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268 lines
11 KiB
Java
268 lines
11 KiB
Java
// Diff.java
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// ---------
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// part of YaCy
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// (C) by Michael Peter Christen; mc@yacy.net
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2007
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// Created 03.02.2007
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//
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// This file is contributed by Franz Brausze
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//
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// $LastChangedDate$
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// $LastChangedRevision$
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// $LastChangedBy$
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package net.yacy.data;
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import java.util.ArrayList;
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import net.yacy.document.parser.html.CharacterCoding;
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/**
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* This class provides a diff-functionality.
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*/
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public class Diff {
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private final ArrayList <Part> parts = new ArrayList<Part>();
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protected final Object[] original;
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protected final Object[] changed;
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/**
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* @param original the original <code>String</code>
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* @param changed the new <code>String</code>
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* @throws NullPointerException if one of the arguments is <code>null</code>
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*/
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public Diff(final String original, final String changed) {
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this(original, changed, 1);
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}
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/**
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* @param original the original <code>String</code>
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* @param changed the new <code>String</code>
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* @param minConsecutive the minimum number of consecutive equal characters in
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* both Strings. Smaller seperations will only be performed on the end of either
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* String if needed
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* @throws NullPointerException if <code>original</code> or <code>changed</code> is
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* <code>null</code>
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*/
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public Diff(final String original, final String changed, final int minConsecutive) {
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if (original == null || changed == null) throw new NullPointerException("input Strings must be null");
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this.original = new Comparable[original.length()];
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for (int i=0; i<original.length(); i++)
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this.original[i] = Character.valueOf(original.charAt(i));
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this.changed = new Comparable[changed.length()];
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for (int i=0; i<changed.length(); i++)
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this.changed[i] = Character.valueOf(changed.charAt(i));
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parse((minConsecutive > 0) ? minConsecutive : 1);
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}
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public Diff(final Object[] original, final Object[] changed, final int minConsecutive) {
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if (original == null || changed == null) throw new NullPointerException("input Objects must be null");
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this.original = original;
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this.changed = changed;
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parse((minConsecutive > 0) ? minConsecutive : 1);
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}
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private void parse(final int minLength) {
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/* Matrix: find as long diagonals as possible,
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* delete the old horizontally and add the new vertically
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*
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* ~ OLD ~
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* |T|H|E| |F|I|R|S|T| |S|E|N|T|E|N|C|E|
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* T|#| | | | | | | |#| | | | |#| | | | |
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* H| |#| | | | | | | | | | | | | | | | |
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* E| | |#| | | | | | | | |#| | |#| | |#|
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* | | | |#| | | | | |#| | | | | | | | |
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* N| | | | | | | | | | | | |#| | |#| | |
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* E| | |#| | | | | | | | |#| | |#| | |#|
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* ~ X| | | | | | | | | | | | | | | | | | |
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* N T|#| | | | | | | |#| | | | |#| | | | |
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* E | | | |#| | | | | |#| | | | | | | | |
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* W S| | | | | | | |#| | |#| | | | | | | |
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* ~ E| | |#| | | | | | | | |#| | |#| | |#|
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* N| | | | | | | | | | | | |#| | |#| | |
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* T|#| | | | | | | |#| | | | |#| | | | |
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* E| | |#| | | | | | | | |#| | |#| | |#|
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* N| | | | | | | | | | | | |#| | |#| | |
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* C| | | | | | | | | | | | | | | | |#| |
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* E| | |#| | | | | | | | |#| | |#| | |#|
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*/
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final boolean[][] matrix = new boolean[this.changed.length][this.original.length];
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for (int y=0; y<this.changed.length; y++)
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for (int x=0; x<this.original.length; x++)
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matrix[y][x] = this.original[x].equals(this.changed[y]);
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int s = 0, t = 0;
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int[] tmp;
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while ((tmp = findDiagonal(s, t, matrix, minLength)) != null) {
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addReplacementParts(s, t, tmp[0], tmp[1]);
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this.parts.add(new Part(Part.UNCHANGED, tmp[0], s = tmp[0] + tmp[2]));
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t = tmp[1] + tmp[2];
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}
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addReplacementParts(s, t, this.original.length, this.changed.length);
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}
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private void addReplacementParts(final int startx, final int starty, final int endx, final int endy) {
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if (startx < endx) this.parts.add(new Part(Part.DELETED, startx, endx));
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if (starty < endy) this.parts.add(new Part(Part.ADDED, starty, endy));
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}
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/** Search for a diagonal with minimal length <code>minLength</code> line by line in a submatrix
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* <code>{ x, y, matrix[0].length, matrix.length}</code> of the <code>matrix</code>:<br>
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* <code> {_1,__,__} -> X axis</code><br>
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* <code> ,{__,_1,__} </code><br>
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* <code> ,{__,__,_1} </code><br>
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* <ul>
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* TODO: some optimisation ideas
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* <li>search for a better algorithm on the inet!!! :) </li>
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* <li>pass only the part of the matrix where the search takes place - not the whole matrix everytime</li>
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* <li>break the inner loop if the rest of the matrix is smaller than minLength (and no diagonal has been found yet) </li>
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* <li>return diagonal topologicaly closest to the {0,0} </li>
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* </ul>
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* @param x the starting position of the search on the optical horizontal axis
