symfony · nicolas-grekas · Jul 12, 2022 · Jun 9, 2022
diff --git a/.github/expected-missing-return-types.diff b/.github/expected-missing-return-types.diff
@@ -1087,6 +1087,17 @@ index f7ef22df5c..9439e9526f 100644
 +    public static function prepare($values, $objectsPool, &$refsPool, &$objectsCount, &$valuesAreStatic): array
      {
          $refs = $values;
+diff --git a/src/Symfony/Component/VarExporter/Internal/GhostObjectState.php b/src/Symfony/Component/VarExporter/Internal/GhostObjectState.php
+index 471c1a6b91..2e19d2ab2d 100644
+--- a/src/Symfony/Component/VarExporter/Internal/GhostObjectState.php
++++ b/src/Symfony/Component/VarExporter/Internal/GhostObjectState.php
+@@ -54,5 +54,5 @@ class GhostObjectState
+      * @return bool Returns true when fully-initializing, false when partial-initializing
+      */
+-    public function initialize($instance, $propertyName, $propertyScope)
++    public function initialize($instance, $propertyName, $propertyScope): bool
+     {
+         if (!$this->status) {
 diff --git a/src/Symfony/Component/Workflow/Event/Event.php b/src/Symfony/Component/Workflow/Event/Event.php
 index cd7fab7896..b340eba38e 100644
 --- a/src/Symfony/Component/Workflow/Event/Event.php

diff --git a/src/Symfony/Component/VarExporter/CHANGELOG.md b/src/Symfony/Component/VarExporter/CHANGELOG.md
@@ -4,6 +4,7 @@ CHANGELOG
 6.2
 ---
 
+ * Add `LazyGhostObjectTrait`
  * Add `Hydrator::hydrate()`
  * Preserve PHP references also when using `Hydrator::hydrate()` or `Instantiator::instantiate()`
  * Add support for hydrating from native (array) casts

diff --git a/src/Symfony/Component/VarExporter/Instantiator.php b/src/Symfony/Component/VarExporter/Instantiator.php
@@ -54,6 +54,6 @@ public static function instantiate(string $class, array $properties = [], array
             $instance = unserialize('O:'.\strlen($class).':"'.$class.'":0:{}');
         }
 
