1 files changed, 42 insertions, 0 deletions
diff --git a/vendor/ipl/stdlib/src/PriorityQueue.php b/vendor/ipl/stdlib/src/PriorityQueue.php
new file mode 100644
index 0000000..9047af4
--- /dev/null
+++ b/vendor/ipl/stdlib/src/PriorityQueue.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace ipl\Stdlib;
+
+use Generator;
+use SplPriorityQueue;
+
+/**
+ * Stable priority queue that also maintains insertion order for items with the same priority
+ */
+class PriorityQueue extends SplPriorityQueue
+{
+    /** @var int */
+    protected $serial = PHP_INT_MAX;
+
+    /**
+     * @inheritDoc
+     *
+     * Maintains insertion order for items with the same priority.
+     */
+    public function insert($value, $priority): bool
+    {
+        return parent::insert($value, [$priority, $this->serial--]);
+    }
+
+    /**
+     * Yield all items as priority-value pairs
+     *
+     * @return Generator
+     */
+    public function yieldAll()
+    {
+        // Clone queue because the SplPriorityQueue acts as a heap and thus items are removed upon iteration
+        $queue = clone $this;
+
+        $queue->setExtractFlags(static::EXTR_BOTH);
+
+        foreach ($queue as $item) {
+            yield $item['priority'][0] => $item['data'];
+        }
+    }
+}