<?php

/*

 * This file is part of Twig.

 *

 * (c) 2010 Fabien Potencier

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

class Twig_Extensions_Grammar_Optional extends Twig_Extensions_Grammar

{

    protected $grammar;

    public function __construct()

    {

        $this->grammar = array();

        foreach (func_get_args() as $grammar) {

            $this->addGrammar($grammar);

        }

    }

    public function __toString()

    {

        $repr = array();

        foreach ($this->grammar as $grammar) {

            $repr[] = (string) $grammar;

        }

        return sprintf('[%s]', implode(' ', $repr));

    }

    public function addGrammar(Twig_Extensions_GrammarInterface $grammar)

    {

        $this->grammar[] = $grammar;

    }

    public function parse(Twig_Token $token)

    {

        // test if we have the optional element before consuming it

        if ($this->grammar[0] instanceof Twig_Extensions_Grammar_Constant) {

            if (!$this->parser->getStream()->test($this->grammar[0]->getType(), $this->grammar[0]->getName())) {

                return array();

            }

        } elseif ($this->grammar[0] instanceof Twig_Extensions_Grammar_Name) {

            if (!$this->parser->getStream()->test(Twig_Token::NAME_TYPE)) {

                return array();

            }

        } elseif ($this->parser->getStream()->test(Twig_Token::BLOCK_END_TYPE)) {

            // if this is not a Constant or a Name, it must be the last element of the tag

            return array();

        }

        $elements = array();

        foreach ($this->grammar as $grammar) {

            $grammar->setParser($this->parser);

            $element = $grammar->parse($token);

            if (is_array($element)) {

                $elements = array_merge($elements, $element);

            } else {

                $elements[$grammar->getName()] = $element;

            }

        }

        return $elements;

    }

}