/* <pre><nowiki> */
/*
JavaScript diff algorithm by [[User:Cacycle]] (http://en.wikipedia.org/wiki/User_talk:Cacycle).
Outputs html/css-formatted new text with changes like deletions, inserts, and block moves highlighted.
The program works only for the mozilla browsers Mozilla, Mozilla Firefox, and Mozilla SeaMonkey.
The code is currently under active development and might change rapidly.
An implementation of:
Paul Heckel: A technique for isolating differences between files
Communications of the ACM 21(4):264 (1978)
http://doi.acm.org/10.1145/359460.359467
* Word types have been optimized for Wikipedia source texts
* Additional post-pass 5 code for resolving islands caused by adding
two common words at the end of sequences of common words
* Additional detection of block borders and color coding of moved blocks and their original position
This code is used by [[User:Cacycle/editor.js]] ([[User:Cacycle/editor]]).
Usage: var htmlText = stringDiff(oldText, newText);
To install the style sheets you have to run: SetupDiff(); (not needed for editor)
This code has been released into the public domain.
Datastructures:
text: an object that holds all text related datastructures
.newWords: consecutive words of the new text (N)
.oldWords: consecutive words of the old text (O)
.newToOld: array of corresponding word number in old text (NA)
.oldToNew: array of corresponding word number in new text (OA)
.message: output message for testing purposes
symbol['word']: symbol table for passes 1 - 3, holds words as a hash
.newCtr: new word occurences counter (NC)
.oldCtr: old word occurences counter (OC)
.toNew: table last old word number
.toOld: last new word number (OLNA)
block: an object that holds block move information
blocks indexed after new text:
.newStart: new text word number of start of this block
.newLength: element number of this block including non-words
.newWords: true word number of this block
.newNumber: corresponding block index in old text
.newBlock: moved-block-number of a block that has been moved here
.newLeft: moved-block-number of a block that has been moved from this border leftwards
.newRight: moved-block-number of a block that has been moved from this border rightwards
.newLeftIndex: index number of a block that has been moved from this border leftwards
.newRightIndex: index number of a block that has been moved from this border rightwards
blocks indexed after old text:
.oldStart: word number of start of this block
.oldToNew: corresponding new text word number of start
.oldLength: element number of this block including non-words
.oldWords: true word number of this block
*/
// css for diff view elements
var styleDelete = styleDelete || 'font-weight: normal; text-decoration: none; color: #ffffff; background-color: #990033;';
var styleInsert = styleInsert || 'font-weight: normal; text-decoration: none; color: #ffffff; background-color: #009933;';
var styleMoved = styleMoved || 'font-weight: bold; vertical-align: text-bottom; font-size: xx-small; padding: 0; border: solid 1px';
var styleColor = styleColor || [
'background-color: #ffff44;',
'background-color: #b0ff90;',
'background-color: #ffcc99;',
'background-color: #99ffff;',
'background-color: #99ccff;',
'background-color: #cc99ff;',
'background-color: #ff99cc;',
'background-color: #ffd040;',
'background-color: #d0d0d0;'
];
// html for block move indicators, {block} is replaced by the block number
var htmlMovedRight = htmlMovedRight || '<input type="button" value=">" class="diffMoved{block}">';
var htmlMovedLeft = htmlMovedLeft || '<input type="button" value="<" class="diffMoved{block}">';
var htmlBlockStart = htmlBlockStart || '<span class="diffBlock{block}">';
var htmlBlockEnd = htmlBlockEnd || '</span>';
// minimal number of real words for a moved block (0 for always displaying block move indicators)
var blockMinLength = blockMinLength || 3;
// exclude identical sequence starts and endings from highlighting of changed text
