--- /dev/null
+<?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>
+ *
+ * @internal
+ */
+class Unescaper
+{
+ /**
+ * Parser and Inline assume UTF-8 encoding, so escaped Unicode characters
+ * must be converted to that encoding.
+ *
+ * @deprecated since version 2.5, to be removed in 3.0
+ *
+ * @internal
+ */
+ const ENCODING = 'UTF-8';
+
+ /**
+ * Regex fragment that matches an escaped character in a double quoted string.
+ */
+ 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 $value A single quoted string
+ *
+ * @return string The unescaped string
+ */
+ public function unescapeSingleQuotedString($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 $value An escaped character
+ *
+ * @return string The unescaped character
+ *
+ * @internal This method is public to be usable as callback. It should not
+ * be used in user code. Should be changed in 3.0.
+ */
+ public function unescapeCharacter($value)
+ {
+ switch ($value[1]) {
+ case '0':
+ return "\x0";
+ case 'a':
+ return "\x7";
+ case 'b':
+ return "\x8";
+ case 't':
+ return "\t";
+ case "\t":
+ return "\t";
+ case 'n':
+ return "\n";
+ case 'v':
+ return "\xB";
+ case 'f':
+ return "\xC";
+ case 'r':
+ return "\r";
+ case 'e':
+ return "\x1B";
+ case ' ':
+ return ' ';
+ case '"':
+ return '"';
+ case '/':
+ return '/';
+ case '\\':
+ return '\\';
+ case 'N':
+ // U+0085 NEXT LINE
+ return "\xC2\x85";
+ case '_':
+ // U+00A0 NO-BREAK SPACE
+ return "\xC2\xA0";
+ case 'L':
+ // U+2028 LINE SEPARATOR
+ return "\xE2\x80\xA8";
+ case 'P':
+ // U+2029 PARAGRAPH SEPARATOR
+ return "\xE2\x80\xA9";
+ case 'x':
+ return self::utf8chr(hexdec(substr($value, 2, 2)));
+ case 'u':
+ return self::utf8chr(hexdec(substr($value, 2, 4)));
+ case 'U':
+ return self::utf8chr(hexdec(substr($value, 2, 8)));
+ default:
+ @trigger_error('Not escaping a backslash in a double-quoted string is deprecated since Symfony 2.8 and will throw a ParseException in 3.0.', E_USER_DEPRECATED);
+
+ return $value;
+ }
+ }
+
+ /**
+ * Get the UTF-8 character for the given code point.
+ *
+ * @param int $c The unicode code point
+ *
+ * @return string The corresponding UTF-8 character
+ */
+ private static function utf8chr($c)
+ {
+ 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);
+ }
+}