001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.internal;
014
015import java.util.*;
016import java.util.function.*;
017
018/**
019 * Combines an {@link Iterable} with a {@link Function} so that you can map
020 * entries while iterating over them.
021 *
022 * @param <I> The unmapped type.
023 * @param <E> The mapped type.
024 */
025public class MappedIterable<I,E> implements Iterable<E> {
026
027   final Iterator<I> i;
028   final Function<I,E> f;
029
030   /**
031    * Constructor.
032    *
033    * @param i The original iterable being wrapped.
034    * @param f The function to use to convert from unmapped to mapped types.
035    */
036   protected MappedIterable(Iterable<I> i, Function<I,E> f) {
037      this.i = i.iterator();
038      this.f = f;
039   }
040
041   /**
042    * Constructor.
043    *
044    * @param i The original iterable being wrapped.
045    * @param f The function to use to convert from unmapped to mapped types.
046    * @return A new iterable.
047    */
048   public static <I,E> Iterable<E> of(Iterable<I> i, Function<I,E> f) {
049      return new MappedIterable<>(i, f);
050   }
051
052   @Override
053   public Iterator<E> iterator() {
054      return new Iterator<E>() {
055         @Override
056         public boolean hasNext() {
057            return i.hasNext();
058         }
059         @Override
060         public E next() {
061            return f.apply(i.next());
062         }
063      };
064   }
065}