1 files changed, 96 insertions, 0 deletions
diff --git a/src/kv.h b/src/kv.h
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+/*
+ * Copyright © 2021 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef INC_KV_H
+#define INC_KV_H
+
+#include <stdbool.h>
+
+#include "intdefs.h"
+
+/*
+ * Maximum length of a single token. Since this code is trying to avoid dynamic
+ * memory allocations, this arbitrary limit is chosen to accomodate all known
+ * "reasonable" tokens likely to come in any real files, probably.
+ */
+#define KV_TOKEN_MAX 512
+
+/*
+ * Contains all the state associated with parsing (lexing?) a KeyValues file.
+ * Should be zeroed out prior to the first call (initialise with `= {0};`).
+ */
+struct kv_parser {
+	ushort line, col;	/* the current line and column in the text */
+	schar state;		/* internal, shouldn't usually be touched directly */
+	bool incomment;		/* internal */
+	ushort nestlvl;		/* internal */
+	const char *errmsg; /* the error message, *IF* parsing just failed */
+
+	// trying to avoid dynamic allocations - valve's own parser seems to have
+	// a similar limit as well and our use case doesn't really need to worry
+	// about stupid massive values, so it's fine
+	char *outp;
+	char tokbuf[KV_TOKEN_MAX];
+};
+
+#define KV_PARSER_ERROR -1
+
+/*
+ * These are the tokens that can be receieved by a kv_parser_cb (below).
+ * The x-macro and string descriptions are given to allow for easy debug
+ * stringification. Note that this "parser" is really just lexing out these
+ * tokens - handling the actual structure of the file should be done in the
+ * callback. This is so that data can be streamed rather than all read into
+ * memory at once.
+ */
+#define KV_TOKENS(X) \
+	X(KV_IDENT, "ident") \
+	X(KV_IDENT_QUOTED, "quoted-ident") \
+	X(KV_VAL, "value") \
+	X(KV_VAL_QUOTED, "quoted-value") \
+	X(KV_NEST_START, "object-start") \
+	X(KV_NEST_END, "object-end")
+
+#define _ENUM(s, ignore) s,
+enum kv_token { KV_TOKENS(_ENUM) };
+#undef _ENUM
+
+typedef void (*kv_parser_cb)(enum kv_token type, const char *p, uint len,
+		void *ctxt);
+
+/*
+ * Feed a block of text into the lexer. This would usually be a block of data
+ * read in from a file.
+ *
+ * The lexer is reentrant and can be fed arbitrarily sized blocks of data at a
+ * time. The function may return early in the event of an error; you must check
+ * if parser->state == KV_PARSER_ERROR between calls! Continuing to try parsing
+ * after an error is undefined.
+ */
+// FIXME: revise API usage so errors aren't passed through "state" value
+void kv_parser_feed(struct kv_parser *this, const char *in, uint sz,
+		kv_parser_cb cb, void *ctxt);
+
+/*
+ * This indicates that parsing is done; if the state is midway through a token
+ * this will be converted into an error state which can be checked in the same
+ * way as noted above.
+ */
+void kv_parser_done(struct kv_parser *this);
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80