134 lines
4.2 KiB
Java
134 lines
4.2 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.text.diff;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* This class gathers all the {@link EditCommand commands} needed to transform
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* one objects sequence into another objects sequence.
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* <p>
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* An edit script is the most general view of the differences between two
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* sequences. It is built as the result of the comparison between two sequences
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* by the {@link StringsComparator StringsComparator} class. The user can
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* walk through it using the <em>visitor</em> design pattern.
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* </p>
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* <p>
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* It is guaranteed that the objects embedded in the {@link InsertCommand insert
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* commands} come from the second sequence and that the objects embedded in
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* either the {@link DeleteCommand delete commands} or {@link KeepCommand keep
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* commands} come from the first sequence. This can be important if subclassing
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* is used for some elements in the first sequence and the {@code equals}
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* method is specialized.
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* </p>
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*
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* @see StringsComparator
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* @see EditCommand
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* @see CommandVisitor
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* @see ReplacementsHandler
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*
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* @param <T> object type
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* @since 1.0
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*/
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public class EditScript<T> {
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/** Container for the commands. */
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private final List<EditCommand<T>> commands;
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/** Length of the longest common subsequence. */
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private int lcsLength;
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/** Number of modifications. */
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private int modifications;
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/**
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* Constructs a new empty script.
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*/
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public EditScript() {
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commands = new ArrayList<>();
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lcsLength = 0;
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modifications = 0;
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}
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/**
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* Appends a delete command to the script.
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*
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* @param command command to add
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*/
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public void append(final DeleteCommand<T> command) {
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commands.add(command);
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++modifications;
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}
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/**
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* Appends an insert command to the script.
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*
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* @param command command to add
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*/
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public void append(final InsertCommand<T> command) {
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commands.add(command);
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++modifications;
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}
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/**
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* Appends a keep command to the script.
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*
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* @param command command to add
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*/
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public void append(final KeepCommand<T> command) {
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commands.add(command);
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++lcsLength;
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}
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/**
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* Gets the length of the Longest Common Subsequence (LCS). The length of the
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* longest common subsequence is the number of {@link KeepCommand keep
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* commands} in the script.
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*
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* @return length of the Longest Common Subsequence
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*/
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public int getLCSLength() {
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return lcsLength;
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}
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/**
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* Gets the number of effective modifications. The number of effective
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* modification is the number of {@link DeleteCommand delete} and
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* {@link InsertCommand insert} commands in the script.
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*
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* @return number of effective modifications
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*/
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public int getModifications() {
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return modifications;
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}
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/**
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* Visits the script. The script implements the <em>visitor</em> design
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* pattern, this method is the entry point to which the user supplies its
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* own visitor, the script will be responsible to drive it through the
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* commands in order and call the appropriate method as each command is
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* encountered.
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*
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* @param visitor the visitor that will visit all commands in turn
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*/
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public void visit(final CommandVisitor<T> visitor) {
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commands.forEach(command -> command.accept(visitor));
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}
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}
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