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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  /**
  15   * Unescaper encapsulates unescaping rules for single and double-quoted
  16   * YAML strings.
  17   *
  18   * @author Matthew Lewinski <matthew@lewinski.org>
  19   *
  20   * @internal
  21   */
  22  class Unescaper
  23  {
  24      /**
  25       * Parser and Inline assume UTF-8 encoding, so escaped Unicode characters
  26       * must be converted to that encoding.
  27       *
  28       * @deprecated since version 2.5, to be removed in 3.0
  29       *
  30       * @internal
  31       */
  32      const ENCODING = 'UTF-8';
  33  
  34      /**
  35       * Regex fragment that matches an escaped character in a double quoted string.
  36       */
  37      const REGEX_ESCAPED_CHARACTER = '\\\\(x[0-9a-fA-F]{2}|u[0-9a-fA-F]{4}|U[0-9a-fA-F]{8}|.)';
  38  
  39      /**
  40       * Unescapes a single quoted string.
  41       *
  42       * @param string $value A single quoted string
  43       *
  44       * @return string The unescaped string
  45       */
  46      public function unescapeSingleQuotedString($value)
  47      {
  48          return str_replace('\'\'', '\'', $value);
  49      }
  50  
  51      /**
  52       * Unescapes a double quoted string.
  53       *
  54       * @param string $value A double quoted string
  55       *
  56       * @return string The unescaped string
  57       */
  58      public function unescapeDoubleQuotedString($value)
  59      {
  60          $self = $this;
  61          $callback = function ($match) use ($self) {
  62              return $self->unescapeCharacter($match[0]);
  63          };
  64  
  65          // evaluate the string
  66          return preg_replace_callback('/'.self::REGEX_ESCAPED_CHARACTER.'/u', $callback, $value);
  67      }
  68  
  69      /**
  70       * Unescapes a character that was found in a double-quoted string.
  71       *
  72       * @param string $value An escaped character
  73       *
  74       * @return string The unescaped character
  75       *
  76       * @internal This method is public to be usable as callback. It should not
  77       *           be used in user code. Should be changed in 3.0.
  78       */
  79      public function unescapeCharacter($value)
  80      {
  81          switch ($value[1]) {
  82              case '0':
  83                  return "\x0";
  84              case 'a':
  85                  return "\x7";
  86              case 'b':
  87                  return "\x8";
  88              case 't':
  89                  return "\t";
  90              case "\t":
  91                  return "\t";
  92              case 'n':
  93                  return "\n";
  94              case 'v':
  95                  return "\xB";
  96              case 'f':
  97                  return "\xC";
  98              case 'r':
  99                  return "\r";
 100              case 'e':
 101                  return "\x1B";
 102              case ' ':
 103                  return ' ';
 104              case '"':
 105                  return '"';
 106              case '/':
 107                  return '/';
 108              case '\\':
 109                  return '\\';
 110              case 'N':
 111                  // U+0085 NEXT LINE
 112                  return "\xC2\x85";
 113              case '_':
 114                  // U+00A0 NO-BREAK SPACE
 115                  return "\xC2\xA0";
 116              case 'L':
 117                  // U+2028 LINE SEPARATOR
 118                  return "\xE2\x80\xA8";
 119              case 'P':
 120                  // U+2029 PARAGRAPH SEPARATOR
 121                  return "\xE2\x80\xA9";
 122              case 'x':
 123                  return self::utf8chr(hexdec(substr($value, 2, 2)));
 124              case 'u':
 125                  return self::utf8chr(hexdec(substr($value, 2, 4)));
 126              case 'U':
 127                  return self::utf8chr(hexdec(substr($value, 2, 8)));
 128              default:
 129                  @trigger_error('Not escaping a backslash in a double-quoted string is deprecated since Symfony 2.8 and will throw a ParseException in 3.0.', E_USER_DEPRECATED);
 130  
 131                  return $value;
 132          }
 133      }
 134  
 135      /**
 136       * Get the UTF-8 character for the given code point.
 137       *
 138       * @param int $c The unicode code point
 139       *
 140       * @return string The corresponding UTF-8 character
 141       */
 142      private static function utf8chr($c)
 143      {
 144          if (0x80 > $c %= 0x200000) {
 145              return \chr($c);
 146          }
 147          if (0x800 > $c) {
 148              return \chr(0xC0 | $c >> 6).\chr(0x80 | $c & 0x3F);
 149          }
 150          if (0x10000 > $c) {
 151              return \chr(0xE0 | $c >> 12).\chr(0x80 | $c >> 6 & 0x3F).\chr(0x80 | $c & 0x3F);
 152          }
 153  
 154          return \chr(0xF0 | $c >> 18).\chr(0x80 | $c >> 12 & 0x3F).\chr(0x80 | $c >> 6 & 0x3F).\chr(0x80 | $c & 0x3F);
 155      }
 156  }