--- /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\Extractor;
+
+/**
+ * Base class used by classes that extract translation messages from files.
+ *
+ * @author Marcos D. Sánchez <marcosdsanchez@gmail.com>
+ */
+abstract class AbstractFileExtractor
+{
+ /**
+ * @param string|array $resource files, a file or a directory
+ *
+ * @return array
+ */
+ protected function extractFiles($resource)
+ {
+ if (is_array($resource) || $resource instanceof \Traversable) {
+ $files = array();
+ foreach ($resource as $file) {
+ if ($this->canBeExtracted($file)) {
+ $files[] = $this->toSplFileInfo($file);
+ }
+ }
+ } elseif (is_file($resource)) {
+ $files = $this->canBeExtracted($resource) ? array($this->toSplFileInfo($resource)) : array();
+ } else {
+ $files = $this->extractFromDirectory($resource);
+ }
+
+ return $files;
+ }
+
+ /**
+ * @param string $file
+ *
+ * @return \SplFileInfo
+ */
+ private function toSplFileInfo($file)
+ {
+ return ($file instanceof \SplFileInfo) ? $file : new \SplFileInfo($file);
+ }
+
+ /**
+ * @param string $file
+ *
+ * @return bool
+ *
+ * @throws \InvalidArgumentException
+ */
+ protected function isFile($file)
+ {
+ if (!is_file($file)) {
+ throw new \InvalidArgumentException(sprintf('The "%s" file does not exist.', $file));
+ }
+
+ return true;
+ }
+
+ /**
+ * @param string $file
+ *
+ * @return bool
+ */
+ abstract protected function canBeExtracted($file);
+
+ /**
+ * @param string|array $resource files, a file or a directory
+ *
+ * @return array files to be extracted
+ */
+ abstract protected function extractFromDirectory($resource);
+}