/**
直接读取一个slice的值，这个slice的值可能是string也可能是数字
*/
func getSliceValue(pre uint8, suf uint8, array *[]byte, inputFile string, param *Parameters) string {
var returnValue string
switch pre {
case 0: //then the next 6 bits represent the length
reIndex(array, inputFile, uint64(suf), param)
returnValue = assembelString(getArraySlice((*param).SliceStart, (*param).SliceEnd, array))
case 64: //then an additional byte is read from the stream. The combined 14 bits represent the length
reIndexSliceEnd(array, inputFile, 1, param)
slice := getArraySlice((*param).SliceStart, (*param).SliceEnd, array)
//把slice里边的两个字节转换成数字
slice_value := changeByteToUint64(slice, binary.BigEndian)
value := slice_value & 0x3FFF
reIndex(array, inputFile, uint64(value), param)
returnValue = assembelString(getArraySlice((*param).SliceStart, (*param).SliceEnd, array))
case 128: //hen the remaining 6 bits are discarded. Additional 4 bytes are read from the stream, and those 4 bytes represent the length
// (in big endian format in RDB version 6)
var slice_value uint64
reIndex(array, inputFile, 4, param)
slice := getArraySlice((*param).SliceStart, (*param).SliceEnd, array)
//把slice里边的四个字节转换成数字
slice_value = changeByteToUint64(slice, binary.BigEndian)
reIndex(array, inputFile, slice_value, param)
returnValue = assembelString(getArraySlice((*param).SliceStart, (*param).SliceEnd, array))
case 192: //then the next object is encoded in a special format. The remaining 6 bits indicate the format
switch suf {
case 0: //0 indicates that an 8 bit integer follows.
reIndex(array, inputFile, 1, param)
returnValue = strconv.FormatInt(changeByteToInt64(getArraySlice((*param).SliceStart, (*param).SliceEnd, array), binary.LittleEndian), 10)
case 1: //1 indicates that a 16 bit integer follows.
reIndex(array, inputFile, 2, param)
returnValue = strconv.FormatInt(changeByteToInt64(getArraySlice((*param).SliceStart, (*param).SliceEnd, array), binary.LittleEndian), 10)
case 2: //2 indicates that a 32 bit integer follows.
reIndex(array, inputFile, 4, param)
returnValue = strconv.FormatInt(changeByteToInt64(getArraySlice((*param).SliceStart, (*param).SliceEnd, array), binary.LittleEndian), 10)
case 3, 4: //实验证明C3代表压缩的字符串，不是C4
//读取压缩字符串的长度
compressed_length := readOneByteAndGetNum(array, inputFile, param)
//读取未压缩字符串的长度
uncompressed_length := readOneByteAndGetNum(array, inputFile, param)
//解压缩字符串
reIndex(array, inputFile, compressed_length, param)
in_data := (*array)[(*param).SliceStart:(*param).SliceEnd]
uncompressedByte := lzf.Lzf_dcompress(in_data, uncompressed_length)
str := string(uncompressedByte)
returnValue = str
}
}
return returnValue
}
/**
读取代表内容的字节，并根据值类型解析
此方法只被：ZipMap Encoding, ZipList Encoding, parseIntSetEncoding调用，因为
他们在压缩的时候是所有值联合压缩
*/
func readContentByteAndParse(array *[]byte, types int, inputFile string, param *Parameters) int {
var length int
var pContentSlice *[]byte
//首先读取一个字节，按照这个字节的前两个bit和后六个bit的值来判断
//改如何读取后边的Content内容
slice := readNextNByte(array, inputFile, 1, param)
pre, suf := calByte(slice[0])
switch pre {
case 0: //then the next 6 bits represent the length
contentSlice := readNextNByte(array, inputFile, uint64(suf), param)
pContentSlice = &contentSlice
length = callParseFunc(pContentSlice, types, param)
case 64: //then an additional byte is read from the stream. The combined 14 bits represent the length
reIndexSliceEnd(array, inputFile, 1, param)
slice := getArraySlice((*param).SliceStart, (*param).SliceEnd, array)
//把slice里边的两个字节转换成数字
slice_value := changeByteToUint64(slice, binary.BigEndian)
//获取后14个bit代表的数字
value := slice_value & 0x3FFF
contentSlice := readNextNByte(array, inputFile, uint64(value), param)
pContentSlice = &contentSlice
length = callParseFunc(pContentSlice, types, param)
case 128: //hen the remaining 6 bits are discarded. Additional 4 bytes are read from the stream, and those 4 bytes represent the length
//(in big endian format in RDB version 6)
var slice_value uint64
//读取后4个bytes
reIndex(array, inputFile, 4, param)
slice := getArraySlice((*param).SliceStart, (*param).SliceEnd, array)
//把slice里边的四个字节转换成数字
slice_value = changeByteToUint64(slice, binary.BigEndian)
//读取这4bytes代表的数字的字节
contentSlice := readNextNByte(array, inputFile, uint64(slice_value), param)
pContentSlice = &contentSlice
length = callParseFunc(pContentSlice, types, param)
case 192: //then the next object is encoded in a special format. The remaining 6 bits indicate the format
//在读取代表内容的字节里边，这里应该用不到,除了压缩
switch suf {
case 0: //0 indicates that an 8 bit integer follows.
reIndex(array, inputFile, 1, param)
slice_value := changeByteToInt64(getArraySlice((*param).SliceStart, (*param).SliceEnd, array), binary.LittleEndian)
contentSlice := readNextNByte(array, inputFile, uint64(slice_value), param)
pContentSlice = &contentSlice
length = callParseFunc(pContentSlice, types, param)
case 1: //1 indicates that a 16 bit integer follows.
reIndex(array, inputFile, 2, param)
slice_value := changeByteToInt64(getArraySlice((*param).SliceStart, (*param).SliceEnd, array), binary.LittleEndian)
contentSlice := readNextNByte(array, inputFile, uint64(slice_value), param)
pContentSlice = &contentSlice
length = callParseFunc(pContentSlice, types, param)
case 2: //2 indicates that a 32 bit integer follows.
reIndex(array, inputFile, 4, param)
slice_value := changeByteToInt64(getArraySlice((*param).SliceStart, (*param).SliceEnd, array), binary.LittleEndian)
contentSlice := readNextNByte(array, inputFile, uint64(slice_value), param)
pContentSlice = &contentSlice
length = callParseFunc(pContentSlice, types, param)
case 3, 4: //4 indicates that a compressed string follows.
//读取压缩字符串的长度
compressed_length := readOneByteAndGetNum(array, inputFile, param)
//读取未压缩字符串的长度
uncompressed_length := readOneByteAndGetNum(array, inputFile, param)
//解压缩字符串
reIndex(array, inputFile, compressed_length, param)
in_data := (*array)[(*param).SliceStart:(*param).SliceEnd]
unComByte := lzf.Lzf_dcompress(in_data, uncompressed_length)
var pUnComByte *[]byte = &unComByte
length = callParseFunc(pUnComByte, types, param)
}
}
return length
}