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   1  <?php
   2  
   3  /*
   4   * This file is part of the Symfony package.
   5   *
   6   * (c) Fabien Potencier <fabien@symfony.com>
   7   *
   8   * For the full copyright and license information, please view the LICENSE
   9   * file that was distributed with this source code.
  10   */
  11  
  12  namespace Symfony\Component\Yaml;
  13  
  14  use Symfony\Component\Yaml\Exception\ParseException;
  15  
  16  /**
  17   * Unescaper encapsulates unescaping rules for single and double-quoted
  18   * YAML strings.
  19   *
  20   * @author Matthew Lewinski <matthew@lewinski.org>
  21   *
  22   * @internal
  23   */
  24  class Unescaper
  25  {
  26      /**
  27       * Regex fragment that matches an escaped character in a double quoted string.
  28       */
  29      const REGEX_ESCAPED_CHARACTER = '\\\\(x[0-9a-fA-F]{2}|u[0-9a-fA-F]{4}|U[0-9a-fA-F]{8}|.)';
  30  
  31      /**
  32       * Unescapes a single quoted string.
  33       *
  34       * @param string $value A single quoted string
  35       *
  36       * @return string The unescaped string
  37       */
  38      public function unescapeSingleQuotedString($value)
  39      {
  40          return str_replace('\'\'', '\'', $value);
  41      }
  42  
  43      /**
  44       * Unescapes a double quoted string.
  45       *
  46       * @param string $value A double quoted string
  47       *
  48       * @return string The unescaped string
  49       */
  50      public function unescapeDoubleQuotedString($value)
  51      {
  52          $callback = function ($match) {
  53              return $this->unescapeCharacter($match[0]);
  54          };
  55  
  56          // evaluate the string
  57          return preg_replace_callback('/'.self::REGEX_ESCAPED_CHARACTER.'/u', $callback, $value);
  58      }
  59  
  60      /**
  61       * Unescapes a character that was found in a double-quoted string.
  62       *
  63       * @param string $value An escaped character
  64       *
  65       * @return string The unescaped character
  66       */
  67      private function unescapeCharacter($value)
  68      {
  69          switch ($value[1]) {
  70              case '0':
  71                  return "\x0";
  72              case 'a':
  73                  return "\x7";
  74              case 'b':
  75                  return "\x8";
  76              case 't':
  77                  return "\t";
  78              case "\t":
  79                  return "\t";
  80              case 'n':
  81                  return "\n";
  82              case 'v':
  83                  return "\xB";
  84              case 'f':
  85                  return "\xC";
  86              case 'r':
  87                  return "\r";
  88              case 'e':
  89                  return "\x1B";
  90              case ' ':
  91                  return ' ';
  92              case '"':
  93                  return '"';
  94              case '/':
  95                  return '/';
  96              case '\\':
  97                  return '\\';
  98              case 'N':
  99                  // U+0085 NEXT LINE
 100                  return "\xC2\x85";
 101              case '_':
 102                  // U+00A0 NO-BREAK SPACE
 103                  return "\xC2\xA0";
 104              case 'L':
 105                  // U+2028 LINE SEPARATOR
 106                  return "\xE2\x80\xA8";
 107              case 'P':
 108                  // U+2029 PARAGRAPH SEPARATOR
 109                  return "\xE2\x80\xA9";
 110              case 'x':
 111                  return self::utf8chr(hexdec(substr($value, 2, 2)));
 112              case 'u':
 113                  return self::utf8chr(hexdec(substr($value, 2, 4)));
 114              case 'U':
 115                  return self::utf8chr(hexdec(substr($value, 2, 8)));
 116              default:
 117                  throw new ParseException(sprintf('Found unknown escape character "%s".', $value));
 118          }
 119      }
 120  
 121      /**
 122       * Get the UTF-8 character for the given code point.
 123       *
 124       * @param int $c The unicode code point
 125       *
 126       * @return string The corresponding UTF-8 character
 127       */
 128      private static function utf8chr($c)
 129      {
 130          if (0x80 > $c %= 0x200000) {
 131              return \chr($c);
 132          }
 133          if (0x800 > $c) {
 134              return \chr(0xC0 | $c >> 6).\chr(0x80 | $c & 0x3F);
 135          }
 136          if (0x10000 > $c) {
 137              return \chr(0xE0 | $c >> 12).\chr(0x80 | $c >> 6 & 0x3F).\chr(0x80 | $c & 0x3F);
 138          }
 139  
 140          return \chr(0xF0 | $c >> 18).\chr(0x80 | $c >> 12 & 0x3F).\chr(0x80 | $c >> 6 & 0x3F).\chr(0x80 | $c & 0x3F);
 141      }
 142  }