--- /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\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * Removes unused service definitions from the container.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+class RemoveUnusedDefinitionsPass implements RepeatablePassInterface
+{
+ private $repeatedPass;
+
+ /**
+ * {@inheritdoc}
+ */
+ public function setRepeatedPass(RepeatedPass $repeatedPass)
+ {
+ $this->repeatedPass = $repeatedPass;
+ }
+
+ /**
+ * Processes the ContainerBuilder to remove unused definitions.
+ *
+ * @param ContainerBuilder $container
+ */
+ public function process(ContainerBuilder $container)
+ {
+ $compiler = $container->getCompiler();
+ $formatter = $compiler->getLoggingFormatter();
+ $graph = $compiler->getServiceReferenceGraph();
+
+ $hasChanged = false;
+ foreach ($container->getDefinitions() as $id => $definition) {
+ if ($definition->isPublic()) {
+ continue;
+ }
+
+ if ($graph->hasNode($id)) {
+ $edges = $graph->getNode($id)->getInEdges();
+ $referencingAliases = array();
+ $sourceIds = array();
+ foreach ($edges as $edge) {
+ $node = $edge->getSourceNode();
+ $sourceIds[] = $node->getId();
+
+ if ($node->isAlias()) {
+ $referencingAliases[] = $node->getValue();
+ }
+ }
+ $isReferenced = (count(array_unique($sourceIds)) - count($referencingAliases)) > 0;
+ } else {
+ $referencingAliases = array();
+ $isReferenced = false;
+ }
+
+ if (1 === count($referencingAliases) && false === $isReferenced) {
+ $container->setDefinition((string) reset($referencingAliases), $definition);
+ $definition->setPublic(true);
+ $container->removeDefinition($id);
+ $compiler->addLogMessage($formatter->formatRemoveService($this, $id, 'replaces alias '.reset($referencingAliases)));
+ } elseif (0 === count($referencingAliases) && false === $isReferenced) {
+ $container->removeDefinition($id);
+ $compiler->addLogMessage($formatter->formatRemoveService($this, $id, 'unused'));
+ $hasChanged = true;
+ }
+ }
+
+ if ($hasChanged) {
+ $this->repeatedPass->setRepeat();
+ }
+ }
+}