var wordDiff = wordDiff || true;
// enable recursive diff to resolve problematic sequences
var recursiveDiff = recursiveDiff || true;
// show block moves
var showBlockMoves = showBlockMoves || true;
// html tag to be used for insertions (ins or span)
var insTag = insTag || 'span';
// html tag to be used for deletions (del or span)
var delTag = delTag || 'span';
// global variables
var i;
var j;
var m;
var n;
var diffStyleMax;
// SetupDiff: install style sheets
function SetupDiff() {
var insert = document.getElementsByTagName('head')[0];
if (insert != null) {
var html = '';
html += '<style type="text/css">\n';
html += '.diffDelete { ' + styleDelete + ' }\n';
html += '.diffInsert { ' + styleInsert + ' }\n';
i = 0;
while (styleColor[i] != null) {
html += '.diffBlock' + (i + 1) + ' { ' + styleColor[i] + ' }\n';
html += '.diffMoved' + (i + 1) + ' { ' + styleColor[i] + ' ' + styleMoved + ' }\n';
i ++;
}
diffStyleMax = i;
html += '</style>\n';
insert.innerHTML += html;
}
return;
}
// StringDiff: main program
// input: oldText, newText, strings containing the texts
// returns: html diff
function StringDiff(oldText, newText) {
var text = {};
text.newWords = [];
text.oldWords = [];
text.newToOld = [];
text.oldToNew = [];
text.message = '';
var block = {};
var outText;
// split new and old text into words
SplitText(oldText, newText, text);
// calculate diff information
TextDiff(text);
//detect block borders and moved blocks
DetectBlocks(text, block);
// process diff data into formatted html text
outText = DiffToHtml(text, block);
return(outText);
}
// SplitText: split new and old text into words
// input: oldText, newText, strings containing the texts
// changes: text.newWords and text.oldWords, arrays containing the texts in arrays of words
function SplitText(oldText, newText, text) {
// convert strange spaces
oldText = oldText.replace(/[\t\v\u00A0\u2028\u2029]+/g, ' ');
newText = newText.replace(/[\t\v\u00A0\u2028\u2029]+/g, ' ');
// split old text into words
var result;
do {
// / | | | | | | | | | | | | | | /
result = /[\w]+|\[\[|\]\]|\{\{|\}\}|\n+| +|&\w+;|'''|''|=+|\{\||\|\}|\|\-|./g.exec(oldText);
if (result != null) {
text.oldWords.push(result[0]);
}
} while (result != null);
// split new text into words
do {
result = /[\w]+|\[\[|\]\]|\{\{|\}\}|\n+| +|&\w+;|'''|''|=+|\{\||\|\}|\|\-|./g.exec(newText);
if (result != null) {
text.newWords.push(result[0]);
}
} while (result != null);
return;
}
// TextDiff: calculate diff information
// input: text.newWords and text.oldWords, arrays containing the texts in arrays of words
// optionally for recursive calls: newStart, newEnd, oldStart, oldEnd, recursionLevel
// changes: text.newToOld and text.oldToNew, containing the line numbers in the other version
function TextDiff(text, newStart, newEnd, oldStart, oldEnd, recursionLevel) {
symbol = new Object();
symbol.newCtr = [];
symbol.oldCtr = [];
symbol.toNew = [];
symbol.toOld = [];
// set defaults
newStart = newStart || 0;
newEnd = newEnd || text.newWords.length;
oldStart = oldStart || 0;
oldEnd = oldEnd || text.oldWords.length;
recursionLevel = recursionLevel || 0;
// pass 1: parse new text into symbol table s
var word;
for (i = newStart; i < newEnd; i ++) {
word = text.newWords[i];
// add new entry to symbol table
if ( symbol[word] == null) {
symbol[word] = { newCtr: 0, oldCtr: 0, toNew: null, toOld: null };
}
// increment symbol table word counter for new text
symbol[word].newCtr ++;
// add last word number in new text
symbol[word].toNew = i;
}
// pass 2: parse old text into symbol table
for (j = oldStart; j < oldEnd; j ++) {
word = text.oldWords[j];
// add new entry to symbol table
if ( symbol[word] == null) {
symbol[word] = { newCtr: 0, oldCtr: 0, toNew: null, toOld: null };
}
// increment symbol table word counter for old text
symbol[word].oldCtr ++;
// add last word number in old text
symbol[word].toOld = j;
}
// pass 3: connect unique words
for (i in symbol) {
