/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE
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* or https://OpenDS.dev.java.net/OpenDS.LICENSE.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE. If applicable,
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* add the following below this CDDL HEADER, with the fields enclosed
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* by brackets "[]" replaced with your own identifying information:
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* Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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*
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* Copyright 2009 Sun Microsystems, Inc.
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*/
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package com.sun.opends.sdk.util;
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import java.util.Iterator;
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/**
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* Utility methods for manipulating {@link Iterable}s.
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*/
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public final class Iterables
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{
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private static final class EmptyIterable<M> implements Iterable<M>
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{
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/**
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* {@inheritDoc}
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*/
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public Iterator<M> iterator()
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{
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return Iterators.empty();
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}
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}
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private static final class FilteredIterable<M, P> implements
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Iterable<M>
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{
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private final Iterable<M> iterable;
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private final P parameter;
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private final Predicate<? super M, P> predicate;
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// Constructed via factory methods.
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private FilteredIterable(Iterable<M> iterable,
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Predicate<? super M, P> predicate, P p)
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{
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this.iterable = iterable;
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this.predicate = predicate;
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this.parameter = p;
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}
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/**
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* {@inheritDoc}
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*/
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public Iterator<M> iterator()
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{
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return Iterators
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.filter(iterable.iterator(), predicate, parameter);
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}
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}
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private static final class SingletonIterable<M> implements
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Iterable<M>
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{
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private final M value;
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// Constructed via factory methods.
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private SingletonIterable(M value)
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{
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this.value = value;
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}
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/**
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* {@inheritDoc}
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*/
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public Iterator<M> iterator()
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{
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return Iterators.singleton(value);
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}
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}
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private static final class ArrayIterable<M> implements Iterable<M>
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{
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private final M[] a;
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// Constructed via factory methods.
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private ArrayIterable(M[] a)
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{
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this.a = a;
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}
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/**
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* {@inheritDoc}
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*/
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public Iterator<M> iterator()
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{
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return Iterators.arrayIterator(a);
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}
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}
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private static final class TransformedIterable<M, N, P> implements
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Iterable<N>
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{
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private final Function<? super M, ? extends N, P> function;
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private final Iterable<M> iterable;
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private final P parameter;
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// Constructed via factory methods.
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private TransformedIterable(Iterable<M> iterable,
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Function<? super M, ? extends N, P> function, P p)
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{
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this.iterable = iterable;
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this.function = function;
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this.parameter = p;
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}
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/**
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* {@inheritDoc}
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*/
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public Iterator<N> iterator()
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{
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return Iterators.transform(iterable.iterator(), function,
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parameter);
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}
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}
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private static final class UnmodifiableIterable<M> implements
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Iterable<M>
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{
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private final Iterable<M> iterable;
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// Constructed via factory methods.
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private UnmodifiableIterable(Iterable<M> iterable)
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{
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this.iterable = iterable;
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}
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/**
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* {@inheritDoc}
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*/
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public Iterator<M> iterator()
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{
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return Iterators.unmodifiable(iterable.iterator());
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}
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}
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private static final Iterable<Object> EMPTY_ITERABLE =
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new EmptyIterable<Object>();
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/**
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* Returns an immutable empty iterable.
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*
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* @param <M>
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* The required type of the empty iterable.
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* @return An immutable empty iterable.
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*/
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@SuppressWarnings("unchecked")
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public static <M> Iterable<M> empty()
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{
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return (Iterable<M>) EMPTY_ITERABLE;
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}
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/**
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* Returns a filtered view of {@code iterable} containing only those
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* elements which match {@code predicate}. The returned iterable's
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* iterator supports element removal via the {@code remove()} method
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* subject to any constraints imposed by {@code iterable}.
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*
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* @param <M>
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* The type of elements contained in {@code iterable}.
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* @param <P>
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* The type of the additional parameter to the predicate's
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* {@code matches} method. Use {@link java.lang.Void} for
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* predicates that do not need an additional parameter.
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* @param iterable
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* The iterable to be filtered.
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* @param predicate
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* The predicate.
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* @param p
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* A predicate specified parameter.
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* @return A filtered view of {@code iterable} containing only those
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* elements which match {@code predicate}.
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*/
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public static <M, P> Iterable<M> filter(Iterable<M> iterable,
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Predicate<? super M, P> predicate, P p)
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{
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return new FilteredIterable<M, P>(iterable, predicate, p);
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}
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/**
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* Returns a filtered view of {@code iterable} containing only those
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* elements which match {@code predicate}. The returned iterable's
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* iterator supports element removal via the {@code remove()} method
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* subject to any constraints imposed by {@code iterable}.
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*
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* @param <M>
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* The type of elements contained in {@code iterable}.
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* @param iterable
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* The iterable to be filtered.
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* @param predicate
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* The predicate.
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* @return A filtered view of {@code iterable} containing only those
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* elements which match {@code predicate}.
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*/
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public static <M> Iterable<M> filter(Iterable<M> iterable,
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Predicate<? super M, Void> predicate)
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{
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return new FilteredIterable<M, Void>(iterable, predicate, null);
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}
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/**
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* Returns an iterable containing the single element {@code value}.
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* The returned iterable's iterator does not support element removal
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* via the {@code remove()} method.
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*
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* @param <M>
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* The type of the single element {@code value}.
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* @param value
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* The single element.
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* @return An iterable containing the single element {@code value}.
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*/
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public static <M> Iterable<M> singleton(M value)
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{
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return new SingletonIterable<M>(value);
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}
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/**
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* Returns an iterable containing the elements of {@code a}. The
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* returned iterable's iterator does not support element removal via
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* the {@code remove()} method.
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*
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* @param <M>
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* The type of elements contained in {@code a}.
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* @param a
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* The array of elements.
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* @return An iterable containing the elements of {@code a}.
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*/
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public static <M> Iterable<M> arrayIterable(M[] a)
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{
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return new ArrayIterable<M>(a);
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}
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/**
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* Returns a view of {@code iterable} whose values have been mapped to
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* elements of type {@code N} using {@code function}. The returned
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* iterable's iterator supports element removal via the {@code
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* remove()} method subject to any constraints imposed by {@code
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* iterable}.
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*
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* @param <M>
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* The type of elements contained in {@code iterable}.
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* @param <N>
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* The type of elements contained in the returned iterable.
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* @param <P>
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* The type of the additional parameter to the function's
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* {@code apply} method. Use {@link java.lang.Void} for
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* functions that do not need an additional parameter.
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* @param iterable
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* The iterable to be transformed.
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* @param function
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* The function.
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* @param p
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* A predicate specified parameter.
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* @return A view of {@code iterable} whose values have been mapped to
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* elements of type {@code N} using {@code function}.
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*/
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public static <M, N, P> Iterable<N> transform(Iterable<M> iterable,
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Function<? super M, ? extends N, P> function, P p)
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{
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return new TransformedIterable<M, N, P>(iterable, function, p);
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}
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/**
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* Returns a view of {@code iterable} whose values have been mapped to
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* elements of type {@code N} using {@code function}. The returned
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* iterable's iterator supports element removal via the {@code
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* remove()} method subject to any constraints imposed by {@code
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* iterable}.
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*
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* @param <M>
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* The type of elements contained in {@code iterable}.
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* @param <N>
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* The type of elements contained in the returned iterable.
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* @param iterable
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* The iterable to be transformed.
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* @param function
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* The function.
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* @return A view of {@code iterable} whose values have been mapped to
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* elements of type {@code N} using {@code function}.
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*/
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public static <M, N> Iterable<N> transform(Iterable<M> iterable,
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Function<? super M, ? extends N, Void> function)
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{
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return new TransformedIterable<M, N, Void>(iterable, function, null);
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}
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/**
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* Returns a read-only view of {@code iterable} whose iterator does
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* not support element removal via the {@code remove()}. Attempts to
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* use the {@code remove()} method will result in a {@code
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* UnsupportedOperationException}.
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*
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* @param <M>
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* The type of elements contained in {@code iterable}.
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* @param iterable
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* The iterable to be made read-only.
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* @return A read-only view of {@code iterable} whose iterator does
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* not support element removal via the {@code remove()}.
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*/
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public static <M> Iterable<M> unmodifiable(Iterable<M> iterable)
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{
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return new UnmodifiableIterable<M>(iterable);
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}
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// Prevent instantiation
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private Iterables()
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{
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// Do nothing.
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}
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}
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