PHPLIB-609: Allow CachingIterator to handle Iterators with non-unique keys

src/Model/CachingIterator.php

@@ -25,7 +25,6 @@
 
 use function count;
 use function current;
-use function key;
 use function next;
 use function reset;
 
@@ -40,6 +39,9 @@
  */
 class CachingIterator implements Countable, Iterator
 {
+    private const FIELD_KEY = 0;
+    private const FIELD_VALUE = 1;
+
     /** @var array */
     private $items = [];
 
@@ -87,7 +89,9 @@ public function count()
     #[ReturnTypeWillChange]
     public function current()
     {
-        return current($this->items);
+        $currentItem = current($this->items);
+
+        return $currentItem !== false ? $currentItem[self::FIELD_VALUE] : false;
     }
 
     /**
@@ -97,7 +101,9 @@ public function current()
     #[ReturnTypeWillChange]
     public function key()
     {
-        return key($this->items);
+        $currentItem = current($this->items);
+
+        return $currentItem !== false ? $currentItem[self::FIELD_KEY] : null;
     }
 
     /**
@@ -165,6 +171,10 @@ private function storeCurrentItem()
             return;
         }
 
-        $this->items[$this->iterator->key()] = $this->iterator->current();
+        // Storing a new item in the internal cache
+        $this->items[] = [
+            self::FIELD_KEY => $this->iterator->key(),
+            self::FIELD_VALUE => $this->iterator->current(),
+        ];
     }
 }

tests/Model/CachingIteratorTest.php

@@ -152,6 +152,26 @@ public function rewind(): void
         $this->assertCount(1, $iterator);
     }
 
+    public function testCountNonUniqueKeys(): void
+    {
+        $iterator = new CachingIterator($this->getNonUniqueTraversable([1, 2, 3]));
+        $this->assertCount(3, $iterator);
+    }
+
+    public function testIterationNonUniqueKeys(): void
+    {
+        $iterator = new CachingIterator($this->getNonUniqueTraversable([1, 2, 3]));
+
+        $expectedItem = 1;
+
+        foreach ($iterator as $key => $item) {
+            $this->assertSame(0, $key);
+            $this->assertSame($expectedItem++, $item);
+        }
+
+        $this->assertFalse($iterator->valid());
+    }
+
     private function getTraversable($items)
     {
         foreach ($items as $item) {
@@ -162,4 +182,15 @@ private function getTraversable($items)
             }
         }
     }
+
+    private function getNonUniqueTraversable($items)
+    {
+        foreach ($items as $item) {
+            if ($item instanceof Exception) {
+                throw $item;
+            } else {
+                yield 0 => $item;
+            }
+        }
+    }
 }