/*
* ====================================================================
*
* The Apache Software License, Version 1.1
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* Copyright (c) 1999-2003 The Apache Software Foundation.
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* "This product includes software developed by the
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package org.apache.wicket.util.diff;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import org.apache.wicket.util.diff.myers.MyersDiff;
/**
* 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 specified, a default algorithm is used.
* </p>
*
* @version $Revision: 1.1 $ $Date: 2006/03/12 00:24:21 $
* @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 original
* the original text that will be compared
*/
public Diff(final Object[] original)
{
this(original, null);
}
/**
* Create a differencing object using the given algorithm
*
* @param original
* the original text that will be compared
* @param algorithm
* the difference algorithm to use.
*/
public Diff(final Object[] original, final DiffAlgorithm algorithm)
{
if (original == null)
{
throw new IllegalArgumentException();
}
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
* @throws DifferentiationFailedException
*/
public static Revision diff(final Object[] orig, final 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
* @throws DifferentiationFailedException
*/
public static Revision diff(final Object[] orig, final Object[] rev,
final 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
* @throws DifferentiationFailedException
*/
public Revision diff(final 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(final Object[] orig, final 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.
* @return String
*/
public static String arrayToString(final 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(final 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(final 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(final Object[] text, final long seed)
{
List<Object> 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(final 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 generation.
* @return The shuffled sequence.
*/
public static Object[] shuffle(final Object[] text, final long seed)
{
List<Object> result = new ArrayList<>(Arrays.asList(text));
Collections.shuffle(result);
return result.toArray();
}
/**
* Generate a random sequence of the given size.
*
* @param size
* the size of the sequence to generate.
* @return The generated sequence.
*/
public static Object[] randomSequence(final int size)
{
return randomSequence(size, size);
}
/**
* Generate a random sequence of the given size.
*
* @param size
* the size of the sequence to generate.
* @param seed
* a seed value for randomizing the generation.
* @return The generated sequence.
*/
public static Object[] randomSequence(final int size, final long seed)
{
Integer[] result = new Integer[size];
Random r = new Random(seed);
for (int i = 0; i < result.length; i++)
{
result[i] = r.nextInt(size);
}
return result;
}
}