RegexRecursiveFilterIterator.php

<?php

namespace Drupal\Core\Plugin\Discovery;


/**
 * Iterates over files whose names match a regular expression in a directory.
 */
class RegexRecursiveFilterIterator extends \RecursiveFilterIterator {
    
    /**
     * RegexRecursiveFilterIterator constructor.
     *
     * @param \RecursiveIterator $iterator
     *   The iterator.
     * @param string $regex
     *   The regular expression to match, including delimiters. For example,
     *   /\.yml$/ would list only files ending in .yml.
     */
    public function __construct(\RecursiveIterator $iterator, string $regex = '') {
        parent::__construct($iterator);
    }
    
    /**
     * {@inheritdoc}
     */
    public function accept() : bool {
        
        /** @var \SplFileInfo $file_info */
        $file_info = $this->getInnerIterator()
            ->current();
        if ($file_info->isDir()) {
            // Enter into subdirectory.
            return TRUE;
        }
        // Return if file matches regular expression.
        return $file_info->isFile() && preg_match($this->regex, $file_info->getFilename());
    }
    
    /**
     * {@inheritdoc}
     */
    public function getChildren() : ?\RecursiveFilterIterator {
        $children = parent::getChildren();
        if ($children instanceof self && empty($children->regex)) {
            $children->regex = $this->regex;
        }
        return $children;
    }

}