<?php

/*

 * This file is part of Twig.

 *

 * (c) 2009 Fabien Potencier

 * (c) 2009 Armin Ronacher

 *

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

 * file that was distributed with this source code.

 */

/**

 * Represents a token stream.

 *

 * @package twig

 * @author  Fabien Potencier <fabien@symfony.com>

 */

class Twig_TokenStream

{

    protected $tokens;

    protected $current;

    protected $filename;

    /**

     * Constructor.

     *

     * @param array  $tokens   An array of tokens

     * @param string $filename The name of the filename which tokens are associated with

     */

    public function __construct(array $tokens, $filename = null)

    {

        $this->tokens     = $tokens;

        $this->current    = 0;

        $this->filename   = $filename;

    }

    /**

     * Returns a string representation of the token stream.

     *

     * @return string

     */

    public function __toString()

    {

        return implode("\n", $this->tokens);

    }

    /**

     * Sets the pointer to the next token and returns the old one.

     *

     * @return Twig_Token

     */

    public function next()

    {

        if (!isset($this->tokens[++$this->current])) {

            throw new Twig_Error_Syntax('Unexpected end of template', -1, $this->filename);

        }

        return $this->tokens[$this->current - 1];

    }

    /**

     * Tests a token and returns it or throws a syntax error.

     *

     * @return Twig_Token

     */

    public function expect($type, $value = null, $message = null)

    {

        $token = $this->tokens[$this->current];

        if (!$token->test($type, $value)) {

            $line = $token->getLine();

            throw new Twig_Error_Syntax(sprintf('%sUnexpected token "%s" of value "%s" ("%s" expected%s)',

                $message ? $message.'. ' : '',

                Twig_Token::typeToEnglish($token->getType(), $line), $token->getValue(),

                Twig_Token::typeToEnglish($type, $line), $value ? sprintf(' with value "%s"', $value) : ''),

                $line,

                $this->filename

            );

        }

        $this->next();

        return $token;

    }

    /**

     * Looks at the next token.

     *

     * @param integer $number

     *

     * @return Twig_Token

     */

    public function look($number = 1)

    {

        if (!isset($this->tokens[$this->current + $number])) {

            throw new Twig_Error_Syntax('Unexpected end of template', -1, $this->filename);

        }

        return $this->tokens[$this->current + $number];

    }

    /**

     * Tests the current token

     *

     * @return bool

     */

    public function test($primary, $secondary = null)

    {

        return $this->tokens[$this->current]->test($primary, $secondary);

    }

    /**

     * Checks if end of stream was reached

     *

     * @return bool

     */

    public function isEOF()

    {

        return $this->tokens[$this->current]->getType() === Twig_Token::EOF_TYPE;

    }

    /**

     * Gets the current token

     *

     * @return Twig_Token

     */

    public function getCurrent()

    {

        return $this->tokens[$this->current];

    }

    /**

     * Gets the filename associated with this stream

     *

     * @return string

     */

    public function getFilename()

    {

        return $this->filename;

    }

}