.WindowConfig|nil
+
+---@class cmp.CompletionConfig
+---@field public autocomplete cmp.TriggerEvent[]
+---@field public completeopt string
+---@field public get_trigger_characters fun(trigger_characters: string[]): string[]
+---@field public keyword_length number
+---@field public keyword_pattern string
+
+---@class cmp.WindowConfig
+---@field public border string|string[]
+---@field public winhighlight string
+---@field public zindex number|nil
+---@field public max_width number|nil
+---@field public max_height number|nil
+
+---@class cmp.ConfirmationConfig
+---@field public default_behavior cmp.ConfirmBehavior
+---@field public get_commit_characters fun(commit_characters: string[]): string[]
+
+---@class cmp.MatchingConfig
+---@field public disallow_fuzzy_matching boolean
+---@field public disallow_partial_matching boolean
+---@field public disallow_prefix_unmatching boolean
+
+---@class cmp.SortingConfig
+---@field public priority_weight number
+---@field public comparators function[]
+
+---@class cmp.FormattingConfig
+---@field public fields cmp.ItemField[]
+---@field public format fun(entry: cmp.Entry, vim_item: vim.CompletedItem): vim.CompletedItem
+
+---@class cmp.SnippetConfig
+---@field public expand fun(args: cmp.SnippetExpansionParams)
+
+---@class cmp.ExperimentalConfig
+---@field public ghost_text cmp.GhostTextConfig|false
+
+---@class cmp.GhostTextConfig
+---@field hl_group string
+
+---@class cmp.SourceConfig
+---@field public name string
+---@field public option table|nil
+---@field public priority number|nil
+---@field public trigger_characters string[]|nil
+---@field public keyword_pattern string|nil
+---@field public keyword_length number|nil
+---@field public max_item_count number|nil
+---@field public group_index number|nil
+
+---@class cmp.ViewConfig
+---@field public entries cmp.EntriesConfig
+
+---@alias cmp.EntriesConfig cmp.CustomEntriesConfig|cmp.NativeEntriesConfig|cmp.WildmenuEntriesConfig|string
+
+---@class cmp.CustomEntriesConfig
+---@field name 'custom'
+---@field selection_order 'top_down'|'near_cursor'
+
+---@class cmp.NativeEntriesConfig
+---@field name 'native'
+
+---@class cmp.WildmenuEntriesConfig
+---@field name 'wildmenu'
+---@field separator string|nil
+
+return cmp
diff --git a/start/cmp/lua/cmp/types/init.lua b/start/cmp/lua/cmp/types/init.lua
new file mode 100644
index 0000000..c4f601e
--- /dev/null
+++ b/start/cmp/lua/cmp/types/init.lua
@@ -0,0 +1,7 @@
+local types = {}
+
+types.cmp = require('cmp.types.cmp')
+types.lsp = require('cmp.types.lsp')
+types.vim = require('cmp.types.vim')
+
+return types
diff --git a/start/cmp/lua/cmp/types/lsp.lua b/start/cmp/lua/cmp/types/lsp.lua
new file mode 100644
index 0000000..4af54a9
--- /dev/null
+++ b/start/cmp/lua/cmp/types/lsp.lua
@@ -0,0 +1,197 @@
+local misc = require('cmp.utils.misc')
+
+---@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/
+---@class lsp
+local lsp = {}
+
+lsp.Position = {
+  ---Convert lsp.Position to vim.Position
+  ---@param buf number|string
+  ---@param position lsp.Position
+  ---@return vim.Position
+  to_vim = function(buf, position)
+    if not vim.api.nvim_buf_is_loaded(buf) then
+      vim.fn.bufload(buf)
+    end
+    local lines = vim.api.nvim_buf_get_lines(buf, position.line, position.line + 1, false)
+    if #lines > 0 then
+      return {
+        row = position.line + 1,
+        col = misc.to_vimindex(lines[1], position.character),
+      }
+    end
+    return {
+      row = position.line + 1,
+      col = position.character + 1,
+    }
+  end,
+  ---Convert vim.Position to lsp.Position
+  ---@param buf number|string
+  ---@param position vim.Position
+  ---@return lsp.Position
+  to_lsp = function(buf, position)
+    if not vim.api.nvim_buf_is_loaded(buf) then
+      vim.fn.bufload(buf)
+    end
+    local lines = vim.api.nvim_buf_get_lines(buf, position.row - 1, position.row, false)
+    if #lines > 0 then
+      return {
+        line = position.row - 1,
+        character = misc.to_utfindex(lines[1], position.col),
+      }
+    end
+    return {
+      line = position.row - 1,
+      character = position.col - 1,
+    }
+  end,
+}
+
+lsp.Range = {
+  ---Convert lsp.Range to vim.Range
+  ---@param buf number|string
+  ---@param range lsp.Range
+  ---@return vim.Range
+  to_vim = function(buf, range)
+    return {
+      start = lsp.Position.to_vim(buf, range.start),
+      ['end'] = lsp.Position.to_vim(buf, range['end']),
+    }
+  end,
+
+  ---Convert vim.Range to lsp.Range
+  ---@param buf number|string
+  ---@param range vim.Range
+  ---@return lsp.Range
+  to_lsp = function(buf, range)
+    return {
+      start = lsp.Position.to_lsp(buf, range.start),
+      ['end'] = lsp.Position.to_lsp(buf, range['end']),
+    }
+  end,
+}
+
+---@alias lsp.CompletionTriggerKind 1 | 2 | 3
+lsp.CompletionTriggerKind = {
+  Invoked = 1,
+  TriggerCharacter = 2,
+  TriggerForIncompleteCompletions = 3,
+}
+
+---@alias lsp.InsertTextFormat 1 | 2
+lsp.InsertTextFormat = {}
+lsp.InsertTextFormat.PlainText = 1
+lsp.InsertTextFormat.Snippet = 2
+
+---@alias lsp.InsertTextMode 1 | 2
+lsp.InsertTextMode = {
+  AsIs = 1,
+  AdjustIndentation = 2,
+}
+
+---@alias lsp.MarkupKind 'plaintext' | 'markdown'
+lsp.MarkupKind = {
+  PlainText = 'plaintext',
+  Markdown = 'markdown',
+}
+
+---@alias lsp.CompletionItemTag 1
+lsp.CompletionItemTag = {
+  Deprecated = 1,
+}
+
+---@alias lsp.CompletionItemKind 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25
+lsp.CompletionItemKind = {
+  Text = 1,
+  Method = 2,
+  Function = 3,
+  Constructor = 4,
+  Field = 5,
+  Variable = 6,
+  Class = 7,
+  Interface = 8,
+  Module = 9,
+  Property = 10,
+  Unit = 11,
+  Value = 12,
+  Enum = 13,
+  Keyword = 14,
+  Snippet = 15,
+  Color = 16,
+  File = 17,
+  Reference = 18,
+  Folder = 19,
+  EnumMember = 20,
+  Constant = 21,
+  Struct = 22,
+  Event = 23,
+  Operator = 24,
+  TypeParameter = 25,
+}
+lsp.CompletionItemKind = vim.tbl_add_reverse_lookup(lsp.CompletionItemKind)
+
+---@class lsp.CompletionContext
+---@field public triggerKind lsp.CompletionTriggerKind
+---@field public triggerCharacter string|nil
+
+---@class lsp.CompletionList
+---@field public isIncomplete boolean
+---@field public items lsp.CompletionItem[]
+
+---@alias lsp.CompletionResponse lsp.CompletionList|lsp.CompletionItem[]|nil
+
+---@class lsp.MarkupContent
+---@field public kind lsp.MarkupKind
+---@field public value string
+
+---@class lsp.Position
+---@field public line number
+---@field public character number
+
+---@class lsp.Range
+---@field public start lsp.Position
+---@field public end lsp.Position
+
+---@class lsp.Command
+---@field public title string
+---@field public command string
+---@field public arguments any[]|nil
+
+---@class lsp.TextEdit
+---@field public range lsp.Range|nil
+---@field public newText string
+
+---@class lsp.InsertReplaceTextEdit
+---@field public insert lsp.Range|nil
+---@field public replace lsp.Range|nil
+---@field public newText string
+
+---@class lsp.CompletionItemLabelDetails
+---@field public detail string|nil
+---@field public description string|nil
+
+---@class lsp.CompletionItem
+---@field public label string
+---@field public labelDetails lsp.CompletionItemLabelDetails|nil
+---@field public kind lsp.CompletionItemKind|nil
+---@field public tags lsp.CompletionItemTag[]|nil
+---@field public detail string|nil
+---@field public documentation lsp.MarkupContent|string|nil
+---@field public deprecated boolean|nil
+---@field public preselect boolean|nil
+---@field public sortText string|nil
+---@field public filterText string|nil
+---@field public insertText string|nil
+---@field public insertTextFormat lsp.InsertTextFormat
+---@field public insertTextMode lsp.InsertTextMode
+---@field public textEdit lsp.TextEdit|lsp.InsertReplaceTextEdit|nil
+---@field public additionalTextEdits lsp.TextEdit[]
+---@field public commitCharacters string[]|nil
+---@field public command lsp.Command|nil
+---@field public data any|nil
+---
+---TODO: Should send the issue for upstream?
+---@field public word string|nil
+---@field public dup boolean|nil
+
+return lsp
diff --git a/start/cmp/lua/cmp/types/lsp_spec.lua b/start/cmp/lua/cmp/types/lsp_spec.lua
new file mode 100644
index 0000000..fc2b857
--- /dev/null
+++ b/start/cmp/lua/cmp/types/lsp_spec.lua
@@ -0,0 +1,47 @@
+local spec = require('cmp.utils.spec')
+local lsp = require('cmp.types.lsp')
+
+describe('types.lsp', function()
+  before_each(spec.before)
+  describe('Position', function()
+    vim.fn.setline('1', {
+      'あいうえお',
+      'かきくけこ',
+      'さしすせそ',
+    })
+    local vim_position, lsp_position
+
+    local bufnr = vim.api.nvim_get_current_buf()
+    vim_position = lsp.Position.to_vim(bufnr, { line = 1, character = 3 })
+    assert.are.equal(vim_position.row, 2)
+    assert.are.equal(vim_position.col, 10)
+    lsp_position = lsp.Position.to_lsp(bufnr, vim_position)
+    assert.are.equal(lsp_position.line, 1)
+    assert.are.equal(lsp_position.character, 3)
+
+    vim_position = lsp.Position.to_vim(bufnr, { line = 1, character = 0 })
+    assert.are.equal(vim_position.row, 2)
+    assert.are.equal(vim_position.col, 1)
+    lsp_position = lsp.Position.to_lsp(bufnr, vim_position)
+    assert.are.equal(lsp_position.line, 1)
+    assert.are.equal(lsp_position.character, 0)
+
+    vim_position = lsp.Position.to_vim(bufnr, { line = 1, character = 5 })
+    assert.are.equal(vim_position.row, 2)
+    assert.are.equal(vim_position.col, 16)
+    lsp_position = lsp.Position.to_lsp(bufnr, vim_position)
+    assert.are.equal(lsp_position.line, 1)
+    assert.are.equal(lsp_position.character, 5)
+
+    -- overflow (lsp -> vim)
+    vim_position = lsp.Position.to_vim(bufnr, { line = 1, character = 6 })
+    assert.are.equal(vim_position.row, 2)
+    assert.are.equal(vim_position.col, 16)
+
+    -- overflow(vim -> lsp)
+    vim_position.col = vim_position.col + 1
+    lsp_position = lsp.Position.to_lsp(bufnr, vim_position)
+    assert.are.equal(lsp_position.line, 1)
+    assert.are.equal(lsp_position.character, 5)
+  end)
+end)
diff --git a/start/cmp/lua/cmp/types/vim.lua b/start/cmp/lua/cmp/types/vim.lua
new file mode 100644
index 0000000..95e757d
--- /dev/null
+++ b/start/cmp/lua/cmp/types/vim.lua
@@ -0,0 +1,20 @@
+---@class vim.CompletedItem
+---@field public word string
+---@field public abbr string|nil
+---@field public kind string|nil
+---@field public menu string|nil
+---@field public equal 1|nil
+---@field public empty 1|nil
+---@field public dup 1|nil
+---@field public id any
+---@field public abbr_hl_group string|nil
+---@field public kind_hl_group string|nil
+---@field public menu_hl_group string|nil
+
+---@class vim.Position
+---@field public row number
+---@field public col number
+
+---@class vim.Range
+---@field public start vim.Position
+---@field public end vim.Position
diff --git a/start/cmp/lua/cmp/utils/api.lua b/start/cmp/lua/cmp/utils/api.lua
new file mode 100644
index 0000000..d053409
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/api.lua
@@ -0,0 +1,69 @@
+local api = {}
+
+local CTRL_V = vim.api.nvim_replace_termcodes('<C-v>', true, true, true)
+local CTRL_S = vim.api.nvim_replace_termcodes('<C-s>', true, true, true)
+
+api.get_mode = function()
+  local mode = vim.api.nvim_get_mode().mode:sub(1, 1)
+  if mode == 'i' then
+    return 'i' -- insert
+  elseif mode == 'v' or mode == 'V' or mode == CTRL_V then
+    return 'x' -- visual
+  elseif mode == 's' or mode == 'S' or mode == CTRL_S then
+    return 's' -- select
+  elseif mode == 'c' and vim.fn.getcmdtype() ~= '=' then
+    return 'c' -- cmdline
+  end
+end
+
+api.is_insert_mode = function()
+  return api.get_mode() == 'i'
+end
+
+api.is_cmdline_mode = function()
+  return api.get_mode() == 'c'
+end
+
+api.is_select_mode = function()
+  return api.get_mode() == 's'
+end
+
+api.is_visual_mode = function()
+  return api.get_mode() == 'x'
+end
+
+api.is_suitable_mode = function()
+  local mode = api.get_mode()
+  return mode == 'i' or mode == 'c'
+end
+
+api.get_current_line = function()
+  if api.is_cmdline_mode() then
+    return vim.fn.getcmdline()
+  end
+  return vim.api.nvim_get_current_line()
+end
+
+api.get_cursor = function()
+  if api.is_cmdline_mode() then
+    return { vim.o.lines - (vim.api.nvim_get_option('cmdheight') or 1) + 1, vim.fn.getcmdpos() - 1 }
+  end
+  return vim.api.nvim_win_get_cursor(0)
+end
+
+api.get_screen_cursor = function()
+  if api.is_cmdline_mode() then
+    local cursor = api.get_cursor()
+    return { cursor[1], cursor[2] + 1 }
+  end
+  local cursor = api.get_cursor()
+  local pos = vim.fn.screenpos(0, cursor[1], cursor[2] + 1)
+  return { pos.row, pos.col - 1 }
+end
+
+api.get_cursor_before_line = function()
+  local cursor = api.get_cursor()
+  return string.sub(api.get_current_line(), 1, cursor[2])
+end
+
+return api
diff --git a/start/cmp/lua/cmp/utils/api_spec.lua b/start/cmp/lua/cmp/utils/api_spec.lua
new file mode 100644
index 0000000..5363b48
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/api_spec.lua
@@ -0,0 +1,46 @@
+local spec = require('cmp.utils.spec')
+local keymap = require('cmp.utils.keymap')
+local feedkeys = require('cmp.utils.feedkeys')
+local api = require('cmp.utils.api')
+
+describe('api', function()
+  describe('get_cursor', function()
+    before_each(spec.before)
+    it('insert-mode', function()
+      local cursor
+      feedkeys.call(keymap.t('i\t1234567890'), 'nx', function()
+        cursor = api.get_cursor()
+      end)
+      assert.are.equal(cursor[2], 11)
+    end)
+    it('cmdline-mode', function()
+      local cursor
+      keymap.set_map(0, 'c', '<Plug>(cmp-spec-spy)', function()
+        cursor = api.get_cursor()
+      end, { expr = true, noremap = true })
+      feedkeys.call(keymap.t(':\t1234567890'), 'n')
+      feedkeys.call(keymap.t('<Plug>(cmp-spec-spy)'), 'x')
+      assert.are.equal(cursor[2], 11)
+    end)
+  end)
+
+  describe('get_cursor_before_line', function()
+    before_each(spec.before)
+    it('insert-mode', function()
+      local cursor_before_line
+      feedkeys.call(keymap.t('i\t1234567890<Left><Left>'), 'nx', function()
+        cursor_before_line = api.get_cursor_before_line()
+      end)
+      assert.are.same(cursor_before_line, '\t12345678')
+    end)
+    it('cmdline-mode', function()
+      local cursor_before_line
+      keymap.set_map(0, 'c', '<Plug>(cmp-spec-spy)', function()
+        cursor_before_line = api.get_cursor_before_line()
+      end, { expr = true, noremap = true })
+      feedkeys.call(keymap.t(':\t1234567890<Left><Left>'), 'n')
+      feedkeys.call(keymap.t('<Plug>(cmp-spec-spy)'), 'x')
+      assert.are.same(cursor_before_line, '\t12345678')
+    end)
+  end)
+end)
diff --git a/start/cmp/lua/cmp/utils/async.lua b/start/cmp/lua/cmp/utils/async.lua
new file mode 100644
index 0000000..13f126b
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/async.lua
@@ -0,0 +1,127 @@
+local async = {}
+
+---@class cmp.AsyncThrottle
+---@field public running boolean
+---@field public timeout number
+---@field public sync function(self: cmp.AsyncThrottle, timeout: number|nil)
+---@field public stop function
+---@field public __call function
+
+---@param fn function
+---@param timeout number
+---@return cmp.AsyncThrottle
+async.throttle = function(fn, timeout)
+  local time = nil
+  local timer = vim.loop.new_timer()
+  return setmetatable({
+    running = false,
+    timeout = timeout,
+    sync = function(self, timeout_)
+      vim.wait(timeout_ or 1000, function()
+        return not self.running
+      end)
+    end,
+    stop = function()
+      time = nil
+      timer:stop()
+    end,
+  }, {
+    __call = function(self, ...)