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* @param y the starting position of the search on the optical vertical axis<br>
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* @param matrix the matrix to search through
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* @param minLength the minimal desired length of a diagonal to find
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* @return a vector in the form <code>{ diagStartX, diagStartY, diagLength }</code> where <code> diagLength >= minLength</code>
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*/
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private static int[] findDiagonal(final int x, final int y, final boolean[][] matrix, final int minLength) {
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int rx, ry, yy, xx, i;
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for (yy=y; yy<matrix.length; yy++)
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for (xx=x; xx<matrix[yy].length; xx++)
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if (matrix[yy][xx]) { // reverse order! [y][x]
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// save position
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rx = xx;
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ry = yy;
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// follow diagonal as long as far as possible
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for (i=1; (yy + i)<matrix.length && (xx + i)<matrix[yy].length; i++)
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if (!matrix[yy + i][xx + i])
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break;
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if (i >= minLength)
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return new int[] { rx, ry, i }; // swap back the x and y axes for better readability
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}
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return null;
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}
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/**
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* @return the original <code>Object[]</code> passed to this class on instantiation
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*/
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public Object[] getOriginal() { return this.original; }
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/**
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* @return the new <code>Object[]</code> passed to this class on instantiation
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*/
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public Object[] getNew() { return this.changed; }
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/**
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* A diff is composed of different parts. Each of these parts stands for an
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* operation, like "do nothing", "add" or "delete".
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*
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* @see Part
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* @return all parts this diff consists of in correct order
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*/
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public Part[] getParts() { return this.parts.toArray(new Part[this.parts.size()]); }
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@Override
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public String toString() {
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final StringBuilder sb = new StringBuilder(this.parts.size() * 20);
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for (final Part part :parts)
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sb.append(part.toString()).append("\n");
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return sb.toString();
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}
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/**
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* This class represents a part of the diff, meaning one operation
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* (or one line of a "normal" diff)
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*/
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public class Part {
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/** The string this diff-part cares about has not been changed */
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public static final int UNCHANGED = 0;
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/** The string this diff-part cares about has been added in the new version */
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public static final int ADDED = 1;
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/** The string this diff-part cares about has been removed in the new version */
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public static final int DELETED = 2;
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private final int action;
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private final int posOld;
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private final int posNew;
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Part(final int action, final int posOld, final int posNew) {
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this.action = action;
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this.posOld = posOld;
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this.posNew = posNew;
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}
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/**
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* @return whether the string shan't be changed, shall be added or deleted
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*/
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public int getAction() { return this.action; }
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public int getPosOld() { return this.posOld; }
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public int getPosNew() { return this.posNew; }
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/**
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* @return the plain string this diff-part cares about
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*/
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public String getString() {
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final StringBuilder sb = new StringBuilder(this.posNew - this.posOld);
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if (this.action == ADDED) {
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for (int i = this.posOld; i < this.posNew; i++)
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sb.append(Diff.this.changed[i]);
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} else {
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for (int i = this.posOld; i < this.posNew; i++)
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sb.append(Diff.this.original[i]);
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}
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return sb.toString();
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}
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/**
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* @return the string this diff-part cares about in typical diff-notation:
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* <dl>
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* <dt>unchanged</dt><dd>"<code> STRING</code>"</dd>
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* <dt>added</dt><dd>"<code>+ STRING</code>"</dd>
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* <dt>deleted</dt><dd>"<code>- STRING</code>"</dd>
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* </dl>
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*/
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@Override
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public String toString() {
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return ((this.action == UNCHANGED) ? " " :
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(this.action == ADDED) ? "+" : "-") + " " + getString();
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}
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}
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public static String toHTML(final Diff[] diffs) {
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final StringBuilder sb = new StringBuilder(diffs.length * 60);
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Diff.Part[] ps;
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for (Diff d : diffs) {
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sb.append("<p class=\"diff\">\n");
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ps = d.getParts();
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for (Diff.Part part :ps) {
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sb.append("<span\nclass=\"");
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switch (part.getAction()) {
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case Diff.Part.UNCHANGED: sb.append("unchanged"); break;
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case Diff.Part.ADDED: sb.append("added"); break;
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case Diff.Part.DELETED: sb.append("deleted"); break;
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}
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sb.append("\">").append(CharacterCoding.unicode2html(part.getString(), true).replaceAll("\n", "<br />"));
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sb.append("</span>");
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}
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sb.append("</p>");
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}
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return sb.toString();
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}
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} |