User:Mms/diff.js

/* */

/*

Name:   diff.js Version: 0.9.4 (September 23, 2007) Info:   http://en.wikipedia.org/wiki/User:Cacycle/diff Code:   http://en.wikipedia.org/wiki/User:Cacycle/diff.js

JavaScript diff algorithm by en:User:Cacycle (http://en.wikipedia.org/wiki/User_talk:Cacycle). Outputs html/css-formatted new text with highlighted deletions, inserts, and block moves.

The program uses cross-browser code and should work with all modern browsers. It has been tested with: This program is also compatibel with Greasemonkey
 * Mozilla Firefox 1.5.0.1
 * Mozilla SeaMonkey 1.0
 * Opera 8.53
 * Internet Explorer 6.0.2900.2180
 * Internet Explorer 7.0.5730.11

An implementation of the word-based algorithm from:

Communications of the ACM 21(4):264 (1978) http://doi.acm.org/10.1145/359460.359467

With the following additional feature:

two common words at the end of sequences of common words
 * Word types have been optimized for MediaWiki source texts
 * Additional post-pass 5 code for resolving islands caused by adding
 * Additional detection of block borders and color coding of moved blocks and their original position
 * Optional "intelligent" omission of unchanged parts from the output

This code is used by the MediaWiki in-browser text editors en:User:Cacycle/editor and en:User:Cacycle/wikEd and the enhanced diff view tool wikEdDiff en:User:Cacycle/wikEd.

Usage: var htmlText = WDiffString(oldText, newText);

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 change indicators window.wDiffStyleDelete = window.wDiffStyleDelete || 'font-weight: normal; text-decoration: none; color: #ffffff; background-color: #990033;'; window.wDiffStyleInsert = window.wDiffStyleInsert || 'font-weight: normal; text-decoration: none; color: #ffffff; background-color: #009933;'; window.wDiffStyleMoved = window.wDiffStyleMoved  || 'font-weight: bold; vertical-align: text-bottom; font-size: xx-small; padding: 0; border: solid 1px;'; window.wDiffStyleBlock = window.wDiffStyleBlock  || [ 'background-color: #ffff80;', 'background-color: #c0ffff;', 'background-color: #ffd0f0;', 'background-color: #ffe080;', 'background-color: #aaddff;', 'background-color: #ddaaff;', 'background-color: #ffbbbb;', 'background-color: #d8ffa0;', 'background-color: #d0d0d0;' ];

// html for change indicators, {number} is replaced by the block number // {block} is replaced by the block style, class and html comments are important for shortening the output window.wDiffHtmlMovedRight = window.wDiffHtmlMovedRight  || ''; window.wDiffHtmlMovedLeft  = window.wDiffHtmlMovedLeft   || '';

window.wDiffHtmlBlockStart = window.wDiffHtmlBlockStart  || ''; window.wDiffHtmlBlockEnd   = window.wDiffHtmlBlockEnd    || ' ';

window.wDiffHtmlDeleteStart = window.wDiffHtmlDeleteStart || ''; window.wDiffHtmlDeleteEnd  = window.wDiffHtmlDeleteEnd   || ' ';

window.wDiffHtmlInsertStart = window.wDiffHtmlInsertStart || ''; window.wDiffHtmlInsertEnd  = window.wDiffHtmlInsertEnd   || ' ';

// minimal number of real words for a moved block (0 for always displaying block move indicators) window.wDiffBlockMinLength = window.wDiffBlockMinLength || 3;

// exclude identical sequence starts and endings from change marking window.wDiffWordDiff = window.wDiffWordDiff || true;

// enable recursive diff to resolve problematic sequences window.wDiffRecursiveDiff = window.wDiffRecursiveDiff || true;

// enable block move display window.wDiffShowBlockMoves = window.wDiffShowBlockMoves || true;

// remove unchanged parts from final output

// characters before diff tag to search for previous heading, paragraph, line break, cut characters window.wDiffHeadingBefore  = window.wDiffHeadingBefore   || 1500; window.wDiffParagraphBefore = window.wDiffParagraphBefore || 1500; window.wDiffLineBeforeMax  = window.wDiffLineBeforeMax   || 1000; window.wDiffLineBeforeMin  = window.wDiffLineBeforeMin   || 500; window.wDiffBlankBeforeMax = window.wDiffBlankBeforeMax  || 1000; window.wDiffBlankBeforeMin = window.wDiffBlankBeforeMin  || 500; window.wDiffCharsBefore    = window.wDiffCharsBefore     || 500;

