text-motion: introduce text_line_char_{get,set}

2 files changed, 31 insertions, 6 deletions

diff --git a/text-motions.c b/text-motions.c
index f62ba22..9d40c33 100644
--- a/text-motions.c
+++ b/text-motions.c
@@ -166,6 +166,27 @@ size_t text_line_offset(Text *txt, size_t pos, size_t off) {
 	return it.pos;
 }
 
+size_t text_line_char_set(Text *txt, size_t pos, int count) {
+	char c;
+	size_t bol = text_line_begin(txt, pos);
+	Iterator it = text_iterator_get(txt, bol);
+	while (count-- > 0 && text_iterator_byte_get(&it, &c) && c != '\r' && c != '\n')
+		text_iterator_char_next(&it, NULL);
+	return it.pos;
+}
+
+int text_line_char_get(Text *txt, size_t pos) {
+	char c;
+	int count = 0;
+	size_t bol = text_line_begin(txt, pos);
+	Iterator it = text_iterator_get(txt, bol);
+	while (text_iterator_byte_get(&it, &c) && it.pos < pos && c != '\r' && c != '\n') {
+		text_iterator_char_next(&it, NULL);
+		count++;
+	}
+	return count;
+}
+
 size_t text_line_char_next(Text *txt, size_t pos) {
 	char c;
 	Iterator it = text_iterator_get(txt, pos);
@@ -185,15 +206,15 @@ size_t text_line_char_prev(Text *txt, size_t pos) {
 }
 
 size_t text_line_up(Text *txt, size_t pos) {
-	size_t bol = text_line_begin(txt, pos);
-	size_t prev = text_line_prev(txt, bol);
-	return text_line_offset(txt, prev, pos - bol);
+	int count = text_line_char_get(txt, pos);
+	size_t prev = text_line_prev(txt, pos);
+	return text_line_char_set(txt, prev, count);
 }
 
 size_t text_line_down(Text *txt, size_t pos) {
-	size_t bol = text_line_begin(txt, pos);
-	size_t next = text_line_next(txt, bol);
-	return text_line_offset(txt, next, pos - bol);
+	int count = text_line_char_get(txt, pos);
+	size_t next = text_line_next(txt, pos);
+	return text_line_char_set(txt, next, count);
 }
 
 size_t text_range_line_first(Text *txt, Filerange *r) {
diff --git a/text-motions.h b/text-motions.h
index 72878cd..c89c256 100644
--- a/text-motions.h
+++ b/text-motions.h
@@ -36,6 +36,10 @@ size_t text_line_lastchar(Text*, size_t pos);
 size_t text_line_end(Text*, size_t pos);
 size_t text_line_next(Text*, size_t pos);
 size_t text_line_offset(Text*, size_t pos, size_t off);
+/* get character count of the line upto `pos' */
+int text_line_char_get(Text*, size_t pos);
+/* get position of the `count' character in the line containing `pos' */
+size_t text_line_char_set(Text*, size_t pos, int count);
 /* move to the next/previous character on the same line */
 size_t text_line_char_next(Text*, size_t pos);
 size_t text_line_char_prev(Text*, size_t pos);