--- /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\Loader;
+
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\Exception\MappingException;
+
+/**
+ * Base loader for validation metadata.
+ *
+ * This loader supports the loading of constraints from Symfony's default
+ * namespace (see {@link DEFAULT_NAMESPACE}) using the short class names of
+ * those constraints. Constraints can also be loaded using their fully
+ * qualified class names. At last, namespace aliases can be defined to load
+ * constraints with the syntax "alias:ShortName".
+ *
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+abstract class AbstractLoader implements LoaderInterface
+{
+ /**
+ * The namespace to load constraints from by default.
+ */
+ const DEFAULT_NAMESPACE = '\\Symfony\\Component\\Validator\\Constraints\\';
+
+ /**
+ * @var array
+ */
+ protected $namespaces = array();
+
+ /**
+ * Adds a namespace alias.
+ *
+ * The namespace alias can be used to reference constraints from specific
+ * namespaces in {@link newConstraint()}:
+ *
+ * $this->addNamespaceAlias('mynamespace', '\\Acme\\Package\\Constraints\\');
+ *
+ * $constraint = $this->newConstraint('mynamespace:NotNull');
+ *
+ * @param string $alias The alias
+ * @param string $namespace The PHP namespace
+ */
+ protected function addNamespaceAlias($alias, $namespace)
+ {
+ $this->namespaces[$alias] = $namespace;
+ }
+
+ /**
+ * Creates a new constraint instance for the given constraint name.
+ *
+ * @param string $name The constraint name. Either a constraint relative
+ * to the default constraint namespace, or a fully
+ * qualified class name. Alternatively, the constraint
+ * may be preceded by a namespace alias and a colon.
+ * The namespace alias must have been defined using
+ * {@link addNamespaceAlias()}.
+ * @param mixed $options The constraint options
+ *
+ * @return Constraint
+ *
+ * @throws MappingException If the namespace prefix is undefined
+ */
+ protected function newConstraint($name, $options = null)
+ {
+ if (strpos($name, '\\') !== false && class_exists($name)) {
+ $className = (string) $name;
+ } elseif (strpos($name, ':') !== false) {
+ list($prefix, $className) = explode(':', $name, 2);
+
+ if (!isset($this->namespaces[$prefix])) {
+ throw new MappingException(sprintf('Undefined namespace prefix "%s"', $prefix));
+ }
+
+ $className = $this->namespaces[$prefix].$className;
+ } else {
+ $className = self::DEFAULT_NAMESPACE.$name;
+ }
+
+ return new $className($options);
+ }
+}