+      local args = { ... }
+
+      if time == nil then
+        time = vim.loop.now()
+      end
+
+      self.running = true
+      timer:stop()
+      timer:start(math.max(1, self.timeout - (vim.loop.now() - time)), 0, function()
+        vim.schedule(function()
+          time = nil
+          fn(unpack(args))
+          self.running = false
+        end)
+      end)
+    end,
+  })
+end
+
+---Control async tasks.
+async.step = function(...)
+  local tasks = { ... }
+  local next
+  next = function(...)
+    if #tasks > 0 then
+      table.remove(tasks, 1)(next, ...)
+    end
+  end
+  table.remove(tasks, 1)(next)
+end
+
+---Timeout callback function
+---@param fn function
+---@param timeout number
+---@return function
+async.timeout = function(fn, timeout)
+  local timer
+  local done = false
+  local callback = function(...)
+    if not done then
+      done = true
+      timer:stop()
+      timer:close()
+      fn(...)
+    end
+  end
+  timer = vim.loop.new_timer()
+  timer:start(timeout, 0, function()
+    callback()
+  end)
+  return callback
+end
+
+---@alias cmp.AsyncDedup fun(callback: function): function
+
+---Create deduplicated callback
+---@return function
+async.dedup = function()
+  local id = 0
+  return function(callback)
+    id = id + 1
+
+    local current = id
+    return function(...)
+      if current == id then
+        callback(...)
+      end
+    end
+  end
+end
+
+---Convert async process as sync
+async.sync = function(runner, timeout)
+  local done = false
+  runner(function()
+    done = true
+  end)
+  vim.wait(timeout, function()
+    return done
+  end, 10, false)
+end
+
+---Wait and callback for next safe state.
+async.debounce_next_tick = function(callback)
+  local running = false
+  return function()
+    if running then
+      return
+    end
+    running = true
+    vim.schedule(function()
+      running = false
+      callback()
+    end)
+  end
+end
+
+return async
diff --git a/start/cmp/lua/cmp/utils/async_spec.lua b/start/cmp/lua/cmp/utils/async_spec.lua
new file mode 100644
index 0000000..62f5379
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/async_spec.lua
@@ -0,0 +1,69 @@
+local async = require('cmp.utils.async')
+
+describe('utils.async', function()
+  it('throttle', function()
+    local count = 0
+    local now
+    local f = async.throttle(function()
+      count = count + 1
+    end, 100)
+
+    -- 1. delay for 100ms
+    now = vim.loop.now()
+    f.timeout = 100
+    f()
+    vim.wait(1000, function()
+      return count == 1
+    end)
+    assert.is.truthy(math.abs(f.timeout - (vim.loop.now() - now)) < 10)
+
+    -- 2. delay for 500ms
+    now = vim.loop.now()
+    f.timeout = 500
+    f()
+    vim.wait(1000, function()
+      return count == 2
+    end)
+    assert.is.truthy(math.abs(f.timeout - (vim.loop.now() - now)) < 10)
+
+    -- 4. delay for 500ms and wait 100ms (remain 400ms)
+    f.timeout = 500
+    f()
+    vim.wait(100) -- remain 400ms
+
+    -- 5. call immediately (100ms already elapsed from No.4)
+    now = vim.loop.now()
+    f.timeout = 100
+    f()
+    vim.wait(1000, function()
+      return count == 3
+    end)
+    assert.is.truthy(math.abs(vim.loop.now() - now) < 10)
+  end)
+  it('step', function()
+    local done = false
+    local step = {}
+    async.step(function(next)
+      vim.defer_fn(function()
+        table.insert(step, 1)
+        next()
+      end, 10)
+    end, function(next)
+      vim.defer_fn(function()
+        table.insert(step, 2)
+        next()
+      end, 10)
+    end, function(next)
+      vim.defer_fn(function()
+        table.insert(step, 3)
+        next()
+      end, 10)
+    end, function()
+      done = true
+    end)
+    vim.wait(1000, function()
+      return done
+    end)
+    assert.are.same(step, { 1, 2, 3 })
+  end)
+end)
diff --git a/start/cmp/lua/cmp/utils/autocmd.lua b/start/cmp/lua/cmp/utils/autocmd.lua
new file mode 100644
index 0000000..438e231
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/autocmd.lua
@@ -0,0 +1,53 @@
+local debug = require('cmp.utils.debug')
+
+local autocmd = {}
+
+autocmd.group = vim.api.nvim_create_augroup('___cmp___', { clear = true })
+
+autocmd.events = {}
+
+---Subscribe autocmd
+---@param events string|string[]
+---@param callback function
+---@return function
+autocmd.subscribe = function(events, callback)
+  events = type(events) == 'string' and { events } or events
+
+  for _, event in ipairs(events) do
+    if not autocmd.events[event] then
+      autocmd.events[event] = {}
+      vim.api.nvim_create_autocmd(event, {
+        desc = ('nvim-cmp: autocmd: %s'):format(event),
+        group = autocmd.group,
+        callback = function()
+          autocmd.emit(event)
+        end,
+      })
+    end
+    table.insert(autocmd.events[event], callback)
+  end
+
+  return function()
+    for _, event in ipairs(events) do
+      for i, callback_ in ipairs(autocmd.events[event]) do
+        if callback_ == callback then
+          table.remove(autocmd.events[event], i)
+          break
+        end
+      end
+    end
+  end
+end
+
+---Emit autocmd
+---@param event string
+autocmd.emit = function(event)
+  debug.log(' ')
+  debug.log(string.format('>>> %s', event))
+  autocmd.events[event] = autocmd.events[event] or {}
+  for _, callback in ipairs(autocmd.events[event]) do
+    callback()
+  end
+end
+
+return autocmd
diff --git a/start/cmp/lua/cmp/utils/binary.lua b/start/cmp/lua/cmp/utils/binary.lua
new file mode 100644
index 0000000..c6a7088
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/binary.lua
@@ -0,0 +1,33 @@
+local binary = {}
+
+---Insert item to list to ordered index
+---@param list any[]
+---@param item any
+---@param func fun(a: any, b: any): 1|-1|0
+binary.insort = function(list, item, func)
+  table.insert(list, binary.search(list, item, func), item)
+end
+
+---Search suitable index from list
+---@param list any[]
+---@param item any
+---@param func fun(a: any, b: any): 1|-1|0
+---@return number
+binary.search = function(list, item, func)
+  local s = 1
+  local e = #list
+  while s <= e do
+    local idx = math.floor((e + s) / 2)
+    local diff = func(item, list[idx])
+    if diff > 0 then
+      s = idx + 1
+    elseif diff < 0 then
+      e = idx - 1
+    else
+      return idx + 1
+    end
+  end
+  return s
+end
+
+return binary
diff --git a/start/cmp/lua/cmp/utils/binary_spec.lua b/start/cmp/lua/cmp/utils/binary_spec.lua
new file mode 100644
index 0000000..92fe129
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/binary_spec.lua
@@ -0,0 +1,28 @@
+local binary = require('cmp.utils.binary')
+
+describe('utils.binary', function()
+  it('insort', function()
+    local func = function(a, b)
+      return a.score - b.score
+    end
+    local list = {}
+    binary.insort(list, { id = 'a', score = 1 }, func)
+    binary.insort(list, { id = 'b', score = 5 }, func)
+    binary.insort(list, { id = 'c', score = 2.5 }, func)
+    binary.insort(list, { id = 'd', score = 2 }, func)
+    binary.insort(list, { id = 'e', score = 8 }, func)
+    binary.insort(list, { id = 'g', score = 8 }, func)
+    binary.insort(list, { id = 'h', score = 7 }, func)
+    binary.insort(list, { id = 'i', score = 6 }, func)
+    binary.insort(list, { id = 'j', score = 4 }, func)
+    assert.are.equal(list[1].id, 'a')
+    assert.are.equal(list[2].id, 'd')
+    assert.are.equal(list[3].id, 'c')
+    assert.are.equal(list[4].id, 'j')
+    assert.are.equal(list[5].id, 'b')
+    assert.are.equal(list[6].id, 'i')
+    assert.are.equal(list[7].id, 'h')
+    assert.are.equal(list[8].id, 'e')
+    assert.are.equal(list[9].id, 'g')
+  end)
+end)
diff --git a/start/cmp/lua/cmp/utils/buffer.lua b/start/cmp/lua/cmp/utils/buffer.lua
new file mode 100644
index 0000000..63171c9
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/buffer.lua
@@ -0,0 +1,28 @@
+local buffer = {}
+
+buffer.cache = {}
+
+---@return number buf
+buffer.get = function(name)
+  local buf = buffer.cache[name]
+  if buf and vim.api.nvim_buf_is_valid(buf) then
+    return buf
+  else
+    return nil
+  end
+end
+
+---@return number buf
+---@return boolean created_new
+buffer.ensure = function(name)
+  local created_new = false
+  local buf = buffer.get(name)
+  if not buf then
+    created_new = true
+    buf = vim.api.nvim_create_buf(false, true)
+    buffer.cache[name] = buf
+  end
+  return buf, created_new
+end
+
+return buffer
diff --git a/start/cmp/lua/cmp/utils/cache.lua b/start/cmp/lua/cmp/utils/cache.lua
new file mode 100644
index 0000000..8607b2a
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/cache.lua
@@ -0,0 +1,58 @@
+---@class cmp.Cache
+---@field public entries any
+local cache = {}
+
+cache.new = function()
+  local self = setmetatable({}, { __index = cache })
+  self.entries = {}
+  return self
+end
+
+---Get cache value
+---@param key string
+---@return any|nil
+cache.get = function(self, key)
+  key = self:key(key)
+  if self.entries[key] ~= nil then
+    return self.entries[key]
+  end
+  return nil
+end
+
+---Set cache value explicitly
+---@param key string
+---@vararg any
+cache.set = function(self, key, value)
+  key = self:key(key)
+  self.entries[key] = value
+end
+
+---Ensure value by callback
+---@param key string
+---@param callback fun(): any
+cache.ensure = function(self, key, callback)
+  local value = self:get(key)
+  if value == nil then
+    local v = callback()
+    self:set(key, v)
+    return v
+  end
+  return value
+end
+
+---Clear all cache entries
+cache.clear = function(self)
+  self.entries = {}
+end
+
+---Create key
+---@param key string|table
+---@return string
+cache.key = function(_, key)
+  if type(key) == 'table' then
+    return table.concat(key, ':')
+  end
+  return key
+end
+
+return cache
diff --git a/start/cmp/lua/cmp/utils/char.lua b/start/cmp/lua/cmp/utils/char.lua
new file mode 100644
index 0000000..6e18994
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/char.lua
@@ -0,0 +1,117 @@
+local _
+
+local alpha = {}
+_ = string.gsub('abcdefghijklmnopqrstuvwxyz', '.', function(char)
+  alpha[string.byte(char)] = true
+end)
+
+local ALPHA = {}
+_ = string.gsub('ABCDEFGHIJKLMNOPQRSTUVWXYZ', '.', function(char)
+  ALPHA[string.byte(char)] = true
+end)
+
+local digit = {}
+_ = string.gsub('1234567890', '.', function(char)
+  digit[string.byte(char)] = true
+end)
+
+local white = {}
+_ = string.gsub(' \t\n', '.', function(char)
+  white[string.byte(char)] = true
+end)
+
+local char = {}
+
+---@param byte number
+---@return boolean
+char.is_upper = function(byte)
+  return ALPHA[byte]
+end
+
+---@param byte number
+---@return boolean
+char.is_alpha = function(byte)
+  return alpha[byte] or ALPHA[byte]
+end
+
+---@param byte number
+---@return boolean
+char.is_digit = function(byte)
+  return digit[byte]
+end
+
+---@param byte number
+---@return boolean
+char.is_white = function(byte)
+  return white[byte]
+end
+
+---@param byte number
+---@return boolean
+char.is_symbol = function(byte)
+  return not (char.is_alnum(byte) or char.is_white(byte))
+end
+
+---@param byte number
+---@return boolean
+char.is_printable = function(byte)
+  return string.match(string.char(byte), '^%c$') == nil
+end
+
+---@param byte number
+---@return boolean
+char.is_alnum = function(byte)
+  return char.is_alpha(byte) or char.is_digit(byte)
+end
+
+---@param text string
+---@param index number
+---@return boolean
+char.is_semantic_index = function(text, index)
+  if index <= 1 then
+    return true
+  end
+
+  local prev = string.byte(text, index - 1)
+  local curr = string.byte(text, index)
+
+  if not char.is_upper(prev) and char.is_upper(curr) then
+    return true
+  end
+  if char.is_symbol(curr) or char.is_white(curr) then
+    return true
+  end
+  if not char.is_alpha(prev) and char.is_alpha(curr) then
+    return true
+  end
+  if not char.is_digit(prev) and char.is_digit(curr) then
+    return true
+  end
+  return false
+end
+
+---@param text string
+---@param current_index number
+---@return boolean
+char.get_next_semantic_index = function(text, current_index)
+  for i = current_index + 1, #text do
+    if char.is_semantic_index(text, i) then
+      return i
+    end
+  end
+  return #text + 1
+end
+
+---Ignore case match
+---@param byte1 number
+---@param byte2 number
+---@return boolean
+char.match = function(byte1, byte2)
+  if not char.is_alpha(byte1) or not char.is_alpha(byte2) then
+    return byte1 == byte2
+  end
+  local diff = byte1 - byte2
+  return diff == 0 or diff == 32 or diff == -32
+end
+
+return char
diff --git a/start/cmp/lua/cmp/utils/debug.lua b/start/cmp/lua/cmp/utils/debug.lua
new file mode 100644
index 0000000..c8b0dba
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/debug.lua
@@ -0,0 +1,20 @@
+local debug = {}
+
+debug.flag = false
+
+---Print log
+---@vararg any
+debug.log = function(...)
+  if debug.flag then
+    local data = {}
+    for _, v in ipairs({ ... }) do
+      if not vim.tbl_contains({ 'string', 'number', 'boolean' }, type(v)) then
+        v = vim.inspect(v)
+      end
+      table.insert(data, v)
+    end
+    print(table.concat(data, '\t'))
+  end
+end
+
+return debug
diff --git a/start/cmp/lua/cmp/utils/event.lua b/start/cmp/lua/cmp/utils/event.lua
new file mode 100644
index 0000000..662d573
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/event.lua
@@ -0,0 +1,51 @@
+---@class cmp.Event
+---@field private events table<string, function[]>
+local event = {}
+
+---Create vents
+event.new = function()
+  local self = setmetatable({}, { __index = event })
+  self.events = {}
+  return self
+end
+
+---Add event listener
+---@param name string
+---@param callback function
+---@return function
+event.on = function(self, name, callback)
+  if not self.events[name] then
+    self.events[name] = {}
+  end
+  table.insert(self.events[name], callback)
+  return function()
+    self:off(name, callback)
+  end
+end
+
+---Remove event listener
+---@param name string
+---@param callback function
+event.off = function(self, name, callback)
+  for i, callback_ in ipairs(self.events[name] or {}) do
+    if callback_ == callback then
+      table.remove(self.events[name], i)
+      break
+    end
+  end
+end
+
+---Remove all events
+event.clear = function(self)
+  self.events = {}
+end
+
+---Emit event
+---@param name string
+event.emit = function(self, name, ...)
+  for _, callback in ipairs(self.events[name] or {}) do
+    callback(...)
