1: <?php
  2: 
  3: /*
  4:  * This file is part of the Symfony package.
  5:  * (c) Fabien Potencier <fabien@symfony.com>
  6:  *
  7:  * For the full copyright and license information, please view the LICENSE
  8:  * file that was distributed with this source code.
  9:  */
 10: 
 11: namespace Symfony\Component\Yaml;
 12: 
 13: /**
 14:  * Unescaper encapsulates unescaping rules for single and double-quoted
 15:  * YAML strings.
 16:  *
 17:  * @author Matthew Lewinski <matthew@lewinski.org>
 18:  */
 19: class Unescaper
 20: {
 21:     // Parser and Inline assume UTF-8 encoding, so escaped Unicode characters
 22:     // must be converted to that encoding.
 23:     const ENCODING = 'UTF-8';
 24: 
 25:     // Regex fragment that matches an escaped character in a double quoted
 26:     // string.
 27:     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})";
 28: 
 29:     /**
 30:      * Unescapes a single quoted string.
 31:      *
 32:      * @param string $value A single quoted string.
 33:      *
 34:      * @return string The unescaped string.
 35:      */
 36:     public function unescapeSingleQuotedString($value)
 37:     {
 38:         return str_replace('\'\'', '\'', $value);
 39:     }
 40: 
 41:     /**
 42:      * Unescapes a double quoted string.
 43:      *
 44:      * @param string $value A double quoted string.
 45:      *
 46:      * @return string The unescaped string.
 47:      */
 48:     public function unescapeDoubleQuotedString($value)
 49:     {
 50:         $self = $this;
 51:         $callback = function($match) use ($self) {
 52:             return $self->unescapeCharacter($match[0]);
 53:         };
 54: 
 55:         // evaluate the string
 56:         return preg_replace_callback('/'.self::REGEX_ESCAPED_CHARACTER.'/u', $callback, $value);
 57:     }
 58: 
 59:     /**
 60:      * Unescapes a character that was found in a double-quoted string
 61:      *
 62:      * @param string $value An escaped character
 63:      *
 64:      * @return string The unescaped character
 65:      */
 66:     public function unescapeCharacter($value)
 67:     {
 68:         switch ($value{1}) {
 69:             case '0':
 70:                 return "\x0";
 71:             case 'a':
 72:                 return "\x7";
 73:             case 'b':
 74:                 return "\x8";
 75:             case 't':
 76:                 return "\t";
 77:             case "\t":
 78:                 return "\t";
 79:             case 'n':
 80:                 return "\n";
 81:             case 'v':
 82:                 return "\xb";
 83:             case 'f':
 84:                 return "\xc";
 85:             case 'r':
 86:                 return "\xd";
 87:             case 'e':
 88:                 return "\x1b";
 89:             case ' ':
 90:                 return ' ';
 91:             case '"':
 92:                 return '"';
 93:             case '/':
 94:                 return '/';
 95:             case '\\':
 96:                 return '\\';
 97:             case 'N':
 98:                 // U+0085 NEXT LINE
 99:                 return $this->convertEncoding("\x00\x85", self::ENCODING, 'UCS-2BE');
100:             case '_':
101:                 // U+00A0 NO-BREAK SPACE
102:                 return $this->convertEncoding("\x00\xA0", self::ENCODING, 'UCS-2BE');
103:             case 'L':
104:                 // U+2028 LINE SEPARATOR
105:                 return $this->convertEncoding("\x20\x28", self::ENCODING, 'UCS-2BE');
106:             case 'P':
107:                 // U+2029 PARAGRAPH SEPARATOR
108:                 return $this->convertEncoding("\x20\x29", self::ENCODING, 'UCS-2BE');
109:             case 'x':
110:                 $char = pack('n', hexdec(substr($value, 2, 2)));
111: 
112:                 return $this->convertEncoding($char, self::ENCODING, 'UCS-2BE');
113:             case 'u':
114:                 $char = pack('n', hexdec(substr($value, 2, 4)));
115: 
116:                 return $this->convertEncoding($char, self::ENCODING, 'UCS-2BE');
117:             case 'U':
118:                 $char = pack('N', hexdec(substr($value, 2, 8)));
119: 
120:                 return $this->convertEncoding($char, self::ENCODING, 'UCS-4BE');
121:         }
122:     }
123: 
124:     /**
125:      * Convert a string from one encoding to another.
126:      *
127:      * @param string $value The string to convert
128:      * @param string $to    The input encoding
129:      * @param string $from  The output encoding
130:      *
131:      * @return string The string with the new encoding
132:      *
133:      * @throws RuntimeException if no suitable encoding function is found (iconv or mbstring)
134:      */
135:     private function convertEncoding($value, $to, $from)
136:     {
137:         if (function_exists('mb_convert_encoding')) {
138:             return mb_convert_encoding($value, $to, $from);
139:         } elseif (function_exists('iconv')) {
140:             return iconv($from, $to, $value);
141:         }
142: 
143:         throw new RuntimeException('No suitable convert encoding function (install the iconv or mbstring extension).');
144:     }
145: }
146: