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[COLLECTIONS-464] Add first version of a FluentIterable implementatio…
…n, cleanup recently toString methods in IterableUtils, add SkippingIterator and additional methods to IteratorUtils and IterableUtils. git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1681783 13f79535-47bb-0310-9956-ffa450edef68
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src/main/java/org/apache/commons/collections4/FluentIterable.java
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| /* | ||
| * Licensed to the Apache Software Foundation (ASF) under one or more | ||
| * contributor license agreements. See the NOTICE file distributed with | ||
| * this work for additional information regarding copyright ownership. | ||
| * The ASF licenses this file to You under the Apache License, Version 2.0 | ||
| * (the "License"); you may not use this file except in compliance with | ||
| * the License. You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package org.apache.commons.collections4; | ||
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| import java.util.Arrays; | ||
| import java.util.Collection; | ||
| import java.util.Enumeration; | ||
| import java.util.Iterator; | ||
| import java.util.List; | ||
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| /** | ||
| * A FluentIterable provides a powerful yet simple API for manipulating Iterable instances in a fluent manner. | ||
| * <p> | ||
| * A FluentIterable can be created either from an Iterable or from a set of elements. | ||
| * The following types of methods are provided: | ||
| * <ul> | ||
| * <li>fluent methods which return a new {@code FluentIterable} instance | ||
| * <li>conversion methods which copy the FluentIterable's contents into a new collection or array (e.g. toList()) | ||
| * <li>utility methods which answer questions about the FluentIterable's contents (e.g. size(), anyMatch(Predicate)) | ||
| * <li> | ||
| * </ul> | ||
| * <p> | ||
| * The following example outputs the first 3 even numbers in the range [1, 10] into a list: | ||
| * <pre> | ||
| * FluentIterable | ||
| * .of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) | ||
| * .filter(new Predicate<Integer>() { | ||
| * public boolean evaluate(Integer number) { | ||
| * return number % 2 == 0; | ||
| * } | ||
| * ) | ||
| * .transform(TransformerUtils.stringValueTransformer()) | ||
| * .limit(3) | ||
| * .toList(); | ||
| * </pre> | ||
| * | ||
| * @param <E> the element type | ||
| * @since 4.1 | ||
| * @version $Id: $ | ||
| */ | ||
| public class FluentIterable<E> implements Iterable<E> { | ||
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| private final Iterable<E> iterable; | ||
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| // Static factory methods | ||
| // ---------------------------------------------------------------------- | ||
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| public static <T> FluentIterable<T> of(T... elements) { | ||
| return of(Arrays.asList(elements)); | ||
| } | ||
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| public static <T> FluentIterable<T> of(Iterable<T> iterable) { | ||
| if (iterable == null) { | ||
| throw new NullPointerException("Iterable must not be null"); | ||
| } | ||
| if (iterable instanceof FluentIterable<?>) { | ||
| return (FluentIterable<T>) iterable; | ||
| } else { | ||
| return new FluentIterable<T>(iterable); | ||
| } | ||
| } | ||
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| // Constructor | ||
| // ---------------------------------------------------------------------- | ||
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| private FluentIterable(final Iterable<E> iterable) { | ||
| this.iterable = iterable; | ||
| } | ||
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| // fluent construction methods | ||
| // ---------------------------------------------------------------------- | ||
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| public FluentIterable<E> append(final E... elements) { | ||
| return append(Arrays.asList(elements)); | ||
| } | ||
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| public FluentIterable<E> append(final Iterable<E> other) { | ||
| return of(IterableUtils.chainedIterable(iterable, other)); | ||
| } | ||
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| public FluentIterable<E> eval() { | ||
| return of(toList()); | ||
| } | ||
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| public FluentIterable<E> filter(final Predicate<E> predicate) { | ||
| return of(IterableUtils.filteredIterable(iterable, predicate)); | ||
| } | ||
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| public FluentIterable<E> limit(final int maxSize) { | ||
| return of(IterableUtils.boundedIterable(iterable, maxSize)); | ||
| } | ||
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| public FluentIterable<E> loop() { | ||
| return of(IterableUtils.loopingIterable(iterable)); | ||
| } | ||
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| public FluentIterable<E> skip(int elementsToSkip) { | ||
| return of(IterableUtils.skippingIterable(iterable, elementsToSkip)); | ||
| } | ||
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| public <O> FluentIterable<O> transform(final Transformer<? super E, ? extends O> transformer) { | ||
| return of(IterableUtils.transformedIterable(iterable, transformer)); | ||
| } | ||
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| public FluentIterable<E> unique() { | ||
| return of(IterableUtils.uniqueIterable(iterable)); | ||
| } | ||
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| // convenience methods | ||
| // ---------------------------------------------------------------------- | ||
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| public Iterator<E> iterator() { | ||
| return iterable.iterator(); | ||
| } | ||
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| public Enumeration<E> asEnumeration() { | ||
| return IteratorUtils.asEnumeration(iterator()); | ||
| } | ||
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| public boolean allMatch(final Predicate<? super E> predicate) { | ||
| return IterableUtils.matchesAll(iterable, predicate); | ||
| } | ||
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| public boolean anyMatch(final Predicate<? super E> predicate) { | ||
| return IterableUtils.matchesAny(iterable, predicate); | ||
| } | ||
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| public boolean isEmpty() { | ||
| return IterableUtils.isEmpty(iterable); | ||
| } | ||
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| public boolean contains(final Object object) { | ||
| return IterableUtils.contains(iterable, object); | ||
| } | ||
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| public E get(int position) { | ||
| return IterableUtils.get(iterable, position); | ||
| } | ||
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| public int size() { | ||
| return IterableUtils.size(iterable); | ||
| } | ||
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| public void copyInto(final Collection<? super E> collection) { | ||
| if (collection == null) { | ||
| throw new NullPointerException("Collection must not be null"); | ||
| } | ||
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| for (final E element : iterable) { | ||
| collection.add(element); | ||
| } | ||
| } | ||
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| public E[] toArray(final Class<E> arrayClass) { | ||
| return IteratorUtils.toArray(iterator(), arrayClass); | ||
| } | ||
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| public List<E> toList() { | ||
| return IteratorUtils.toList(iterator()); | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| return IterableUtils.toString(iterable); | ||
| } | ||
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| } |
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