text-motions: add text_line_prev function

2 files changed, 17 insertions, 2 deletions

diff --git a/text-motions.c b/text-motions.c
index 25ff87c..15fdd2d 100644
--- a/text-motions.c
+++ b/text-motions.c
@@ -73,6 +73,20 @@ size_t text_find_char_prev(Text *txt, size_t pos, const char *s, size_t len) {
 	return matched == 0 ? it.pos : pos;
 }
 
+size_t text_line_prev(Text *txt, size_t pos) {
+	char c;
+	Iterator it = text_iterator_get(txt, pos);
+	if (!text_iterator_byte_get(&it, &c))
+		return pos;
+	if (c == '\r')
+		text_iterator_byte_prev(&it, &c);
+	if (c == '\n')
+		text_iterator_byte_prev(&it, &c);
+	while (text_iterator_byte_get(&it, &c) && c != '\n')
+		text_iterator_byte_prev(&it, NULL);
+	return it.pos;
+}
+
 size_t text_line_begin(Text *txt, size_t pos) {
 	char c;
 	Iterator it = text_iterator_get(txt, pos);
diff --git a/text-motions.h b/text-motions.h
index e549402..dc9b66a 100644
--- a/text-motions.h
+++ b/text-motions.h
@@ -24,9 +24,10 @@ size_t text_find_char_prev(Text*, size_t pos, const char *s, size_t len);
 /*        begin            finish        next
  *        v                v             v
  *  \n[\r]      I am a line!       \n[\r]
- *              ^                  ^
- *              start              end
+ *  ^           ^                  ^
+ *  prev        start              end
  */
+size_t text_line_prev(Text*, size_t pos);
 size_t text_line_begin(Text*, size_t pos);
 size_t text_line_start(Text*, size_t pos);
 size_t text_line_finish(Text*, size_t pos);