    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} 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 * </p>
    028 *
    029 * @param <T> the type of object to apply this command.
    030 * @see SequencesComparator
    031 * @see EditScript
    032 * @since 4.0
    033 */
    034public class KeepCommand<T> extends EditCommand<T> {
    035
    036    /**
    037     * Simple constructor. Creates a new instance of KeepCommand
    038     *
    039     * @param object  the object belonging to both sequences (the object is a
    040     *   reference to the instance in the first sequence which is known
    041     *   to be equal to an instance in the second sequence)
    042     */
    043    public KeepCommand(final T object) {
    044        super(object);
    045    }
    046
    047    /**
    048     * Accept a visitor. When a {@code KeepCommand} accepts a visitor, it
    049     * calls its {@link CommandVisitor#visitKeepCommand visitKeepCommand} method.
    050     *
    051     * @param visitor  the visitor to be accepted
    052     */
    053    @Override
    054    public void accept(final CommandVisitor<T> visitor) {
    055        visitor.visitKeepCommand(getObject());
    056    }
    057}