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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.
 */
/**
 * This package provides classes to compare two sequences of objects.
 * 

* The two sequences can hold any object type, as only the * equals method is used to compare the elements of the * sequences. It is guaranteed that the comparisons will always be done * as o1.equals(o2) where o1 belongs to the * first sequence and o2 belongs to the second * sequence. This can be important if subclassing is used for some * elements in the first sequence and the equals method is * specialized. *

* Comparison can be seen from two points of view: either as giving the * smallest modification allowing to transform the first sequence into * the second one, or as giving the longest sequence which is a * subsequence of both initial sequences. The equals method * is used to compare objects, so any object can be put into * sequences. Modifications include deleting, inserting or keeping one * object, starting from the beginning of the first sequence. Like most * algorithms of the same type, objects transpositions are not * supported. This means that if a sequence (A, B) is * compared to (B, A), the result will be either the * sequence of three commands delete A, keep B, * insert A or the sequence insert B, * keep A, delete B. *

* The package uses a very efficient comparison algorithm designed by * Eugene W. Myers and described in his paper: An O(ND) * Difference Algorithm and Its Variations. This algorithm produces * the shortest possible * {@link org.apache.commons.collections4.sequence.EditScript edit script} containing * all the {@link org.apache.commons.collections4.sequence.EditCommand commands} * needed to transform the first sequence into the second one. * The entry point for the user to this algorithm is the * {@link org.apache.commons.collections4.sequence.SequencesComparator} class. *

* As explained in Gene Myers paper, the edit script is equivalent to all * other representations and contains all the needed information either * to perform the transformation, of course, or to retrieve the longest * common subsequence for example. *

* If the user needs a very fine grained access to the comparison result, * he needs to go through this script by providing a visitor implementing * the {@link org.apache.commons.collections4.sequence.CommandVisitor} interface. *

* Sometimes however, a more synthetic approach is needed. If the user * prefers to see the differences between the two sequences as global * replacement operations acting on complete subsequences of * the original sequences, he will provide an object implementing the * simple {@link org.apache.commons.collections4.sequence.ReplacementsHandler} interface, * using an instance of the {@link org.apache.commons.collections4.sequence.ReplacementsFinder} * class as a command converting layer between his object and the edit script. The number of * objects which are common to both initial arrays and hence are skipped between each call to the user * {@link org.apache.commons.collections4.sequence.ReplacementsHandler#handleReplacement handleReplacement} * method is also provided. This allows the user to keep track of the current index in * both arrays if he needs so. * * @version $Id: package-info.java 1479338 2013-05-05 15:21:44Z tn $ */ package org.apache.commons.collections4.sequence;





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