001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.sequence;
018
019/**
020 * Command representing the keeping of one object present in both sequences.
021 * <p>
022 * When one object of the first sequence <code>equals</code> another objects in
023 * the second sequence at the right place, the {@link EditScript edit script}
024 * transforming the first sequence into the second sequence uses an instance of
025 * this class to represent the keeping of this object. The objects embedded in
026 * these type of commands always come from the first sequence.
027 *
028 * @see SequencesComparator
029 * @see EditScript
030 *
031 * @since 4.0
032 */
033public class KeepCommand<T> extends EditCommand<T> {
034
035    /**
036     * Simple constructor. Creates a new instance of KeepCommand
037     *
038     * @param object  the object belonging to both sequences (the object is a
039     *   reference to the instance in the first sequence which is known
040     *   to be equal to an instance in the second sequence)
041     */
042    public KeepCommand(final T object) {
043        super(object);
044    }
045
046    /**
047     * Accept a visitor. When a <code>KeepCommand</code> accepts a visitor, it
048     * calls its {@link CommandVisitor#visitKeepCommand visitKeepCommand} method.
049     *
050     * @param visitor  the visitor to be accepted
051     */
052    @Override
053    public void accept(final CommandVisitor<T> visitor) {
054        visitor.visitKeepCommand(getObject());
055    }
056}