+  end
+end
+
+return event
diff --git a/start/cmp/lua/cmp/utils/feedkeys.lua b/start/cmp/lua/cmp/utils/feedkeys.lua
new file mode 100644
index 0000000..cd20f60
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/feedkeys.lua
@@ -0,0 +1,53 @@
+local keymap = require('cmp.utils.keymap')
+local misc = require('cmp.utils.misc')
+
+local feedkeys = {}
+
+feedkeys.call = setmetatable({
+  callbacks = {},
+}, {
+  __call = function(self, keys, mode, callback)
+    local is_insert = string.match(mode, 'i') ~= nil
+    local is_immediate = string.match(mode, 'x') ~= nil
+
+    local queue = {}
+    if #keys > 0 then
+      table.insert(queue, { keymap.t('<Cmd>setlocal lazyredraw<CR>'), 'n' })
+      table.insert(queue, { keymap.t('<Cmd>setlocal textwidth=0<CR>'), 'n' })
+      table.insert(queue, { keymap.t('<Cmd>setlocal backspace=2<CR>'), 'n' })
+      table.insert(queue, { keys, string.gsub(mode, '[itx]', ''), true })
+      table.insert(queue, { keymap.t('<Cmd>setlocal %slazyredraw<CR>'):format(vim.o.lazyredraw and '' or 'no'), 'n' })
+      table.insert(queue, { keymap.t('<Cmd>setlocal textwidth=%s<CR>'):format(vim.bo.textwidth or 0), 'n' })
+      table.insert(queue, { keymap.t('<Cmd>setlocal backspace=%s<CR>'):format(vim.go.backspace or 2), 'n' })
+    end
+
+    if callback then
+      local id = misc.id('cmp.utils.feedkeys.call')
+      self.callbacks[id] = callback
+      table.insert(queue, { keymap.t('<Cmd>call v:lua.cmp.utils.feedkeys.call.run(%s)<CR>'):format(id), 'n', true })
+    end
+
+    if is_insert then
+      for i = #queue, 1, -1 do
+        vim.api.nvim_feedkeys(queue[i][1], queue[i][2] .. 'i', queue[i][3])
+      end
+    else
+      for i = 1, #queue do
+        vim.api.nvim_feedkeys(queue[i][1], queue[i][2], queue[i][3])
+      end
+    end
+
+    if is_immediate then
+      vim.api.nvim_feedkeys('', 'x', true)
+    end
+  end,
+})
+misc.set(_G, { 'cmp', 'utils', 'feedkeys', 'call', 'run' }, function(id)
+  if feedkeys.call.callbacks[id] then
+    feedkeys.call.callbacks[id]()
+    feedkeys.call.callbacks[id] = nil
+  end
+  return ''
+end)
+
+return feedkeys
diff --git a/start/cmp/lua/cmp/utils/feedkeys_spec.lua b/start/cmp/lua/cmp/utils/feedkeys_spec.lua
new file mode 100644
index 0000000..24fba71
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/feedkeys_spec.lua
@@ -0,0 +1,56 @@
+local spec = require('cmp.utils.spec')
+local keymap = require('cmp.utils.keymap')
+
+local feedkeys = require('cmp.utils.feedkeys')
+
+describe('feedkeys', function()
+  before_each(spec.before)
+
+  it('dot-repeat', function()
+    local reg
+    feedkeys.call(keymap.t('iaiueo<Esc>'), 'nx', function()
+      reg = vim.fn.getreg('.')
+    end)
+    assert.are.equal(reg, keymap.t('aiueo'))
+  end)
+
+  it('textwidth', function()
+    vim.cmd([[setlocal textwidth=6]])
+    feedkeys.call(keymap.t('iaiueo '), 'nx')
+    feedkeys.call(keymap.t('aaiueoaiueo'), 'nx')
+    assert.are.same(vim.api.nvim_buf_get_lines(0, 0, -1, false), {
+      'aiueo aiueoaiueo',
+    })
+  end)
+
+  it('bacckspace', function()
+    vim.cmd([[setlocal backspace=0]])
+    feedkeys.call(keymap.t('iaiueo'), 'nx')
+    feedkeys.call(keymap.t('a<BS><BS>'), 'nx')
+    assert.are.same(vim.api.nvim_buf_get_lines(0, 0, -1, false), {
+      'aiu',
+    })
+  end)
+
+  it('testability', function()
+    feedkeys.call('i', 'n', function()
+      feedkeys.call('', 'n', function()
+        feedkeys.call('aiueo', 'in')
+      end)
+      feedkeys.call('', 'n', function()
+        feedkeys.call(keymap.t('<BS><BS><BS><BS><BS>'), 'in')
+      end)
+      feedkeys.call('', 'n', function()
+        feedkeys.call(keymap.t('abcde'), 'in')
+      end)
+      feedkeys.call('', 'n', function()
+        feedkeys.call(keymap.t('<BS><BS><BS><BS><BS>'), 'in')
+      end)
+      feedkeys.call('', 'n', function()
+        feedkeys.call(keymap.t('12345'), 'in')
+      end)
+    end)
+    feedkeys.call('', 'x')
+    assert.are.same(vim.api.nvim_buf_get_lines(0, 0, -1, false), { '12345' })
+  end)
+end)
diff --git a/start/cmp/lua/cmp/utils/highlight.lua b/start/cmp/lua/cmp/utils/highlight.lua
new file mode 100644
index 0000000..867632a
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/highlight.lua
@@ -0,0 +1,31 @@
+local highlight = {}
+
+highlight.keys = {
+  'fg',
+  'bg',
+  'bold',
+  'italic',
+  'reverse',
+  'standout',
+  'underline',
+  'undercurl',
+  'strikethrough',
+}
+
+highlight.inherit = function(name, source, settings)
+  for _, key in ipairs(highlight.keys) do
+    if not settings[key] then
+      local v = vim.fn.synIDattr(vim.fn.hlID(source), key)
+      if key == 'fg' or key == 'bg' then
+        local n = tonumber(v, 10)
+        v = type(n) == 'number' and n or v
+      else
+        v = v == 1
+      end
+      settings[key] = v == '' and 'NONE' or v
+    end
+  end
+  vim.api.nvim_set_hl(0, name, settings)
+end
+
+return highlight
diff --git a/start/cmp/lua/cmp/utils/keymap.lua b/start/cmp/lua/cmp/utils/keymap.lua
new file mode 100644
index 0000000..aea5c1d
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/keymap.lua
@@ -0,0 +1,251 @@
+local misc = require('cmp.utils.misc')
+local buffer = require('cmp.utils.buffer')
+local api = require('cmp.utils.api')
+
+local keymap = {}
+
+---Shortcut for nvim_replace_termcodes
+---@param keys string
+---@return string
+keymap.t = function(keys)
+  return (string.gsub(keys, '(<[A-Za-z0-9\\%-%[%]%^@]->)', function(match)
+    return vim.api.nvim_eval(string.format([["\%s"]], match))
+  end))
+end
+
+---Normalize key sequence.
+---@param keys string
+---@return string
+keymap.normalize = function(keys)
+  local normalize_buf = buffer.ensure('cmp.util.keymap.normalize')
+  vim.api.nvim_buf_set_keymap(normalize_buf, 't', keys, '<Plug>(cmp.utils.keymap.normalize)', {})
+  for _, map in ipairs(vim.api.nvim_buf_get_keymap(normalize_buf, 't')) do
+    if keymap.equals(map.rhs, '<Plug>(cmp.utils.keymap.normalize)') then
+      vim.api.nvim_buf_del_keymap(normalize_buf, 't', keys)
+      return map.lhs
+    end
+  end
+  vim.api.nvim_buf_del_keymap(normalize_buf, 't', keys)
+  return keys
+end
+
+---Return vim notation keymapping (simple conversion).
+---@param s string
+---@return string
+keymap.to_keymap = setmetatable({
+  ['<CR>'] = { '\n', '\r', '\r\n' },
+  ['<Tab>'] = { '\t' },
+  ['<BSlash>'] = { '\\' },
+  ['<Bar>'] = { '|' },
+  ['<Space>'] = { ' ' },
+}, {
+  __call = function(self, s)
+    return string.gsub(s, '.', function(c)
+      for key, chars in pairs(self) do
+        if vim.tbl_contains(chars, c) then
+          return key
+        end
+      end
+      return c
+    end)
+  end,
+})
+
+---Mode safe break undo
+keymap.undobreak = function()
+  if not api.is_insert_mode() then
+    return ''
+  end
+  return keymap.t('<C-g>u')
+end
+
+---Mode safe join undo
+keymap.undojoin = function()
+  if not api.is_insert_mode() then
+    return ''
+  end
+  return keymap.t('<C-g>U')
+end
+
+---Create backspace keys.
+---@param count number
+---@return string
+keymap.backspace = function(count)
+  if type(count) == 'string' then
+    count = vim.fn.strchars(count, true)
+  end
+  if count <= 0 then
+    return ''
+  end
+  local keys = {}
+  table.insert(keys, keymap.t(string.rep('<BS>', count)))
+  return table.concat(keys, '')
+end
+
+---Update indentkeys.
+---@param expr string
+---@return string
+keymap.indentkeys = function(expr)
+  return string.format(keymap.t('<Cmd>set indentkeys=%s<CR>'), expr and vim.fn.escape(expr, '| \t\\') or '')
+end
+
+---Return two key sequence are equal or not.
+---@param a string
+---@param b string
+---@return boolean
+keymap.equals = function(a, b)
+  return keymap.t(a) == keymap.t(b)
+end
+
+---Register keypress handler.
+keymap.listen = function(mode, lhs, callback)
+  lhs = keymap.normalize(keymap.to_keymap(lhs))
+
+  local existing = keymap.get_map(mode, lhs)
+  local id = string.match(existing.rhs, 'v:lua%.cmp%.utils%.keymap%.set_map%((%d+)%)')
+  if id and keymap.set_map.callbacks[tonumber(id, 10)] then
+    return
+  end
+
+  local bufnr = existing.buffer and vim.api.nvim_get_current_buf() or -1
+  local fallback = keymap.fallback(bufnr, mode, existing)
+  keymap.set_map(bufnr, mode, lhs, function()
+    local ignore = false
+    ignore = ignore or (mode == 'c' and vim.fn.getcmdtype() == '=')
+    if ignore then
+      fallback()
+    else
+      callback(lhs, misc.once(fallback))
+    end
+  end, {
+    expr = false,
+    noremap = true,
+    silent = true,
+  })
+end
+
+---Fallback
+keymap.fallback = function(bufnr, mode, map)
+  return function()
+    if map.expr then
+      local fallback_expr = string.format('<Plug>(cmp.u.k.fallback_expr:%s)', map.lhs)
+      keymap.set_map(bufnr, mode, fallback_expr, function()
+        return keymap.solve(bufnr, mode, map).keys
+      end, {
+        expr = true,
+        noremap = map.noremap,
+        script = map.script,
+        nowait = map.nowait,
+        silent = map.silent and mode ~= 'c',
+      })
+      vim.api.nvim_feedkeys(keymap.t(fallback_expr), 'im', true)
+    elseif not map.callback then
+      local solved = keymap.solve(bufnr, mode, map)
+      vim.api.nvim_feedkeys(solved.keys, solved.mode, true)
+    else
+      map.callback()
+    end
+  end
+end
+
+---Solve
+keymap.solve = function(bufnr, mode, map)
+  local lhs = keymap.t(map.lhs)
+  local rhs = map.expr and (map.callback and map.callback() or vim.api.nvim_eval(keymap.t(map.rhs))) or keymap.t(map.rhs)
+
+  if map.noremap then
+    return { keys = rhs, mode = 'in' }
+  end
+
+  if string.find(rhs, lhs, 1, true) == 1 then
+    local recursive = string.format('<SNR>0_(cmp.u.k.recursive:%s)', lhs)
+    keymap.set_map(bufnr, mode, recursive, lhs, {
+      noremap = true,
+      script = map.script,
+      nowait = map.nowait,
+      silent = map.silent and mode ~= 'c',
+    })
+    return { keys = keymap.t(recursive) .. string.gsub(rhs, '^' .. vim.pesc(lhs), ''), mode = 'im' }
+  end
+  return { keys = rhs, mode = 'im' }
+end
+
+---Get map
+---@param mode string
+---@param lhs string
+---@return table
+keymap.get_map = function(mode, lhs)
+  lhs = keymap.normalize(lhs)
+
+  for _, map in ipairs(vim.api.nvim_buf_get_keymap(0, mode)) do
+    if keymap.equals(map.lhs, lhs) then
+      return {
+        lhs = map.lhs,
+        rhs = map.rhs or '',
+        expr = map.expr == 1,
+        callback = map.callback,
+        noremap = map.noremap == 1,
+        script = map.script == 1,
+        silent = map.silent == 1,
+        nowait = map.nowait == 1,
+        buffer = true,
+      }
+    end
+  end
+
+  for _, map in ipairs(vim.api.nvim_get_keymap(mode)) do
+    if keymap.equals(map.lhs, lhs) then
+      return {
+        lhs = map.lhs,
+        rhs = map.rhs or '',
+        expr = map.expr == 1,
+        callback = map.callback,
+        noremap = map.noremap == 1,
+        script = map.script == 1,
+        silent = map.silent == 1,
+        nowait = map.nowait == 1,
+        buffer = false,
+      }
+    end
+  end
+
+  return {
+    lhs = lhs,
+    rhs = lhs,
+    expr = false,
+    callback = nil,
+    noremap = true,
+    script = false,
+    silent = true,
+    nowait = false,
+    buffer = false,
+  }
+end
+
+---Set keymapping
+keymap.set_map = setmetatable({
+  callbacks = {},
+}, {
+  __call = function(self, bufnr, mode, lhs, rhs, opts)
+    if type(rhs) == 'function' then
+      local id = misc.id('cmp.utils.keymap.set_map')
+      self.callbacks[id] = rhs
+      if opts.expr then
+        rhs = ('v:lua.cmp.utils.keymap.set_map(%s)'):format(id)
+      else
+        rhs = ('<Cmd>call v:lua.cmp.utils.keymap.set_map(%s)<CR>'):format(id)
+      end
+    end
+
+    if bufnr == -1 then
+      vim.api.nvim_set_keymap(mode, lhs, rhs, opts)
+    else
+      vim.api.nvim_buf_set_keymap(bufnr, mode, lhs, rhs, opts)
+    end
+  end,
+})
+misc.set(_G, { 'cmp', 'utils', 'keymap', 'set_map' }, function(id)
+  return keymap.set_map.callbacks[id]() or ''
+end)
+
+return keymap
diff --git a/start/cmp/lua/cmp/utils/keymap_spec.lua b/start/cmp/lua/cmp/utils/keymap_spec.lua
new file mode 100644
index 0000000..959783f
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/keymap_spec.lua
@@ -0,0 +1,187 @@
+local spec = require('cmp.utils.spec')
+local api = require('cmp.utils.api')
+local feedkeys = require('cmp.utils.feedkeys')
+
+local keymap = require('cmp.utils.keymap')
+
+describe('keymap', function()
+  before_each(spec.before)
+
+  it('t', function()
+    for _, key in ipairs({
+      '<F1>',
+      '<C-a>',
+      '<C-]>',
+      '<C-[>',
+      '<C-^>',
+      '<C-@>',
+      '<C-\\>',
+      '<Tab>',
+      '<S-Tab>',
+      '<Plug>(example)',
+      '<C-r>="abc"<CR>',
+      '<Cmd>normal! ==<CR>',
+    }) do
+      assert.are.equal(keymap.t(key), vim.api.nvim_replace_termcodes(key, true, true, true))
+      assert.are.equal(keymap.t(key .. key), vim.api.nvim_replace_termcodes(key .. key, true, true, true))
+      assert.are.equal(keymap.t(key .. key .. key), vim.api.nvim_replace_termcodes(key .. key .. key, true, true, true))
+    end
+  end)
+
+  it('to_keymap', function()
+    assert.are.equal(keymap.to_keymap('\n'), '<CR>')
+    assert.are.equal(keymap.to_keymap('<CR>'), '<CR>')
+    assert.are.equal(keymap.to_keymap('|'), '<Bar>')
+  end)
+
+  describe('fallback', function()
+    before_each(spec.before)
+
+    local run_fallback = function(keys, fallback)
+      local state = {}
+      feedkeys.call(keys, '', function()
+        fallback()
+      end)
+      feedkeys.call('', '', function()
+        if api.is_cmdline_mode() then
+          state.buffer = { api.get_current_line() }
+        else
+          state.buffer = vim.api.nvim_buf_get_lines(0, 0, -1, false)
+        end
+        state.cursor = api.get_cursor()
+      end)
+      feedkeys.call('', 'x')
+      return state
+    end
+
+    describe('basic', function()
+      it('<Plug>', function()
+        vim.api.nvim_buf_set_keymap(0, 'i', '<Plug>(pairs)', '()<Left>', { noremap = true })
+        vim.api.nvim_buf_set_keymap(0, 'i', '(', '<Plug>(pairs)', { noremap = false })
+        local fallback = keymap.fallback(0, 'i', keymap.get_map('i', '('))
+        local state = run_fallback('i', fallback)
+        assert.are.same({ '()' }, state.buffer)
+        assert.are.same({ 1, 1 }, state.cursor)
+      end)
+
+      it('<C-r>=', function()
+        vim.api.nvim_buf_set_keymap(0, 'i', '(', '<C-r>="()"<CR><Left>', {})
+        local fallback = keymap.fallback(0, 'i', keymap.get_map('i', '('))
+        local state = run_fallback('i', fallback)
+        assert.are.same({ '()' }, state.buffer)
+        assert.are.same({ 1, 1 }, state.cursor)
+      end)
+
+      it('callback', function()
+        vim.api.nvim_buf_set_keymap(0, 'i', '(', '', {
+          callback = function()
+            vim.api.nvim_feedkeys('()' .. keymap.t('<Left>'), 'int', true)
+          end,
+        })
+        local fallback = keymap.fallback(0, 'i', keymap.get_map('i', '('))
+        local state = run_fallback('i', fallback)
+        assert.are.same({ '()' }, state.buffer)
+        assert.are.same({ 1, 1 }, state.cursor)
+      end)
+
+      it('expr-callback', function()
+        vim.api.nvim_buf_set_keymap(0, 'i', '(', '', {
+          expr = true,
+          noremap = false,
+          silent = true,
+          callback = function()
+            return '()' .. keymap.t('<Left>')
+          end,
+        })
+        local fallback = keymap.fallback(0, 'i', keymap.get_map('i', '('))
+        local state = run_fallback('i', fallback)
+        assert.are.same({ '()' }, state.buffer)
+        assert.are.same({ 1, 1 }, state.cursor)
+      end)
+
+      -- it('cmdline default <Tab>', function()
+      --   local fallback = keymap.fallback(0, 'c', keymap.get_map('c', '<Tab>'))
+      --   local state = run_fallback(':', fallback)
+      --   assert.are.same({ '' }, state.buffer)
+      --   assert.are.same({ 1, 0 }, state.cursor)
+      -- end)
+    end)
+
+    describe('recursive', function()
+      it('non-expr', function()
+        vim.api.nvim_buf_set_keymap(0, 'i', '(', '()<Left>', {
+          expr = false,
+          noremap = false,
+          silent = true,
+        })
+        local fallback = keymap.fallback(0, 'i', keymap.get_map('i', '('))
+        local state = run_fallback('i', fallback)
+        assert.are.same({ '()' }, state.buffer)
+        assert.are.same({ 1, 1 }, state.cursor)
+      end)
+
+      it('expr', function()
+        vim.api.nvim_buf_set_keymap(0, 'i', '(', '"()<Left>"', {
+          expr = true,
+          noremap = false,
+          silent = true,
+        })
+        local fallback = keymap.fallback(0, 'i', keymap.get_map('i', '('))
+        local state = run_fallback('i', fallback)
+        assert.are.same({ '()' }, state.buffer)
+        assert.are.same({ 1, 1 }, state.cursor)
+      end)
+
+      it('expr-callback', function()
+        pcall(function()
+          vim.api.nvim_buf_set_keymap(0, 'i', '(', '', {
+            expr = true,
+            noremap = false,
+            silent = true,
+            callback = function()
+              return keymap.t('()<Left>')
+            end,
+          })
+          local fallback = keymap.fallback(0, 'i', keymap.get_map('i', '('))
+          local state = run_fallback('i', fallback)
+          assert.are.same({ '()' }, state.buffer)
+          assert.are.same({ 1, 1 }, state.cursor)
+        end)
+      end)
+    end)
+  end)
+
+  describe('realworld', function()
+    before_each(spec.before)
+
+    it('#226', function()
+      keymap.listen('i', '<c-n>', function(_, fallback)
+        fallback()
+      end)
+      vim.api.nvim_feedkeys(keymap.t('iaiueo<CR>a<C-n><C-n>'), 'tx', true)
+      assert.are.same({ 'aiueo', 'aiueo' }, vim.api.nvim_buf_get_lines(0, 0, -1, true))
+    end)
+
+    it('#414', function()
+      keymap.listen('i', '<M-j>', function()
+        vim.api.nvim_feedkeys(keymap.t('<C-n>'), 'int', true)
+      end)
+      vim.api.nvim_feedkeys(keymap.t('iaiueo<CR>a<M-j><M-j>'), 'tx', true)
+      assert.are.same({ 'aiueo', 'aiueo' }, vim.api.nvim_buf_get_lines(0, 0, -1, true))
+    end)
+
+    it('#744', function()
+      vim.api.nvim_buf_set_keymap(0, 'i', '<C-r>', 'recursive', {
+        noremap = true,
+      })
+      vim.api.nvim_buf_set_keymap(0, 'i', '<CR>', '<CR>recursive', {
+        noremap = false,
+      })
+      keymap.listen('i', '<CR>', function(_, fallback)
+        fallback()
+      end)
+      feedkeys.call(keymap.t('i<CR>'), 'tx')
+      assert.are.same({ '', 'recursive' }, vim.api.nvim_buf_get_lines(0, 0, -1, true))
+    end)
+  end)
+end)
diff --git a/start/cmp/lua/cmp/utils/misc.lua b/start/cmp/lua/cmp/utils/misc.lua
new file mode 100644
index 0000000..7c6d0e7
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/misc.lua
@@ -0,0 +1,253 @@
+local misc = {}
+
+---Create once callback
+---@param callback function
+---@return function
+misc.once = function(callback)
+  local done = false
+  return function(...)
