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('iconv')) {

   138             return iconv($from, $to, $value);

   139         } elseif (function_exists('mb_convert_encoding')) {

   140             return mb_convert_encoding($value, $to, $from);

   141         }

   142 

   143         throw new \RuntimeException('No suitable convert encoding function (install the iconv or mbstring extension).');

   144     }

   145 }