/*
 * 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.collection;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.apache.commons.collections4.Transformer;

Decorates another Collection to transform objects that are added. 

The add methods are affected by this class.
Thus objects must be removed or searched for using their transformed form.
For example, if the transformation converts Strings to Integers, you must
use the Integer form to remove objects.


This class is Serializable from Commons Collections 3.1.

Type parameters:
<E> – the type of the elements in the collection
Since:
3.0/**
 * Decorates another {@link Collection} to transform objects that are added.
 * <p>
 * The add methods are affected by this class.
 * Thus objects must be removed or searched for using their transformed form.
 * For example, if the transformation converts Strings to Integers, you must
 * use the Integer form to remove objects.
 * </p>
 * <p>
 * This class is Serializable from Commons Collections 3.1.
 * </p>
 *
 * @param <E> the type of the elements in the collection
 * @since 3.0
 */
public class TransformedCollection<E> extends AbstractCollectionDecorator<E> {

    
Serialization version /** Serialization version */
    private static final long serialVersionUID = 8692300188161871514L;

    
The transformer to use /** The transformer to use */
    protected final Transformer<? super E, ? extends E> transformer;

    
Factory method to create a transforming collection.
 If there are any elements already in the collection being decorated, they are NOT transformed. Contrast this with transformedCollection(Collection<Object>, Transformer<? super Object,? extends Object>). 
Params:
coll –  the collection to decorate, must not be null
transformer –  the transformer to use for conversion, must not be null
Type parameters:
<E> – the type of the elements in the collection
Throws:
NullPointerException – if collection or transformer is null
Returns:
a new transformed collection
Since:
4.0/**
     * Factory method to create a transforming collection.
     * <p>
     * If there are any elements already in the collection being decorated, they
     * are NOT transformed.
     * Contrast this with {@link #transformedCollection(Collection, Transformer)}.
     *
     * @param <E> the type of the elements in the collection
     * @param coll  the collection to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @return a new transformed collection
     * @throws NullPointerException if collection or transformer is null
     * @since 4.0
     */
    public static <E> TransformedCollection<E> transformingCollection(final Collection<E> coll,
            final Transformer<? super E, ? extends E> transformer) {
        return new TransformedCollection<>(coll, transformer);
    }

    
Factory method to create a transforming collection that will transform
existing contents of the specified collection.
 If there are any elements already in the collection being decorated, they will be transformed by this method. Contrast this with transformingCollection(Collection<Object>, Transformer<? super Object,? extends Object>). 
Params:
collection –  the collection to decorate, must not be null
transformer –  the transformer to use for conversion, must not be null
Type parameters:
<E> – the type of the elements in the collection
Throws:
NullPointerException – if collection or transformer is null
Returns:
a new transformed Collection
Since:
4.0/**
     * Factory method to create a transforming collection that will transform
     * existing contents of the specified collection.
     * <p>
     * If there are any elements already in the collection being decorated, they
     * will be transformed by this method.
     * Contrast this with {@link #transformingCollection(Collection, Transformer)}.
     *
     * @param <E> the type of the elements in the collection
     * @param collection  the collection to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @return a new transformed Collection
     * @throws NullPointerException if collection or transformer is null
     * @since 4.0
     */
    public static <E> TransformedCollection<E> transformedCollection(final Collection<E> collection,
            final Transformer<? super E, ? extends E> transformer) {

        final TransformedCollection<E> decorated = new TransformedCollection<>(collection, transformer);
        // null collection & transformer are disallowed by the constructor call above
        if (collection.size() > 0) {
            @SuppressWarnings("unchecked") // collection is of type E
            final E[] values = (E[]) collection.toArray(); // NOPMD - false positive for generics
            collection.clear();
            for (final E value : values) {
                decorated.decorated().add(transformer.transform(value));
            }
        }
        return decorated;
    }

    //-----------------------------------------------------------------------
    
Constructor that wraps (not copies).

If there are any elements already in the collection being decorated, they
are NOT transformed.
Params:
coll –  the collection to decorate, must not be null
transformer –  the transformer to use for conversion, must not be null
Throws:
NullPointerException – if collection or transformer is null/**
     * Constructor that wraps (not copies).
     * <p>
     * If there are any elements already in the collection being decorated, they
     * are NOT transformed.
     *
     * @param coll  the collection to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @throws NullPointerException if collection or transformer is null
     */
    protected TransformedCollection(final Collection<E> coll, final Transformer<? super E, ? extends E> transformer) {
        super(coll);
        if (transformer == null) {
            throw new NullPointerException("Transformer must not be null");
        }
        this.transformer = transformer;
    }

    
Transforms an object.

The transformer itself may throw an exception if necessary.
Params:
object –  the object to transform
Returns:
a transformed object/**
     * Transforms an object.
     * <p>
     * The transformer itself may throw an exception if necessary.
     *
     * @param object  the object to transform
     * @return a transformed object
     */
    protected E transform(final E object) {
        return transformer.transform(object);
    }

    
Transforms a collection.

The transformer itself may throw an exception if necessary.
Params:
coll –  the collection to transform
Returns:
a transformed object/**
     * Transforms a collection.
     * <p>
     * The transformer itself may throw an exception if necessary.
     *
     * @param coll  the collection to transform
     * @return a transformed object
     */
    protected Collection<E> transform(final Collection<? extends E> coll) {
        final List<E> list = new ArrayList<>(coll.size());
        for (final E item : coll) {
            list.add(transform(item));
        }
        return list;
    }

    //-----------------------------------------------------------------------
    @Override
    public boolean add(final E object) {
        return decorated().add(transform(object));
    }

    @Override
    public boolean addAll(final Collection<? extends E> coll) {
        return decorated().addAll(transform(coll));
    }

}