it.unimi.dsi.bits

Class PrefixCoderTransformationStrategy

java.lang.Object

it.unimi.dsi.bits.PrefixCoderTransformationStrategy

All Implemented Interfaces:

TransformationStrategy<CharSequence>, Serializable

Direct Known Subclasses:

HuTuckerTransformationStrategy

public class PrefixCoderTransformationStrategy
extends Object
implements TransformationStrategy<CharSequence>

A transformation strategy mapping strings using a prefix-free encoder.

The actual encoding must be provided via a map from characters to symbols, and a set of codewords. The default return value of the map will be used for unknown characters.

This strategy creates a new LongArrayBitVector each time toBitVector(CharSequence) is invoked.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected it.unimi.dsi.fastutil.chars.Char2IntOpenHashMap	char2symbol
protected BitVector[]	codeWord
protected boolean	prefixFree

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	PrefixCoderTransformationStrategy(BitVector[] codeWord, it.unimi.dsi.fastutil.chars.Char2IntOpenHashMap char2symbol, boolean prefixFree)
	PrefixCoderTransformationStrategy(PrefixCoder coder, it.unimi.dsi.fastutil.chars.Char2IntOpenHashMap char2symbol, boolean prefixFree) Create a new transformation strategy based on a prefix-free coder.
protected	PrefixCoderTransformationStrategy(PrefixCoderTransformationStrategy transformationStrategy)

Method Summary

Methods

Modifier and Type	Method and Description
PrefixCoderTransformationStrategy	copy() Returns a copy of this transformation strategy.
long	numBits() The (approximate) number of bits occupied by this transformation.
LongArrayBitVector	toBitVector(CharSequence s) Returns a bit vector representation of the given object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

codeWord

protected final BitVector[] codeWord

char2symbol

protected final it.unimi.dsi.fastutil.chars.Char2IntOpenHashMap char2symbol

prefixFree

protected final boolean prefixFree

Constructor Detail

PrefixCoderTransformationStrategy

public PrefixCoderTransformationStrategy(PrefixCoder coder,
                                 it.unimi.dsi.fastutil.chars.Char2IntOpenHashMap char2symbol,
                                 boolean prefixFree)

Create a new transformation strategy based on a prefix-free coder.

Parameters:

coder - a prefix-free coder.

char2symbol - a map from character to symbols (the default returned value will be used for unknown symbols).

prefixFree - whether it is required that the resulting bit vectors are prefix-free: in this case, symbol 0 will be appended to each string, and will not be allowed to appear in any string.

PrefixCoderTransformationStrategy

protected PrefixCoderTransformationStrategy(PrefixCoderTransformationStrategy transformationStrategy)

PrefixCoderTransformationStrategy

protected PrefixCoderTransformationStrategy(BitVector[] codeWord,
                                 it.unimi.dsi.fastutil.chars.Char2IntOpenHashMap char2symbol,
                                 boolean prefixFree)

Method Detail

toBitVector

public LongArrayBitVector toBitVector(CharSequence s)

Description copied from interface: TransformationStrategy

Returns a bit vector representation of the given object.

Specified by:

toBitVector in interface TransformationStrategy<CharSequence>

Parameters:

s - the object to be turned into bit representation.

Returns:

a bit vector representation of object.

numBits

public long numBits()

Description copied from interface: TransformationStrategy

The (approximate) number of bits occupied by this transformation.

Specified by:

numBits in interface TransformationStrategy<CharSequence>

Returns:

the (approximate) number of bits occupied by this transformation.

copy

public PrefixCoderTransformationStrategy copy()

Description copied from interface: TransformationStrategy

Returns a copy of this transformation strategy.

Specified by:

copy in interface TransformationStrategy<CharSequence>

Returns:

a copy of this transformation strategy.