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This project creates the diff library used by RWiki
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/*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2003 The Apache Software Foundation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowledgement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgement may appear in the software itself,
* if and wherever such third-party acknowledgements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
*
* Within this library, the word text means a unit of information
* subject to version control.
*
* Text is represented as Object[] because the diff engine is
* capable of handling more than plain ascci. In fact, arrays of any type that
* implements {@link java.lang.Object#hashCode hashCode()} and
* {@link java.lang.Object#equals equals()} correctly can be subject to
* differencing using this library.
*
*
* This library provides a framework in which different differencing algorithms
* may be used. If no algorithm is specififed, a default algorithm is used.
*
*
* @version $Revision$ $Date: 2006-04-12 18:30:19 +0100 (Wed, 12 Apr
* 2006) $
* @author Juanco Anez
* @see Delta
* @see DiffAlgorithm modifications: 27 Apr 2003 bwm Added some comments whilst
* trying to figure out the algorithm 03 May 2003 bwm Factored out the
* algorithm implementation into a separate difference algorithm class to
* allow pluggable algorithms.
*/
public class Diff extends ToString
{
/** The standard line separator. */
public static final String NL = System.getProperty("line.separator");
/** The line separator to use in RCS format output. */
public static final String RCS_EOL = "\n";
/** The original sequence. */
protected final Object[] orig;
/** The differencing algorithm to use. */
protected DiffAlgorithm algorithm;
/**
* Create a differencing object using the default algorithm
*
* @param the
* original text that will be compared
*/
public Diff(Object[] original)
{
this(original, null);
}
/**
* Create a differencing object using the given algorithm
*
* @param o
* the original text which will be compared against
* @param algorithm
* the difference algorithm to use.
*/
public Diff(Object[] original, DiffAlgorithm algorithm)
{
if (original == null)
{
throw new IllegalArgumentException();
}
this.orig = original;
if (algorithm != null)
this.algorithm = algorithm;
else
this.algorithm = defaultAlgorithm();
}
protected DiffAlgorithm defaultAlgorithm()
{
return new MyersDiff();
}
/**
* compute the difference between an original and a revision.
*
* @param orig
* the original
* @param rev
* the revision to compare with the original.
* @return a Revision describing the differences
*/
public static Revision diff(Object[] orig, Object[] rev)
throws DifferentiationFailedException
{
if (orig == null || rev == null)
{
throw new IllegalArgumentException();
}
return diff(orig, rev, null);
}
/**
* compute the difference between an original and a revision.
*
* @param orig
* the original
* @param rev
* the revision to compare with the original.
* @param algorithm
* the difference algorithm to use
* @return a Revision describing the differences
*/
public static Revision diff(Object[] orig, Object[] rev,
DiffAlgorithm algorithm) throws DifferentiationFailedException
{
if (orig == null || rev == null)
{
throw new IllegalArgumentException();
}
return new Diff(orig, algorithm).diff(rev);
}
/**
* compute the difference between the original and a revision.
*
* @param rev
* the revision to compare with the original.
* @return a Revision describing the differences
*/
public Revision diff(Object[] rev) throws DifferentiationFailedException
{
if (orig.length == 0 && rev.length == 0)
return new Revision();
else
return algorithm.diff(orig, rev);
}
/**
* Compares the two input sequences.
*
* @param orig
* The original sequence.
* @param rev
* The revised sequence.
* @return true if the sequences are identical. False otherwise.
*/
public static boolean compare(Object[] orig, Object[] rev)
{
if (orig.length != rev.length)
{
return false;
}
else
{
for (int i = 0; i < orig.length; i++)
{
if (!orig[i].equals(rev[i]))
{
return false;
}
}
return true;
}
}
/**
* Converts an array of {@link Object Object} to a string using
* {@link Diff#NL Diff.NL} as the line separator.
*
* @param o
* the array of objects.
*/
public static String arrayToString(Object[] o)
{
return arrayToString(o, Diff.NL);
}
/**
* Edits all of the items in the input sequence.
*
* @param text
* The input sequence.
* @return A sequence of the same length with all the lines differing from
* the corresponding ones in the input.
*/
public static Object[] editAll(Object[] text)
{
Object[] result = new String[text.length];
for (int i = 0; i < text.length; i++)
result[i] = text[i] + " ";
return result;
}
/**
* Performs random edits on the input sequence. Useful for testing.
*
* @param text
* The input sequence.
* @return The sequence with random edits performed.
*/
public static Object[] randomEdit(Object[] text)
{
return randomEdit(text, text.length);
}
/**
* Performs random edits on the input sequence. Useful for testing.
*
* @param text
* The input sequence.
* @param seed
* A seed value for the randomizer.
* @return The sequence with random edits performed.
*/
public static Object[] randomEdit(Object[] text, long seed)
{
List result = new ArrayList(Arrays.asList(text));
Random r = new Random(seed);
int nops = r.nextInt(10);
for (int i = 0; i < nops; i++)
{
boolean del = r.nextBoolean();
int pos = r.nextInt(result.size() + 1);
int len = Math.min(result.size() - pos, 1 + r.nextInt(4));
if (del && result.size() > 0)
{ // delete
result.subList(pos, pos + len).clear();
}
else
{
for (int k = 0; k < len; k++, pos++)
{
result.add(pos, "[" + i + "] random edit[" + i + "][" + i
+ "]");
}
}
}
return result.toArray();
}
/**
* Shuffles around the items in the input sequence.
*
* @param text
* The input sequence.
* @return The shuffled sequence.
*/
public static Object[] shuffle(Object[] text)
{
return shuffle(text, text.length);
}
/**
* Shuffles around the items in the input sequence.
*
* @param text
* The input sequence.
* @param seed
* A seed value for randomizing the suffle.
* @return The shuffled sequence.
*/
public static Object[] shuffle(Object[] text, long seed)
{
List result = new ArrayList(Arrays.asList(text));
Collections.shuffle(result);
return result.toArray();
}
/**
* Generate a random sequence of the given size.
*
* @param The
* size of the sequence to generate.
* @return The generated sequence.
*/
public static Object[] randomSequence(int size)
{
return randomSequence(size, size);
}
/**
* Generate a random sequence of the given size.
*
* @param The
* size of the sequence to generate.
* @param seed
* A seed value for randomizing the generation.
* @return The generated sequence.
*/
public static Object[] randomSequence(int size, long seed)
{
Integer[] result = new Integer[size];
Random r = new Random(seed);
for (int i = 0; i < result.length; i++)
{
result[i] = Integer.valueOf(r.nextInt(size));
}
return result;
}
}