Package me.lemire.longcompression

Interface SkippableLongCODEC

All Known Implementing Classes:

LongBinaryPacking, LongJustCopy, LongVariableByte, SkippableLongComposition

public interface SkippableLongCODEC

Interface describing a standard CODEC to compress longs. This is a variation on the LongCODEC interface meant to be used for random access (i.e., given a large array, you can segment it and decode just the subarray you need). The main difference is that we must specify the number of longs we wish to decode. This information should be stored elsewhere. This interface was designed by the Terrier team for their search engine.

Author:

Benoit Lacelle

Method Summary

Modifier and Type	Method	Description
void	headlessCompress(long[] in, IntWrapper inpos, int inlength, long[] out, IntWrapper outpos)	Compress data from an array to another array.
void	headlessUncompress(long[] in, IntWrapper inpos, int inlength, long[] out, IntWrapper outpos, int num)	Uncompress data from an array to another array.

Method Details

headlessCompress

void headlessCompress(long[] in,
 IntWrapper inpos,
 int inlength,
 long[] out,
 IntWrapper outpos)

Compress data from an array to another array. Both inpos and outpos are modified to represent how much data was read and written to. If 12 longs (inlength = 12) are compressed to 3 longs, then inpos will be incremented by 12 while outpos will be incremented by 3. We use IntWrapper to pass the values by reference.

Parameters:

in - input array

inpos - where to start reading in the array

inlength - how many longs to compress

out - output array

outpos - where to write in the output array

headlessUncompress

void headlessUncompress(long[] in,
 IntWrapper inpos,
 int inlength,
 long[] out,
 IntWrapper outpos,
 int num)

Uncompress data from an array to another array. Both inpos and outpos parameters are modified to indicate new positions after read/write.

Parameters:

in - array containing data in compressed form

inpos - where to start reading in the array

inlength - length of the compressed data (ignored by some schemes)

out - array where to write the uncompressed output

outpos - where to start writing the uncompressed output in out

num - number of longs we want to decode, the actual number of longs decoded can be less