From 3b48035f5b9475293ff614c2d5193cf525e55a44 Mon Sep 17 00:00:00 2001
From: WormHeamer
Date: Thu, 1 Jan 2026 21:37:44 -0500
Subject: make regex line ends more consistent across chunks

---
 regex.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

(limited to 'regex.c')

diff --git a/regex.c b/regex.c
index 6fe4809..1c42126 100644
--- a/regex.c
+++ b/regex.c
@@ -824,7 +824,7 @@ static inline isize re_search_try_match(ReSearch *s, size_t i, size_t n) {
 	}
 	isize found_i = -1;
 	ReThreadStepFlags f = 0;
-	if (i + start == 0) f = RE_THREAD_AT_START;
+	if (i == 0 && (s->flags & (RE_SEARCH_FIRST_CHUNK | RE_SEARCH_WAS_NEWLINE))) f = RE_THREAD_AT_START;
 
 	for (; i < n && s->tcur.n > 0; i++) {
 		s->c = (unsigned char)s->buf[i];
@@ -854,7 +854,7 @@ void re_search_start(ReSearch *s, RegEx *re, Arena *a) {
 		.a = a,
 		.re = re,
 		.grp = new_arr(a, ReSpan, re->groups),
-		.flags = RE_SEARCH_FIRST_CHUNK
+		.flags = 0
 	};
 	re_threadlist_alloc(&s->tcur, re->op.n, a);
 	re_threadlist_alloc(&s->tnext, re->op.n, a);
@@ -872,6 +872,9 @@ void re_search_last_chunk(ReSearch *s) {
 	s->flags |= RE_SEARCH_LAST_CHUNK;
 }
 
+void re_search_first_chunk(ReSearch *s) {
+	s->flags |= RE_SEARCH_FIRST_CHUNK;
+}
 
 /* searching */
 
@@ -879,6 +882,18 @@ void re_search_last_chunk(ReSearch *s) {
  * check s->flags to find if the match is done yet
  */
 
+static inline void re_search_chunk_fin(ReSearch *s) {
+	u32 n = s->buf_len;
+	s->buf_idx = n;
+	if (n > 0) {
+		if (s->buf[n-1] == '\n') {
+			s->flags |= RE_SEARCH_WAS_NEWLINE;
+		} else {
+			s->flags &= ~RE_SEARCH_WAS_NEWLINE;
+		}
+	}
+}
+
 int re_search_match_at_start(ReSearch *s, ReMatch *m) {
 	size_t i = s->buf_idx;
 	size_t n = s->buf_len;
@@ -901,7 +916,7 @@ int re_search_match_at_start(ReSearch *s, ReMatch *m) {
 			}
 		}
 	}
-	s->buf_idx = s->buf_len;
+	re_search_chunk_fin(s);
 	return 0;
 }
 
@@ -917,7 +932,7 @@ int re_search_match(ReSearch *s, ReMatch *m) {
 		s->buf_idx = i++;
 		if (re_search_match_at_start(s, m)) return 1;
 	}
-	s->buf_idx = n;
+	re_search_chunk_fin(s);
 	return 0;
 }
 
@@ -929,6 +944,7 @@ ReMatchList re_match_all(RegEx *re, Str s, Arena *a) {
 	ReMatch m;
 	re_search_start(&sr, re, a);
 	re_search_chunk(&sr, s.s, s.n);
+	re_search_first_chunk(&sr);
 	re_search_last_chunk(&sr);
 	while (re_search_match(&sr, &m)) {
 		ReSpan *grp = new_arr(a, ReSpan, re->groups);
@@ -943,6 +959,7 @@ int re_match_full(RegEx *re, Str s, Arena *a) {
 	ReMatch m;
 	re_search_start(&sr, re, a);
 	re_search_chunk(&sr, s.s, s.n);
+	re_search_first_chunk(&sr);
 	re_search_last_chunk(&sr);
 	return re_search_match(&sr, &m) && m.extent.start == 0 && m.extent.len == s.n;
 }
@@ -951,6 +968,7 @@ int re_match(RegEx *re, Str s, ReMatch *out, Arena *a) {
 	ReSearch sr = { 0 };
 	re_search_start(&sr, re, a);
 	re_search_chunk(&sr, s.s, s.n);
+	re_search_first_chunk(&sr);
 	re_search_last_chunk(&sr);
 	return re_search_match(&sr, out);
 }
-- 
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