symfony/src/Symfony/Component/Yaml/Escaper.php

<?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\Yaml;

/**
 * Escaper encapsulates escaping rules for single and double-quoted
 * YAML strings.
 *
 * @author Matthew Lewinski <matthew@lewinski.org>
 */
class Escaper
{
    // Characters that would cause a dumped string to require double quoting.
    const REGEX_CHARACTER_TO_ESCAPE = "[\\x00-\\x1f]|\xc2\x85|\xc2\xa0|\xe2\x80\xa8|\xe2\x80\xa9";

    // Mapping arrays for escaping a double quoted string. The backslash is
    // first to ensure proper escaping because str_replace operates iteratively
    // on the input arrays. This ordering of the characters avoids the use of strtr,
    // which performs more slowly.
    private static $escapees = array('\\\\', '\\"', '"',
                                     "\x00",  "\x01",  "\x02",  "\x03",  "\x04",  "\x05",  "\x06",  "\x07",
                                     "\x08",  "\x09",  "\x0a",  "\x0b",  "\x0c",  "\x0d",  "\x0e",  "\x0f",
                                     "\x10",  "\x11",  "\x12",  "\x13",  "\x14",  "\x15",  "\x16",  "\x17",
                                     "\x18",  "\x19",  "\x1a",  "\x1b",  "\x1c",  "\x1d",  "\x1e",  "\x1f",
                                     "\xc2\x85", "\xc2\xa0", "\xe2\x80\xa8", "\xe2\x80\xa9");
    private static $escaped  = array('\\"', '\\\\', '\\"',
                                     "\\0",   "\\x01", "\\x02", "\\x03", "\\x04", "\\x05", "\\x06", "\\a",
                                     "\\b",   "\\t",   "\\n",   "\\v",   "\\f",   "\\r",   "\\x0e", "\\x0f",
                                     "\\x10", "\\x11", "\\x12", "\\x13", "\\x14", "\\x15", "\\x16", "\\x17",
                                     "\\x18", "\\x19", "\\x1a", "\\e",   "\\x1c", "\\x1d", "\\x1e", "\\x1f",
                                     "\\N", "\\_", "\\L", "\\P");

    /**
     * Determines if a PHP value would require double quoting in YAML.
     *
     * @param string $value A PHP value
     *
     * @return bool    True if the value would require double quotes.
     */
    public static function requiresDoubleQuoting($value)
    {
        return preg_match('/'.self::REGEX_CHARACTER_TO_ESCAPE.'/u', $value);
    }

    /**
     * Escapes and surrounds a PHP value with double quotes.
     *
     * @param string $value A PHP value
     *
     * @return string The quoted, escaped string
     */
    public static function escapeWithDoubleQuotes($value)
    {
        return sprintf('"%s"', str_replace(self::$escapees, self::$escaped, $value));
    }

    /**
     * Determines if a PHP value would require single quoting in YAML.
     *
     * @param string $value A PHP value
     *
     * @return bool    True if the value would require single quotes.
     */
    public static function requiresSingleQuoting($value)
    {
        return preg_match('/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ \- ? | < > = ! % @ ` ]/x', $value);
    }

    /**
     * Escapes and surrounds a PHP value with single quotes.
     *
     * @param string $value A PHP value
     *
     * @return string The quoted, escaped string
     */
    public static function escapeWithSingleQuotes($value)
    {
        return sprintf("'%s'", str_replace('\'', '\'\'', $value));
    }
}