de.unkrig.commons.lang.protocol

Class TransformerUtil

java.lang.Object

de.unkrig.commons.lang.protocol.TransformerUtil

public final class TransformerUtil
extends java.lang.Object

Various Transformer-related utility methods.

Method Summary

Modifier and Type	Method and Description
static <I,O> Transformer<I,O>	addMappings(Transformer<? super I,O> transformer, java.lang.Object... keysAndValues)
static <I,O,EX extends java.lang.RuntimeException> Transformer<I,O>	asTransformer(TransformerWhichThrows<? super I,? extends O,EX> source) Converts a TransformerWhichThrows into a Transformer.
static <I,O,EX extends java.lang.Throwable> TransformerWhichThrows<I,O,EX>	asTransformerWhichThrows(Transformer<? super I,? extends O> source) Converts a Transformer into a TransformerWhichThrows.
static <I,O> Transformer<I,O>	cache(Transformer<? super I,O> delegate) A transformer which lets a delegate transform the inputs, but at most once for each non-equal input.
static <I,O> Transformer<I,O>	combine(I extraInput, O extraOutput, Transformer<? super I,O> delegate)
static <I,O,EX extends java.lang.Throwable> TransformerWhichThrows<I,O,EX>	combine(I extraInput, O extraOutput, TransformerWhichThrows<? super I,O,EX> delegate)
static <I,O> Transformer<I,O>	fromMappings(java.lang.Object... keysAndValues)
static <O,I extends O> Transformer<I,O>	identity()
static <I,O,EX extends java.lang.Throwable> Transformer<I,O>	ignoreExceptions(java.lang.Class<EX> exceptionClass, TransformerWhichThrows<I,O,EX> delegate, O defaultValue) Wraps the delegate such that its declared exception is caught, ignored, and the defaultValue is returned.

Methods inherited from class java.lang.Object

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

Method Detail

identity

public static <O,I extends O> Transformer<I,O> identity()

Returns:

A Transformer that transforms any object reference to itself.

asTransformerWhichThrows

public static <I,O,EX extends java.lang.Throwable> TransformerWhichThrows<I,O,EX> asTransformerWhichThrows(Transformer<? super I,? extends O> source)

Converts a Transformer into a TransformerWhichThrows.

That is possible iff:

• The target's input type is a subclass of the source's input type, and
• The source's output type is a subclass of the target's output type.

Type Parameters:

I - The transformers' input type

O - The transformers' output type

EX - The target transformer's exception

asTransformer

public static <I,O,EX extends java.lang.RuntimeException> Transformer<I,O> asTransformer(TransformerWhichThrows<? super I,? extends O,EX> source)

Converts a TransformerWhichThrows into a Transformer.

That is possible iff:

• The target's input type is a subclass of the source's input type, and
• The source's output type is a subclass of the target's output type
• The source's exception is a subclass of RuntimeException.

Type Parameters:

I - The transformers' input type

O - The transformers' output type

EX - The source transformer's exception

combine

public static <I,O> Transformer<I,O> combine(I extraInput,
                                             O extraOutput,
                                             Transformer<? super I,O> delegate)

Returns:

A Transformer which calls the delegate, except when the subject equals the extraInput, when it returns extraOutput

combine

public static <I,O,EX extends java.lang.Throwable> TransformerWhichThrows<I,O,EX> combine(I extraInput,
                                                                                          O extraOutput,
                                                                                          TransformerWhichThrows<? super I,O,EX> delegate)

Returns:

A TransformerWhichThrows which calls the delegate, except when the subject equals the extraInput, when it returns extraOutput

addMappings

public static <I,O> Transformer<I,O> addMappings(Transformer<? super I,O> transformer,
                                                 java.lang.Object... keysAndValues)

Returns:

A Transformer in which the given keys and values override the mappings of the delegate.

fromMappings

public static <I,O> Transformer<I,O> fromMappings(java.lang.Object... keysAndValues)

Returns:

A Transformer in which the given keys and values override the mappings of the delegate.

cache

public static <I,O> Transformer<I,O> cache(Transformer<? super I,O> delegate)

A transformer which lets a delegate transform the inputs, but at most once for each non-equal input.

ignoreExceptions

public static <I,O,EX extends java.lang.Throwable> Transformer<I,O> ignoreExceptions(java.lang.Class<EX> exceptionClass,
                                                                                     TransformerWhichThrows<I,O,EX> delegate,
                                                                                     O defaultValue)

Wraps the delegate such that its declared exception is caught, ignored, and the defaultValue is returned.