try and prevent 0-length splits occurring

1 files changed, 51 insertions, 35 deletions

diff --git a/txt.c b/txt.c
index 36af521..3bd9eb4 100644
--- a/txt.c
+++ b/txt.c
@@ -94,48 +94,65 @@ static int txt_are_pieces_adjacent(Txt *t, u32 a, u32 b) {
 	return pa->buf == pb->buf && pa->ofs + pa->n == pb->ofs;
 }
 
-static TxtLoc txt_join_or_kill(TxtLoc l) {
-	Txt *b = l.t;
-	while (l.t->ptbl.v[l.p].n == 0 && b->ptbl.n > 1) {
-		txt_remove_piece(b, l.p);
-		if (l.p >= b->ptbl.n) {
-			l.p = b->ptbl.n - 1;
-			l.i = b->ptbl.v[l.p].n;
-		}
+static int txt_trim_empty(TxtLoc *lp) {
+	TxtLoc l = *lp;
+	int deleted = 0;
+	while (l.p > 0 && l.t->ptbl.v[l.p-1].n == 0) {
+		txt_remove_piece(l.t, l.p - 1);
+		l.p--;
+		deleted = 1;
 	}
-	while (l.p + 1 < b->ptbl.n && l.t->ptbl.v[l.p + 1].n == 0) {
-		txt_remove_piece(b, l.p + 1);
-		if (l.p >= b->ptbl.n) {
-			l.p = b->ptbl.n - 1;
-			l.i = b->ptbl.v[l.p].n;
-		}
+	while (l.p + 1 < l.t->ptbl.n && l.t->ptbl.v[l.p+1].n == 0) {
+		txt_remove_piece(l.t, l.p + 1);
+		deleted = 1;
 	}
-	if (l.p + 1 < b->ptbl.n && txt_are_pieces_adjacent(b, l.p, l.p + 1)) {
-		b->ptbl.v[l.p].n += b->ptbl.v[l.p+1].n;
-		txt_remove_piece(b, l.p + 1);
-		if (l.p >= b->ptbl.n) {
-			l.p = b->ptbl.n - 1;
-			l.i = b->ptbl.v[l.p].n;
+	while (l.t->ptbl.n > 1 && l.t->ptbl.v[l.p].n == 0) {
+		txt_remove_piece(l.t, l.p);
+		if (l.p >= l.t->ptbl.n) {
+			l.p = l.t->ptbl.n - 1;
+			l.i = l.t->ptbl.v[l.p].n;
 		}
+		deleted = 1;
 	}
-	if (l.p > 0 && txt_are_pieces_adjacent(b, l.p - 1, l.p)) {
-		l.i = b->ptbl.v[l.p - 1].n;
-		b->ptbl.v[l.p - 1].n += b->ptbl.v[l.p].n;
-		txt_remove_piece(b, l.p);
-		l.p--;
-		ASSERT(l.p < b->ptbl.n);
-	}
-	return l;
+	*lp = l;
+	return deleted;
 }
 
 static inline TxtLoc resolve_loc(TxtLoc l) {
-	if (l.p + 1 < l.t->ptbl.n && l.i == l.t->ptbl.v[l.p].n) {
+	while (l.p + 1 < l.t->ptbl.n && l.i == l.t->ptbl.v[l.p].n) {
 		l.p++;
 		l.i = 0;
 	}
+	ASSERT(txt_valid_loc(l));
 	return l;
 }
 
+static TxtLoc txt_post_edit(TxtLoc l) {
+	l = resolve_loc(l);
+	ASSERT(txt_valid_loc(l));
+loop:
+	if (txt_trim_empty(&l)) {
+		ASSERT(txt_valid_loc(l));
+		goto loop;
+	}
+	if (l.p > 0 && txt_are_pieces_adjacent(l.t, l.p - 1, l.p)) {
+		l.i = l.t->ptbl.v[l.p - 1].n;
+		l.t->ptbl.v[l.p - 1].n += l.t->ptbl.v[l.p].n;
+		txt_remove_piece(l.t, l.p);
+		l.p--;
+		ASSERT(txt_valid_loc(l));
+		goto loop;
+	}
+	if (l.p + 1 < l.t->ptbl.n && txt_are_pieces_adjacent(l.t, l.p, l.p + 1)) {
+		l.t->ptbl.v[l.p].n += l.t->ptbl.v[l.p + 1].n;
+		txt_remove_piece(l.t, l.p + 1);
+		ASSERT(txt_valid_loc(l));
+		goto loop;
+	}
+	ASSERT(txt_valid_loc(l));
+	return resolve_loc(l);
+}
+
 TxtLoc txt_insert(TxtLoc l, const char *s, u32 n) {
 	l = txt_add_piece(l.t, l);
 	TxtPiece *p = &l.t->ptbl.v[l.p];
@@ -148,9 +165,7 @@ TxtLoc txt_insert(TxtLoc l, const char *s, u32 n) {
 	p->n += n;
 	l.t->len += n;
 	l.i = p->n;
-	l = txt_join_or_kill(l);
-	l.i = l.t->ptbl.v[l.p].n;
-	return resolve_loc(l);
+	return txt_post_edit(l);
 }
 
 TxtLoc txt_insert_c(TxtLoc l, u32 ch) {
@@ -166,7 +181,7 @@ TxtLoc txt_delete(TxtLoc l, u32 n) {
 	l.p = pi;
 	l.i = l.t->ptbl.v[l.p].n;
 	for (;;) {
-		ASSERT(l.i == l.t->ptbl.v[l.p].n);
+		if (l.i != l.t->ptbl.v[l.p].n) break;
 		if (l.i >= n) {
 			l.i -= n;
 			l.t->ptbl.v[l.p].n -= n;
@@ -179,9 +194,9 @@ TxtLoc txt_delete(TxtLoc l, u32 n) {
 			l.p = l.p - 1;
 			l.i = l.t->ptbl.v[l.p].n;
 		}
-		l = txt_join_or_kill(l);
+		while (txt_trim_empty(&l));
 	}
-	return resolve_loc(txt_join_or_kill(l));
+	return txt_post_edit(l);
 }
 
 u32 txt_range_len(TxtLoc lo, TxtLoc hi) {
@@ -270,6 +285,7 @@ void txt_write_range(int fd, TxtLoc lo, TxtLoc hi) {
 		lo.p++;
 		lo.i = 0;
 	}
+	ASSERT(lo.p == hi.p);
 	if (hi.i > lo.i) {
 		TxtPiece *p = &lo.t->ptbl.v[lo.p];
 		write(fd, lo.t->buf[p->buf].s + p->ofs + lo.i, hi.i - lo.i);