-        return Hydrator::hydrate($instance, $properties, $scopedProperties);
+        return $properties || $scopedProperties ? Hydrator::hydrate($instance, $properties, $scopedProperties) : $instance;
     }
 }
diff --git a/src/Symfony/Component/VarExporter/Internal/EmptyScope.php b/src/Symfony/Component/VarExporter/Internal/EmptyScope.php
@@ -0,0 +1,19 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\VarExporter\Internal;
+
+/**
+ * @internal
+ */
+enum EmptyScope
+{
+}
diff --git a/src/Symfony/Component/VarExporter/Internal/GhostObjectRegistry.php b/src/Symfony/Component/VarExporter/Internal/GhostObjectRegistry.php
@@ -0,0 +1,126 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\VarExporter\Internal;
+
+/**
+ * Stores the state of lazy ghost objects and caches related reflection information.
+ *
+ * As a micro-optimization, this class uses no type declarations.
+ *
+ * @internal
+ */
+class GhostObjectRegistry
+{
+    /**
+     * @var array<int, GhostObjectState>
+     */
+    public static $states = [];
+
+    /**
+     * @var array<class-string, \ReflectionClass>
+     */
+    public static $classReflectors = [];
+
+    /**
+     * @var array<class-string, array<string, mixed>>
+     */
+    public static $defaultProperties = [];
+
+    /**
+     * @var array<class-string, list<\Closure>>
+     */
+    public static $classResetters = [];
+
+    /**
+     * @var array<class-string, array{get: \Closure, set: \Closure, isset: \Closure, unset: \Closure}>
+     */
+    public static $classAccessors = [];
+
+    /**
+     * @var array<class-string, array{get: int, set: bool, isset: bool, unset: bool, clone: bool, serialize: bool, sleep: bool, destruct: bool}>
+     */
+    public static $parentMethods = [];
+
+    public static function getClassResetters($class)
+    {
+        $classProperties = [];
+        $propertyScopes = Hydrator::$propertyScopes[$class] ??= Hydrator::getPropertyScopes($class);
+
+        foreach ($propertyScopes as $key => [$scope, $name, $readonlyScope]) {
+            if ('lazyGhostObjectId' !== $name && null !== ($propertyScopes["\0$scope\0$name"] ?? $propertyScopes["\0*\0$name"] ?? $readonlyScope)) {
+                $classProperties[$readonlyScope ?? $scope][$name] = $key;
+            }
+        }
+
+        $resetters = [];
+        foreach ($classProperties as $scope => $properties) {
+            $resetters[] = \Closure::bind(static function ($instance, $skippedProperties = []) use ($properties) {
+                foreach ($properties as $name => $key) {
+                    if (!\array_key_exists($key, $skippedProperties)) {
+                        unset($instance->$name);
+                    }
+                }
+            }, null, $scope);
+        }
+
+        $resetters[] = static function ($instance, $skippedProperties = []) {
+            foreach ((array) $instance as $name => $value) {
+                if ("\0" !== ($name[0] ?? '') && !\array_key_exists($name, $skippedProperties)) {
+                    unset($instance->$name);
+                }
+            }
+        };
+
+        return $resetters;
+    }
+
+    public static function getClassAccessors($class)
+    {
+        return \Closure::bind(static function () {
+            return [
+                'get' => static function &($instance, $name, $readonly) {
+                    if (!$readonly) {
+                        return $instance->$name;
+                    }
+                    $value = $instance->$name;
+
+                    return $value;
+                },
+                'set' => static function ($instance, $name, $value) {
+                    $instance->$name = $value;
+                },
+                'isset' => static function ($instance, $name) {
+                    return isset($instance->$name);
+                },
+                'unset' => static function ($instance, $name) {
+                    unset($instance->$name);
+                },
+            ];
+        }, null, $class)();
+    }
+
+    public static function getParentMethods($class)
+    {
+        $parent = get_parent_class($class);
+
+        return [
+            'get' => $parent && method_exists($parent, '__get') ? ((new \ReflectionMethod($parent, '__get'))->returnsReference() ? 2 : 1) : 0,
+            'set' => $parent && method_exists($parent, '__set'),
+            'isset' => $parent && method_exists($parent, '__isset'),
+            'unset' => $parent && method_exists($parent, '__unset'),
+            'clone' => $parent && method_exists($parent, '__clone'),
+            'serialize' => $parent && method_exists($parent, '__serialize'),
+            'sleep' => $parent && method_exists($parent, '__sleep'),
+            'destruct' => $parent && method_exists($parent, '__destruct'),
+        ];
+    }
+}
diff --git a/src/Symfony/Component/VarExporter/Internal/GhostObjectState.php b/src/Symfony/Component/VarExporter/Internal/GhostObjectState.php
@@ -0,0 +1,87 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\VarExporter\Internal;
+
+use Symfony\Component\VarExporter\Hydrator;
+
+/**
+ * Keeps the state of lazy ghost objects.
+ *
+ * As a micro-optimization, this class uses no type declarations.
+ *
+ * @internal
+ */
+class GhostObjectState
+{
+    public const STATUS_INITIALIZED_PARTIAL = 1;
+    public const STATUS_UNINITIALIZED_FULL = 2;
+    public const STATUS_INITIALIZED_FULL = 3;
+
+    public \Closure $initializer;
+
+    /**
+     * @var array<class-string|'*', array<string, true>>
+     */
+    public $preInitUnsetProperties;
+
+    /**
+     * @var array<string, true>
+     */
+    public $preInitSetProperties = [];
+
+    /**
+     * @var array<class-string|'*', array<string, true>>
+     */
+    public $unsetProperties = [];
+
+    /**
+     * One of self::STATUS_*.
+     *
+     * @var int
+     */
+    public $status;
+
+    /**
+     * @return bool Returns true when fully-initializing, false when partial-initializing
+     */
+    public function initialize($instance, $propertyName, $propertyScope)
+    {
+        if (!$this->status) {
+            $this->status = 1 < (new \ReflectionFunction($this->initializer))->getNumberOfRequiredParameters() ? self::STATUS_INITIALIZED_PARTIAL : self::STATUS_UNINITIALIZED_FULL;
+            $this->preInitUnsetProperties ??= $this->unsetProperties;
+        }
+
+        if (self::STATUS_INITIALIZED_FULL === $this->status) {
+            return true;
+        }
+
+        if (self::STATUS_UNINITIALIZED_FULL === $this->status) {
+            if ($defaultProperties = array_diff_key(GhostObjectRegistry::$defaultProperties[\get_class($instance)], (array) $instance)) {
+                Hydrator::hydrate($instance, $defaultProperties);
+            }
+
+            $this->status = self::STATUS_INITIALIZED_FULL;
+            ($this->initializer)($instance);
+
+            return true;
+        }
+
+        $value = ($this->initializer)(...[$instance, $propertyName, $propertyScope]);
+
+        $propertyScope ??= \get_class($instance);
+        $accessor = GhostObjectRegistry::$classAccessors[$propertyScope] ??= GhostObjectRegistry::getClassAccessors($propertyScope);
+
+        $accessor['set']($instance, $propertyName, $value);
+
+        return false;
+    }
+}
diff --git a/src/Symfony/Component/VarExporter/LazyGhostObjectInterface.php b/src/Symfony/Component/VarExporter/LazyGhostObjectInterface.php
@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\VarExporter;
+
+interface LazyGhostObjectInterface
+{
+    /**
+     * Forces initialization of a lazy ghost object.
+     */
+    public function initializeLazyGhostObject(): void;
+
+    /**
+     * @return bool Returns false when the object cannot be reset, ie when it's not a ghost object
+     */
+    public function resetLazyGhostObject(): bool;
+}