net.automatalib.commons.util.mappings

Class Mappings

java.lang.Object

net.automatalib.commons.util.mappings.Mappings

public final class Mappings
extends Object

Collection of various methods dealing with Mappings.

Author:

Malte Isberner

Method Summary

Modifier and Type	Method and Description
static <D,R> Collection<R>	apply(Mapping<? super D,R> mapping, Collection<? extends D> coll) Applies a mapping to a collection, resulting in a collection containing the result of applying the specified mapping to each element in the collection.
static <D,R> Iterable<R>	apply(Mapping<? super D,R> mapping, Iterable<? extends D> it) Applies a mapping to an iterable.
static <D,R> Iterator<R>	apply(Mapping<? super D,R> mapping, Iterator<? extends D> baseIt) Applies a mapping to an iterator.
static <D,R> List<R>	apply(Mapping<? super D,R> mapping, List<? extends D> list) Applies a mapping to a list, resulting in a list containing the result of applying the specified mapping to each element in the list.
static <D,I,R> Mapping<D,R>	compose(Mapping<D,? extends I> first, Mapping<? super I,R> second) Retrieves the composition of two mappings, i.e., that mapping that results from applying the Mapping.get(Object) method consecutively.
static <D,R> Mapping<D,R>	fromMap(Map<D,R> map)
static <T> Mapping<T,T>	identity() Retrieves the identity mapping, which maps each domain value to itself.
static <D> D	idGet(Mapping<D,D> mapping, D key)
static <D,R> R	nullGet(Mapping<? super D,? extends R> mapping, D key)
static <D,R> Mapping<D,R>	nullMapping() Retrieves the null mapping, which maps each domain value to null.
static <D,R> R	safeGet(Mapping<? super D,R> mapping, D key, R fallback) Safely retrieves a value from a mapping.
static <D> Mapping<D,String>	toStringMapping() Returns a mapping that maps objects to their String representation, as obtained by String.valueOf(Object).
static <S,T extends S> Mapping<T,S>	upcast() Returns a mapping that maps objects to a supertype representation.

Methods inherited from class java.lang.Object

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

Method Detail

nullMapping

public static <D,R> Mapping<D,R> nullMapping()

Retrieves the null mapping, which maps each domain value to null.

Type Parameters:

D - domain class.

R - range class.

Returns:

the null mapping.

identity

public static <T> Mapping<T,T> identity()

Retrieves the identity mapping, which maps each domain value to itself.

Type Parameters:

T - domain/range class.

Returns:

the identity mapping.

toStringMapping

public static <D> Mapping<D,String> toStringMapping()

Returns a mapping that maps objects to their String representation, as obtained by String.valueOf(Object).

Returns:

the "toString()" mapping

upcast

public static <S,T extends S> Mapping<T,S> upcast()

Returns a mapping that maps objects to a supertype representation.

Returns:

the "upcast" mapping

compose

public static <D,I,R> Mapping<D,R> compose(Mapping<D,? extends I> first,
                                           Mapping<? super I,R> second)

Retrieves the composition of two mappings, i.e., that mapping that results from applying the Mapping.get(Object) method consecutively.

Type Parameters:

D - domain class of the first (and resulting) mapping.

I - intermediate object class, range class of the first and domain class of the second mapping.

R - range class of the second (and resulting) mapping.

Parameters:

first - first mapping.

second - second mapping.

Returns:

the composed mapping.

apply

public static <D,R> Collection<R> apply(Mapping<? super D,R> mapping,
                                        Collection<? extends D> coll)

Applies a mapping to a collection, resulting in a collection containing the result of applying the specified mapping to each element in the collection.

Note that more specific properties of the specified collection won't be preserved: If the given collection is e.g. a set, and the provided mapping is not bijective, then the resulting collections may contain some values multiple times.

Type Parameters:

D - domain class.

R - range class.

Parameters:

mapping - the mapping to apply.

coll - the collection.

Returns:

the mapped collection.

apply

public static <D,R> Iterator<R> apply(Mapping<? super D,R> mapping,
                                      Iterator<? extends D> baseIt)

Applies a mapping to an iterator. For the behavior, see apply(Mapping, Iterable). The resulting iterator supports each operation which the underlying supports.

Type Parameters:

D - domain class.

R - range class.

Parameters:

mapping - the mapping to apply.

baseIt - the underlying iterator.

Returns:

the mapped iterator.

apply

public static <D,R> List<R> apply(Mapping<? super D,R> mapping,
                                  List<? extends D> list)

Applies a mapping to a list, resulting in a list containing the result of applying the specified mapping to each element in the list.

Parameters:

mapping - the mapping to apply.

list - the list.

Returns:

the mapped list.

apply

public static <D,R> Iterable<R> apply(Mapping<? super D,R> mapping,
                                      Iterable<? extends D> it)

Applies a mapping to an iterable. The result is an iterable whose iterator returns the results of applying the specified mapping to each of the elements returned by the original iterable.

Type Parameters:

D - domain class.

R - range clas.

Parameters:

mapping - the mapping to apply.

it - the underlying iterable.

Returns:

the mapped iterable.

idGet

public static <D> D idGet(Mapping<D,D> mapping,
                          D key)

safeGet

public static <D,R> R safeGet(Mapping<? super D,R> mapping,
                              D key,
                              R fallback)

Safely retrieves a value from a mapping. If the mapping is null or returns a null value, the given fallback value is returned.

Parameters:

mapping - the mapping.

key - the key.

fallback - the fallback value to return if either the mapping or the originally returned value are null.

Returns:

the value returned by the specified mapping, or the fallback value.

nullGet

public static <D,R> R nullGet(Mapping<? super D,? extends R> mapping,
                              D key)

fromMap

public static <D,R> Mapping<D,R> fromMap(Map<D,R> map)