Attributes: Add rebind() and rebindCallback

src/Attributes.php

@@ -4,8 +4,11 @@
 
 use ArrayAccess;
 use ArrayIterator;
+use Closure;
 use InvalidArgumentException;
 use IteratorAggregate;
+use ReflectionException;
+use ReflectionFunction;
 use Traversable;
 
 use function ipl\Stdlib\get_php_type;
@@ -509,12 +512,77 @@ public function getIterator(): Traversable
         return new ArrayIterator($this->attributes);
     }
 
+    /**
+     * Rebind all {@see self::$callbacks} and {@see self::$setterCallbacks} that point to `$oldThis` to `$newThis`.
+     *
+     * @param object $oldThis
+     * @param object $newThis
+     *
+     * @return void
+     * @throws ReflectionException
+     */
+    public function rebind(object $oldThis, object $newThis): void
+    {
+        $this->rebindCallback($this->callbacks, true, $oldThis, $newThis);
+        $this->rebindCallback($this->setterCallbacks, false, $oldThis, $newThis);
+    }
+
+    /**
+     * Helper Method for {@see self::rebind()}
+     *
+     * Loops over all `$callbacks`, binds them to `$newThis` where `$oldThis` matches and
+     * overwrites the existing callback either in {@see self::$callbacks} or {@see self::$setterCallbacks}, depending
+     * on `$isGetter`.
+     *
+     * @param callable[] $callbacks
+     * @param bool       $isGetter
+     * @param object     $oldThis
+     * @param object     $newThis
+     *
+     * @return void
+     * @throws ReflectionException
+     */
+    private function rebindCallback(array $callbacks, bool $isGetter, object $oldThis, object $newThis): void
+    {
+        foreach ($callbacks as $key => $callback) {
+            if (! $callback instanceof Closure) {
+                if (is_array($callback) && ! is_string($callback[0])) {
+                    if (spl_object_id($callback[0]) == spl_object_id($oldThis)) {
+                        $this->registerAttributeCallback(
+                            $key,
+                            $isGetter ? Closure::fromCallable($callback)->bindTo($newThis) : null,
+                            ! $isGetter ? Closure::fromCallable($callback)->bindTo($newThis) : null
+                        );
+                    }
+                }
+
+                continue;
+            }
+
+            $closureThis = (new ReflectionFunction($callback))
+                ->getClosureThis();
+
+            // Closure is most likely static
+            if ($closureThis === null) {
+                continue;
+            }
+
+            $closureThisHash = spl_object_id($closureThis);
+
+            if ($closureThisHash == spl_object_id($oldThis)) {
+                $this->registerAttributeCallback(
+                    $key,
+                    $isGetter ? Closure::fromCallable($callback)->bindTo($newThis) : null,
+                    ! $isGetter ? Closure::fromCallable($callback)->bindTo($newThis) : null
+                );
+            }
+        }
+    }
+
     public function __clone()
     {
         foreach ($this->attributes as &$attribute) {
             $attribute = clone $attribute;
         }
-
-        // TODO(lippserd): Rebind callbacks. However that should work then :).
     }
 }