1 files changed, 96 insertions, 0 deletions
diff --git a/src/build/vec.h b/src/build/vec.h
new file mode 100644
index 0000000..50b0a3b
--- /dev/null
+++ b/src/build/vec.h
@@ -0,0 +1,96 @@
+/* This file is dedicated to the public domain. */
+
+#ifndef INC_VEC_H
+#define INC_VEC_H
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "../intdefs.h"
+
+struct _vec {
+	uint sz;
+	uint max;
+	void *data;
+};
+
+/*
+ * A dynamic array with push, pop and concatenate operations.
+ *
+ * Usage: struct VEC(my_type) myvec = {0};
+ * Or: struct myvec VEC(my_type);
+ * Or: typedef struct VEC(my_type) myvec;
+ */
+#define VEC(type) { \
+	uint sz; \
+	uint max; \
+	type *data; \
+}
+
+#if defined(__GNUC__) || defined(__clang__)
+__attribute__((unused)) // heck off gcc
+#endif
+static bool _vec_ensure(struct _vec *v, uint tsize, uint newmax) {
+	// FIXME: potential overflow at least on 32-bit hosts (if any!?).
+	// should use reallocarray or something but didn't feel like porting right
+	// now. consider doing later.
+	void *new = realloc(v->data, tsize * newmax);
+	if (new) { v->data = new; v->max = newmax; }
+	return !!new;
+}
+
+#if defined(__GNUC__) || defined(__clang__)
+__attribute__((unused)) // heck off gcc 2
+#endif
+static bool _vec_make_room(struct _vec *v, uint tsize, uint addcnt) {
+	// this overflow check is probably unnecessary, but just in case
+	u64 chk = v->max + addcnt;
+	if (chk > 1u << 30) { errno = ENOMEM; return false; }
+	u32 x = chk;
+	if (x < 16) {
+		x = 16;
+	}
+	else {
+		// round up to next 2*n
+		--x;
+		x |= x >> 1; x |= x >> 2; x |= x >> 4; x |= x >> 8; x |= x >> 16;
+		x++;
+	}
+	return _vec_ensure(v, tsize, x);
+}
+
+// internal: for reuse by vec0
+#define _vec_push(v, val, slack) ( \
+	((v)->sz + (slack) < (v)->max || \
+			_vec_make_room((struct _vec *)(v), sizeof(val), 1)) && \
+	((v)->data[(v)->sz++ - slack] = (val), true) \
+)
+
+#define _vec_pushall(v, vals, n, slack) ( \
+	((v)->sz + (n) + (slack) <= (v)->max || \
+			_vec_make_room((struct _vec *)(v), sizeof(*(vals)), (n))) && \
+	(memcpy((v)->data + (v)->sz - (slack), (vals), (n) * sizeof(*(vals))), \
+			(v)->sz += (n), true) \
+)
+
+/*
+ * Appends an item to the end of a vector. Gives true on success and false if
+ * memory allocation fails.
+ */
+#define vec_push(v, val) _vec_push(v, val, 0)
+
+/*
+ * Appends n items from an array to the end of a vector. Gives true on success
+ * and false if memory allocation fails.
+ */
+#define vec_pushall(v, vals, n) _vec_pushall(v, vals, n, 0)
+
+/*
+ * Removes an item from the end of a vector and gives that item.
+ */
+#define vec_pop(v) ((v)->data[--(v)->sz])
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80