From aca4240f6a32423df5f95de6a9354b524fe57ec5 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Thu, 1 Nov 2018 13:46:17 +0000 Subject: prio-queue: add 'peek' operation When consuming a priority queue, it can be convenient to inspect the next object that will be dequeued without actually dequeueing it. Our existing library did not have such a 'peek' operation, so add it as prio_queue_peek(). Add a reference-level comparison in t/helper/test-prio-queue.c so this method is exercised by t0009-prio-queue.sh. Further, add a test that checks the behavior when the compare function is NULL (i.e. the queue becomes a stack). Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano --- t/helper/test-prio-queue.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) (limited to 't/helper/test-prio-queue.c') diff --git a/t/helper/test-prio-queue.c b/t/helper/test-prio-queue.c index 9807b649b1..5bc9c46ea5 100644 --- a/t/helper/test-prio-queue.c +++ b/t/helper/test-prio-queue.c @@ -22,14 +22,24 @@ int cmd__prio_queue(int argc, const char **argv) struct prio_queue pq = { intcmp }; while (*++argv) { - if (!strcmp(*argv, "get")) - show(prio_queue_get(&pq)); - else if (!strcmp(*argv, "dump")) { - int *v; - while ((v = prio_queue_get(&pq))) - show(v); - } - else { + if (!strcmp(*argv, "get")) { + void *peek = prio_queue_peek(&pq); + void *get = prio_queue_get(&pq); + if (peek != get) + BUG("peek and get results do not match"); + show(get); + } else if (!strcmp(*argv, "dump")) { + void *peek; + void *get; + while ((peek = prio_queue_peek(&pq))) { + get = prio_queue_get(&pq); + if (peek != get) + BUG("peek and get results do not match"); + show(get); + } + } else if (!strcmp(*argv, "stack")) { + pq.compare = NULL; + } else { int *v = malloc(sizeof(*v)); *v = atoi(*argv); prio_queue_put(&pq, v); -- cgit 1.2.3-korg