--- /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\Translation\Catalogue;
+
+/**
+ * Target operation between two catalogues:
+ * intersection = source ∩ target = {x: x ∈ source ∧ x ∈ target}
+ * all = intersection ∪ (target ∖ intersection) = target
+ * new = all ∖ source = {x: x ∈ target ∧ x ∉ source}
+ * obsolete = source ∖ all = source ∖ target = {x: x ∈ source ∧ x ∉ target}
+ * Basically, the result contains messages from the target catalogue.
+ *
+ * @author Michael Lee <michael.lee@zerustech.com>
+ */
+class TargetOperation extends AbstractOperation
+{
+ /**
+ * {@inheritdoc}
+ */
+ protected function processDomain($domain)
+ {
+ $this->messages[$domain] = array(
+ 'all' => array(),
+ 'new' => array(),
+ 'obsolete' => array(),
+ );
+
+ // For 'all' messages, the code can't be simplified as ``$this->messages[$domain]['all'] = $target->all($domain);``,
+ // because doing so will drop messages like {x: x ∈ source ∧ x ∉ target.all ∧ x ∈ target.fallback}
+ //
+ // For 'new' messages, the code can't be simplied as ``array_diff_assoc($this->target->all($domain), $this->source->all($domain));``
+ // because doing so will not exclude messages like {x: x ∈ target ∧ x ∉ source.all ∧ x ∈ source.fallback}
+ //
+ // For 'obsolete' messages, the code can't be simplifed as ``array_diff_assoc($this->source->all($domain), $this->target->all($domain))``
+ // because doing so will not exclude messages like {x: x ∈ source ∧ x ∉ target.all ∧ x ∈ target.fallback}
+
+ foreach ($this->source->all($domain) as $id => $message) {
+ if ($this->target->has($id, $domain)) {
+ $this->messages[$domain]['all'][$id] = $message;
+ $this->result->add(array($id => $message), $domain);
+ if (null !== $keyMetadata = $this->source->getMetadata($id, $domain)) {
+ $this->result->setMetadata($id, $keyMetadata, $domain);
+ }
+ } else {
+ $this->messages[$domain]['obsolete'][$id] = $message;
+ }
+ }
+
+ foreach ($this->target->all($domain) as $id => $message) {
+ if (!$this->source->has($id, $domain)) {
+ $this->messages[$domain]['all'][$id] = $message;
+ $this->messages[$domain]['new'][$id] = $message;
+ $this->result->add(array($id => $message), $domain);
+ if (null !== $keyMetadata = $this->target->getMetadata($id, $domain)) {
+ $this->result->setMetadata($id, $keyMetadata, $domain);
+ }
+ }
+ }
+ }
+}