+    if done then
+      return
+    end
+    done = true
+    callback(...)
+  end
+end
+
+---Return concatenated list
+---@param list1 any[]
+---@param list2 any[]
+---@return any[]
+misc.concat = function(list1, list2)
+  local new_list = {}
+  for _, v in ipairs(list1) do
+    table.insert(new_list, v)
+  end
+  for _, v in ipairs(list2) do
+    table.insert(new_list, v)
+  end
+  return new_list
+end
+
+---Repeat values
+---@generic T
+---@param str_or_tbl T
+---@param count number
+---@return T
+misc.rep = function(str_or_tbl, count)
+  if type(str_or_tbl) == 'string' then
+    return string.rep(str_or_tbl, count)
+  end
+  local rep = {}
+  for _ = 1, count do
+    for _, v in ipairs(str_or_tbl) do
+      table.insert(rep, v)
+    end
+  end
+  return rep
+end
+
+---Return the valu is empty or not.
+---@param v any
+---@return boolean
+misc.empty = function(v)
+  if not v then
+    return true
+  end
+  if v == vim.NIL then
+    return true
+  end
+  if type(v) == 'string' and v == '' then
+    return true
+  end
+  if type(v) == 'table' and vim.tbl_isempty(v) then
+    return true
+  end
+  if type(v) == 'number' and v == 0 then
+    return true
+  end
+  return false
+end
+
+---The symbol to remove key in misc.merge.
+misc.none = vim.NIL
+
+---Merge two tables recursively
+---@generic T
+---@param v1 T
+---@param v2 T
+---@return T
+misc.merge = function(v1, v2)
+  local merge1 = type(v1) == 'table' and (not vim.tbl_islist(v1) or vim.tbl_isempty(v1))
+  local merge2 = type(v2) == 'table' and (not vim.tbl_islist(v2) or vim.tbl_isempty(v2))
+  if merge1 and merge2 then
+    local new_tbl = {}
+    for k, v in pairs(v2) do
+      new_tbl[k] = misc.merge(v1[k], v)
+    end
+    for k, v in pairs(v1) do
+      if v2[k] == nil and v ~= misc.none then
+        new_tbl[k] = v
+      end
+    end
+    return new_tbl
+  end
+  if v1 == misc.none then
+    return nil
+  end
+  if v1 == nil then
+    if v2 == misc.none then
+      return nil
+    else
+      return v2
+    end
+  end
+  if v1 == true then
+    if merge2 then
+      return v2
+    end
+    return {}
+  end
+
+  return v1
+end
+
+---Generate id for group name
+misc.id = setmetatable({
+  group = {},
+}, {
+  __call = function(_, group)
+    misc.id.group[group] = misc.id.group[group] or 0
+    misc.id.group[group] = misc.id.group[group] + 1
+    return misc.id.group[group]
+  end,
+})
+
+---Check the value is nil or not.
+---@param v boolean
+---@return boolean
+misc.safe = function(v)
+  if v == nil or v == vim.NIL then
+    return nil
+  end
+  return v
+end
+
+---Treat 1/0 as bool value
+---@param v boolean|1|0
+---@param def boolean
+---@return boolean
+misc.bool = function(v, def)
+  if misc.safe(v) == nil then
+    return def
+  end
+  return v == true or v == 1
+end
+
+---Set value to deep object
+---@param t table
+---@param keys string[]
+---@param v any
+misc.set = function(t, keys, v)
+  local c = t
+  for i = 1, #keys - 1 do
+    local key = keys[i]
+    c[key] = misc.safe(c[key]) or {}
+    c = c[key]
+  end
+  c[keys[#keys]] = v
+end
+
+---Copy table
+---@generic T
+---@param tbl T
+---@return T
+misc.copy = function(tbl)
+  if type(tbl) ~= 'table' then
+    return tbl
+  end
+
+  if vim.tbl_islist(tbl) then
+    local copy = {}
+    for i, value in ipairs(tbl) do
+      copy[i] = misc.copy(value)
+    end
+    return copy
+  end
+
+  local copy = {}
+  for key, value in pairs(tbl) do
+    copy[key] = misc.copy(value)
+  end
+  return copy
+end
+
+---Safe version of vim.str_utfindex
+---@param text string
+---@param vimindex number|nil
+---@return number
+misc.to_utfindex = function(text, vimindex)
+  vimindex = vimindex or #text + 1
+  return vim.str_utfindex(text, math.max(0, math.min(vimindex - 1, #text)))
+end
+
+---Safe version of vim.str_byteindex
+---@param text string
+---@param utfindex number
+---@return number
+misc.to_vimindex = function(text, utfindex)
+  utfindex = utfindex or #text
+  for i = utfindex, 1, -1 do
+    local s, v = pcall(function()
+      return vim.str_byteindex(text, i) + 1
+    end)
+    if s then
+      return v
+    end
+  end
+  return utfindex + 1
+end
+
+---Mark the function as deprecated
+misc.deprecated = function(fn, msg)
+  local printed = false
+  return function(...)
+    if not printed then
+      print(msg)
+      printed = true
+    end
+    return fn(...)
+  end
+end
+
+--Redraw
+misc.redraw = setmetatable({
+  doing = false,
+  force = false,
+  termcode = vim.api.nvim_replace_termcodes('<C-r><Esc>', true, true, true),
+}, {
+  __call = function(self, force)
+    if vim.tbl_contains({ '/', '?' }, vim.fn.getcmdtype()) then
+      if vim.o.incsearch then
+        return vim.api.nvim_feedkeys(self.termcode, 'in', true)
+      end
+    end
+
+    if self.doing then
+      return
+    end
+    self.doing = true
+    self.force = not not force
+    vim.schedule(function()
+      if self.force then
+        vim.cmd([[redraw!]])
+      else
+        vim.cmd([[redraw]])
+      end
+      self.doing = false
+      self.force = false
+    end)
+  end,
+})
+
+return misc
diff --git a/start/cmp/lua/cmp/utils/misc_spec.lua b/start/cmp/lua/cmp/utils/misc_spec.lua
new file mode 100644
index 0000000..f687155
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/misc_spec.lua
@@ -0,0 +1,63 @@
+local spec = require('cmp.utils.spec')
+
+local misc = require('cmp.utils.misc')
+
+describe('misc', function()
+  before_each(spec.before)
+
+  it('merge', function()
+    local merged
+    merged = misc.merge({
+      a = {},
+    }, {
+      a = {
+        b = 1,
+      },
+    })
+    assert.are.equal(merged.a.b, 1)
+
+    merged = misc.merge({
+      a = {
+        i = 1,
+      },
+    }, {
+      a = {
+        c = 2,
+      },
+    })
+    assert.are.equal(merged.a.i, 1)
+    assert.are.equal(merged.a.c, 2)
+
+    merged = misc.merge({
+      a = false,
+    }, {
+      a = {
+        b = 1,
+      },
+    })
+    assert.are.equal(merged.a, false)
+
+    merged = misc.merge({
+      a = misc.none,
+    }, {
+      a = {
+        b = 1,
+      },
+    })
+    assert.are.equal(merged.a, nil)
+
+    merged = misc.merge({
+      a = misc.none,
+    }, {
+      a = nil,
+    })
+    assert.are.equal(merged.a, nil)
+
+    merged = misc.merge({
+      a = nil,
+    }, {
+      a = misc.none,
+    })
+    assert.are.equal(merged.a, nil)
+  end)
+end)
diff --git a/start/cmp/lua/cmp/utils/pattern.lua b/start/cmp/lua/cmp/utils/pattern.lua
new file mode 100644
index 0000000..1481e84
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/pattern.lua
@@ -0,0 +1,28 @@
+local pattern = {}
+
+pattern._regexes = {}
+
+pattern.regex = function(p)
+  if not pattern._regexes[p] then
+    pattern._regexes[p] = vim.regex(p)
+  end
+  return pattern._regexes[p]
+end
+
+pattern.offset = function(p, text)
+  local s, e = pattern.regex(p):match_str(text)
+  if s then
+    return s + 1, e + 1
+  end
+  return nil, nil
+end
+
+pattern.matchstr = function(p, text)
+  local s, e = pattern.offset(p, text)
+  if s then
+    return string.sub(text, s, e)
+  end
+  return nil
+end
+
+return pattern
diff --git a/start/cmp/lua/cmp/utils/spec.lua b/start/cmp/lua/cmp/utils/spec.lua
new file mode 100644
index 0000000..a4b2c83
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/spec.lua
@@ -0,0 +1,92 @@
+local context = require('cmp.context')
+local source = require('cmp.source')
+local types = require('cmp.types')
+local config = require('cmp.config')
+
+local spec = {}
+
+spec.before = function()
+  vim.cmd([[
+    bdelete!
+    enew!
+    imapclear
+    imapclear <buffer>
+    cmapclear
+    cmapclear <buffer>
+    smapclear
+    smapclear <buffer>
+    xmapclear
+    xmapclear <buffer>
+    tmapclear
+    tmapclear <buffer>
+    setlocal noswapfile
+    setlocal virtualedit=all
+    setlocal completeopt=menu,menuone,noselect
+  ]])
+  config.set_global({
+    sources = {
+      { name = 'spec' },
+    },
+    snippet = {
+      expand = function(args)
+        local ctx = context.new()
+        vim.api.nvim_buf_set_text(ctx.bufnr, ctx.cursor.row - 1, ctx.cursor.col - 1, ctx.cursor.row - 1, ctx.cursor.col - 1, vim.split(string.gsub(args.body, '%$0', ''), '\n'))
+        for i, t in ipairs(vim.split(args.body, '\n')) do
+          local s = string.find(t, '$0', 1, true)
+          if s then
+            if i == 1 then
+              vim.api.nvim_win_set_cursor(0, { ctx.cursor.row, ctx.cursor.col + s - 2 })
+            else
+              vim.api.nvim_win_set_cursor(0, { ctx.cursor.row + i - 1, s - 1 })
+            end
+            break
+          end
+        end
+      end,
+    },
+  })
+  config.set_cmdline({
+    sources = {
+      { name = 'spec' },
+    },
+  }, ':')
+end
+
+spec.state = function(text, row, col)
+  vim.fn.setline(1, text)
+  vim.fn.cursor(row, col)
+  local ctx = context.empty()
+  local s = source.new('spec', {
+    complete = function() end,
+  })
+  return {
+    context = function()
+      return ctx
+    end,
+    source = function()
+      return s
+    end,
+    backspace = function()
+      vim.fn.feedkeys('x', 'nx')
+      vim.fn.feedkeys('h', 'nx')
+      ctx = context.new(ctx, { reason = types.cmp.ContextReason.Auto })
+      s:complete(ctx, function() end)
+      return ctx
+    end,
+    input = function(char)
+      vim.fn.feedkeys(('i%s'):format(char), 'nx')
+      vim.fn.feedkeys(string.rep('l', #char), 'nx')
+      ctx.prev_context = nil
+      ctx = context.new(ctx, { reason = types.cmp.ContextReason.Auto })
+      s:complete(ctx, function() end)
+      return ctx
+    end,
+    manual = function()
+      ctx = context.new(ctx, { reason = types.cmp.ContextReason.Manual })
+      s:complete(ctx, function() end)
+      return ctx
+    end,
+  }
+end
+
+return spec
diff --git a/start/cmp/lua/cmp/utils/str.lua b/start/cmp/lua/cmp/utils/str.lua
new file mode 100644
index 0000000..bca210c
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/str.lua
@@ -0,0 +1,178 @@
+local char = require('cmp.utils.char')
+
+local str = {}
+
+local INVALIDS = {}
+INVALIDS[string.byte("'")] = true
+INVALIDS[string.byte('"')] = true
+INVALIDS[string.byte('=')] = true
+INVALIDS[string.byte('$')] = true
+INVALIDS[string.byte('(')] = true
+INVALIDS[string.byte('[')] = true
+INVALIDS[string.byte('<')] = true
+INVALIDS[string.byte('{')] = true
+INVALIDS[string.byte(' ')] = true
+INVALIDS[string.byte('\t')] = true
+INVALIDS[string.byte('\n')] = true
+INVALIDS[string.byte('\r')] = true
+
+local NR_BYTE = string.byte('\n')
+
+local PAIRS = {}
+PAIRS[string.byte('<')] = string.byte('>')
+PAIRS[string.byte('[')] = string.byte(']')
+PAIRS[string.byte('(')] = string.byte(')')
+PAIRS[string.byte('{')] = string.byte('}')
+PAIRS[string.byte('"')] = string.byte('"')
+PAIRS[string.byte("'")] = string.byte("'")
+
+---Return if specified text has prefix or not
+---@param text string
+---@param prefix string
+---@return boolean
+str.has_prefix = function(text, prefix)
+  if #text < #prefix then
+    return false
+  end
+  for i = 1, #prefix do
+    if not char.match(string.byte(text, i), string.byte(prefix, i)) then
+      return false
+    end
+  end
+  return true
+end
+
+---get_common_string
+str.get_common_string = function(text1, text2)
+  local min = math.min(#text1, #text2)
+  for i = 1, min do
+    if not char.match(string.byte(text1, i), string.byte(text2, i)) then
+      return string.sub(text1, 1, i - 1)
+    end
+  end
+  return string.sub(text1, 1, min)
+end
+
+---Remove suffix
+---@param text string
+---@param suffix string
+---@return string
+str.remove_suffix = function(text, suffix)
+  if #text < #suffix then
+    return text
+  end
+
+  local i = 0
+  while i < #suffix do
+    if string.byte(text, #text - i) ~= string.byte(suffix, #suffix - i) then
+      return text
+    end
+    i = i + 1
+  end
+  return string.sub(text, 1, -#suffix - 1)
+end
+
+---trim
+---@param text string
+---@return string
+str.trim = function(text)
+  local s = 1
+  for i = 1, #text do
+    if not char.is_white(string.byte(text, i)) then
+      s = i
+      break
+    end
+  end
+
+  local e = #text
+  for i = #text, 1, -1 do
+    if not char.is_white(string.byte(text, i)) then
+      e = i
+      break
+    end
+  end
+  if s == 1 and e == #text then
+    return text
+  end
+  return string.sub(text, s, e)
+end
+
+---get_word
+---@param text string
+---@param stop_char number
+---@param min_length number
+---@return string
+str.get_word = function(text, stop_char, min_length)
+  min_length = min_length or 0
+
+  local has_alnum = false
+  local stack = {}
+  local word = {}
+  local add = function(c)
+    table.insert(word, string.char(c))
+    if stack[#stack] == c then
+      table.remove(stack, #stack)
+    else
+      if PAIRS[c] then
+        table.insert(stack, c)
+      end
+    end
+  end
+  for i = 1, #text do
+    local c = string.byte(text, i, i)
+    if #word < min_length then
+      table.insert(word, string.char(c))
+    elseif not INVALIDS[c] then
+      add(c)
+      has_alnum = has_alnum or char.is_alnum(c)
+    elseif not has_alnum then
+      add(c)
+    elseif #stack ~= 0 then
+      add(c)
+      if has_alnum and #stack == 0 then
+        break
+      end
+    else
+      break
+    end
+  end
+  if stop_char and word[#word] == string.char(stop_char) then
+    table.remove(word, #word)
+  end
+  return table.concat(word, '')
+end
+
+---Oneline
+---@param text string
+---@return string
+str.oneline = function(text)
+  for i = 1, #text do
+    if string.byte(text, i) == NR_BYTE then
+      return string.sub(text, 1, i - 1)
+    end
+  end
+  return text
+end
+
+---Escape special chars
+---@param text string
+---@param chars string[]
+---@return string
+str.escape = function(text, chars)
+  table.insert(chars, '\\')
+  local escaped = {}
+  local i = 1
+  while i <= #text do
+    local c = string.sub(text, i, i)
+    if vim.tbl_contains(chars, c) then
+      table.insert(escaped, '\\')
+      table.insert(escaped, c)
+    else
+      table.insert(escaped, c)
+    end
+    i = i + 1
+  end
+  return table.concat(escaped, '')
+end
+
+return str
diff --git a/start/cmp/lua/cmp/utils/str_spec.lua b/start/cmp/lua/cmp/utils/str_spec.lua
new file mode 100644
