From bc2d733a47782c614e20012b4dfe31b651f60fca Mon Sep 17 00:00:00 2001
From: Pol Dellaiera <pol.dellaiera@protonmail.com>
Date: Mon, 6 Jan 2020 19:22:05 +0100
Subject: [PATCH] Fix behavior of ::filter() operation.

---
 spec/loophp/collection/CollectionSpec.php | 15 +++++++++++----
 src/Operation/Filter.php                  |  6 ++++--
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/spec/loophp/collection/CollectionSpec.php b/spec/loophp/collection/CollectionSpec.php
index 437de795a..2bd1230e3 100644
--- a/spec/loophp/collection/CollectionSpec.php
+++ b/spec/loophp/collection/CollectionSpec.php
@@ -467,7 +467,7 @@ public function it_can_explode(): void
             );
     }
 
-    public function it_can_filter_its_element(): void
+    public function it_can_filter(): void
     {
         $input = array_merge([0, false], range(1, 10));
 
@@ -488,10 +488,17 @@ public function it_can_filter_its_element(): void
             ->normalize()
             ->shouldIterateAs([1, 3, 5, 7, 9]);
 
-        $this
-            ->filter()
+        $this::with(['afooe', 'fooe', 'allo', 'llo'])
+            ->filter(
+                static function ($value) {
+                    return 0 === mb_strpos($value, 'a');
+                },
+                static function ($value) {
+                    return mb_strlen($value) - 1 === mb_strpos($value, 'o');
+                }
+            )
             ->normalize()
-            ->shouldIterateAs([]);
+            ->shouldIterateAs(['allo']);
     }
 
     public function it_can_flatten(): void
diff --git a/src/Operation/Filter.php b/src/Operation/Filter.php
index 5f5d31319..8d2aac6af 100644
--- a/src/Operation/Filter.php
+++ b/src/Operation/Filter.php
@@ -38,11 +38,13 @@ public function on(iterable $collection): Closure
         $callbacks = $this->callbacks;
 
         return static function () use ($callbacks, $collection): Generator {
-            $iterator = $collection;
+            $iterator = new IterableIterator($collection);
 
             foreach ($callbacks as $callback) {
-                yield from $iterator = new CallbackFilterIterator(new IterableIterator($iterator), $callback);
+                $iterator = new CallbackFilterIterator($iterator, $callback);
             }
+
+            yield from $iterator;
         };
     }
 }