--- /dev/null
+<?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\Validator\Mapping\Factory;
+
+use Symfony\Component\Validator\Exception\NoSuchMetadataException;
+use Symfony\Component\Validator\Mapping\Cache\CacheInterface;
+use Symfony\Component\Validator\Mapping\ClassMetadata;
+use Symfony\Component\Validator\Mapping\ClassMetadataInterface;
+use Symfony\Component\Validator\Mapping\Loader\LoaderChain;
+use Symfony\Component\Validator\Mapping\Loader\LoaderInterface;
+
+/**
+ * Creates new {@link ClassMetadataInterface} instances.
+ *
+ * Whenever {@link getMetadataFor()} is called for the first time with a given
+ * class name or object of that class, a new metadata instance is created and
+ * returned. On subsequent requests for the same class, the same metadata
+ * instance will be returned.
+ *
+ * You can optionally pass a {@link LoaderInterface} instance to the constructor.
+ * Whenever a new metadata instance is created, it is passed to the loader,
+ * which can configure the metadata based on configuration loaded from the
+ * filesystem or a database. If you want to use multiple loaders, wrap them in a
+ * {@link LoaderChain}.
+ *
+ * You can also optionally pass a {@link CacheInterface} instance to the
+ * constructor. This cache will be used for persisting the generated metadata
+ * between multiple PHP requests.
+ *
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class LazyLoadingMetadataFactory implements MetadataFactoryInterface
+{
+ /**
+ * The loader for loading the class metadata.
+ *
+ * @var LoaderInterface|null
+ */
+ protected $loader;
+
+ /**
+ * The cache for caching class metadata.
+ *
+ * @var CacheInterface|null
+ */
+ protected $cache;
+
+ /**
+ * The loaded metadata, indexed by class name.
+ *
+ * @var ClassMetadata[]
+ */
+ protected $loadedClasses = array();
+
+ /**
+ * Creates a new metadata factory.
+ *
+ * @param LoaderInterface|null $loader The loader for configuring new metadata
+ * @param CacheInterface|null $cache The cache for persisting metadata
+ * between multiple PHP requests
+ */
+ public function __construct(LoaderInterface $loader = null, CacheInterface $cache = null)
+ {
+ $this->loader = $loader;
+ $this->cache = $cache;
+ }
+
+ /**
+ * {@inheritdoc}
+ *
+ * If the method was called with the same class name (or an object of that
+ * class) before, the same metadata instance is returned.
+ *
+ * If the factory was configured with a cache, this method will first look
+ * for an existing metadata instance in the cache. If an existing instance
+ * is found, it will be returned without further ado.
+ *
+ * Otherwise, a new metadata instance is created. If the factory was
+ * configured with a loader, the metadata is passed to the
+ * {@link LoaderInterface::loadClassMetadata()} method for further
+ * configuration. At last, the new object is returned.
+ */
+ public function getMetadataFor($value)
+ {
+ if (!is_object($value) && !is_string($value)) {
+ throw new NoSuchMetadataException(sprintf('Cannot create metadata for non-objects. Got: %s', gettype($value)));
+ }
+
+ $class = ltrim(is_object($value) ? get_class($value) : $value, '\\');
+
+ if (isset($this->loadedClasses[$class])) {
+ return $this->loadedClasses[$class];
+ }
+
+ if (null !== $this->cache && false !== ($metadata = $this->cache->read($class))) {
+ // Include constraints from the parent class
+ $this->mergeConstraints($metadata);
+
+ return $this->loadedClasses[$class] = $metadata;
+ }
+
+ if (!class_exists($class) && !interface_exists($class)) {
+ throw new NoSuchMetadataException(sprintf('The class or interface "%s" does not exist.', $class));
+ }
+
+ $metadata = new ClassMetadata($class);
+
+ if (null !== $this->loader) {
+ $this->loader->loadClassMetadata($metadata);
+ }
+
+ if (null !== $this->cache) {
+ $this->cache->write($metadata);
+ }
+
+ // Include constraints from the parent class
+ $this->mergeConstraints($metadata);
+
+ return $this->loadedClasses[$class] = $metadata;
+ }
+
+ private function mergeConstraints(ClassMetadata $metadata)
+ {
+ // Include constraints from the parent class
+ if ($parent = $metadata->getReflectionClass()->getParentClass()) {
+ $metadata->mergeConstraints($this->getMetadataFor($parent->name));
+ }
+
+ $interfaces = $metadata->getReflectionClass()->getInterfaces();
+
+ $interfaces = array_filter($interfaces, function ($interface) use ($parent, $interfaces) {
+ $interfaceName = $interface->getName();
+
+ if ($parent && $parent->implementsInterface($interfaceName)) {
+ return false;
+ }
+
+ foreach ($interfaces as $i) {
+ if ($i !== $interface && $i->implementsInterface($interfaceName)) {
+ return false;
+ }
+ }
+
+ return true;
+ });
+
+ // Include constraints from all directly implemented interfaces
+ foreach ($interfaces as $interface) {
+ if ('Symfony\Component\Validator\GroupSequenceProviderInterface' === $interface->name) {
+ continue;
+ }
+ $metadata->mergeConstraints($this->getMetadataFor($interface->name));
+ }
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function hasMetadataFor($value)
+ {
+ if (!is_object($value) && !is_string($value)) {
+ return false;
+ }
+
+ $class = ltrim(is_object($value) ? get_class($value) : $value, '\\');
+
+ if (class_exists($class) || interface_exists($class)) {
+ return true;
+ }
+
+ return false;
+ }
+}