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<?php
/*
* This file is part of the Symfony package.
* (c) Fabien Potencier <fabien@symfony.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Symfony\Component\Yaml;
/**
* Unescaper encapsulates unescaping rules for single and double-quoted
* YAML strings.
*
* @author Matthew Lewinski <matthew@lewinski.org>
*/
class Unescaper
{
// Parser and Inline assume UTF-8 encoding, so escaped Unicode characters
// must be converted to that encoding.
const ENCODING = 'UTF-8';
// Regex fragment that matches an escaped character in a double quoted
// string.
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})";
/**
* Unescapes a single quoted string.
*
* @param string $value A single quoted string.
*
* @return string The unescaped string.
*/
public function unescapeSingleQuotedString($value)
{
return str_replace('\'\'', '\'', $value);
}
/**
* Unescapes a double quoted string.
*
* @param string $value A double quoted string.
*
* @return string The unescaped string.
*/
public function unescapeDoubleQuotedString($value)
{
$self = $this;
$callback = function($match) use ($self) {
return $self->unescapeCharacter($match[0]);
};
// evaluate the string
return preg_replace_callback('/'.self::REGEX_ESCAPED_CHARACTER.'/u', $callback, $value);
}
/**
* Unescapes a character that was found in a double-quoted string
*
* @param string $value An escaped character
*
* @return string The unescaped character
*/
public function unescapeCharacter($value)
{
switch ($value{1}) {
case '0':
return "\x0";
case 'a':
return "\x7";
case 'b':
return "\x8";
case 't':
return "\t";
case "\t":
return "\t";
case 'n':
return "\n";
case 'v':
return "\xb";
case 'f':
return "\xc";
case 'r':
return "\xd";
case 'e':
return "\x1b";
case ' ':
return ' ';
case '"':
return '"';
case '/':
return '/';
case '\\':
return '\\';
case 'N':
// U+0085 NEXT LINE
return $this->convertEncoding("\x00\x85", self::ENCODING, 'UCS-2BE');
case '_':
// U+00A0 NO-BREAK SPACE
return $this->convertEncoding("\x00\xA0", self::ENCODING, 'UCS-2BE');
case 'L':
// U+2028 LINE SEPARATOR
return $this->convertEncoding("\x20\x28", self::ENCODING, 'UCS-2BE');
case 'P':
// U+2029 PARAGRAPH SEPARATOR
return $this->convertEncoding("\x20\x29", self::ENCODING, 'UCS-2BE');
case 'x':
$char = pack('n', hexdec(substr($value, 2, 2)));
return $this->convertEncoding($char, self::ENCODING, 'UCS-2BE');
case 'u':
$char = pack('n', hexdec(substr($value, 2, 4)));
return $this->convertEncoding($char, self::ENCODING, 'UCS-2BE');
case 'U':
$char = pack('N', hexdec(substr($value, 2, 8)));
return $this->convertEncoding($char, self::ENCODING, 'UCS-4BE');
}
}
/**
* Convert a string from one encoding to another.
*
* @param string $value The string to convert
* @param string $to The input encoding
* @param string $from The output encoding
*
* @return string The string with the new encoding
*
* @throws RuntimeException if no suitable encoding function is found (iconv or mbstring)
*/
private function convertEncoding($value, $to, $from)
{
if (function_exists('mb_convert_encoding')) {
return mb_convert_encoding($value, $to, $from);
} elseif (function_exists('iconv')) {
return iconv($from, $to, $value);
}
throw new RuntimeException('No suitable convert encoding function (install the iconv or mbstring extension).');
}
}
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