<?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.

 */

/**

 * Lexes a template string.

 *

 * @package    twig

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

 */

class Twig_Lexer implements Twig_LexerInterface

{

    protected $tokens;

    protected $code;

    protected $cursor;

    protected $lineno;

    protected $end;

    protected $state;

    protected $brackets;

    protected $env;

    protected $filename;

    protected $options;

    protected $operatorRegex;

    const STATE_DATA  = 0;

    const STATE_BLOCK = 1;

    const STATE_VAR   = 2;

    const REGEX_NAME   = '/[A-Za-z_][A-Za-z0-9_]*/A';

    const REGEX_NUMBER = '/[0-9]+(?:\.[0-9]+)?/A';

    const REGEX_STRING = '/"([^"\\\\]*(?:\\\\.[^"\\\\]*)*)"|\'([^\'\\\\]*(?:\\\\.[^\'\\\\]*)*)\'/As';

    const PUNCTUATION  = '()[]{}?:.,|';

    public function __construct(Twig_Environment $env, array $options = array())

    {

        $this->env = $env;

        $this->options = array_merge(array(

            'tag_comment'     => array('{#', '#}'),

            'tag_block'       => array('{%', '%}'),

            'tag_variable'    => array('{{', '}}'),

            'whitespace_trim' => '-',

        ), $options);

    }

    /**

     * Tokenizes a source code.

     *

     * @param  string $code     The source code

     * @param  string $filename A unique identifier for the source code

     *

     * @return Twig_TokenStream A token stream instance

     */

    public function tokenize($code, $filename = null)

    {

        if (function_exists('mb_internal_encoding') && ((int) ini_get('mbstring.func_overload')) & 2) {

            $mbEncoding = mb_internal_encoding();

            mb_internal_encoding('ASCII');

        }

        $this->code = str_replace(array("\r\n", "\r"), "\n", $code);

        $this->filename = $filename;

        $this->cursor = 0;

        $this->lineno = 1;

        $this->end = strlen($this->code);

        $this->tokens = array();

        $this->state = self::STATE_DATA;

        $this->brackets = array();

        while ($this->cursor < $this->end) {

            // dispatch to the lexing functions depending

            // on the current state

            switch ($this->state) {

                case self::STATE_DATA:

                    $this->lexData();

                    break;

                case self::STATE_BLOCK:

                    $this->lexBlock();

                    break;

                case self::STATE_VAR:

                    $this->lexVar();

                    break;

            }

        }

        $this->pushToken(Twig_Token::EOF_TYPE);

        if (!empty($this->brackets)) {

            list($expect, $lineno) = array_pop($this->brackets);

            throw new Twig_Error_Syntax(sprintf('Unclosed "%s"', $expect), $lineno, $this->filename);

        }

        if (isset($mbEncoding)) {

            mb_internal_encoding($mbEncoding);

        }

        return new Twig_TokenStream($this->tokens, $this->filename);

    }

    protected function lexData()

    {

        $pos = $this->end;

        $append = '';

        // Find the first token after the cursor

        foreach (array('tag_comment', 'tag_variable', 'tag_block') as $type) {

            $tmpPos = strpos($this->code, $this->options[$type][0], $this->cursor);

            if (false !== $tmpPos && $tmpPos < $pos) {

                $trimBlock = false;

                $append = '';

                $pos = $tmpPos;

                $token = $this->options[$type][0];

                if (strpos($this->code, $this->options['whitespace_trim'], $pos) === ($pos + strlen($token))) {

                    $trimBlock = true;

                    $append = $this->options['whitespace_trim'];

                }

            }

        }

        // if no matches are left we return the rest of the template as simple text token

        if ($pos === $this->end) {

            $this->pushToken(Twig_Token::TEXT_TYPE, substr($this->code, $this->cursor));

            $this->cursor = $this->end;

            return;