// characters after diff tag to search for next heading, paragraph, line break, or characters window.wDiffHeadingAfter  = window.wDiffHeadingAfter   || 1500; window.wDiffParagraphAfter = window.wDiffParagraphAfter || 1500; window.wDiffLineAfterMax  = window.wDiffLineAfterMax   || 1000; window.wDiffLineAfterMin  = window.wDiffLineAfterMin   || 500; window.wDiffBlankAfterMax = window.wDiffBlankAfterMax  || 1000; window.wDiffBlankAfterMin = window.wDiffBlankAfterMin  || 500; window.wDiffCharsAfter    = window.wDiffCharsAfter     || 500;

// maximal fragment distance to join close fragments window.wDiffFragmentJoin = window.wDiffFragmentJoin || 1000; window.wDiffOmittedChars = window.wDiffOmittedChars || '…'; window.wDiffOmittedLines = window.wDiffOmittedLines || ''; window.wDiffNoChange    = window.wDiffNoChange     || '';

// compatibility fix for old name of main function window.StringDiff = window.WDiffString;

// WDiffString: main program // input: oldText, newText, strings containing the texts // returns: html diff

window.WDiffString = function(oldText, newText) { // IE / Mac fix oldText = oldText.replace(/(\r\n)/g, '\n'); newText = newText.replace(/(\r\n)/g, '\n');

var text = {}; text.newWords = []; text.oldWords = []; text.newToOld = []; text.oldToNew = []; text.message = ''; var block = {}; var outText = '';

// trap trivial changes: no change if (oldText == newText) { outText = newText; outText = WDiffEscape(outText); outText = WDiffHtmlFormat(outText); return(outText); }

// trap trivial changes: old text deleted if ( (oldText == null) || (oldText.length == 0) ) { outText = newText; outText = WDiffEscape(outText); outText = WDiffHtmlFormat(outText); outText = wDiffHtmlInsertStart + outText + wDiffHtmlInsertEnd; return(outText); }

// trap trivial changes: new text deleted if ( (newText == null) || (newText.length == 0) ) { outText = oldText; outText = WDiffEscape(outText); outText = WDiffHtmlFormat(outText); outText = wDiffHtmlDeleteStart + outText + wDiffHtmlDeleteEnd; return(outText); }

// split new and old text into words WDiffSplitText(oldText, newText, text);

// calculate diff information WDiffText(text);

//detect block borders and moved blocks WDiffDetectBlocks(text, block);

// process diff data into formatted html text outText = WDiffToHtml(text, block);

// IE fix outText = outText.replace(/> ( *) $1<');

return(outText); }

// WDiffSplitText: 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

window.WDiffSplitText = function(oldText, newText, text) {

// convert strange spaces oldText = oldText.replace(/[\t\u000b\u00a0\u2028\u2029]+/g, ' '); newText = newText.replace(/[\t\u000b\u00a0\u2028\u2029]+/g, ' ');

// split old text into words

//             /     |    |    |    |    |   |  |     |   |  |  |    |    |    | /	var pattern = /[\w]+|\[\[|\]\]|\{\{|\}\}|\n+| +|&\w+;|'||=+|\{\||\|\}|\|\-|./g; var result; do { result = pattern.exec(oldText); if (result != null) { text.oldWords.push(result[0]); }	} while (result != null);

// split new text into words do { result = pattern.exec(newText); if (result != null) { text.newWords.push(result[0]); }	} while (result != null);

return; }

// WDiffText: 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

window.WDiffText = function(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;

// limit recursion depth if (recursionLevel > 10) { return; }

// pass 1: parse new text into symbol table s

var word; for (var 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 (var 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 (var 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 adjacent identical words downwards

for (var 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 adjacent identical words upwards

for (var 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 (wDiffRecursiveDiff) { 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) ) { WDiffText(text, iStart, iEnd, jStart, jEnd, recursionLevel + 1); }					}				}				i = iEnd; }			else { i ++; }		}	}

