some bugfixes

1 files changed, 48 insertions, 16 deletions

diff --git a/txt.c b/txt.c
index b71bba3..daa02e5 100644
--- a/txt.c
+++ b/txt.c
@@ -35,12 +35,12 @@ u32 txt_split_piece(Txt *b, u32 pi, u32 i) {
 
 TxtLoc txt_at(Txt *b, u32 cur) {
 	for (u32 i = 0; i < b->ptbl.n; i++) {
-		if (cur <= b->ptbl.v[i].n) {
+		if (cur < b->ptbl.v[i].n) {
 			return (TxtLoc) { i, cur };
 		}
 		cur -= b->ptbl.v[i].n;
 	}
-	return (TxtLoc) { 0, 0 };
+	return (TxtLoc) { b->ptbl.n - 1, b->ptbl.v[b->ptbl.n - 1].n };
 }
 
 void txt_buf_append(Txt *b, TxtBufIdx bi, const char *s, u32 n) {
@@ -54,18 +54,29 @@ void txt_buf_append(Txt *b, TxtBufIdx bi, const char *s, u32 n) {
 	buf->n += n;
 }
 
-u32 txt_insert(Txt *b, u32 cur, const char *s, u32 n) {
-	TxtLoc l = txt_at(b, cur);
+u32 txt_add_piece(Txt *b, TxtLoc l) {
+	if (l.p > 0 && !l.i) {
+		l.p--;
+		l.i = b->ptbl.v[l.p].n;
+	}
 	if (l.p < b->ptbl.n) {
 		TxtPiece *p = &b->ptbl.v[l.p];
 		int mid = p->ofs + l.i < b->buf[p->buf].n;
 		if (p->buf == TXT_SRC || mid) {
 			l.p = txt_split_piece(b, l.p, l.i);
-			txt_insert_piece(b, l.p, TXT_ADD, b->buf[TXT_ADD].n, 0);
+			goto insert;
 		}
 	} else {
+insert:
+		if (b->ptbl.v[l.p].n == 0) txt_remove_piece(b, l.p);
 		txt_insert_piece(b, l.p, TXT_ADD, b->buf[TXT_ADD].n, 0);
 	}
+	return l.p;
+}
+
+u32 txt_insert(Txt *b, u32 cur, const char *s, u32 n) {
+	TxtLoc l = txt_at(b, cur);
+	l.p = txt_add_piece(b, l);
 	TxtPiece *p = &b->ptbl.v[l.p];
 	txt_buf_append(b, p->buf, s, n);
 	p->n += n;
@@ -78,23 +89,44 @@ u32 txt_insert_c(Txt *b, u32 cur, char ch) {
 	return txt_insert(b, cur, &ch, 1);
 }
 
+static int txt_are_pieces_adjacent(Txt *t, u32 a, u32 b) {
+	TxtPiece *pa = &t->ptbl.v[a];
+	TxtPiece *pb = &t->ptbl.v[b];
+	return pa->buf == pb->buf && pa->ofs + pa->n == pb->ofs;
+}
+
+static void txt_join_or_kill(Txt *b, u32 pi) {
+	if (b->ptbl.v[pi].n == 0 && !(pi == 0 && b->ptbl.n == 1)) {
+		txt_remove_piece(b, pi);
+	}
+	if (pi + 1 < b->ptbl.n && txt_are_pieces_adjacent(b, pi, pi + 1)) {
+		b->ptbl.v[pi].n += b->ptbl.v[pi+1].n;
+		txt_remove_piece(b, pi + 1);
+	}
+}
+
 u32 txt_delete(Txt *b, u32 cur, u32 n) {
 	TxtLoc l = txt_at(b, cur);
-	txt_split_piece(b, l.p, l.i);
-	TxtPiece *p = &b->ptbl.v[l.p];
+	u32 pi = txt_split_piece(b, l.p, l.i);
+	if (pi > 0) pi--;
 	if (n > cur) n = cur;
 	cur -= n;
 	b->len -= n;
-	while (n > p->n) {
-		n -= p->n;
-		if (l.p + 1 < b->ptbl.n) txt_remove_piece(b, l.p);
-		b->ptbl.n--;
-		if (!l.p) return cur;
-		l.p--;
-		p = &b->ptbl.v[l.p];
+	for (;;) {
+		TxtPiece *p = &b->ptbl.v[pi];
+		if (n >= p->n) {
+			n -= p->n;
+			p->n = 0;
+			if (pi > 0 || b->ptbl.n > 1) txt_remove_piece(b, pi);
+		} else {
+			p->n -= n;
+			n = 0;
+			break;
+		}
+		if (pi == 0) break;
+		pi--;
 	}
-	p->n -= n;
-	if (p->n == 0) txt_remove_piece(b, l.p);
+	txt_join_or_kill(b, pi);
 	return cur;
 }