Class CHDMinimalPerfectHashFunction.Builder<T>

java.lang.Object

it.unimi.dsi.sux4j.mph.CHDMinimalPerfectHashFunction.Builder<T>

Enclosing class:

CHDMinimalPerfectHashFunction<T>

public static class CHDMinimalPerfectHashFunction.Builder<T>
extends Object

A builder class for CHDMinimalPerfectHashFunction.

Since:

3.2.0

Author:

Sebastiano Vigna

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	built	Whether build() has already been called.
protected ChunkedHashStore<T>	chunkedHashStore
protected Iterable<? extends T>	keys
protected int	lambda
protected double	loadFactor
protected int	signatureWidth
protected File	tempDir
protected it.unimi.dsi.bits.TransformationStrategy<? super T>	transform

Constructor Summary

Constructors

Constructor	Description
Builder()

Method Summary

Modifier and Type	Method	Description
CHDMinimalPerfectHashFunction<T>	build()	Builds a minimal perfect hash function.
CHDMinimalPerfectHashFunction.Builder<T>	keys(Iterable<? extends T> keys)	Specifies the keys to hash; if you have specified a it.unimi.dsi.sux4j.io.ChunkedHashStore, it can be null.
CHDMinimalPerfectHashFunction.Builder<T>	lambda(int lambda)	Specifies the average size of a bucket.
CHDMinimalPerfectHashFunction.Builder<T>	loadFactor(int loadFactor)	Specifies the load factor.
CHDMinimalPerfectHashFunction.Builder<T>	signed(int signatureWidth)	Specifies that the resulting CHDMinimalPerfectHashFunction should be signed using a given number of bits per key.
CHDMinimalPerfectHashFunction.Builder<T>	store(ChunkedHashStore<T> chunkedHashStore)	Specifies a chunked hash store containing the keys.
CHDMinimalPerfectHashFunction.Builder<T>	tempDir(File tempDir)	Specifies a temporary directory for the it.unimi.dsi.sux4j.io.ChunkedHashStore.
CHDMinimalPerfectHashFunction.Builder<T>	transform(it.unimi.dsi.bits.TransformationStrategy<? super T> transform)	Specifies the transformation strategy for the keys to hash; the strategy can be raw.

Methods inherited from class Object

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

Field Details

keys

protected Iterable<? extends T> keys

transform

protected it.unimi.dsi.bits.TransformationStrategy<? super T> transform

signatureWidth

protected int signatureWidth

tempDir

protected File tempDir

lambda

protected int lambda

loadFactor

protected double loadFactor

chunkedHashStore

protected ChunkedHashStore<T> chunkedHashStore

built

protected boolean built

Whether build() has already been called.

Constructor Details

Builder

public Builder()

Method Details

keys

public CHDMinimalPerfectHashFunction.Builder<T> keys(Iterable<? extends T> keys)

Specifies the keys to hash; if you have specified a it.unimi.dsi.sux4j.io.ChunkedHashStore, it can be null.

Parameters:

keys - the keys to hash.

Returns:

this builder.

lambda

public CHDMinimalPerfectHashFunction.Builder<T> lambda(int lambda)

Specifies the average size of a bucket.

Parameters:

lambda - the average size of a bucket.

Returns:

this builder.

loadFactor

public CHDMinimalPerfectHashFunction.Builder<T> loadFactor(int loadFactor)

Specifies the load factor.

Parameters:

loadFactor - the load factor.

Returns:

this builder.

transform

public CHDMinimalPerfectHashFunction.Builder<T> transform(it.unimi.dsi.bits.TransformationStrategy<? super T> transform)

Specifies the transformation strategy for the keys to hash; the strategy can be raw.

Parameters:

transform - a transformation strategy for the keys to hash.

Returns:

this builder.

signed

public CHDMinimalPerfectHashFunction.Builder<T> signed(int signatureWidth)

Specifies that the resulting CHDMinimalPerfectHashFunction should be signed using a given number of bits per key.

Parameters:

signatureWidth - a signature width, or 0 for no signature.

Returns:

this builder.

tempDir

public CHDMinimalPerfectHashFunction.Builder<T> tempDir(File tempDir)

Specifies a temporary directory for the it.unimi.dsi.sux4j.io.ChunkedHashStore.

Parameters:

tempDir - a temporary directory for the it.unimi.dsi.sux4j.io.ChunkedHashStore files, or null for the standard temporary directory.

Returns:

this builder.

store

public CHDMinimalPerfectHashFunction.Builder<T> store(ChunkedHashStore<T> chunkedHashStore)

Specifies a chunked hash store containing the keys.

Parameters:

chunkedHashStore - a chunked hash store containing the keys, or null; the store can be unchecked, but in this case you must specify keys and a transform (otherwise, in case of a hash collision in the store an IllegalStateException will be thrown).

Returns:

this builder.

build

public CHDMinimalPerfectHashFunction<T> build()
                                       throws IOException

Builds a minimal perfect hash function.

Returns:

a CHDMinimalPerfectHashFunction instance with the specified parameters.

Throws:

IllegalStateException - if called more than once.

IOException