/*
 * 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.iterators;

import java.util.Iterator;

import org.apache.commons.collections4.Transformer;

Decorates an iterator such that each element returned is transformed.
Since:
1.0/**
 * Decorates an iterator such that each element returned is transformed.
 *
 * @since 1.0
 */
public class TransformIterator<I, O> implements Iterator<O> {

    
The iterator being used /** The iterator being used */
    private Iterator<? extends I> iterator;
    
The transformer being used /** The transformer being used */
    private Transformer<? super I, ? extends O> transformer;

    //-----------------------------------------------------------------------
    
Constructs a new TransformIterator that will not function until the setIterator and setTransformer(Transformer) methods are invoked. /**
     * Constructs a new <code>TransformIterator</code> that will not function
     * until the {@link #setIterator(Iterator) setIterator} and
     * {@link #setTransformer(Transformer)} methods are invoked.
     */
    public TransformIterator() {
        super();
    }

    
Constructs a new TransformIterator that won't transform
elements from the given iterator.
Params:
iterator –  the iterator to use/**
     * Constructs a new <code>TransformIterator</code> that won't transform
     * elements from the given iterator.
     *
     * @param iterator  the iterator to use
     */
    public TransformIterator(final Iterator<? extends I> iterator) {
        super();
        this.iterator = iterator;
    }

    
Constructs a new TransformIterator that will use the
given iterator and transformer.  If the given transformer is null,
then objects will not be transformed.
Params:
iterator –  the iterator to use
transformer –  the transformer to use/**
     * Constructs a new <code>TransformIterator</code> that will use the
     * given iterator and transformer.  If the given transformer is null,
     * then objects will not be transformed.
     *
     * @param iterator  the iterator to use
     * @param transformer  the transformer to use
     */
    public TransformIterator(final Iterator<? extends I> iterator,
                             final Transformer<? super I, ? extends O> transformer) {
        super();
        this.iterator = iterator;
        this.transformer = transformer;
    }

    //-----------------------------------------------------------------------
    @Override
    public boolean hasNext() {
        return iterator.hasNext();
    }

    
Gets the next object from the iteration, transforming it using the
current transformer. If the transformer is null, no transformation
occurs and the object from the iterator is returned directly.
Throws:
NoSuchElementException – if there are no more elements
Returns:
the next object/**
     * Gets the next object from the iteration, transforming it using the
     * current transformer. If the transformer is null, no transformation
     * occurs and the object from the iterator is returned directly.
     *
     * @return the next object
     * @throws java.util.NoSuchElementException if there are no more elements
     */
    @Override
    public O next() {
        return transform(iterator.next());
    }

    @Override
    public void remove() {
        iterator.remove();
    }

    //-----------------------------------------------------------------------
    
Gets the iterator this iterator is using.
Returns:
the iterator./**
     * Gets the iterator this iterator is using.
     *
     * @return the iterator.
     */
    public Iterator<? extends I> getIterator() {
        return iterator;
    }

    
Sets the iterator for this iterator to use.
If iteration has started, this effectively resets the iterator.
Params:
iterator –  the iterator to use/**
     * Sets the iterator for this iterator to use.
     * If iteration has started, this effectively resets the iterator.
     *
     * @param iterator  the iterator to use
     */
    public void setIterator(final Iterator<? extends I> iterator) {
        this.iterator = iterator;
    }

    //-----------------------------------------------------------------------
    
Gets the transformer this iterator is using.
Returns:
the transformer./**
     * Gets the transformer this iterator is using.
     *
     * @return the transformer.
     */
    public Transformer<? super I, ? extends O> getTransformer() {
        return transformer;
    }

    
Sets the transformer this the iterator to use.
A null transformer is a no-op transformer.
Params:
transformer –  the transformer to use/**
     * Sets the transformer this the iterator to use.
     * A null transformer is a no-op transformer.
     *
     * @param transformer  the transformer to use
     */
    public void setTransformer(final Transformer<? super I, ? extends O> transformer) {
        this.transformer = transformer;
    }

    //-----------------------------------------------------------------------
    
Transforms the given object using the transformer.
If the transformer is null, the original object is returned as-is.
Params:
source –  the object to transform
Returns:
the transformed object/**
     * Transforms the given object using the transformer.
     * If the transformer is null, the original object is returned as-is.
     *
     * @param source  the object to transform
     * @return the transformed object
     */
    protected O transform(final I source) {
        return transformer.transform(source);
    }
}