// find words in the symbol table that occur only once in both versions
if ( (symbol[i].newCtr == 1) && (symbol[i].oldCtr == 1) ) {
var toNew = symbol[i].toNew;
var toOld = symbol[i].toOld;
// do not use spaces as unique markers
if ( ! /\s/.test( text.newWords[toNew] ) ) {
// connect from new to old and from old to new
text.newToOld[toNew] = toOld;
text.oldToNew[toOld] = toNew;
}
}
}
// pass 4: connect following identical words downwards
for (i = newStart; i < newEnd - 1; i ++) {
// find already connected pairs
if (text.newToOld[i] != null) {
j = text.newToOld[i];
// check if the following words are not yet connected
if ( (text.newToOld[i + 1] == null) && (text.oldToNew[j + 1] == null) ) {
// if the following words are the same connect them
if ( text.newWords[i + 1] == text.oldWords[j + 1] ) {
text.newToOld[i + 1] = j + 1;
text.oldToNew[j + 1] = i + 1;
}
}
}
}
// pass 5: connect following identical words upwards
for (i = newEnd - 1; i > newStart; i --) {
// find already connected pairs
if (text.newToOld[i] != null) {
j = text.newToOld[i];
// check if the preceeding words are not yet connected
if ( (text.newToOld[i - 1] == null) && (text.oldToNew[j - 1] == null) ) {
// if the preceeding words are the same connect them
if ( text.newWords[i - 1] == text.oldWords[j - 1] ) {
text.newToOld[i - 1] = j - 1;
text.oldToNew[j - 1] = i - 1;
}
}
}
}
// recursively diff still unresolved regions downwards
if (recursiveDiff && true) {
i = newStart;
j = oldStart;
while (i < newEnd) {
if (text.newToOld[i - 1] != null) {
j = text.newToOld[i - 1] + 1;
}
// check for the start of an unresolved sequence
if ( (text.newToOld[i] == null) && (text.oldToNew[j] == null) ) {
// determine the ends of the sequences
var iStart = i;
var iEnd = i;
while ( (text.newToOld[iEnd] == null) && (iEnd < newEnd) ) {
iEnd ++;
}
var iLength = iEnd - iStart;
var jStart = j;
var jEnd = j;
while ( (text.oldToNew[jEnd] == null) && (jEnd < oldEnd) ) {
jEnd ++;
}
var jLength = jEnd - jStart;
// recursively diff the unresolved sequence
if ( (iLength > 0) && (jLength > 0) ) {
if ( (iLength > 1) || (jLength > 1) ) {
if ( (iStart != newStart) || (iEnd != newEnd) || (jStart != oldStart) || (jEnd != oldEnd) ) {
TextDiff(text, iStart, iEnd, jStart, jEnd, recursionLevel + 1);
}
}
}
i = iEnd;
}
else {
i ++;
}
}
}
// recursively diff still unresolved regions upwards
if (recursiveDiff && true) {
i = newEnd - 1;
j = oldEnd - 1;
while (i >= newStart) {
if (text.newToOld[i + 1] != null) {
j = text.newToOld[i + 1] - 1;
}
// check for the start of an unresolved sequence
if ( (text.newToOld[i] == null) && (text.oldToNew[j] == null) ) {
// determine the ends of the sequences
var iStart = i;
var iEnd = i + 1;
while ( (text.newToOld[iStart - 1] == null) && (iStart >= newStart) ) {
iStart --;
}
var iLength = iEnd - iStart;
var jStart = j;
var jEnd = j + 1;
while ( (text.oldToNew[jStart - 1] == null) && (jStart >= oldStart) ) {
jStart --;
}
var jLength = jEnd - jStart;
// recursively diff the unresolved sequence
if ( (iLength > 0) && (jLength > 0) ) {
if ( (iLength > 1) || (jLength > 1) ) {
if ( (iStart != newStart) || (iEnd != newEnd) || (jStart != oldStart) || (jEnd != oldEnd) ) {
TextDiff(text, iStart, iEnd, jStart, jEnd, recursionLevel + 1);
}
}
}
i = iStart - 1;
}
else {
i --;
}
}
}
return;
}
// DiffToHtml: process diff data into formatted html text
// input: text.newWords and text.oldWords, arrays containing the texts in arrays of words
// text.newToOld and text.oldToNew, containing the line numbers in the other version
// block data structure
// returns: outText, a html string
function DiffToHtml(text, block) {
var outText = text.message;
var blockNumber = 0;
i = 0;
j = 0;
do {
var movedIndex = [];
var movedBlock = [];
var movedLeft = [];
var blockText = '';
var identText = '';
var delText = '';
var insText = '';
var identStart = '';
var identEnd = '';
// detect block boundary
if ( (text.newToOld[i] != j) || (blockNumber == 0 ) ) {
