From d723f8a5d54f098f0cf378e5dcf3a7d4ec049822 Mon Sep 17 00:00:00 2001
From: WormHeamer
Date: Wed, 31 Dec 2025 05:01:16 -0500
Subject: add regex search (only forwards for now)

---
 regex.h | 126 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 regex.h

(limited to 'regex.h')

diff --git a/regex.h b/regex.h
new file mode 100644
index 0000000..38089d3
--- /dev/null
+++ b/regex.h
@@ -0,0 +1,126 @@
+#ifndef REGEX_H
+#define REGEX_H
+
+#include <stdint.h>
+
+#include "arena.h"
+#include "dynarr.h"
+#include "str.h"
+
+typedef enum : u8 {
+	RE_CHAR,
+	RE_CHAR_NOT,
+	RE_CHAR_ANY,
+	RE_CHAR_SET,
+	RE_CHAR_RANGE,
+	RE_CHAR_RANGE_NOT,
+	RE_CHAR_SET_PACKED,
+	RE_CHAR_SET_PACKED_NOT,
+	RE_LINE_START,
+	RE_LINE_END,
+	RE_MATCH,
+	RE_FAIL,
+	RE_JUMP,
+	RE_SPLIT,
+	RE_GROUP_START,
+	RE_GROUP_END,
+	RE_LABEL /* only used during codegen */
+} ReOpType;
+
+typedef union {
+	struct {
+		ReOpType op;
+		union {
+			uint32_t c;
+			struct {
+				u16 a, b;
+			};
+		};
+	};
+	u64 align;
+} ReOp;
+
+typedef struct {
+	uint32_t min, max;
+} ReChRange;
+
+typedef struct {
+	/* sorted list of non-overlapping character ranges */
+	ReChRange *v;
+	uint32_t n;
+	int invert;
+} ReChSet;
+
+/* for RE_CHAR */
+typedef enum {
+	C_ANY = 0x80000000,
+	C_LINE_START,
+	C_LINE_END,
+	C_EOF = 0xffffffff
+} ReChSpecial;
+
+typedef struct {
+	DYNARR(ReOp) op;
+	DYNARR(ReChSet) cset;
+	uint32_t groups;
+	u8 first_byte; /* 0 if unknown */
+} RegEx;
+
+typedef struct {
+	uint32_t start, len;
+} ReSpan;
+
+typedef struct {
+	ReSpan extent;
+	ReSpan *grp;
+} ReMatch;
+
+typedef DYNARR(ReMatch) ReMatchList;
+
+typedef struct {
+	u32 i;
+	ReSpan *grp;
+} ReThread;
+
+typedef struct {
+	ReThread *v;
+	uintmax_t *set;
+	size_t n;
+} ReThreadList;
+
+typedef enum {
+	RE_SEARCH_FIRST_CHUNK = 1,
+	RE_SEARCH_LAST_CHUNK  = 2,
+	RE_SEARCH_MID_MATCH   = 4,
+} ReSearchFlags;
+
+typedef struct {
+	Arena *a;
+	RegEx *re;
+	ReSpan *grp;
+	const char *buf;
+	size_t buf_len, buf_idx;
+	size_t total_idx;
+	size_t match_start, match_end;
+	ReThreadList tcur, tnext;
+	ReSearchFlags flags;
+	uint32_t c, c_prev;
+} ReSearch;
+
+typedef enum {
+	RE_COMP_NO_GROUPS = 1
+} ReCompFlags;
+
+int re_comp(RegEx *re, Str src, Arena *perm, Arena *scratch);
+int re_comp_ex(RegEx *re, Str src, Arena *perm, Arena *scratch, ReCompFlags flags);
+
+void re_search_start(ReSearch *s, RegEx *re, Arena *a);
+void re_search_chunk(ReSearch *s, const char *buf, size_t n);
+void re_search_last_chunk(ReSearch *s);
+int re_search_match(ReSearch *s, ReMatch *m);
+
+ReMatchList re_match_all(RegEx *re, Str s, Arena *a);
+int re_match_full(RegEx *re, Str s, Arena *a);
+int re_match(RegEx *re, Str s, ReMatch *out, Arena *a);
+
+#endif
-- 
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