/*
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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.AbstractCollection;
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import java.util.Collection;
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import java.util.Iterator;
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/**
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* Additional {@code Collection} based utility methods.
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*/
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public final class Collections2
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{
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private static final class TransformedCollection<M, N, P> extends
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AbstractCollection<N> implements Collection<N>
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{
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private final Collection<M> collection;
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private final Function<? super M, ? extends N, P> funcMtoN;
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private final Function<? super N, ? extends M, P> funcNtoM;
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private final P p;
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private TransformedCollection(Collection<M> collection,
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Function<? super M, ? extends N, P> funcMtoN,
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Function<? super N, ? extends M, P> funcNtoM, P p)
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{
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this.collection = collection;
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this.funcMtoN = funcMtoN;
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this.funcNtoM = funcNtoM;
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this.p = p;
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}
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/**
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* {@inheritDoc}
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*/
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public boolean add(N e)
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{
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return collection.add(funcNtoM.apply(e, p));
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}
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/**
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* {@inheritDoc}
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*/
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public void clear()
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{
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collection.clear();
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}
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/**
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* {@inheritDoc}
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*/
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@SuppressWarnings("unchecked")
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public boolean contains(Object o)
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{
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N tmp = (N) o;
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return collection.contains(funcNtoM.apply(tmp, p));
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}
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/**
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* {@inheritDoc}
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*/
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public boolean isEmpty()
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{
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return collection.isEmpty();
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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(collection.iterator(), funcMtoN, p);
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}
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/**
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* {@inheritDoc}
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*/
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@SuppressWarnings("unchecked")
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public boolean remove(Object o)
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{
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N tmp = (N) o;
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return collection.remove(funcNtoM.apply(tmp, p));
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}
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/**
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* {@inheritDoc}
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*/
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public int size()
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{
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return collection.size();
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}
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}
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/**
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* Returns a view of {@code collection} whose values have been mapped
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* to elements of type {@code N} using {@code funcMtoN}. The returned
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* collection supports all operations.
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*
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* @param <M>
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* The type of elements contained in {@code collection}.
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* @param <N>
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* The type of elements contained in the returned collection.
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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 collection
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* The collection to be transformed.
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* @param funcMtoN
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* A function which maps values of type {@code M} to values
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* of type {@code N}. This function will be used when
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* retrieving values from {@code collection}.
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* @param funcNtoM
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* A function which maps values of type {@code N} to values
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* of type {@code M}. This function will be used when
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* performing queries and adding values to {@code collection}
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* .
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* @param p
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* A predicate specified parameter.
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* @return A view of {@code collection} whose values have been mapped
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* to elements of type {@code N} using {@code funcMtoN}.
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*/
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public static <M, N, P> Collection<N> transform(
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Collection<M> collection,
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Function<? super M, ? extends N, P> funcMtoN,
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Function<? super N, ? extends M, P> funcNtoM, P p)
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{
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return new TransformedCollection<M, N, P>(collection, funcMtoN,
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funcNtoM, p);
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}
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/**
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* Returns a view of {@code collection} whose values have been mapped
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* to elements of type {@code N} using {@code funcMtoN}. The returned
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* collection supports all operations.
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*
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* @param <M>
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* The type of elements contained in {@code collection}.
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* @param <N>
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* The type of elements contained in the returned collection.
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* @param collection
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* The collection to be transformed.
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* @param funcMtoN
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* A function which maps values of type {@code M} to values
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* of type {@code N}. This function will be used when
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* retrieving values from {@code collection}.
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* @param funcNtoM
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* A function which maps values of type {@code N} to values
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* of type {@code M}. This function will be used when
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* performing queries and adding values to {@code collection}
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* .
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* @return A view of {@code collection} whose values have been mapped
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* to elements of type {@code N} using {@code funcMtoN}.
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*/
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public static <M, N> Collection<N> transform(
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Collection<M> collection,
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Function<? super M, ? extends N, Void> funcMtoN,
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Function<? super N, ? extends M, Void> funcNtoM)
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{
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return new TransformedCollection<M, N, Void>(collection, funcMtoN,
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funcNtoM, null);
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}
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// Prevent instantiation
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private Collections2()
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{
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// Do nothing.
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}
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}
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