index 0000000..1a21855
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/str_spec.lua
@@ -0,0 +1,29 @@
+local str = require('cmp.utils.str')
+
+describe('utils.str', function()
+  it('get_word', function()
+    assert.are.equal(str.get_word('print'), 'print')
+    assert.are.equal(str.get_word('$variable'), '$variable')
+    assert.are.equal(str.get_word('print()'), 'print')
+    assert.are.equal(str.get_word('["cmp#confirm"]'), '["cmp#confirm"]')
+    assert.are.equal(str.get_word('"devDependencies":', string.byte('"')), '"devDependencies')
+    assert.are.equal(str.get_word('"devDependencies": ${1},', string.byte('"')), '"devDependencies')
+    assert.are.equal(str.get_word('#[cfg(test)]'), '#[cfg(test)]')
+    assert.are.equal(str.get_word('import { GetStaticProps$1 } from "next";', nil, 9), 'import { GetStaticProps')
+  end)
+
+  it('remove_suffix', function()
+    assert.are.equal(str.remove_suffix('log()', '$0'), 'log()')
+    assert.are.equal(str.remove_suffix('log()$0', '$0'), 'log()')
+    assert.are.equal(str.remove_suffix('log()${0}', '${0}'), 'log()')
+    assert.are.equal(str.remove_suffix('log()${0:placeholder}', '${0}'), 'log()${0:placeholder}')
+  end)
+
+  it('escape', function()
+    assert.are.equal(str.escape('plain', {}), 'plain')
+    assert.are.equal(str.escape('plain\\', {}), 'plain\\\\')
+    assert.are.equal(str.escape('plain\\"', {}), 'plain\\\\"')
+    assert.are.equal(str.escape('pla"in', { '"' }), 'pla\\"in')
+    assert.are.equal(str.escape('call("")', { '"' }), 'call(\\"\\")')
+  end)
+end)
diff --git a/start/cmp/lua/cmp/utils/window.lua b/start/cmp/lua/cmp/utils/window.lua
new file mode 100644
index 0000000..a8a271e
--- /dev/null
+++ b/start/cmp/lua/cmp/utils/window.lua
@@ -0,0 +1,313 @@
+local cache = require('cmp.utils.cache')
+local misc = require('cmp.utils.misc')
+local buffer = require('cmp.utils.buffer')
+local api = require('cmp.utils.api')
+
+---@class cmp.WindowStyle
+---@field public relative string
+---@field public row number
+---@field public col number
+---@field public width number
+---@field public height number
+---@field public border string|string[]|nil
+---@field public zindex number|nil
+
+---@class cmp.Window
+---@field public name string
+---@field public win number|nil
+---@field public thumb_win number|nil
+---@field public sbar_win number|nil
+---@field public style cmp.WindowStyle
+---@field public opt table<string, any>
+---@field public buffer_opt table<string, any>
+---@field public cache cmp.Cache
+local window = {}
+
+---new
+---@return cmp.Window
+window.new = function()
+  local self = setmetatable({}, { __index = window })
+  self.name = misc.id('cmp.utils.window.new')
+  self.win = nil
+  self.sbar_win = nil
+  self.thumb_win = nil
+  self.style = {}
+  self.cache = cache.new()
+  self.opt = {}
+  self.buffer_opt = {}
+  return self
+end
+
+---Set window option.
+---NOTE: If the window already visible, immediately applied to it.
+---@param key string
+---@param value any
+window.option = function(self, key, value)
+  if vim.fn.exists('+' .. key) == 0 then
+    return
+  end
+
+  if value == nil then
+    return self.opt[key]
+  end
+
+  self.opt[key] = value
+  if self:visible() then
+    vim.api.nvim_win_set_option(self.win, key, value)
+  end
+end
+
+---Set buffer option.
+---NOTE: If the buffer already visible, immediately applied to it.
+---@param key string
+---@param value any
+window.buffer_option = function(self, key, value)
+  if vim.fn.exists('+' .. key) == 0 then
+    return
+  end
+
+  if value == nil then
+    return self.buffer_opt[key]
+  end
+
+  self.buffer_opt[key] = value
+  local existing_buf = buffer.get(self.name)
+  if existing_buf then
+    vim.api.nvim_buf_set_option(existing_buf, key, value)
+  end
+end
+
+---Set style.
+---@param style cmp.WindowStyle
+window.set_style = function(self, style)
+  self.style = style
+  local info = self:info()
+
+  if vim.o.lines and vim.o.lines <= info.row + info.height + 1 then
+    self.style.height = vim.o.lines - info.row - info.border_info.vert - 1
+  end
+
+  self.style.zindex = self.style.zindex or 1
+end
+
+---Return buffer id.
+---@return number
+window.get_buffer = function(self)
+  local buf, created_new = buffer.ensure(self.name)
+  if created_new then
+    for k, v in pairs(self.buffer_opt) do
+      vim.api.nvim_buf_set_option(buf, k, v)
+    end
+  end
+  return buf
+end
+
+---Open window
+---@param style cmp.WindowStyle
+window.open = function(self, style)
+  if style then
+    self:set_style(style)
+  end
+
+  if self.style.width < 1 or self.style.height < 1 then
+    return
+  end
+
+  if self.win and vim.api.nvim_win_is_valid(self.win) then
+    vim.api.nvim_win_set_config(self.win, self.style)
+  else
+    local s = misc.copy(self.style)
+    s.noautocmd = true
+    self.win = vim.api.nvim_open_win(self:get_buffer(), false, s)
+    for k, v in pairs(self.opt) do
+      vim.api.nvim_win_set_option(self.win, k, v)
+    end
+  end
+  self:update()
+end
+
+---Update
+window.update = function(self)
+  local info = self:info()
+  if info.scrollable then
+    -- Draw the background of the scrollbar
+
+    if not info.border_info.visible then
+      local style = {
+        relative = 'editor',
+        style = 'minimal',
+        width = 1,
+        height = self.style.height,
+        row = info.row,
+        col = info.col + info.width - info.scrollbar_offset, -- info.col was already contained the scrollbar offset.
+        zindex = (self.style.zindex and (self.style.zindex + 1) or 1),
+      }
+      if self.sbar_win and vim.api.nvim_win_is_valid(self.sbar_win) then
+        vim.api.nvim_win_set_config(self.sbar_win, style)
+      else
+        style.noautocmd = true
+        self.sbar_win = vim.api.nvim_open_win(buffer.ensure(self.name .. 'sbar_buf'), false, style)
+        vim.api.nvim_win_set_option(self.sbar_win, 'winhighlight', 'EndOfBuffer:PmenuSbar,NormalFloat:PmenuSbar')
+      end
+    end
+
+    -- Draw the scrollbar thumb
+    local thumb_height = math.floor(info.inner_height * (info.inner_height / self:get_content_height()) + 0.5)
+    local thumb_offset = math.floor(info.inner_height * (vim.fn.getwininfo(self.win)[1].topline / self:get_content_height()))
+
+    local style = {
+      relative = 'editor',
+      style = 'minimal',
+      width = 1,
+      height = math.max(1, thumb_height),
+      row = info.row + thumb_offset + (info.border_info.visible and info.border_info.top or 0),
+      col = info.col + info.width - 1, -- info.col was already added scrollbar offset.
+      zindex = (self.style.zindex and (self.style.zindex + 2) or 2),
+    }
+    if self.thumb_win and vim.api.nvim_win_is_valid(self.thumb_win) then
+      vim.api.nvim_win_set_config(self.thumb_win, style)
+    else
+      style.noautocmd = true
+      self.thumb_win = vim.api.nvim_open_win(buffer.ensure(self.name .. 'thumb_buf'), false, style)
+      vim.api.nvim_win_set_option(self.thumb_win, 'winhighlight', 'EndOfBuffer:PmenuThumb,NormalFloat:PmenuThumb')
+    end
+  else
+    if self.sbar_win and vim.api.nvim_win_is_valid(self.sbar_win) then
+      vim.api.nvim_win_hide(self.sbar_win)
+      self.sbar_win = nil
+    end
+    if self.thumb_win and vim.api.nvim_win_is_valid(self.thumb_win) then
+      vim.api.nvim_win_hide(self.thumb_win)
+      self.thumb_win = nil
+    end
+  end
+
+  -- In cmdline, vim does not redraw automatically.
+  if api.is_cmdline_mode() then
+    vim.api.nvim_win_call(self.win, function()
+      misc.redraw()
+    end)
+  end
+end
+
+---Close window
+window.close = function(self)
+  if self.win and vim.api.nvim_win_is_valid(self.win) then
+    if self.win and vim.api.nvim_win_is_valid(self.win) then
+      vim.api.nvim_win_hide(self.win)
+      self.win = nil
+    end
+    if self.sbar_win and vim.api.nvim_win_is_valid(self.sbar_win) then
+      vim.api.nvim_win_hide(self.sbar_win)
+      self.sbar_win = nil
+    end
+    if self.thumb_win and vim.api.nvim_win_is_valid(self.thumb_win) then
+      vim.api.nvim_win_hide(self.thumb_win)
+      self.thumb_win = nil
+    end
+  end
+end
+
+---Return the window is visible or not.
+window.visible = function(self)
+  return self.win and vim.api.nvim_win_is_valid(self.win)
+end
+
+---Return win info.
+window.info = function(self)
+  local border_info = self:get_border_info()
+  local info = {
+    row = self.style.row,
+    col = self.style.col,
+    width = self.style.width + border_info.left + border_info.right,
+    height = self.style.height + border_info.top + border_info.bottom,
+    inner_width = self.style.width,
+    inner_height = self.style.height,
+    border_info = border_info,
+    scrollable = false,
+    scrollbar_offset = 0,
+  }
+
+  if self:get_content_height() > info.inner_height then
+    info.scrollable = true
+    if not border_info.visible then
+      info.scrollbar_offset = 1
+      info.width = info.width + 1
+    end
+  end
+
+  return info
+end
+
+---Return border information.
+---@return { top: number, left: number, right: number, bottom: number, vert: number, horiz: number, visible: boolean }
+window.get_border_info = function(self)
+  local border = self.style.border
+  if not border or border == 'none' then
+    return {
+      top = 0,
+      left = 0,
+      right = 0,
+      bottom = 0,
+      vert = 0,
+      horiz = 0,
+      visible = false,
+    }
+  end
+  if type(border) == 'string' then
+    if border == 'shadow' then
+      return {
+        top = 0,
+        left = 0,
+        right = 1,
+        bottom = 1,
+        vert = 1,
+        horiz = 1,
+        visible = false,
+      }
+    end
+    return {
+      top = 1,
+      left = 1,
+      right = 1,
+      bottom = 1,
+      vert = 2,
+      horiz = 2,
+      visible = true,
+    }
+  end
+
+  local new_border = {}
+  while #new_border <= 8 do
+    for _, b in ipairs(border) do
+      table.insert(new_border, type(b) == 'string' and b or b[1])
+    end
+  end
+  local info = {}
+  info.top = new_border[2] == '' and 0 or 1
+  info.right = new_border[4] == '' and 0 or 1
+  info.bottom = new_border[6] == '' and 0 or 1
+  info.left = new_border[8] == '' and 0 or 1
+  info.vert = info.top + info.bottom
+  info.horiz = info.left + info.right
+  info.visible = not (vim.tbl_contains({ '', ' ' }, new_border[2]) and vim.tbl_contains({ '', ' ' }, new_border[4]) and vim.tbl_contains({ '', ' ' }, new_border[6]) and vim.tbl_contains({ '', ' ' }, new_border[8]))
+  return info
+end
+
+---Get scroll height.
+---NOTE: The result of vim.fn.strdisplaywidth depends on the buffer it was called in (see comment in cmp.Entry.get_view).
+---@return number
+window.get_content_height = function(self)
+  if not self:option('wrap') then
+    return vim.api.nvim_buf_line_count(self:get_buffer())
+  end
+  local height = 0
+  vim.api.nvim_buf_call(self:get_buffer(), function()
+    for _, text in ipairs(vim.api.nvim_buf_get_lines(self:get_buffer(), 0, -1, false)) do
+      height = height + math.max(1, math.ceil(vim.fn.strdisplaywidth(text) / self.style.width))
+    end
+  end)
+  return height
+end
+
+return window
diff --git a/start/cmp/lua/cmp/view.lua b/start/cmp/lua/cmp/view.lua
new file mode 100644
index 0000000..981378b
--- /dev/null
+++ b/start/cmp/lua/cmp/view.lua
@@ -0,0 +1,243 @@
+local config = require('cmp.config')
+local async = require('cmp.utils.async')
+local event = require('cmp.utils.event')
+local keymap = require('cmp.utils.keymap')
+local docs_view = require('cmp.view.docs_view')
+local custom_entries_view = require('cmp.view.custom_entries_view')
+local wildmenu_entries_view = require('cmp.view.wildmenu_entries_view')
+local native_entries_view = require('cmp.view.native_entries_view')
+local ghost_text_view = require('cmp.view.ghost_text_view')
+
+---@class cmp.View
+---@field public event cmp.Event
+---@field private resolve_dedup cmp.AsyncDedup
+---@field private native_entries_view cmp.NativeEntriesView
+---@field private custom_entries_view cmp.CustomEntriesView
+---@field private wildmenu_entries_view cmp.CustomEntriesView
+---@field private change_dedup cmp.AsyncDedup
+---@field private docs_view cmp.DocsView
+---@field private ghost_text_view cmp.GhostTextView
+local view = {}
+
+---Create menu
+view.new = function()
+  local self = setmetatable({}, { __index = view })
+  self.resolve_dedup = async.dedup()
+  self.custom_entries_view = custom_entries_view.new()
+  self.native_entries_view = native_entries_view.new()
+  self.wildmenu_entries_view = wildmenu_entries_view.new()
+  self.docs_view = docs_view.new()
+  self.ghost_text_view = ghost_text_view.new()
+  self.event = event.new()
+
+  return self
+end
+
+---Return the view components are available or not.
+---@return boolean
+view.ready = function(self)
+  return self:_get_entries_view():ready()
+end
+
+---OnChange handler.
+view.on_change = function(self)
+  self:_get_entries_view():on_change()
+end
+
+---Open menu
+---@param ctx cmp.Context
+---@param sources cmp.Source[]
+view.open = function(self, ctx, sources)
+  local source_group_map = {}
+  for _, s in ipairs(sources) do
+    local group_index = s:get_source_config().group_index or 0
+    if not source_group_map[group_index] then
+      source_group_map[group_index] = {}
+    end
+    table.insert(source_group_map[group_index], s)
+  end
+
+  local group_indexes = vim.tbl_keys(source_group_map)
+  table.sort(group_indexes, function(a, b)
+    return a ~= b and (a < b) or nil
+  end)
+
+  local entries = {}
+  for _, group_index in ipairs(group_indexes) do
+    local source_group = source_group_map[group_index] or {}
+
+    -- check the source triggered by character
+    local has_triggered_by_symbol_source = false
+    for _, s in ipairs(source_group) do
+      if #s:get_entries(ctx) > 0 then
+        if s.is_triggered_by_symbol then
+          has_triggered_by_symbol_source = true
+          break
+        end
+      end
+    end
+
+    -- create filtered entries.
+    local offset = ctx.cursor.col
+    for i, s in ipairs(source_group) do
+      if s.offset <= ctx.cursor.col then
+        if not has_triggered_by_symbol_source or s.is_triggered_by_symbol then
+          -- source order priority bonus.