if ( ( (text.newToOld[i] != null) || (i >= text.newWords.length) ) && ( (text.oldToNew[j] != null) || (j >= text.oldWords.length) ) ) {
// block moved right
var moved = block.newRight[blockNumber];
if (moved > 0) {
var index = block.newRightIndex[blockNumber];
movedIndex.push(index);
movedBlock.push(moved);
movedLeft.push(false);
}
// block moved left
moved = block.newLeft[blockNumber];
if (moved > 0) {
var index = block.newLeftIndex[blockNumber];
movedIndex.push(index);
movedBlock.push(moved);
movedLeft.push(true);
}
// check if a block starts here
moved = block.newBlock[blockNumber];
if (moved > 0) {
// mark block as inserted text
if (block.newWords[blockNumber] < blockMinLength) {
identStart = '<' + insTag + ' class="diffInsert">';
identEnd = '</' + insTag + '>';
}
// mark block by color
else {
if (moved >= diffStyleMax) {
moved = diffStyleMax;
}
identStart = htmlBlockStart.replace(/\{block\}/, moved);
identEnd = htmlBlockEnd.replace(/\{block\}/, moved);
}
}
if (i >= text.newWords.length) {
i ++;
}
else {
j = text.newToOld[i];
blockNumber ++;
}
}
}
// get the correct order if moved to the left as well as to the right from here
if (movedIndex.length == 2) {
if (movedIndex[0] > movedIndex[1]) {
movedIndex.reverse();
movedBlock.reverse();
movedLeft.reverse();
}
}
// handle left and right block moves from this position
for (m = 0; m < movedIndex.length; m ++) {
// insert the block as deleted text
if (block.newWords[ movedIndex[m] ] < blockMinLength) {
var movedStart = block.newStart[ movedIndex[m] ];
var movedLength = block.newLength[ movedIndex[m] ];
var str = '';
for (n = movedStart; n < movedStart + movedLength; n ++) {
str += text.newWords[n];
}
str = str.replace(/\n/g, '¶<br>');
blockText += '<' + delTag + ' class="diffDelete">' + Escape(str) + '</' + delTag + '>';
}
// add a placeholder / move direction indicator
else {
if (movedBlock[m] >= diffStyleMax) {
movedBlock[m] = diffStyleMax;
}
if (movedLeft[m]) {
blockText += htmlMovedLeft.replace(/\{block\}/, movedBlock[m]);
}
else {
blockText += htmlMovedRight.replace(/\{block\}/, movedBlock[m]);
}
}
}
// collect consecutive identical text
while ( (i < text.newWords.length) && (j < text.oldWords.length) ) {
if ( (text.newToOld[i] == null) || (text.oldToNew[j] == null) ) {
break;
}
if (text.newToOld[i] != j) {
break;
}
identText += text.newWords[i];
i ++;
j ++;
}
// collect consecutive deletions
while ( (text.oldToNew[j] == null) && (j < text.oldWords.length) ) {
delText += text.oldWords[j];
j ++;
}
// collect consecutive inserts
while ( (text.newToOld[i] == null) && (i < text.newWords.length) ) {
insText += text.newWords[i];
i ++;
}
// remove leading and trailing similarities betweein delText and ins from highlighting
var preText = '';
var postText = '';
if (wordDiff) {
if ( (delText != '') && (insText != '') ) {
// remove leading similarities
while ( delText.charAt(0) == insText.charAt(0) ) {
preText = preText + delText.charAt(0);
delText = delText.substr(1);
insText = insText.substr(1);
}
// remove trailing similarities
while ( delText.charAt(delText.length - 1) == insText.charAt(insText.length - 1) ) {
postText = delText.charAt(delText.length - 1) + postText;
delText = delText.substr(0, delText.length - 1);
insText = insText.substr(0, insText.length - 1);
}
}
}
// output the identical text, deletions and inserts
if (blockText != '') {
outText += blockText;
}
if (identText != '') {
outText += identStart + Escape(identText) + identEnd;
}
outText += preText;
if (delText != '') {
delText = '<' + delTag + ' class="diffDelete">' + Escape(delText) + '</' + delTag + '>';
delText = delText.replace(/\n/g, '¶<br>');
outText += delText;
}
if (insText != '') {
insText = '<' + insTag + ' class="diffInsert">' + Escape(insText) + '</' + insTag + '>';
insText = insText.replace(/\n/g, '¶<br>');
outText += insText;
}
outText += postText;
} while (i <= text.newWords.length);
outText += '\n';
outText = outText.replace(/ /g, ' ');