        }

        // push the template text first

        $text = $textContent = substr($this->code, $this->cursor, $pos - $this->cursor);

        if (true === $trimBlock) {

            $text = rtrim($text);

        }

        $this->pushToken(Twig_Token::TEXT_TYPE, $text);

        $this->moveCursor($textContent.$token.$append);

        switch ($token) {

            case $this->options['tag_comment'][0]:

                $this->lexComment();

                break;

            case $this->options['tag_block'][0]:

                // raw data?

                if (preg_match('/\s*raw\s*'.preg_quote($this->options['tag_block'][1], '/').'/As', $this->code, $match, null, $this->cursor)) {

                    $this->moveCursor($match[0]);

                    $this->lexRawData();

                    $this->state = self::STATE_DATA;

                // {% line \d+ %}

                } else if (preg_match('/\s*line\s+(\d+)\s*'.preg_quote($this->options['tag_block'][1], '/').'/As', $this->code, $match, null, $this->cursor)) {

                    $this->moveCursor($match[0]);

                    $this->lineno = (int) $match[1];

                    $this->state = self::STATE_DATA;

                } else {

                    $this->pushToken(Twig_Token::BLOCK_START_TYPE);

                    $this->state = self::STATE_BLOCK;

                }

                break;

            case $this->options['tag_variable'][0]:

                $this->pushToken(Twig_Token::VAR_START_TYPE);

                $this->state = self::STATE_VAR;

                break;

        }

    }

    protected function lexBlock()

    {

        $trimTag = preg_quote($this->options['whitespace_trim'].$this->options['tag_block'][1], '/');

        $endTag = preg_quote($this->options['tag_block'][1], '/');

        if (empty($this->brackets) && preg_match('/\s*(?:'.$trimTag.'\s*|\s*'.$endTag.')\n?/A', $this->code, $match, null, $this->cursor)) {

            $this->pushToken(Twig_Token::BLOCK_END_TYPE);

            $this->moveCursor($match[0]);

            $this->state = self::STATE_DATA;

        } else {

            $this->lexExpression();

        }

    }

    protected function lexVar()

    {

        $trimTag = preg_quote($this->options['whitespace_trim'].$this->options['tag_variable'][1], '/');

        $endTag = preg_quote($this->options['tag_variable'][1], '/');

        if (empty($this->brackets) && preg_match('/\s*'.$trimTag.'\s*|\s*'.$endTag.'/A', $this->code, $match, null, $this->cursor)) {

            $this->pushToken(Twig_Token::VAR_END_TYPE);

            $this->moveCursor($match[0]);

            $this->state = self::STATE_DATA;

        } else {

            $this->lexExpression();

        }

    }

    protected function lexExpression()

    {

        // whitespace

        if (preg_match('/\s+/A', $this->code, $match, null, $this->cursor)) {

            $this->moveCursor($match[0]);

            if ($this->cursor >= $this->end) {

                throw new Twig_Error_Syntax(sprintf('Unexpected end of file: Unclosed "%s"', $this->state === self::STATE_BLOCK ? 'block' : 'variable'));

            }

        }

        // operators

        if (preg_match($this->getOperatorRegex(), $this->code, $match, null, $this->cursor)) {

            $this->pushToken(Twig_Token::OPERATOR_TYPE, $match[0]);

            $this->moveCursor($match[0]);

        }

        // names

        elseif (preg_match(self::REGEX_NAME, $this->code, $match, null, $this->cursor)) {

            $this->pushToken(Twig_Token::NAME_TYPE, $match[0]);

            $this->moveCursor($match[0]);

        }

        // numbers

        elseif (preg_match(self::REGEX_NUMBER, $this->code, $match, null, $this->cursor)) {

            $this->pushToken(Twig_Token::NUMBER_TYPE, ctype_digit($match[0]) ? (int) $match[0] : (float) $match[0]);

            $this->moveCursor($match[0]);

