Merge pull request #109 from gsteel/priority-queue-to-array-ordered

Sort the results of PriorityQueue::toArray() according to priority

docs/book/v4/migration/v3-to-v4.md

@@ -10,6 +10,10 @@ All classes have been updated to make use of parameter and return types. In gene
 
 The addition of property, parameter and return types will cause fatal errors for extending classes that re-define those properties or override changed methods. If you have extended from any classes in laminas-stdlib, you should check that property types and method signatures are compatible and update them if they are not aligned.
 
+### `PriorityQueue::toArray()` Now Returns Data in Order of Priority
+
+In previous versions, `PriorityQueue::toArray()` returned data in insertion order. This method now returns data in priority order making it effectively the same as `iterator_to_array($queue)`, with the exception that you can pass extraction flags to `PriorityQueue::toArray()`.
+
 ## Removed Features
 
 None.

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),
         };
     }
 

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],
         ];