+          local priority = s:get_source_config().priority or ((#source_group - (i - 1)) * config.get().sorting.priority_weight)
+
+          for _, e in ipairs(s:get_entries(ctx)) do
+            e.score = e.score + priority
+            table.insert(entries, e)
+            offset = math.min(offset, e:get_offset())
+          end
+        end
+      end
+    end
+
+    -- sort.
+    local comparetors = config.get().sorting.comparators
+    table.sort(entries, function(e1, e2)
+      for _, fn in ipairs(comparetors) do
+        local diff = fn(e1, e2)
+        if diff ~= nil then
+          return diff
+        end
+      end
+    end)
+
+    -- open
+    if #entries > 0 then
+      self:_get_entries_view():open(offset, entries)
+      break
+    end
+  end
+
+  -- complete_done.
+  if #entries == 0 then
+    self:close()
+  end
+end
+
+---Close menu
+view.close = function(self)
+  if self:visible() then
+    self.event:emit('complete_done', {
+      entry = self:_get_entries_view():get_selected_entry(),
+    })
+  end
+  self:_get_entries_view():close()
+  self.docs_view:close()
+  self.ghost_text_view:hide()
+end
+
+---Abort menu
+view.abort = function(self)
+  self:_get_entries_view():abort()
+  self.docs_view:close()
+  self.ghost_text_view:hide()
+end
+
+---Return the view is visible or not.
+---@return boolean
+view.visible = function(self)
+  return self:_get_entries_view():visible()
+end
+
+---Scroll documentation window if possible.
+---@param delta number
+view.scroll_docs = function(self, delta)
+  self.docs_view:scroll(delta)
+end
+
+---Select prev menu item.
+---@param option cmp.SelectOption
+view.select_next_item = function(self, option)
+  self:_get_entries_view():select_next_item(option)
+end
+
+---Select prev menu item.
+---@param option cmp.SelectOption
+view.select_prev_item = function(self, option)
+  self:_get_entries_view():select_prev_item(option)
+end
+
+---Get offset.
+view.get_offset = function(self)
+  return self:_get_entries_view():get_offset()
+end
+
+---Get entries.
+---@return cmp.Entry[]
+view.get_entries = function(self)
+  return self:_get_entries_view():get_entries()
+end
+
+---Get first entry
+---@param self cmp.Entry|nil
+view.get_first_entry = function(self)
+  return self:_get_entries_view():get_first_entry()
+end
+
+---Get current selected entry
+---@return cmp.Entry|nil
+view.get_selected_entry = function(self)
+  return self:_get_entries_view():get_selected_entry()
+end
+
+---Get current active entry
+---@return cmp.Entry|nil
+view.get_active_entry = function(self)
+  return self:_get_entries_view():get_active_entry()
+end
+
+---Return current configured entries_view
+---@return cmp.CustomEntriesView|cmp.NativeEntriesView
+view._get_entries_view = function(self)
+  self.native_entries_view.event:clear()
+  self.custom_entries_view.event:clear()
+  self.wildmenu_entries_view.event:clear()
+
+  local c = config.get()
+  local v = self.custom_entries_view
+  if (c.view and c.view.entries and (c.view.entries.name or c.view.entries)) == 'wildmenu' then
+    v = self.wildmenu_entries_view
+  elseif (c.view and c.view.entries and (c.view.entries.name or c.view.entries)) == 'native' then
+    v = self.native_entries_view
+  end
+  v.event:on('change', function()
+    self:on_entry_change()
+  end)
+  return v
+end
+
+---On entry change
+view.on_entry_change = async.throttle(function(self)
+  if not self:visible() then
+    return
+  end
+  local e = self:get_selected_entry()
+  if e then
+    for _, c in ipairs(config.get().confirmation.get_commit_characters(e:get_commit_characters())) do
+      keymap.listen('i', c, function(...)
+        self.event:emit('keymap', ...)
+      end)
+    end
+    e:resolve(vim.schedule_wrap(self.resolve_dedup(function()
+      if not self:visible() then
+        return
+      end
+      self.docs_view:open(e, self:_get_entries_view():info())
+    end)))
+  else
+    self.docs_view:close()
+  end
+
+  e = e or self:get_first_entry()
+  if e then
+    self.ghost_text_view:show(e)
+  else
+    self.ghost_text_view:hide()
+  end
+end, 20)
+
+return view
diff --git a/start/cmp/lua/cmp/view/custom_entries_view.lua b/start/cmp/lua/cmp/view/custom_entries_view.lua
new file mode 100644
index 0000000..8020a9b
--- /dev/null
+++ b/start/cmp/lua/cmp/view/custom_entries_view.lua
@@ -0,0 +1,409 @@
+local event = require('cmp.utils.event')
+local autocmd = require('cmp.utils.autocmd')
+local feedkeys = require('cmp.utils.feedkeys')
+local window = require('cmp.utils.window')
+local config = require('cmp.config')
+local types = require('cmp.types')
+local keymap = require('cmp.utils.keymap')
+local misc = require('cmp.utils.misc')
+local api = require('cmp.utils.api')
+
+local SIDE_PADDING = 1
+
+local DEFAULT_HEIGHT = 10 -- @see https://github.com/vim/vim/blob/master/src/popupmenu.c#L45
+
+---@class cmp.CustomEntriesView
+---@field private entries_win cmp.Window
+---@field private offset number
+---@field private active boolean
+---@field private entries cmp.Entry[]
+---@field private column_width any
+---@field public event cmp.Event
+local custom_entries_view = {}
+
+custom_entries_view.ns = vim.api.nvim_create_namespace('cmp.view.custom_entries_view')
+
+custom_entries_view.new = function()
+  local self = setmetatable({}, { __index = custom_entries_view })
+
+  self.entries_win = window.new()
+  self.entries_win:option('conceallevel', 2)
+  self.entries_win:option('concealcursor', 'n')
+  self.entries_win:option('cursorlineopt', 'line')
+  self.entries_win:option('foldenable', false)
+  self.entries_win:option('wrap', false)
+  self.entries_win:option('scrolloff', 0)
+  -- This is done so that strdisplaywidth calculations for lines in the
+  -- custom_entries_view window exactly match with what is really displayed,
+  -- see comment in cmp.Entry.get_view. Setting tabstop to 1 makes all tabs be
+  -- always rendered one column wide, which removes the unpredictability coming
+  -- from variable width of the tab character.
+  self.entries_win:buffer_option('tabstop', 1)
+  self.event = event.new()
+  self.offset = -1
+  self.active = false
+  self.entries = {}
+  self.bottom_up = false
+
+  autocmd.subscribe(
+    'CompleteChanged',
+    vim.schedule_wrap(function()
+      if self:visible() and vim.fn.pumvisible() == 1 then
+        self:close()
+      end
+    end)
+  )
+
+  vim.api.nvim_set_decoration_provider(custom_entries_view.ns, {
+    on_win = function(_, win, buf, top, bot)
+      if win ~= self.entries_win.win or buf ~= self.entries_win:get_buffer() then
+        return
+      end
+
+      local fields = config.get().formatting.fields
+      for i = top, bot do
+        local e = self.entries[i + 1]
+        if e then
+          local v = e:get_view(self.offset, buf)
+          local o = SIDE_PADDING
+          local a = 0
+          for _, field in ipairs(fields) do
+            if field == types.cmp.ItemField.Abbr then
+              a = o
+            end
+            vim.api.nvim_buf_set_extmark(buf, custom_entries_view.ns, i, o, {
+              end_line = i,
+              end_col = o + v[field].bytes,
+              hl_group = v[field].hl_group,
+              hl_mode = 'combine',
+              ephemeral = true,
+            })
+            o = o + v[field].bytes + (self.column_width[field] - v[field].width) + 1
+          end
+
+          for _, m in ipairs(e.matches or {}) do
+            vim.api.nvim_buf_set_extmark(buf, custom_entries_view.ns, i, a + m.word_match_start - 1, {
+              end_line = i,
+              end_col = a + m.word_match_end,
+              hl_group = m.fuzzy and 'CmpItemAbbrMatchFuzzy' or 'CmpItemAbbrMatch',
+              hl_mode = 'combine',
+              ephemeral = true,
+            })
+          end
+        end
+      end
+    end,
+  })
+
+  return self
+end
+
+custom_entries_view.ready = function()
+  return vim.fn.pumvisible() == 0
+end
+
+custom_entries_view.on_change = function(self)
+  self.active = false
+end
+
+custom_entries_view.is_direction_top_down = function(self)
+  local c = config.get()
+  if (c.view and c.view.entries and c.view.entries.selection_order) == 'top_down' then
+    return true
+  elseif c.view.entries == nil or c.view.entries.selection_order == nil then
+    return true
+  else
+    return not self.bottom_up
+  end
+end
+
+custom_entries_view.open = function(self, offset, entries)
+  local completion = config.get().window.completion
+  self.offset = offset
+  self.entries = {}
+  self.column_width = { abbr = 0, kind = 0, menu = 0 }
+
+  local entries_buf = self.entries_win:get_buffer()
+  local lines = {}
+  local dedup = {}
+  local preselect = 0
+  for _, e in ipairs(entries) do
+    local view = e:get_view(offset, entries_buf)
+    if view.dup == 1 or not dedup[e.completion_item.label] then
+      dedup[e.completion_item.label] = true
+      self.column_width.abbr = math.max(self.column_width.abbr, view.abbr.width)
+      self.column_width.kind = math.max(self.column_width.kind, view.kind.width)
+      self.column_width.menu = math.max(self.column_width.menu, view.menu.width)
+      table.insert(self.entries, e)
+      table.insert(lines, ' ')
+      if preselect == 0 and e.completion_item.preselect then
+        preselect = #self.entries
+      end
+    end
+  end
+  vim.api.nvim_buf_set_lines(entries_buf, 0, -1, false, lines)
+  vim.api.nvim_buf_set_option(entries_buf, 'modified', false)
+
+  local width = 0
+  width = width + 1
+  width = width + self.column_width.abbr + (self.column_width.kind > 0 and 1 or 0)
+  width = width + self.column_width.kind + (self.column_width.menu > 0 and 1 or 0)
+  width = width + self.column_width.menu + 1
+
+  local height = vim.api.nvim_get_option('pumheight')
+  height = height ~= 0 and height or #self.entries
+  height = math.min(height, #self.entries)
+
+  local pos = api.get_screen_cursor()
+  local cursor = api.get_cursor()
+  local delta = cursor[2] + 1 - self.offset
+  local row, col = pos[1], pos[2] - delta - 1
+
+  local border_info = window.get_border_info({ style = completion })
+  local border_offset_row = border_info.top + border_info.bottom
+  local border_offset_col = border_info.left + border_info.right
+  if math.floor(vim.o.lines * 0.5) <= row + border_offset_row and vim.o.lines - row - border_offset_row <= math.min(DEFAULT_HEIGHT, height) then
+    height = math.min(height, row - 1)
+    row = row - height - border_offset_row - 1
+    if row < 0 then
+      height = height + row
+    end
+  end
+  if math.floor(vim.o.columns * 0.5) <= col + border_offset_col and vim.o.columns - col - border_offset_col <= width then
+    width = math.min(width, vim.o.columns - 1)
+    col = vim.o.columns - width - border_offset_col - 1
+    if col < 0 then
+      width = width + col
+    end
+  end
+
+  if pos[1] > row then
+    self.bottom_up = true
+  else
+    self.bottom_up = false
+  end
+
+  if not self:is_direction_top_down() then
+    local n = #self.entries
+    for i = 1, math.floor(n / 2) do
+      self.entries[i], self.entries[n - i + 1] = self.entries[n - i + 1], self.entries[i]
+    end
+    if preselect ~= 0 then
+      preselect = #self.entries - preselect + 1
+    end
+  end
+
+  -- Apply window options (that might be changed) on the custom completion menu.
+  self.entries_win:option('winblend', vim.o.pumblend)
+  self.entries_win:option('winhighlight', completion.winhighlight)
+  self.entries_win:open({
+    relative = 'editor',
+    style = 'minimal',
+    row = math.max(0, row),
+    col = math.max(0, col),
+    width = width,
+    height = height,
+    border = completion.border,
+    zindex = completion.zindex or 1001,
+  })
+  -- always set cursor when starting. It will be adjusted on the call to _select
+  vim.api.nvim_win_set_cursor(self.entries_win.win, { 1, 0 })
+  if preselect > 0 and config.get().preselect == types.cmp.PreselectMode.Item then
+    self:_select(preselect, { behavior = types.cmp.SelectBehavior.Select })
+  elseif not string.match(config.get().completion.completeopt, 'noselect') then
+    if self:is_direction_top_down() then
+      self:_select(1, { behavior = types.cmp.SelectBehavior.Select })
+    else
+      self:_select(#self.entries - 1, { behavior = types.cmp.SelectBehavior.Select })
+    end
+  else
+    if self:is_direction_top_down() then
+      self:_select(0, { behavior = types.cmp.SelectBehavior.Select })
+    else
+      self:_select(#self.entries + 1, { behavior = types.cmp.SelectBehavior.Select })
+    end
+  end
+end
+
+custom_entries_view.close = function(self)
+  self.prefix = nil
+  self.offset = -1
+  self.active = false
+  self.entries = {}
+  self.entries_win:close()
+  self.bottom_up = false
+end
+
+custom_entries_view.abort = function(self)
+  if self.prefix then
+    self:_insert(self.prefix)
+  end
+  feedkeys.call('', 'n', function()
+    self:close()
+  end)
+end
+
+custom_entries_view.draw = function(self)
+  local info = vim.fn.getwininfo(self.entries_win.win)[1]
+  local topline = info.topline - 1
+  local botline = info.topline + info.height - 1
+  local texts = {}
+  local fields = config.get().formatting.fields
+  local entries_buf = self.entries_win:get_buffer()
+  for i = topline, botline - 1 do
+    local e = self.entries[i + 1]
+    if e then
+      local view = e:get_view(self.offset, entries_buf)
+      local text = {}
+      table.insert(text, string.rep(' ', SIDE_PADDING))
+      for _, field in ipairs(fields) do
+        table.insert(text, view[field].text)
+        table.insert(text, string.rep(' ', 1 + self.column_width[field] - view[field].width))
+      end
+      table.insert(text, string.rep(' ', SIDE_PADDING))
+      table.insert(texts, table.concat(text, ''))
+    end
+  end
+  vim.api.nvim_buf_set_lines(entries_buf, topline, botline, false, texts)
+  vim.api.nvim_buf_set_option(entries_buf, 'modified', false)
+
+  if api.is_cmdline_mode() then
+    vim.api.nvim_win_call(self.entries_win.win, function()
+      misc.redraw()
+    end)
+  end
+end
+
+custom_entries_view.visible = function(self)
+  return self.entries_win:visible()
+end
+
+custom_entries_view.info = function(self)
+  return self.entries_win:info()
+end
+
+custom_entries_view.select_next_item = function(self, option)
+  if self:visible() then
+    local cursor = vim.api.nvim_win_get_cursor(self.entries_win.win)[1]
+    if self:is_direction_top_down() then
+      cursor = cursor + 1
+    else
+      cursor = cursor - 1
+    end
+    if not self.entries_win:option('cursorline') then
+      cursor = (self:is_direction_top_down() and 1) or #self.entries
+    elseif #self.entries < cursor then
+      cursor = (not self:is_direction_top_down() and #self.entries + 1) or 0
+    end
+    self:_select(cursor, option)
+  end
+end
+
+custom_entries_view.select_prev_item = function(self, option)
+  if self:visible() then
+    local cursor = vim.api.nvim_win_get_cursor(self.entries_win.win)[1]
+    if self:is_direction_top_down() then
+      cursor = cursor - 1
+    else
+      cursor = cursor + 1
+    end
+    if not self.entries_win:option('cursorline') then
+      cursor = (self:is_direction_top_down() and #self.entries) or 1
+    elseif #self.entries < cursor then
+      cursor = (not self:is_direction_top_down() and 0) or #self.entries + 1
+    end
+    self:_select(cursor, option)
+  end
+end
+
+custom_entries_view.get_offset = function(self)
+  if self:visible() then
+    return self.offset
+  end
+  return nil
+end
+
+custom_entries_view.get_entries = function(self)
+  if self:visible() then
+    return self.entries
+  end
+  return {}
+end
+
+custom_entries_view.get_first_entry = function(self)
+  if self:visible() then
+    return (self:is_direction_top_down() and self.entries[1]) or self.entries[#self.entries]
+  end
+end
+
+custom_entries_view.get_selected_entry = function(self)
+  if self:visible() and self.entries_win:option('cursorline') then
+    return self.entries[vim.api.nvim_win_get_cursor(self.entries_win.win)[1]]
+  end
+end
+
+custom_entries_view.get_active_entry = function(self)
+  if self:visible() and self.active then
+    return self:get_selected_entry()
+  end
+end
+
+custom_entries_view._select = function(self, cursor, option)
+  local is_insert = (option.behavior or types.cmp.SelectBehavior.Insert) == types.cmp.SelectBehavior.Insert
+  if is_insert and not self.active then
+    self.prefix = string.sub(api.get_current_line(), self.offset, api.get_cursor()[2]) or ''
+  end
+
+  self.active = cursor > 0 and cursor <= #self.entries and is_insert
+  self.entries_win:option('cursorline', cursor > 0 and cursor <= #self.entries)
+
+  vim.api.nvim_win_set_cursor(self.entries_win.win, {
+    math.max(math.min(cursor, #self.entries), 1),
+    0,
+  })
+
+  if is_insert then
+    self:_insert(self.entries[cursor] and self.entries[cursor]:get_vim_item(self.offset).word or self.prefix)
+  end
+
+  self.entries_win:update()
+  self:draw()
+  self.event:emit('change')
+end
+
+custom_entries_view._insert = setmetatable({
+  pending = false,
+}, {
+  __call = function(this, self, word)
+    word = word or ''
+    if api.is_cmdline_mode() then
+      local cursor = api.get_cursor()
+      vim.api.nvim_feedkeys(keymap.backspace(string.sub(api.get_current_line(), self.offset, cursor[2])) .. word, 'int', true)
+    else
+      if this.pending then
+        return
+      end
+      this.pending = true
+
+      local release = require('cmp').suspend()
+      feedkeys.call('', '', function()
+        local cursor = api.get_cursor()
+        local keys = {}
+        table.insert(keys, keymap.indentkeys())
+        table.insert(keys, keymap.backspace(string.sub(api.get_current_line(), self.offset, cursor[2])))
+        table.insert(keys, word)
+        table.insert(keys, keymap.indentkeys(vim.bo.indentkeys))
+        feedkeys.call(
+          table.concat(keys, ''),
+          'int',
+          vim.schedule_wrap(function()
+            this.pending = false
+            release()
+          end)
+        )
+      end)
+    end
+  end,
+})
+
+return custom_entries_view
diff --git a/start/cmp/lua/cmp/view/docs_view.lua b/start/cmp/lua/cmp/view/docs_view.lua
new file mode 100644
index 0000000..9d2cd3f
--- /dev/null
+++ b/start/cmp/lua/cmp/view/docs_view.lua
@@ -0,0 +1,136 @@
+local window = require('cmp.utils.window')
+local config = require('cmp.config')
+
+---@class cmp.DocsView
+---@field public window cmp.Window
+local docs_view = {}
+
+---Create new floating window module
+docs_view.new = function()
+  local self = setmetatable({}, { __index = docs_view })
+  self.entry = nil
+  self.window = window.new()
+  self.window:option('conceallevel', 2)
+  self.window:option('concealcursor', 'n')
+  self.window:option('foldenable', false)
+  self.window:option('linebreak', true)
+  self.window:option('scrolloff', 0)
+  self.window:option('wrap', true)
+  return self
+end
+
+---Open documentation window
+---@param e cmp.Entry
+---@param view cmp.WindowStyle
+docs_view.open = function(self, e, view)
+  local documentation = config.get().window.documentation
+  if not documentation then
+    return
+  end
+
+  if not e or not view then
+    return self:close()
+  end
+
+  local border_info = window.get_border_info({ style = documentation })
+  local right_space = vim.o.columns - (view.col + view.width) - 1
+  local left_space = view.col - 1
+  local max_width = math.min(documentation.max_width, math.max(left_space, right_space))
+
+  -- Update buffer content if needed.
