fix some logic errors in line navigation

1 files changed, 14 insertions, 12 deletions

diff --git a/txt.c b/txt.c
index 62017c0..d5ee28d 100644
--- a/txt.c
+++ b/txt.c
@@ -418,8 +418,9 @@ TxtLoc prev_newline(TxtLoc l) {
 }
 
 TxtLoc start_of_line(TxtLoc l) {
+	if (at_start(l)) return l;
 	l = prev_newline(l);
-	if (!at_start(l) && txt_byte(l) == '\n') l = cnext(l);
+	if (txt_byte(l) == '\n') l = cnext(l);
 	return l;
 }
 
@@ -436,24 +437,25 @@ u32 get_col(TxtLoc l) {
 
 TxtLoc at_col(TxtLoc l, u32 col) {
 	l = start_of_line(l);
-	while (col--) {
-		if (txt_chr_next(&l) == '\n') {
-			l = bprev(l);
-			break;
-		}
-	}
+	while (col-- && txt_byte(l) != '\n') l = cnext(l);
 	return l;
 }
 
+TxtLoc next_line_start(TxtLoc l) {
+	if (txt_byte(l) == '\n') return cnext(l);
+	return cnext(next_newline(l));
+}
+
+TxtLoc prev_line_start(TxtLoc l) {
+	return start_of_line(prev_newline(l));
+}
+
 TxtLoc prev_line(TxtLoc l) {
-	TxtLoc start = start_of_line(l);
-	return at_col(cprev(start), get_col(l));
+	return at_col(prev_line_start(l), get_col(l));
 }
 
 TxtLoc next_line(TxtLoc l) {
-	TxtLoc end = end_of_line(l);
-	if (at_end(end)) return end;
-	return at_col(cnext(end), get_col(l));
+	return at_col(next_line_start(l), get_col(l));
 }
 
 /* reading chars */