<?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\CssSelector;

use Symfony\Component\CssSelector\Exception\ParseException;

/**

 * Tokenizer lexes a CSS Selector to tokens.

 *

 * This component is a port of the Python lxml library,

 * which is copyright Infrae and distributed under the BSD license.

 *

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

 */

class Tokenizer

{

    /**

     * Takes a CSS selector and returns an array holding the Tokens

     * it contains.

     *

     * @param  string $s The selector to lex.

     *

     * @return array Token[]

     */

    public function tokenize($s)

    {

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

            $mbEncoding = mb_internal_encoding();

            mb_internal_encoding('ASCII');

        }

        $tokens = array();

        $pos = 0;

        $s = preg_replace('#/\*.*?\*/#s', '', $s);

        while (true) {

            if (preg_match('#\s+#A', $s, $match, 0, $pos)) {

                $precedingWhitespacePos = $pos;

                $pos += strlen($match[0]);

            } else {

                $precedingWhitespacePos = 0;

            }

            if ($pos >= strlen($s)) {

                if (isset($mbEncoding)) {

                    mb_internal_encoding($mbEncoding);

                }

                return $tokens;

            }

            if (preg_match('#[+-]?\d*n(?:[+-]\d+)?#A', $s, $match, 0, $pos) && 'n' !== $match[0]) {

                $sym = substr($s, $pos, strlen($match[0]));

                $tokens[] = new Token('Symbol', $sym, $pos);

                $pos += strlen($match[0]);

                continue;

            }

            $c = $s[$pos];

            $c2 = substr($s, $pos, 2);

            if (in_array($c2, array('~=', '|=', '^=', '$=', '*=', '::', '!='))) {

                $tokens[] = new Token('Token', $c2, $pos);

                $pos += 2;

                continue;

            }

            if (in_array($c, array('>', '+', '~', ',', '.', '*', '=', '[', ']', '(', ')', '|', ':', '#'))) {

                if (in_array($c, array('.', '#', '[')) && $precedingWhitespacePos > 0) {

                    $tokens[] = new Token('Token', ' ', $precedingWhitespacePos);

                }

                $tokens[] = new Token('Token', $c, $pos);

                ++$pos;

                continue;

            }

            if ('"' === $c || "'" === $c) {

                // Quoted string

                $oldPos = $pos;

                list($sym, $pos) = $this->tokenizeEscapedString($s, $pos);

                $tokens[] = new Token('String', $sym, $oldPos);

                continue;

            }

            $oldPos = $pos;

            list($sym, $pos) = $this->tokenizeSymbol($s, $pos);

            $tokens[] = new Token('Symbol', $sym, $oldPos);

            continue;

        }

    }

    /**

     * Tokenizes a quoted string (i.e. 'A string quoted with \' characters'),

     * and returns an array holding the unquoted string contained by $s and

     * the new position from which tokenizing should take over.

     *

     * @throws ParseException When expected closing is not found

     *

     * @param  string  $s   The selector string containing the quoted string.

     * @param  integer $pos The starting position for the quoted string.

     *

     * @return array

     */

    private function tokenizeEscapedString($s, $pos)

    {

        $quote = $s[$pos];

        $pos = $pos + 1;

        $start = $pos;

        while (true) {

            $next = strpos($s, $quote, $pos);

            if (false === $next) {

                throw new ParseException(sprintf('Expected closing %s for string in: %s', $quote, substr($s, $start)));

            }

            $result = substr($s, $start, $next - $start);

            if ('\\' === $result[strlen($result) - 1]) {

                // next quote character is escaped

                $pos = $next + 1;

                continue;

            }

            if (false !== strpos($result, '\\')) {

                $result = $this->unescapeStringLiteral($result);

            }

            return array($result, $next + 1);

        }

    }

    /**

     * Unescapes a string literal and returns the unescaped string.

     *

     * @throws ParseException When invalid escape sequence is found

     *

     * @param  string $literal The string literal to unescape.

     *

     * @return string

     */

    private function unescapeStringLiteral($literal)

    {

        return preg_replace_callback('#(\\\\(?:[A-Fa-f0-9]{1,6}(?:\r\n|\s)?|[^A-Fa-f0-9]))#', function ($matches) use ($literal)

        {

            if ($matches[0][0] == '\\' && strlen($matches[0]) > 1) {

                $matches[0] = substr($matches[0], 1);

                if (in_array($matches[0][0], array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'a', 'b', 'c', 'd', 'e', 'f'))) {

                    return chr(trim($matches[0]));

                }

            } else {

                throw new ParseException(sprintf('Invalid escape sequence %s in string %s', $matches[0], $literal));

            }

        }, $literal);

    }

    /**

     * Lexes selector $s and returns an array holding the name of the symbol

     * contained in it and the new position from which tokenizing should take

     * over.

     *

     * @throws ParseException When Unexpected symbol is found

     *

     * @param  string  $s   The selector string.

     * @param  integer $pos The position in $s at which the symbol starts.

     *

     * @return array

     */

    private function tokenizeSymbol($s, $pos)

    {

        $start = $pos;

        if (!preg_match('#[^\w\-]#', $s, $match, PREG_OFFSET_CAPTURE, $pos)) {

            // Goes to end of s

            return array(substr($s, $start), strlen($s));

        }

        $matchStart = $match[0][1];

        if ($matchStart == $pos) {

            throw new ParseException(sprintf('Unexpected symbol: %s at %s', $s[$pos], $pos));

        }

        $result = substr($s, $start, $matchStart - $start);

        $pos = $matchStart;

        return array($result, $pos);

    }

}