+  if not self.entry or e.id ~= self.entry.id then
+    local documents = e:get_documentation()
+    if #documents == 0 then
+      return self:close()
+    end
+
+    self.entry = e
+    vim.api.nvim_buf_call(self.window:get_buffer(), function()
+      vim.cmd([[syntax clear]])
+      vim.api.nvim_buf_set_lines(self.window:get_buffer(), 0, -1, false, {})
+    end)
+    vim.lsp.util.stylize_markdown(self.window:get_buffer(), documents, {
+      max_width = max_width,
+      max_height = documentation.max_height,
+    })
+  end
+
+  -- Calculate window size.
+  local width, height = vim.lsp.util._make_floating_popup_size(vim.api.nvim_buf_get_lines(self.window:get_buffer(), 0, -1, false), {
+    max_width = max_width - border_info.horiz,
+    max_height = documentation.max_height - border_info.vert,
+  })
+  if width <= 0 or height <= 0 then
+    return self:close()
+  end
+
+  -- Calculate window position.
+  local right_col = view.col + view.width
+  local left_col = view.col - width - border_info.horiz
+  local col, left
+  if right_space >= width and left_space >= width then
+    if right_space < left_space then
+      col = left_col
+      left = true
+    else
+      col = right_col
+    end
+  elseif right_space >= width then
+    col = right_col
+  elseif left_space >= width then
+    col = left_col
+    left = true
+  else
+    return self:close()
+  end
+
+  -- Render window.
+  self.window:option('winblend', vim.o.pumblend)
+  self.window:option('winhighlight', documentation.winhighlight)
+  local style = {
+    relative = 'editor',
+    style = 'minimal',
+    width = width,
+    height = height,
+    row = view.row,
+    col = col,
+    border = documentation.border,
+    zindex = documentation.zindex or 50,
+  }
+  self.window:open(style)
+
+  -- Correct left-col for scrollbar existence.
+  if left then
+    style.col = style.col - self.window:info().scrollbar_offset
+    self.window:open(style)
+  end
+end
+
+---Close floating window
+docs_view.close = function(self)
+  self.window:close()
+  self.entry = nil
+end
+
+docs_view.scroll = function(self, delta)
+  if self:visible() then
+    local info = vim.fn.getwininfo(self.window.win)[1] or {}
+    local top = info.topline or 1
+    top = top + delta
+    top = math.max(top, 1)
+    top = math.min(top, self.window:get_content_height() - info.height + 1)
+
+    vim.defer_fn(function()
+      vim.api.nvim_buf_call(self.window:get_buffer(), function()
+        vim.api.nvim_command('normal! ' .. top .. 'zt')
+        self.window:update()
+      end)
+    end, 0)
+  end
+end
+
+docs_view.visible = function(self)
+  return self.window:visible()
+end
+
+return docs_view
diff --git a/start/cmp/lua/cmp/view/ghost_text_view.lua b/start/cmp/lua/cmp/view/ghost_text_view.lua
new file mode 100644
index 0000000..b798ebb
--- /dev/null
+++ b/start/cmp/lua/cmp/view/ghost_text_view.lua
@@ -0,0 +1,97 @@
+local config = require('cmp.config')
+local misc = require('cmp.utils.misc')
+local str = require('cmp.utils.str')
+local types = require('cmp.types')
+local api = require('cmp.utils.api')
+
+---@class cmp.GhostTextView
+local ghost_text_view = {}
+
+ghost_text_view.ns = vim.api.nvim_create_namespace('cmp:GHOST_TEXT')
+
+ghost_text_view.new = function()
+  local self = setmetatable({}, { __index = ghost_text_view })
+  self.win = nil
+  self.entry = nil
+  vim.api.nvim_set_decoration_provider(ghost_text_view.ns, {
+    on_win = function(_, win)
+      return win == self.win
+    end,
+    on_line = function(_)
+      local c = config.get().experimental.ghost_text
+      if not c then
+        return
+      end
+
+      if not self.entry then
+        return
+      end
+
+      local row, col = unpack(vim.api.nvim_win_get_cursor(0))
+      local line = vim.api.nvim_get_current_line()
+      if string.sub(line, col + 1) ~= '' then
+        return
+      end
+
+      local text = self.text_gen(self, line, col)
+      if #text > 0 then
+        vim.api.nvim_buf_set_extmark(0, ghost_text_view.ns, row - 1, col, {
+          right_gravity = false,
+          virt_text = { { text, c.hl_group or 'Comment' } },
+          virt_text_pos = 'overlay',
+          hl_mode = 'combine',
+          ephemeral = true,
+        })
+      end
+    end,
+  })
+  return self
+end
+
+---Generate the ghost text
+---  This function calculates the bytes of the entry to display calculating the number
+---  of character differences instead of just byte difference.
+ghost_text_view.text_gen = function(self, line, cursor_col)
+  local word = self.entry:get_insert_text()
+  if self.entry.completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+    word = vim.lsp.util.parse_snippet(word)
+  end
+  word = str.oneline(word)
+  local word_clen = vim.str_utfindex(word)
+  local cword = string.sub(line, self.entry:get_offset(), cursor_col)
+  local cword_clen = vim.str_utfindex(cword)
+  -- Number of characters from entry text (word) to be displayed as ghost thext
+  local nchars = word_clen - cword_clen
+  -- Missing characters to complete the entry text
+  local text
+  if nchars > 0 then
+    text = string.sub(word, vim.str_byteindex(word, word_clen - nchars) + 1)
+  else
+    text = ''
+  end
+  return text
+end
+
+---Show ghost text
+---@param e cmp.Entry
+ghost_text_view.show = function(self, e)
+  if not api.is_insert_mode() then
+    return
+  end
+  local changed = e ~= self.entry
+  self.win = vim.api.nvim_get_current_win()
+  self.entry = e
+  if changed then
+    misc.redraw(true) -- force invoke decoration provider.
+  end
+end
+
+ghost_text_view.hide = function(self)
+  if self.win and self.entry then
+    self.win = nil
+    self.entry = nil
+    misc.redraw(true) -- force invoke decoration provider.
+  end
+end
+
+return ghost_text_view
diff --git a/start/cmp/lua/cmp/view/native_entries_view.lua b/start/cmp/lua/cmp/view/native_entries_view.lua
new file mode 100644
index 0000000..d8b0b1b
--- /dev/null
+++ b/start/cmp/lua/cmp/view/native_entries_view.lua
@@ -0,0 +1,181 @@
+local event = require('cmp.utils.event')
+local autocmd = require('cmp.utils.autocmd')
+local keymap = require('cmp.utils.keymap')
+local feedkeys = require('cmp.utils.feedkeys')
+local types = require('cmp.types')
+local config = require('cmp.config')
+local api = require('cmp.utils.api')
+
+---@class cmp.NativeEntriesView
+---@field private offset number
+---@field private items vim.CompletedItem
+---@field private entries cmp.Entry[]
+---@field private preselect_index number
+---@field public event cmp.Event
+local native_entries_view = {}
+
+native_entries_view.new = function()
+  local self = setmetatable({}, { __index = native_entries_view })
+  self.event = event.new()
+  self.offset = -1
+  self.items = {}
+  self.entries = {}
+  self.preselect_index = 0
+  autocmd.subscribe('CompleteChanged', function()
+    self.event:emit('change')
+  end)
+  return self
+end
+
+native_entries_view.ready = function(_)
+  if vim.fn.pumvisible() == 0 then
+    return true
+  end
+  return vim.fn.complete_info({ 'mode' }).mode == 'eval'
+end
+
+native_entries_view.on_change = function(self)
+  if #self.entries > 0 and self.offset <= vim.api.nvim_win_get_cursor(0)[2] + 1 then
+    local preselect_enabled = config.get().preselect == types.cmp.PreselectMode.Item
+
+    local completeopt = vim.o.completeopt
+    if self.preselect_index == 1 and preselect_enabled then
+      vim.o.completeopt = 'menu,menuone,noinsert'
+    else
+      vim.o.completeopt = config.get().completion.completeopt
+    end
+    vim.fn.complete(self.offset, self.items)
+    vim.o.completeopt = completeopt
+
+    if self.preselect_index > 1 and preselect_enabled then
+      self:preselect(self.preselect_index)
+    end
+  end
+end
+
+native_entries_view.open = function(self, offset, entries)
+  local dedup = {}
+  local items = {}
+  local dedup_entries = {}
+  local preselect_index = 0
+  for _, e in ipairs(entries) do
+    local item = e:get_vim_item(offset)
+    if item.dup == 1 or not dedup[item.abbr] then
+      dedup[item.abbr] = true
+      table.insert(items, item)
+      table.insert(dedup_entries, e)
+      if preselect_index == 0 and e.completion_item.preselect then
+        preselect_index = #dedup_entries
+      end
+    end
+  end
+  self.offset = offset
+  self.items = items
+  self.entries = dedup_entries
+  self.preselect_index = preselect_index
+  self:on_change()
+end
+
+native_entries_view.close = function(self)
+  if api.is_suitable_mode() and self:visible() then
+    vim.fn.complete(1, {})
+    vim.api.nvim_select_popupmenu_item(-1, false, true, {})
+  end
+  self.offset = -1
+  self.entries = {}
+  self.items = {}
+  self.preselect_index = 0
+end
+
+native_entries_view.abort = function(_)
+  if api.is_suitable_mode() then
+    vim.api.nvim_select_popupmenu_item(-1, true, true, {})
+  end
+end
+
+native_entries_view.visible = function(_)
+  return vim.fn.pumvisible() == 1
+end
+
+native_entries_view.info = function(self)
+  if self:visible() then
+    local info = vim.fn.pum_getpos()
+    return {
+      width = info.width + (info.scrollable and 1 or 0),
+      height = info.height,
+      row = info.row,
+      col = info.col,
+    }
+  end
+end
+
+native_entries_view.preselect = function(self, index)
+  if self:visible() then
+    if index <= #self.entries then
+      vim.api.nvim_select_popupmenu_item(index - 1, false, false, {})
+    end
+  end
+end
+
+native_entries_view.select_next_item = function(self, option)
+  local callback = function()
+    self.event:emit('change')
+  end
+  if self:visible() then
+    if (option.behavior or types.cmp.SelectBehavior.Insert) == types.cmp.SelectBehavior.Insert then
+      feedkeys.call(keymap.t('<C-n>'), 'n', callback)
+    else
+      feedkeys.call(keymap.t('<Down>'), 'n', callback)
+    end
+  end
+end
+
+native_entries_view.select_prev_item = function(self, option)
+  local callback = function()
+    self.event:emit('change')
+  end
+  if self:visible() then
+    if (option.behavior or types.cmp.SelectBehavior.Insert) == types.cmp.SelectBehavior.Insert then
+      feedkeys.call(keymap.t('<C-p>'), 'n', callback)
+    else
+      feedkeys.call(keymap.t('<Up>'), 'n', callback)
+    end
+  end
+end
+
+native_entries_view.get_offset = function(self)
+  if self:visible() then
+    return self.offset
+  end
+  return nil
+end
+
+native_entries_view.get_entries = function(self)
+  if self:visible() then
+    return self.entries
+  end
+  return {}
+end
+
+native_entries_view.get_first_entry = function(self)
+  if self:visible() then
+    return self.entries[1]
+  end
+end
+
+native_entries_view.get_selected_entry = function(self)
+  if self:visible() then
+    local idx = vim.fn.complete_info({ 'selected' }).selected
+    if idx > -1 then
+      return self.entries[math.max(0, idx) + 1]
+    end
+  end
+end
+
+native_entries_view.get_active_entry = function(self)
+  if self:visible() and (vim.v.completed_item or {}).word then
+    return self:get_selected_entry()
+  end
+end
+
+return native_entries_view
diff --git a/start/cmp/lua/cmp/view/wildmenu_entries_view.lua b/start/cmp/lua/cmp/view/wildmenu_entries_view.lua
new file mode 100644
index 0000000..3419164
--- /dev/null
+++ b/start/cmp/lua/cmp/view/wildmenu_entries_view.lua
@@ -0,0 +1,261 @@
+local event = require('cmp.utils.event')
+local autocmd = require('cmp.utils.autocmd')
+local feedkeys = require('cmp.utils.feedkeys')
+local config = require('cmp.config')
+local window = require('cmp.utils.window')
+local types = require('cmp.types')
+local keymap = require('cmp.utils.keymap')
+local misc = require('cmp.utils.misc')
+local api = require('cmp.utils.api')
+
+---@class cmp.CustomEntriesView
+---@field private offset number
+---@field private entries_win cmp.Window
+---@field private active boolean
+---@field private entries cmp.Entry[]
+---@field public event cmp.Event
+local wildmenu_entries_view = {}
+
+wildmenu_entries_view.ns = vim.api.nvim_create_namespace('cmp.view.statusline_entries_view')
+
+wildmenu_entries_view.new = function()
+  local self = setmetatable({}, { __index = wildmenu_entries_view })
+  self.event = event.new()
+  self.offset = -1
+  self.active = false
+  self.entries = {}
+  self.offsets = {}
+  self.selected_index = 0
+  self.entries_win = window.new()
+
+  self.entries_win:option('conceallevel', 2)
+  self.entries_win:option('concealcursor', 'n')
+  self.entries_win:option('cursorlineopt', 'line')
+  self.entries_win:option('foldenable', false)
+  self.entries_win:option('wrap', false)
+  self.entries_win:option('scrolloff', 0)
+  self.entries_win:option('sidescrolloff', 0)
+  self.entries_win:option('winhighlight', 'Normal:Pmenu,FloatBorder:Pmenu,CursorLine:PmenuSel,Search:None')
+  self.entries_win:buffer_option('tabstop', 1)
+
+  autocmd.subscribe(
+    'CompleteChanged',
+    vim.schedule_wrap(function()
+      if self:visible() and vim.fn.pumvisible() == 1 then
+        self:close()
+      end
+    end)
+  )
+
+  vim.api.nvim_set_decoration_provider(wildmenu_entries_view.ns, {
+    on_win = function(_, win, buf, _, _)
+      if win ~= self.entries_win.win or buf ~= self.entries_win:get_buffer() then
+        return
+      end
+
+      for i, e in ipairs(self.entries) do
+        if e then
+          local view = e:get_view(self.offset, buf)
+          vim.api.nvim_buf_set_extmark(buf, wildmenu_entries_view.ns, 0, self.offsets[i], {
+            end_line = 0,
+            end_col = self.offsets[i] + view.abbr.bytes,
+            hl_group = view.abbr.hl_group,
+            hl_mode = 'combine',
+            ephemeral = true,
+          })
+
+          if i == self.selected_index then
+            vim.api.nvim_buf_set_extmark(buf, wildmenu_entries_view.ns, 0, self.offsets[i], {
+              end_line = 0,
+              end_col = self.offsets[i] + view.abbr.bytes,
+              hl_group = 'PmenuSel',
+              hl_mode = 'combine',
+              ephemeral = true,
+            })
+          end
+
+          for _, m in ipairs(e.matches or {}) do
+            vim.api.nvim_buf_set_extmark(buf, wildmenu_entries_view.ns, 0, self.offsets[i] + m.word_match_start - 1, {
+              end_line = 0,
+              end_col = self.offsets[i] + m.word_match_end,
+              hl_group = m.fuzzy and 'CmpItemAbbrMatchFuzzy' or 'CmpItemAbbrMatch',
+              hl_mode = 'combine',
+              ephemeral = true,
+            })
+          end
+        end
+      end
+    end,
+  })
+  return self
+end
+
+wildmenu_entries_view.close = function(self)
+  self.entries_win:close()
+end
+
+wildmenu_entries_view.ready = function()
+  return vim.fn.pumvisible() == 0
+end
+
+wildmenu_entries_view.on_change = function(self)
+  self.active = false
+end
+
+wildmenu_entries_view.open = function(self, offset, entries)
+  self.offset = offset
+  self.entries = {}
+
+  -- Apply window options (that might be changed) on the custom completion menu.
