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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  class Unescaper
  21  {
  22      // Parser and Inline assume UTF-8 encoding, so escaped Unicode characters
  23      // must be converted to that encoding.
  24      // @deprecated since 2.5, to be removed in 3.0
  25      const ENCODING = 'UTF-8';
  26  
  27      // Regex fragment that matches an escaped character in a double quoted
  28      // string.
  29      const REGEX_ESCAPED_CHARACTER = "\\\\([0abt\tnvfre \\\"\\/\\\\N_LP]|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          $self = $this;
  53          $callback = function ($match) use ($self) {
  54              return $self->unescapeCharacter($match[0]);
  55          };
  56  
  57          // evaluate the string
  58          return preg_replace_callback('/'.self::REGEX_ESCAPED_CHARACTER.'/u', $callback, $value);
  59      }
  60  
  61      /**
  62       * Unescapes a character that was found in a double-quoted string.
  63       *
  64       * @param string $value An escaped character
  65       *
  66       * @return string The unescaped character
  67       */
  68      public function unescapeCharacter($value)
  69      {
  70          switch ($value{1}) {
  71              case '0':
  72                  return "\x0";
  73              case 'a':
  74                  return "\x7";
  75              case 'b':
  76                  return "\x8";
  77              case 't':
  78                  return "\t";
  79              case "\t":
  80                  return "\t";
  81              case 'n':
  82                  return "\n";
  83              case 'v':
  84                  return "\xB";
  85              case 'f':
  86                  return "\xC";
  87              case 'r':
  88                  return "\r";
  89              case 'e':
  90                  return "\x1B";
  91              case ' ':
  92                  return ' ';
  93              case '"':
  94                  return '"';
  95              case '/':
  96                  return '/';
  97              case '\\':
  98                  return '\\';
  99              case 'N':
 100                  // U+0085 NEXT LINE
 101                  return "\xC2\x85";
 102              case '_':
 103                  // U+00A0 NO-BREAK SPACE
 104                  return "\xC2\xA0";
 105              case 'L':
 106                  // U+2028 LINE SEPARATOR
 107                  return "\xE2\x80\xA8";
 108              case 'P':
 109                  // U+2029 PARAGRAPH SEPARATOR
 110                  return "\xE2\x80\xA9";
 111              case 'x':
 112                  return self::utf8chr(hexdec(substr($value, 2, 2)));
 113              case 'u':
 114                  return self::utf8chr(hexdec(substr($value, 2, 4)));
 115              case 'U':
 116                  return self::utf8chr(hexdec(substr($value, 2, 8)));
 117          }
 118      }
 119  
 120      /**
 121       * Get the UTF-8 character for the given code point.
 122       *
 123       * @param int $c The unicode code point
 124       *
 125       * @return string The corresponding UTF-8 character
 126       */
 127      private static function utf8chr($c)
 128      {
 129          if (0x80 > $c %= 0x200000) {
 130              return chr($c);
 131          }
 132          if (0x800 > $c) {
 133              return chr(0xC0 | $c >> 6).chr(0x80 | $c & 0x3F);
 134          }
 135          if (0x10000 > $c) {
 136              return chr(0xE0 | $c >> 12).chr(0x80 | $c >> 6 & 0x3F).chr(0x80 | $c & 0x3F);
 137          }
 138  
 139          return chr(0xF0 | $c >> 18).chr(0x80 | $c >> 12 & 0x3F).chr(0x80 | $c >> 6 & 0x3F).chr(0x80 | $c & 0x3F);
 140      }
 141  }