Package com.scurrilous.circe.impl

Class AbstractHashProvider<P extends HashParameters>

java.lang.Object

com.scurrilous.circe.impl.AbstractHashProvider<P>

Type Parameters:

P - base supported hash parameters type

All Implemented Interfaces:

HashProvider

Direct Known Subclasses:

Crc32cSse42Provider, StandardCrcProvider

public abstract class AbstractHashProvider<P extends HashParameters>
extends java.lang.Object
implements HashProvider

Base implementation for hash function providers.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractHashProvider(java.lang.Class<P> parametersClass)	Constructs a new AbstractHashProvider with the given base parameters class.

Method Summary

Modifier and Type	Method	Description
protected StatelessHash	createCacheable(P params, java.util.EnumSet<HashSupport> required)	Called by getCacheable(P, java.util.EnumSet<com.scurrilous.circe.HashSupport>) to create new cacheable stateless hash functions.
StatefulHash	createStateful(HashParameters params)	Creates a stateful hash function using the given parameters.
protected abstract Hash	get(P params, java.util.EnumSet<HashSupport> required)	Requests a hash function using the given parameters and support flags.
protected Hash	getCacheable(P params, java.util.EnumSet<HashSupport> required)	Called by implementations that support caching of stateless hash functions when a cached instance is desired.
IncrementalIntHash	getIncrementalInt(HashParameters params)	Requests an incremental, stateless, int-width hash function with the given parameters.
IncrementalLongHash	getIncrementalLong(HashParameters params)	Requests an incremental, stateless, long-width hash function with the given parameters.
StatelessIntHash	getStatelessInt(HashParameters params)	Requests a stateless, int-width hash function with the given parameters.
StatelessLongHash	getStatelessLong(HashParameters params)	Requests a stateless, long-width hash function with the given parameters.
java.util.EnumSet<HashSupport>	querySupport(HashParameters params)	Returns information about the available implementations corresponding to the given hash algorithm parameters.
protected abstract java.util.EnumSet<HashSupport>	querySupportTyped(P params)	Implemented by subclasses to provide information about the available implementations corresponding to the given hash algorithm parameters.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractHashProvider

protected AbstractHashProvider(java.lang.Class<P> parametersClass)

Constructs a new AbstractHashProvider with the given base parameters class.

Parameters:

parametersClass - the base hash parameters class supported

Method Detail

querySupport

public final java.util.EnumSet<HashSupport> querySupport(HashParameters params)

Description copied from interface: HashProvider

Returns information about the available implementations corresponding to the given hash algorithm parameters.

Specified by:

querySupport in interface HashProvider

Parameters:

params - the hash algorithm parameters

Returns:

a set of flags indicating the level of support

querySupportTyped

protected abstract java.util.EnumSet<HashSupport> querySupportTyped(P params)

Implemented by subclasses to provide information about the available implementations corresponding to the given hash algorithm parameters. Called by querySupport(com.scurrilous.circe.HashParameters) if the hash parameters match the base type supported by this provider.

Parameters:

params - the hash algorithm parameters

Returns:

a set of flags indicating the level of support

get

protected abstract Hash get(P params,
                            java.util.EnumSet<HashSupport> required)

Requests a hash function using the given parameters and support flags. This method is only responsible for checking support flags returned by querySupportTyped(P).

To support caching of stateless hash functions, call getCacheable(P, java.util.EnumSet<com.scurrilous.circe.HashSupport>) from this method and implement createCacheable(P, java.util.EnumSet<com.scurrilous.circe.HashSupport>).

Parameters:

params - the hash algorithm parameters

required - the required hash support flags

Returns:

a hash function

Throws:

java.lang.UnsupportedOperationException - if this provider cannot support the given parameters

getCacheable

protected final Hash getCacheable(P params,
                                  java.util.EnumSet<HashSupport> required)

Called by implementations that support caching of stateless hash functions when a cached instance is desired. If a cached instance is not available, this method calls createCacheable(P, java.util.EnumSet<com.scurrilous.circe.HashSupport>) to create one, which is then cached (if caching is available).

Parameters:

params - the hash algorithm parameters

required - the required hash support flags

Returns:

a hash function

Throws:

java.lang.UnsupportedOperationException - if this provider cannot support the given parameters

createCacheable

protected StatelessHash createCacheable(P params,
                                        java.util.EnumSet<HashSupport> required)

Called by getCacheable(P, java.util.EnumSet<com.scurrilous.circe.HashSupport>) to create new cacheable stateless hash functions. The default implementation simply throws UnsupportedOperationException.

Parameters:

params - the hash algorithm parameters

required - the required hash support flags

Returns:

a stateless hash function

Throws:

java.lang.UnsupportedOperationException - if this provider cannot support the given parameters

createStateful

public StatefulHash createStateful(HashParameters params)

Description copied from interface: HashProvider

Creates a stateful hash function using the given parameters.

Specified by:

createStateful in interface HashProvider

Parameters:

params - the hash algorithm parameters

Returns:

a stateful hash function

getStatelessInt

public StatelessIntHash getStatelessInt(HashParameters params)

Description copied from interface: HashProvider

Requests a stateless, int-width hash function with the given parameters. Because not all stateless hash functions are incremental, this method may be able to return implementations not supported by or more optimized than HashProvider.getIncrementalInt(com.scurrilous.circe.HashParameters).

Specified by:

getStatelessInt in interface HashProvider

Parameters:

params - the hash algorithm parameters

Returns:

a stateless int-width hash function

getStatelessLong

public StatelessLongHash getStatelessLong(HashParameters params)

Description copied from interface: HashProvider

Requests a stateless, long-width hash function with the given parameters. Because not all stateless hash functions are incremental, this method may be able to return implementations not supported by or more optimized than HashProvider.getIncrementalLong(com.scurrilous.circe.HashParameters).

Note that this method may return a less efficient hash function than HashProvider.getStatelessInt(com.scurrilous.circe.HashParameters) for hashes of 32 bits or less.

Specified by:

getStatelessLong in interface HashProvider

Parameters:

params - the hash algorithm parameters

Returns:

a stateless long-width hash function

getIncrementalInt

public IncrementalIntHash getIncrementalInt(HashParameters params)

Description copied from interface: HashProvider

Requests an incremental, stateless, int-width hash function with the given parameters. Note that although an algorithm may be available in incremental form, some potentially more optimized implementations may not support that form, and therefore cannot be provided be this method.

Specified by:

getIncrementalInt in interface HashProvider

Parameters:

params - the hash algorithm parameters

Returns:

a stateful int-width hash function

getIncrementalLong

public IncrementalLongHash getIncrementalLong(HashParameters params)

Description copied from interface: HashProvider

Requests an incremental, stateless, long-width hash function with the given parameters. Note that although an algorithm may be available in incremental form, some potentially more optimized implementations may not support that form, and therefore cannot be provided be this method.

Also note that this method may return a less efficient hash function than HashProvider.getIncrementalInt(com.scurrilous.circe.HashParameters) for hashes of 32 bits or less.

Specified by:

getIncrementalLong in interface HashProvider

Parameters:

params - the hash algorithm parameters

Returns:

a stateful long-width hash function