+  self.entries_win:option('winblend', vim.o.pumblend)
+
+  local dedup = {}
+  local preselect = 0
+  local i = 1
+  for _, e in ipairs(entries) do
+    local view = e:get_view(offset, 0)
+    if view.dup == 1 or not dedup[e.completion_item.label] then
+      dedup[e.completion_item.label] = true
+      table.insert(self.entries, e)
+      if preselect == 0 and e.completion_item.preselect then
+        preselect = i
+      end
+      i = i + 1
+    end
+  end
+
+  self.entries_win:open({
+    relative = 'editor',
+    style = 'minimal',
+    row = vim.o.lines - 2,
+    col = 0,
+    width = vim.o.columns,
+    height = 1,
+    zindex = 1001,
+  })
+  self:draw()
+
+  if preselect > 0 and config.get().preselect == types.cmp.PreselectMode.Item then
+    self:_select(preselect, { behavior = types.cmp.SelectBehavior.Select })
+  elseif not string.match(config.get().completion.completeopt, 'noselect') then
+    self:_select(1, { behavior = types.cmp.SelectBehavior.Select })
+  else
+    self:_select(0, { behavior = types.cmp.SelectBehavior.Select })
+  end
+end
+
+wildmenu_entries_view.abort = function(self)
+  feedkeys.call('', 'n', function()
+    self:close()
+  end)
+end
+
+wildmenu_entries_view.draw = function(self)
+  self.offsets = {}
+
+  local entries_buf = self.entries_win:get_buffer()
+  local texts = {}
+  local offset = 0
+  for _, e in ipairs(self.entries) do
+    local view = e:get_view(self.offset, entries_buf)
+    table.insert(self.offsets, offset)
+    table.insert(texts, view.abbr.text)
+    offset = offset + view.abbr.bytes + #self:_get_separator()
+  end
+
+  vim.api.nvim_buf_set_lines(entries_buf, 0, 1, false, { table.concat(texts, self:_get_separator()) })
+  vim.api.nvim_buf_set_option(entries_buf, 'modified', false)
+
+  vim.api.nvim_win_call(0, function()
+    misc.redraw()
+  end)
+end
+
+wildmenu_entries_view.visible = function(self)
+  return self.entries_win:visible()
+end
+
+wildmenu_entries_view.info = function(self)
+  return self.entries_win:info()
+end
+
+wildmenu_entries_view.select_next_item = function(self, option)
+  if self:visible() then
+    if self.selected_index == 0 or self.selected_index == #self.entries then
+      self:_select(1, option)
+    else
+      self:_select(self.selected_index + 1, option)
+    end
+  end
+end
+
+wildmenu_entries_view.select_prev_item = function(self, option)
+  if self:visible() then
+    if self.selected_index == 0 or self.selected_index <= 1 then
+      self:_select(#self.entries, option)
+    else
+      self:_select(self.selected_index - 1, option)
+    end
+  end
+end
+
+wildmenu_entries_view.get_offset = function(self)
+  if self:visible() then
+    return self.offset
+  end
+  return nil
+end
+
+wildmenu_entries_view.get_entries = function(self)
+  if self:visible() then
+    return self.entries
+  end
+  return {}
+end
+
+wildmenu_entries_view.get_first_entry = function(self)
+  if self:visible() then
+    return self.entries[1]
+  end
+end
+
+wildmenu_entries_view.get_selected_entry = function(self)
+  if self:visible() and self.active then
+    return self.entries[self.selected_index]
+  end
+end
+
+wildmenu_entries_view.get_active_entry = function(self)
+  if self:visible() and self.active then
+    return self:get_selected_entry()
+  end
+end
+
+wildmenu_entries_view._select = function(self, selected_index, option)
+  local is_next = self.selected_index < selected_index
+  self.selected_index = selected_index
+  self.active = (selected_index ~= 0)
+
+  if self.active then
+    local e = self:get_active_entry()
+    if option.behavior == types.cmp.SelectBehavior.Insert then
+      local cursor = api.get_cursor()
+      local word = e:get_vim_item(self.offset).word
+      vim.api.nvim_feedkeys(keymap.backspace(string.sub(api.get_current_line(), self.offset, cursor[2])) .. word, 'int', true)
+    end
+    vim.api.nvim_win_call(self.entries_win.win, function()
+      local view = e:get_view(self.offset, self.entries_win:get_buffer())
+      vim.api.nvim_win_set_cursor(0, { 1, self.offsets[selected_index] + (is_next and view.abbr.bytes or 0) })
+      vim.cmd([[redraw!]]) -- Force refresh for vim.api.nvim_set_decoration_provider
+    end)
+  end
+
+  self.event:emit('change')
+end
+
+wildmenu_entries_view._get_separator = function()
+  local c = config.get()
+  return (c and c.view and c.view.entries and c.view.entries.separator) or '  '
+end
+
+return wildmenu_entries_view
diff --git a/start/cmp/lua/cmp/vim_source.lua b/start/cmp/lua/cmp/vim_source.lua
new file mode 100644
index 0000000..2ee8fbf
--- /dev/null
+++ b/start/cmp/lua/cmp/vim_source.lua
@@ -0,0 +1,53 @@
+local misc = require('cmp.utils.misc')
+
+local vim_source = {}
+
+---@param id number
+---@param args any[]
+vim_source.on_callback = function(id, args)
+  if vim_source.to_callback.callbacks[id] then
+    vim_source.to_callback.callbacks[id](unpack(args))
+  end
+end
+
+---@param callback function
+---@return number
+vim_source.to_callback = setmetatable({
+  callbacks = {},
+}, {
+  __call = function(self, callback)
+    local id = misc.id('cmp.vim_source.to_callback')
+    self.callbacks[id] = function(...)
+      callback(...)
+      self.callbacks[id] = nil
+    end
+    return id
+  end,
+})
+
+---Convert to serializable args.
+---@param args any[]
+vim_source.to_args = function(args)
+  for i, arg in ipairs(args) do
+    if type(arg) == 'function' then
+      args[i] = vim_source.to_callback(arg)
+    end
+  end
+  return args
+end
+
+---@param bridge_id number
+---@param methods string[]
+vim_source.new = function(bridge_id, methods)
+  local self = {}
+  for _, method in ipairs(methods) do
+    self[method] = (function(m)
+      return function(_, ...)
+        return vim.fn['cmp#_method'](bridge_id, m, vim_source.to_args({ ... }))
+      end
+    end)(method)
+  end
+  return self
+end
+
+return vim_source
diff --git a/start/cmp/lua/cmp_nvim_lsp/init.lua b/start/cmp/lua/cmp_nvim_lsp/init.lua
new file mode 100644
index 0000000..9feb93a
--- /dev/null
+++ b/start/cmp/lua/cmp_nvim_lsp/init.lua
@@ -0,0 +1,84 @@
+local source = require('cmp_nvim_lsp.source')
+
+local M = {}
+
+---Registered client and source mapping.
+M.client_source_map = {}
+
+---Setup cmp-nvim-lsp source.
+M.setup = function()
+  vim.cmd([[
+    augroup cmp_nvim_lsp
+      autocmd!
+      autocmd InsertEnter * lua require'cmp_nvim_lsp'._on_insert_enter()
+    augroup END
+  ]])
+end
+
+local if_nil = function(val, default)
+  if val == nil then return default end
+  return val
+end
+
+M.update_capabilities = function(capabilities, override)
+  override = override or {}
+
+  local completionItem = capabilities.textDocument.completion.completionItem
+
+  completionItem.snippetSupport = if_nil(override.snippetSupport, true)
+  completionItem.preselectSupport = if_nil(override.preselectSupport, true)
+  completionItem.insertReplaceSupport = if_nil(override.insertReplaceSupport, true)
+  completionItem.labelDetailsSupport = if_nil(override.labelDetailsSupport, true)
+  completionItem.deprecatedSupport = if_nil(override.deprecatedSupport, true)
+  completionItem.commitCharactersSupport = if_nil(override.commitCharactersSupport, true)
+  completionItem.tagSupport = if_nil(override.tagSupport, { valueSet = { 1 } })
+  completionItem.resolveSupport = if_nil(override.resolveSupport, {
+    properties = {
+      'documentation',
+      'detail',
+      'additionalTextEdits',
+    }
+  })
+
+  return capabilities
+end
+
+---Refresh sources on InsertEnter.
+M._on_insert_enter = function()
+  local cmp = require('cmp')
+
+  local allowed_clients = {}
+
+  -- register all active clients.
+  for _, client in ipairs(vim.lsp.get_active_clients()) do
+    allowed_clients[client.id] = client
+    if not M.client_source_map[client.id] then
+      local s = source.new(client)
+      if s:is_available() then
+        M.client_source_map[client.id] = cmp.register_source('nvim_lsp', s)
+      end
+    end
+  end
+
+  -- register all buffer clients (early register before activation)
+  for _, client in ipairs(vim.lsp.buf_get_clients(0)) do
+    allowed_clients[client.id] = client
+    if not M.client_source_map[client.id] then
+      local s = source.new(client)
+      if s:is_available() then
+        M.client_source_map[client.id] = cmp.register_source('nvim_lsp', s)
+      end
+    end
+  end
+
+  -- unregister stopped/detached clients.
+  for client_id, source_id in pairs(M.client_source_map) do
+    if not allowed_clients[client_id] or allowed_clients[client_id]:is_stopped() then
+      cmp.unregister_source(source_id)
+      M.client_source_map[client_id] = nil
+    end
+  end
+end
+
+return M
+
diff --git a/start/cmp/lua/cmp_nvim_lsp/source.lua b/start/cmp/lua/cmp_nvim_lsp/source.lua
new file mode 100644
index 0000000..d4dd587
--- /dev/null
+++ b/start/cmp/lua/cmp_nvim_lsp/source.lua
@@ -0,0 +1,117 @@
+local source = {}
+
+source.new = function(client)
+  local self = setmetatable({}, { __index = source })
+  self.client = client
+  self.request_ids = {}
+  return self
+end
+
+source.get_debug_name = function(self)
+  return table.concat({ 'nvim_lsp', self.client.name }, ':')
+end
+
+source.is_available = function(self)
+  -- client is stopped.
+  if self.client.is_stopped() then
+    return false
+  end
+
+  -- client is not attached to current buffer.
+  if not vim.lsp.buf_get_clients(vim.api.nvim_get_current_buf())[self.client.id] then
+    return false
+  end
+
+  -- client has no completion capability.
+  if not self:_get(self.client.server_capabilities, { 'completionProvider' }) then
+    return false
+  end
+  return true;
+end
+
+source.get_trigger_characters = function(self)
+  return self:_get(self.client.server_capabilities, { 'completionProvider', 'triggerCharacters' }) or {}
+end
+
+source.complete = function(self, request, callback)
+  local params = vim.lsp.util.make_position_params(0, self.client.offset_encoding)
+  params.context = {}
+  params.context.triggerKind = request.completion_context.triggerKind
+  params.context.triggerCharacter = request.completion_context.triggerCharacter
+
+  self:_request('textDocument/completion', params, function(_, response)
+    callback(response)
+  end)
+end
+
+source.resolve = function(self, completion_item, callback)
+  -- client is stopped.
+  if self.client.is_stopped() then
+    return callback()
+  end
+
+  -- client has no completion capability.
+  if not self:_get(self.client.server_capabilities, { 'completionProvider', 'resolveProvider' }) then
+    return callback()
+  end
+
+  self:_request('completionItem/resolve', completion_item, function(_, response)
+    callback(response or completion_item)
+  end)
+end
+
+source.execute = function(self, completion_item, callback)
+  -- client is stopped.
+  if self.client.is_stopped() then
+    return callback()
+  end
+
+  -- completion_item has no command.
+  if not completion_item.command then
+    return callback()
+  end
+
+  self:_request('workspace/executeCommand', completion_item.command, function(_, _)
+    callback()
+  end)
+end
+
+source._get = function(_, root, paths)
+  local c = root
+  for _, path in ipairs(paths) do
+    c = c[path]
+    if not c then
+      return nil
+    end
+  end
+  return c
+end
+
+source._request = function(self, method, params, callback)
+  if self.request_ids[method] ~= nil then
+    self.client.cancel_request(self.request_ids[method])
+    self.request_ids[method] = nil
+  end
+  local _, request_id
+  _, request_id = self.client.request(method, params, function(arg1, arg2, arg3)
+    if self.request_ids[method] ~= request_id then
+      return
+    end
+    self.request_ids[method] = nil
+
+    -- Text changed, retry
+    if arg1 and arg1.code == -32801 then
+      self:_request(method, params, callback)
+      return
+    end
+
+    if method == arg2 then
+      callback(arg1, arg3) -- old signature
+    else
+      callback(arg1, arg2) -- new signature
+    end
+  end)
+  self.request_ids[method] = request_id
+end
+
+return source
diff --git a/start/cmp/plugin/cmp.lua b/start/cmp/plugin/cmp.lua
new file mode 100644
index 0000000..caf8c27
--- /dev/null
+++ b/start/cmp/plugin/cmp.lua
@@ -0,0 +1,60 @@
+if vim.g.loaded_cmp then
+  return
+end
+vim.g.loaded_cmp = true
+
+if not vim.api.nvim_create_autocmd then
+  return print('[nvim-cmp] Your nvim does not has `nvim_create_autocmd` function. Please update to latest nvim.')
+end
+
+local api = require('cmp.utils.api')
+local types = require('cmp.types')
+local highlight = require('cmp.utils.highlight')
+local autocmd = require('cmp.utils.autocmd')
+
+vim.api.nvim_set_hl(0, 'CmpItemAbbr', { link = 'CmpItemAbbrDefault', default = true })
+vim.api.nvim_set_hl(0, 'CmpItemAbbrDeprecated', { link = 'CmpItemAbbrDeprecatedDefault', default = true })
+vim.api.nvim_set_hl(0, 'CmpItemAbbrMatch', { link = 'CmpItemAbbrMatchDefault', default = true })
+vim.api.nvim_set_hl(0, 'CmpItemAbbrMatchFuzzy', { link = 'CmpItemAbbrMatchFuzzyDefault', default = true })
+vim.api.nvim_set_hl(0, 'CmpItemKind', { link = 'CmpItemKindDefault', default = true })
+vim.api.nvim_set_hl(0, 'CmpItemMenu', { link = 'CmpItemMenuDefault', default = true })
+for kind in pairs(types.lsp.CompletionItemKind) do
+  if type(kind) == 'string' then
+    local name = ('CmpItemKind%s'):format(kind)
+    vim.api.nvim_set_hl(0, name, { link = ('%sDefault'):format(name), default = true })
+  end
+end
+
+autocmd.subscribe('ColorScheme', function()
+  highlight.inherit('CmpItemAbbrDefault', 'Pmenu', { bg = 'NONE', default = true })
+  highlight.inherit('CmpItemAbbrDeprecatedDefault', 'Comment', { bg = 'NONE', default = true })
+  highlight.inherit('CmpItemAbbrMatchDefault', 'Pmenu', { bg = 'NONE', default = true })
+  highlight.inherit('CmpItemAbbrMatchFuzzyDefault', 'Pmenu', { bg = 'NONE', default = true })
+  highlight.inherit('CmpItemKindDefault', 'Special', { bg = 'NONE', default = true })
+  highlight.inherit('CmpItemMenuDefault', 'Pmenu', { bg = 'NONE', default = true })
+  for name in pairs(types.lsp.CompletionItemKind) do
+    if type(name) == 'string' then
+      vim.api.nvim_set_hl(0, ('CmpItemKind%sDefault'):format(name), { link = 'CmpItemKind', default = true })
+    end
+  end
+end)
+autocmd.emit('ColorScheme')
+
+if vim.on_key then
+  vim.on_key(function(keys)
+    if keys == vim.api.nvim_replace_termcodes('<C-c>', true, true, true) then
+      vim.schedule(function()
+        if not api.is_suitable_mode() then
+          autocmd.emit('InsertLeave')
+        end
+      end)
+    end
+  end, vim.api.nvim_create_namespace('cmp.plugin'))
+end
+
+vim.api.nvim_create_user_command('CmpStatus', function()
+  require('cmp').status()
+end, { desc = 'Check status of cmp sources' })
+
+vim.cmd([[doautocmd <nomodeline> User CmpReady]])
+