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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;
use Symfony\Component\Yaml\Exception\ParseException;
/**
* Unescaper encapsulates unescaping rules for single and double-quoted
* YAML strings.
*
* @author Matthew Lewinski <matthew@lewinski.org>
*
* @internal
*/
class Unescaper
{
/**
* Regex fragment that matches an escaped character in a double quoted string.
*/
public const REGEX_ESCAPED_CHARACTER = '\\\\(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
*/
public function unescapeSingleQuotedString(string $value): string
{
return str_replace('\'\'', '\'', $value);
}
/**
* Unescapes a double quoted string.
*
* @param string $value A double quoted string
*/
public function unescapeDoubleQuotedString(string $value): string
{
$callback = fn ($match) => $this->unescapeCharacter($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
*/
private function unescapeCharacter(string $value): string
{
return match ($value[1]) {
'0' => "\x0",
'a' => "\x7",
'b' => "\x8",
't' => "\t",
"\t" => "\t",
'n' => "\n",
'v' => "\xB",
'f' => "\xC",
'r' => "\r",
'e' => "\x1B",
' ' => ' ',
'"' => '"',
'/' => '/',
'\\' => '\\',
// U+0085 NEXT LINE
'N' => "\xC2\x85",
// U+00A0 NO-BREAK SPACE
'_' => "\xC2\xA0",
// U+2028 LINE SEPARATOR
'L' => "\xE2\x80\xA8",
// U+2029 PARAGRAPH SEPARATOR
'P' => "\xE2\x80\xA9",
'x' => self::utf8chr(hexdec(substr($value, 2, 2))),
'u' => self::utf8chr(hexdec(substr($value, 2, 4))),
'U' => self::utf8chr(hexdec(substr($value, 2, 8))),
default => throw new ParseException(sprintf('Found unknown escape character "%s".', $value)),
};
}
/**
* Get the UTF-8 character for the given code point.
*/
private static function utf8chr(int $c): string
{
if (0x80 > $c %= 0x200000) {
return \chr($c);
}
if (0x800 > $c) {
return \chr(0xC0 | $c >> 6).\chr(0x80 | $c & 0x3F);
}
if (0x10000 > $c) {
return \chr(0xE0 | $c >> 12).\chr(0x80 | $c >> 6 & 0x3F).\chr(0x80 | $c & 0x3F);
}
return \chr(0xF0 | $c >> 18).\chr(0x80 | $c >> 12 & 0x3F).\chr(0x80 | $c >> 6 & 0x3F).\chr(0x80 | $c & 0x3F);
}
}
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