/*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2003 The Apache Software Foundation.
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* "This product includes software developed by the
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*
* This software consists of voluntary contributions made by many
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package org.apache.commons.jrcs.diff;
import java.util.*;
import org.apache.commons.jrcs.diff.myers.MyersDiff;
import org.apache.commons.jrcs.util.ToString;
/**
* Implements a differencing engine that works on arrays of {@link Object Object}.
*
* <p>Within this library, the word <i>text</i> means a unit of information
* subject to version control.
*
* <p>Text is represented as <code>Object[]</code> 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.</p>
*
* <p>This library provides a framework in which different differencing
* algorithms may be used. If no algorithm is specififed, a default
* algorithm is used.</p>
*
* @version $Revision: 84222 $ $Date: 2010-11-03 09:15:52 -0400 (Wed, 03 Nov 2010) $
* @author <a href="mailto:juanco@suigeneris.org">Juanco Anez</a>
* @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] + " <edited>";
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;
}
}