outText = outText.replace(/\n/g, '<br>');
return(outText);
}
// Escape: replaces html-sensitive characters in output text with character entities
function Escape(text) {
text = text.replace(/&/g, "&");
text = text.replace(/</g, "<");
text = text.replace(/>/g, ">");
text = text.replace(/"/g, """); //"
return(text);
}
// DetectBlocks: detect block borders and moved blocks
// input: text object, block object
function DetectBlocks(text, block) {
block.oldStart = [];
block.oldToNew = [];
block.oldLength = [];
block.oldWords = [];
block.newStart = [];
block.newLength = [];
block.newWords = [];
block.newNumber = [];
block.newBlock = [];
block.newLeft = [];
block.newRight = [];
block.newLeftIndex = [];
block.newRightIndex = [];
var blockNumber = 0;
var wordCounter = 0;
var realWordCounter = 0;
// get old text block order
if (showBlockMoves) {
j = 0;
i = 0;
do {
// detect block boundaries on old text
if ( (text.oldToNew[j] != i) || (blockNumber == 0 ) ) {
if ( ( (text.oldToNew[j] != null) || (j >= text.oldWords.length) ) && ( (text.newToOld[i] != null) || (i >= text.newWords.length) ) ) {
if (blockNumber > 0) {
block.oldLength[blockNumber - 1] = wordCounter;
block.oldWords[blockNumber - 1] = realWordCounter;
wordCounter = 0;
realWordCounter = 0;
}
if (j >= text.oldWords.length) {
j ++;
}
else {
i = text.oldToNew[j];
block.oldStart[blockNumber] = j;
block.oldToNew[blockNumber] = text.oldToNew[j];
blockNumber ++;
}
}
}
// jump over identical pairs
while ( (i < text.newWords.length) && (j < text.oldWords.length) ) {
if ( (text.newToOld[i] == null) || (text.oldToNew[j] == null) ) {
break;
}
if (text.oldToNew[j] != i) {
break;
}
i ++;
j ++;
wordCounter ++;
if ( /\w/.test( text.newWords[i] ) ) {
realWordCounter ++;
}
}
// jump over consecutive deletions
while ( (text.oldToNew[j] == null) && (j < text.oldWords.length) ) {
j ++;
}
// jump over consecutive inserts
while ( (text.newToOld[i] == null) && (i < text.newWords.length) ) {
i ++;
}
} while (j <= text.oldWords.length);
// get the block order in the new text
var lastMin;
var currMinIndex;
lastMin = null;
// sort the data by increasing start numbers into new text block info
for (i = 0; i < blockNumber; i ++) {
currMin = null;
for (j = 0; j < blockNumber; j ++) {
curr = block.oldToNew[j];
if ( (curr > lastMin) || (lastMin == null) ) {
if ( (curr < currMin) || (currMin == null) ) {
currMin = curr;
currMinIndex = j;
}
}
}
block.newStart[i] = block.oldToNew[currMinIndex];
block.newLength[i] = block.oldLength[currMinIndex];
block.newWords[i] = block.oldWords[currMinIndex];
block.newNumber[i] = currMinIndex;
lastMin = currMin;
}
// detect not moved blocks
for (i = 0; i < blockNumber; i ++) {
if (block.newBlock[i] == null) {
if (block.newNumber[i] == i) {
block.newBlock[i] = 0;
}
}
}
// detect switches of neighbouring blocks
for (i = 0; i < blockNumber - 1; i ++) {
if ( (block.newBlock[i] == null) && (block.newBlock[i + 1] == null) ) {
if (block.newNumber[i] - block.newNumber[i + 1] == 1) {
if ( (block.newNumber[i + 1] - block.newNumber[i + 2] != 1) || (i + 2 >= blockNumber) ) {
// the shorter one is declared the moved one
if (block.newLength[i] < block.newLength[i + 1]) {
block.newBlock[i] = 1;
block.newBlock[i + 1] = 0;
}
else {
block.newBlock[i] = 0;
block.newBlock[i + 1] = 1;
}
}
}
}
}
// mark all others as moved and number the moved blocks
j = 1;
for (i = 0; i < blockNumber; i ++) {
if ( (block.newBlock[i] == null) || (block.newBlock[i] == 1) ) {
block.newBlock[i] = j++;
}
}
// check if a block has been moved from this block border
for (i = 0; i < blockNumber; i ++) {
for (j = 0; j < blockNumber; j ++) {
if (block.newNumber[j] == i) {
if (block.newBlock[j] > 0) {
// block moved right
if (block.newNumber[j] < j) {
block.newRight[i] = block.newBlock[j];
block.newRightIndex[i] = j;
}
// block moved left
else {
block.newLeft[i + 1] = block.newBlock[j];
block.newLeftIndex[i + 1] = j;
}
}
}
}
}
}
return;
}
/* </nowiki></pre> */
