Speeding up each() by unwrapping uneeded nested collections first

src/Collection/CollectionTrait.php

@@ -46,7 +46,11 @@ trait CollectionTrait
      */
     public function each(callable $c)
     {
-        foreach ($this as $k => $v) {
+        $iterator = $this;
+        while (get_class($iterator) === 'Cake\Collection\Collection') {
+            $iterator = $iterator->getInnerIterator();
+        }
+        foreach ($iterator as $k => $v) {
             $c($v, $k);
         }
         return $this;

src/Collection/Iterator/ReplaceIterator.php

@@ -30,6 +30,13 @@ class ReplaceIterator extends Collection
      */
     protected $_callback;
 
+    /**
+     * A reference to the internal iterator this object is wrapping.
+     *
+     * @var \Iterator
+     */
+    protected $_innerIterator;
+
     /**
      * Creates an iterator from another iterator that will modify each of the values
      * by converting them using a callback function.
@@ -45,6 +52,7 @@ public function __construct($items, callable $callback)
     {
         $this->_callback = $callback;
         parent::__construct($items);
+        $this->_innerIterator = $this->getInnerIterator();
     }
 
     /**
@@ -56,6 +64,6 @@ public function __construct($items, callable $callback)
     public function current()
     {
         $callback = $this->_callback;
-        return $callback(parent::current(), $this->key(), $this->getInnerIterator());
+        return $callback(parent::current(), $this->key(), $this->_innerIterator);
     }
 }