Package it.unimi.dsi.sux4j.mph.codec

Interface Codec

All Known Implementing Classes:

Codec.Binary, Codec.Gamma, Codec.Huffman, Codec.Unary, Codec.ZeroCodec

public interface Codec

A class representing a specific instantaneous code for compressed functions. The logic of this code is quite tightly coupled with such functions, and it is unlikely to be resusable elsewhere easily.

Author:

Sebastiano Vigna, Marco Genuzio

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	Codec.Binary	A binary fixed-width codec.
static interface	Codec.Coder	A coder: provides methods to turn symbols into codewords.
static interface	Codec.Decoder	A decoder: provides a method to turn sequences of bits into symbols.
static class	Codec.Gamma	A codec based on Elias's γ code (starting at zero).
static class	Codec.Huffman	A Huffman codec with length-limiting capabilities and a fast canonical decoder.
static class	Codec.Unary	A unary codec (starting at zero).
static class	Codec.ZeroCodec	A degenerate stateless codec (always returns zero).

Method Summary

Modifier and Type	Method	Description
Codec.Coder	getCoder(it.unimi.dsi.fastutil.longs.Long2LongMap frequencies)	Returns a coder for a specific map from symbols to frequencies.

Method Detail

getCoder

Codec.Coder getCoder(it.unimi.dsi.fastutil.longs.Long2LongMap frequencies)

Returns a coder for a specific map from symbols to frequencies.

Note that even instantaneous codes (such as Codec.Unary) need to know the set of symbols, as the returned coder needs to known the maximum codeword length.

Parameters:

frequencies - a map from symbols (longs) to frequencies (longs).

Returns:

a coder for the given map.