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commit 7396d08a074f61cdb0fa7f3d38bd952d22886139
parent 32e5df2da3c2e3478fd228dc3b25a5330c396a5b
Author: John Hawthorn <john.hawthorn@gmail.com>
Date:   Tue,  7 Jun 2016 01:58:41 -0700

Make sorting stable

C's stdlib's qsort isn't a stable sort. We want it to be so that any
equivalent matches are stored in the order they came in.

Diffstat:
M
src/choices.c
 | 
17
+++++++++++++----

1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/src/choices.c b/src/choices.c
@@ -15,12 +15,21 @@ static int cmpchoice(const void *_idx1, const void *_idx2) {
 	const struct scored_result *a = _idx1;
 	const struct scored_result *b = _idx2;
 
-	if (a->score == b->score)
-		return 0;
-	else if (a->score < b->score)
+	if (a->score == b->score) {
+		/* To ensure a stable sort, we must also sort by the string
+		 * pointers. We can do this since we know all the stings are
+		 * from a contiguous memory segment (buffer in choices_t).
+		 */
+		if (a->str < b->str) {
+			return -1;
+		} else {
+			return 1;
+		}
+	} else if (a->score < b->score) {
 		return 1;
-	else
+	} else {
 		return -1;
+	}
 }
 
 static void *safe_realloc(void *buffer, size_t size) {