org.apache.commons.collections4.sequence.EditScript Maven / Gradle / Ivy
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/*
* 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.sequence;
import java.util.ArrayList;
import java.util.List;
/**
* This class gathers all the {@link EditCommand commands} needed to transform
* one objects sequence into another objects sequence.
*
* An edit script is the most general view of the differences between two
* sequences. It is built as the result of the comparison between two sequences
* by the {@link SequencesComparator SequencesComparator} class. The user can
* walk through it using the visitor design pattern.
*
* It is guaranteed that the objects embedded in the {@link InsertCommand insert
* commands} come from the second sequence and that the objects embedded in
* either the {@link DeleteCommand delete commands} or {@link KeepCommand keep
* commands} come from the first sequence. This can be important if subclassing
* is used for some elements in the first sequence and the equals
* method is specialized.
*
* @see SequencesComparator
* @see EditCommand
* @see CommandVisitor
* @see ReplacementsHandler
*
* @since 4.0
*/
public class EditScript {
/** Container for the commands. */
private final List> commands;
/** Length of the longest common subsequence. */
private int lcsLength;
/** Number of modifications. */
private int modifications;
/**
* Simple constructor. Creates a new empty script.
*/
public EditScript() {
commands = new ArrayList<>();
lcsLength = 0;
modifications = 0;
}
/**
* Add a keep command to the script.
*
* @param command command to add
*/
public void append(final KeepCommand command) {
commands.add(command);
++lcsLength;
}
/**
* Add an insert command to the script.
*
* @param command command to add
*/
public void append(final InsertCommand command) {
commands.add(command);
++modifications;
}
/**
* Add a delete command to the script.
*
* @param command command to add
*/
public void append(final DeleteCommand command) {
commands.add(command);
++modifications;
}
/**
* Visit the script. The script implements the visitor design
* pattern, this method is the entry point to which the user supplies its
* own visitor, the script will be responsible to drive it through the
* commands in order and call the appropriate method as each command is
* encountered.
*
* @param visitor the visitor that will visit all commands in turn
*/
public void visit(final CommandVisitor visitor) {
for (final EditCommand command : commands) {
command.accept(visitor);
}
}
/**
* Get the length of the Longest Common Subsequence (LCS). The length of the
* longest common subsequence is the number of {@link KeepCommand keep
* commands} in the script.
*
* @return length of the Longest Common Subsequence
*/
public int getLCSLength() {
return lcsLength;
}
/**
* Get the number of effective modifications. The number of effective
* modification is the number of {@link DeleteCommand delete} and
* {@link InsertCommand insert} commands in the script.
*
* @return number of effective modifications
*/
public int getModifications() {
return modifications;
}
}