On 9/21/2018 1:39 PM, Derrick Stolee via GitGitGadget wrote:
From: Derrick Stolee <dsto...@microsoft.com>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. Signed-off-by: Derrick Stolee <dsto...@microsoft.com> --- prio-queue.c | 9 +++++++++ prio-queue.h | 6 ++++++ t/helper/test-prio-queue.c | 10 +++++++--- 3 files changed, 22 insertions(+), 3 deletions(-) diff --git a/prio-queue.c b/prio-queue.c index a078451872..d3f488cb05 100644 --- a/prio-queue.c +++ b/prio-queue.c @@ -85,3 +85,12 @@ void *prio_queue_get(struct prio_queue *queue) } return result; } + +void *prio_queue_peek(struct prio_queue *queue) +{ + if (!queue->nr) + return NULL; + if (!queue->compare) + return queue->array[queue->nr - 1].data; + return queue->array[0].data; +}
The second branch here is never run by the test suite, as the only consumers never have compare== NULL. I'll add an ability to test this "stack" behavior into t0009-prio-queue.sh.
-Stolee
