From 19c9b8098cd3db1ff98efaa141e9baf959792c20 Mon Sep 17 00:00:00 2001
From: George Steel <george@net-glue.co.uk>
Date: Thu, 14 Sep 2023 22:34:33 +0100
Subject: [PATCH] Sort the results of PriorityQueue::toArray() according to
 priority

Closes #21

Signed-off-by: George Steel <george@net-glue.co.uk>
---
 src/PriorityQueue.php      | 23 ++++++++++++++++-------
 test/PriorityQueueTest.php |  6 +++---
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/src/PriorityQueue.php b/src/PriorityQueue.php
index 3b19136d..8cd49a0b 100644
--- a/src/PriorityQueue.php
+++ b/src/PriorityQueue.php
@@ -17,6 +17,7 @@
 use function serialize;
 use function sprintf;
 use function unserialize;
+use function usort;
 
 /**
  * Re-usable, serializable priority queue implementation
@@ -245,13 +246,12 @@ public function __unserialize(array $data): void
     }
 
     /**
-     * Serialize to an array
-     * By default, returns only the item data, and in the order registered (not
-     * sorted). You may provide one of the EXTR_* flags as an argument, allowing
+     * Serialize to an array, ordered by priority
+     * By default, returns only the item data. You may provide one of the EXTR_* flags as an argument, allowing
      * the ability to return priorities or both data and priority.
      *
      * @param self::EXTR_* $flag
-     * @return array<array-key, mixed>
+     * @return list<mixed>
      * @psalm-return ($flag is self::EXTR_BOTH
      *                      ? list<array{data: TValue, priority: int}>
      *                      : $flag is self::EXTR_PRIORITY
@@ -261,10 +261,19 @@ public function __unserialize(array $data): void
      */
     public function toArray(int $flag = self::EXTR_DATA): array
     {
+        /**
+         * A manual sort is required because $item['priority'] as stored in the inner queue could be an array as
+         * opposed to an integer.
+         */
+        $items = $this->items;
+        usort($items, function (array $a, array $b): int {
+            return $b['priority'] <=> $a['priority'];
+        });
+
         return match ($flag) {
-            self::EXTR_BOTH => $this->items,
-            self::EXTR_PRIORITY => array_map(static fn($item): int => $item['priority'], $this->items),
-            default => array_map(static fn($item): mixed => $item['data'], $this->items),
+            self::EXTR_BOTH => $items,
+            self::EXTR_PRIORITY => array_map(static fn($item): int => $item['priority'], $items),
+            default => array_map(static fn($item): mixed => $item['data'], $items),
         };
     }
 
diff --git a/test/PriorityQueueTest.php b/test/PriorityQueueTest.php
index b7871d11..49c14013 100644
--- a/test/PriorityQueueTest.php
+++ b/test/PriorityQueueTest.php
@@ -56,8 +56,8 @@ public function testSerializationAndDeserializationShouldMaintainState(): void
     public function testRetrievingQueueAsArrayReturnsDataOnlyByDefault(): void
     {
         $expected = [
-            'foo',
             'bar',
+            'foo',
             'baz',
             'bat',
         ];
@@ -68,8 +68,8 @@ public function testRetrievingQueueAsArrayReturnsDataOnlyByDefault(): void
     public function testCanCastToArrayOfPrioritiesOnly(): void
     {
         $expected = [
-            3,
             4,
+            3,
             2,
             1,
         ];
@@ -80,8 +80,8 @@ public function testCanCastToArrayOfPrioritiesOnly(): void
     public function testCanCastToArrayOfDataPriorityPairs(): void
     {
         $expected = [
-            ['data' => 'foo', 'priority' => 3],
             ['data' => 'bar', 'priority' => 4],
+            ['data' => 'foo', 'priority' => 3],
             ['data' => 'baz', 'priority' => 2],
             ['data' => 'bat', 'priority' => 1],
         ];