        }

        // punctuation

        elseif (false !== strpos(self::PUNCTUATION, $this->code[$this->cursor])) {

            // opening bracket

            if (false !== strpos('([{', $this->code[$this->cursor])) {

                $this->brackets[] = array($this->code[$this->cursor], $this->lineno);

            }

            // closing bracket

            elseif (false !== strpos(')]}', $this->code[$this->cursor])) {

                if (empty($this->brackets)) {

                    throw new Twig_Error_Syntax(sprintf('Unexpected "%s"', $this->code[$this->cursor]), $this->lineno, $this->filename);

                }

                list($expect, $lineno) = array_pop($this->brackets);

                if ($this->code[$this->cursor] != strtr($expect, '([{', ')]}')) {

                    throw new Twig_Error_Syntax(sprintf('Unclosed "%s"', $expect), $lineno, $this->filename);

                }

            }

            $this->pushToken(Twig_Token::PUNCTUATION_TYPE, $this->code[$this->cursor]);

            ++$this->cursor;

        }

        // strings

        elseif (preg_match(self::REGEX_STRING, $this->code, $match, null, $this->cursor)) {

            $this->pushToken(Twig_Token::STRING_TYPE, stripcslashes(substr($match[0], 1, -1)));

            $this->moveCursor($match[0]);

        }

        // unlexable

        else {

            throw new Twig_Error_Syntax(sprintf('Unexpected character "%s"', $this->code[$this->cursor]), $this->lineno, $this->filename);

        }

    }

    protected function lexRawData()

    {

        if (!preg_match('/'.preg_quote($this->options['tag_block'][0], '/').'\s*endraw\s*'.preg_quote($this->options['tag_block'][1], '/').'/s', $this->code, $match, PREG_OFFSET_CAPTURE, $this->cursor)) {

            throw new Twig_Error_Syntax(sprintf('Unexpected end of file: Unclosed "block"'));

        }

        $text = substr($this->code, $this->cursor, $match[0][1] - $this->cursor);

        $this->pushToken(Twig_Token::TEXT_TYPE, $text);

        $this->moveCursor($text.$match[0][0]);

    }

    protected function lexComment()

    {

        $commentEndRegex = '/(?:'.preg_quote($this->options['whitespace_trim'], '/')

                           .preg_quote($this->options['tag_comment'][1], '/').'\s*|'

                           .preg_quote($this->options['tag_comment'][1], '/').')\n?/s';

        if (!preg_match($commentEndRegex, $this->code, $match, PREG_OFFSET_CAPTURE, $this->cursor)) {

            throw new Twig_Error_Syntax('Unclosed comment', $this->lineno, $this->filename);

        }

        $this->moveCursor(substr($this->code, $this->cursor, $match[0][1] - $this->cursor).$match[0][0]);

    }

    protected function pushToken($type, $value = '')

    {

        // do not push empty text tokens

        if (Twig_Token::TEXT_TYPE === $type && '' === $value) {

            return;

        }

        $this->tokens[] = new Twig_Token($type, $value, $this->lineno);

    }

    protected function moveCursor($text)

    {

        $this->cursor += strlen($text);

        $this->lineno += substr_count($text, "\n");

    }

    protected function getOperatorRegex()

    {

        if (null !== $this->operatorRegex) {

            return $this->operatorRegex;

        }

        $operators = array_merge(

            array('='),

            array_keys($this->env->getUnaryOperators()),

            array_keys($this->env->getBinaryOperators())

        );

        $operators = array_combine($operators, array_map('strlen', $operators));

        arsort($operators);

        $regex = array();

        foreach ($operators as $operator => $length) {

            // an operator that ends with a character must be followed by

            // a whitespace or a parenthesis

            if (ctype_alpha($operator[$length - 1])) {

                $regex[] = preg_quote($operator, '/').'(?=[ ()])';

            } else {

                $regex[] = preg_quote($operator, '/');

            }

        }

        return $this->operatorRegex = '/'.implode('|', $regex).'/A';

    }

}