Sabberworm\CSS\Parser::parseCharacter PHP Метод

    private function parseCharacter($bIsForIdentifier)
    {
        if ($this->peek() === '\\') {
            $this->consume('\\');
            if ($this->comes('\\n') || $this->comes('\\r')) {
                return '';
            }
            if (preg_match('/[0-9a-fA-F]/Su', $this->peek()) === 0) {
                return $this->consume(1);
            }
            $sUnicode = $this->consumeExpression('/^[0-9a-fA-F]{1,6}/u');
            if ($this->strlen($sUnicode) < 6) {
                //Consume whitespace after incomplete unicode escape
                if (preg_match('/\\s/isSu', $this->peek())) {
                    if ($this->comes('\\r\\n')) {
                        $this->consume(2);
                    } else {
                        $this->consume(1);
                    }
                }
            }
            $iUnicode = intval($sUnicode, 16);
            $sUtf32 = "";
            for ($i = 0; $i < 4; ++$i) {
                $sUtf32 .= chr($iUnicode & 0xff);
                $iUnicode = $iUnicode >> 8;
            }
            return iconv('utf-32le', $this->sCharset, $sUtf32);
        }
        if ($bIsForIdentifier) {
            $peek = ord($this->peek());
            // Ranges: a-z A-Z 0-9 - _
            if ($peek >= 97 && $peek <= 122 || $peek >= 65 && $peek <= 90 || $peek >= 48 && $peek <= 57 || $peek === 45 || $peek === 95 || $peek > 0xa1) {
                return $this->consume(1);
            }
        } else {
            return $this->consume(1);
        }
        return null;
    }