| /* |
| * 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.text.diff; |
| |
| /** |
| * Abstract base class for all commands used to transform an objects sequence |
| * into another one. |
| * <p> |
| * When two objects sequences are compared through the |
| * {@link StringsComparator#getScript StringsComparator.getScript} method, |
| * the result is provided has a {@link EditScript script} containing the commands |
| * that progressively transform the first sequence into the second one. |
| * </p> |
| * <p> |
| * There are only three types of commands, all of which are subclasses of this |
| * abstract class. Each command is associated with one object belonging to at |
| * least one of the sequences. These commands are {@link InsertCommand |
| * InsertCommand} which correspond to an object of the second sequence being |
| * inserted into the first sequence, {@link DeleteCommand DeleteCommand} which |
| * correspond to an object of the first sequence being removed and |
| * {@link KeepCommand KeepCommand} which correspond to an object of the first |
| * sequence which <code>equals</code> an object in the second sequence. It is |
| * guaranteed that comparison is always performed this way (i.e. the |
| * <code>equals</code> method of the object from the first sequence is used and |
| * the object passed as an argument comes from the second sequence) ; this can |
| * be important if subclassing is used for some elements in the first sequence |
| * and the <code>equals</code> method is specialized. |
| * </p> |
| * |
| * <p> |
| * This code has been adapted from Apache Commons Collections 4.0. |
| * </p> |
| * |
| * @see StringsComparator |
| * @see EditScript |
| * |
| * @param <T> object type |
| * @since 1.0 |
| */ |
| public abstract class EditCommand<T> { |
| |
| /** Object on which the command should be applied. */ |
| private final T object; |
| |
| /** |
| * Simple constructor. Creates a new instance of EditCommand |
| * |
| * @param object reference to the object associated with this command, this |
| * refers to an element of one of the sequences being compared |
| */ |
| protected EditCommand(final T object) { |
| this.object = object; |
| } |
| |
| /** |
| * Returns the object associated with this command. |
| * |
| * @return the object on which the command is applied |
| */ |
| protected T getObject() { |
| return object; |
| } |
| |
| /** |
| * Accept a visitor. |
| * <p> |
| * This method is invoked for each commands belonging to |
| * an {@link EditScript EditScript}, in order to implement the visitor design pattern |
| * |
| * @param visitor the visitor to be accepted |
| */ |
| public abstract void accept(CommandVisitor<T> visitor); |
| |
| } |