Reader::unserializeKey PHP Method

    private function unserializeKey()
    {
        $tag = $this->stream->getc();
        switch ($tag) {
            case '0':
                return 0;
            case '1':
                return 1;
            case '2':
                return 2;
            case '3':
                return 3;
            case '4':
                return 4;
            case '5':
                return 5;
            case '6':
                return 6;
            case '7':
                return 7;
            case '8':
                return 8;
            case '9':
                return 9;
            case Tags::TagInteger:
                return $this->readIntegerWithoutTag();
            case Tags::TagLong:
            case Tags::TagDouble:
                return $this->readLongWithoutTag();
            case Tags::TagNull:
                return 'null';
            case Tags::TagEmpty:
                return '';
            case Tags::TagTrue:
                return 'true';
            case Tags::TagFalse:
                return 'false';
            case Tags::TagNaN:
                return (string) log(-1);
            case Tags::TagInfinity:
                return (string) $this->readInfinityWithoutTag();
            case Tags::TagBytes:
                return $this->readBytesWithoutTag();
            case Tags::TagUTF8Char:
                return $this->readUTF8CharWithoutTag();
            case Tags::TagString:
                return $this->readStringWithoutTag();
            case Tags::TagGuid:
                return $this->readGuidWithoutTag();
            case Tags::TagRef:
                return (string) $this->readRef();
            case Tags::TagError:
                throw new Exception($this->privateReadString());
            default:
                throw $this->unexpectedTag($tag);
        }
    }