// recursively diff still unresolved regions upwards

if (wDiffRecursiveDiff) { 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) ) { WDiffText(text, iStart, iEnd, jStart, jEnd, recursionLevel + 1); }					}				}				i = iStart - 1; }			else { i --; }		}	}	return; }

// WDiffToHtml: 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

window.WDiffToHtml = function(text, block) {

var outText = text.message;

var blockNumber = 0; var i = 0; var j = 0; var movedAsInsertion;

// cycle through the new text do { var movedIndex = []; var movedBlock = []; var movedLeft = []; var blockText = ''; var identText = ''; var delText = ''; var insText = ''; var identStart = '';

// check if a block ends here and finish previous block if (movedAsInsertion != null) { if (movedAsInsertion == false) { identStart += wDiffHtmlBlockEnd; }			else { identStart += wDiffHtmlInsertEnd; }			movedAsInsertion = null; }

// 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] < wDiffBlockMinLength) { identStart += wDiffHtmlInsertStart; movedAsInsertion = true; }

// mark block by color else { if (moved > wDiffStyleBlock.length) { moved = wDiffStyleBlock.length; }						identStart += WDiffHtmlCustomize(wDiffHtmlBlockStart, moved - 1); movedAsInsertion = false; }				}

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 (var m = 0; m < movedIndex.length; m ++) {

// insert the block as deleted text if (block.newWords[ movedIndex[m] ] < wDiffBlockMinLength) { var movedStart = block.newStart[ movedIndex[m] ]; var movedLength = block.newLength[ movedIndex[m] ]; var str = ''; for (var n = movedStart; n < movedStart + movedLength; n ++) { str += text.newWords[n]; }				str = WDiffEscape(str); str = str.replace(/\n/g, '&para; '); blockText += wDiffHtmlDeleteStart + str + wDiffHtmlDeleteEnd; }

// add a placeholder / move direction indicator else { if (movedBlock[m] > wDiffStyleBlock.length) { movedBlock[m] = wDiffStyleBlock.length; }				if (movedLeft[m]) { blockText += WDiffHtmlCustomize(wDiffHtmlMovedLeft, movedBlock[m] - 1); }				else { blockText += WDiffHtmlCustomize(wDiffHtmlMovedRight, movedBlock[m] - 1); }			}		}

// 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 (wDiffWordDiff) { if ( (delText != ) && (insText != ) ) {

// remove leading similarities while ( delText.charAt(0) == insText.charAt(0) && (delText != ) && (insText != ) ) { 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) && (delText != ) && (insText != ) ) { 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

// moved from here indicator if (blockText != '') { outText += blockText; }

// identical text if (identText != '') { outText += identStart + WDiffEscape(identText); }		outText += preText;

// deleted text if (delText != '') { delText = wDiffHtmlDeleteStart + WDiffEscape(delText) + wDiffHtmlDeleteEnd; delText = delText.replace(/\n/g, '&para; '); outText += delText; }

// inserted text if (insText != '') { insText = wDiffHtmlInsertStart + WDiffEscape(insText) + wDiffHtmlInsertEnd; insText = insText.replace(/\n/g, '&para; '); outText += insText; }		outText += postText; } while (i <= text.newWords.length);

outText += '\n'; outText = WDiffHtmlFormat(outText);

return(outText); }

// WDiffEscape: replaces html-sensitive characters in output text with character entities

window.WDiffEscape = function(text) {

text = text.replace(/&/g, '&amp;'); text = text.replace(//g, '&gt;'); text = text.replace(/\"/g, '&quot;');

return(text); }

// HtmlCustomize: customize indicator html: replace {number} with the block number, {block} with the block style

window.WDiffHtmlCustomize = function(text, block) {

text = text.replace(/\{number\}/, block); text = text.replace(/\{block\}/, wDiffStyleBlock[block]);

return(text); }

// HtmlFormat: replaces newlines and multiple spaces in text with html code

window.WDiffHtmlFormat = function(text) {

text = text.replace(/ /g, '  '); text = text.replace(/\n/g, ' ');

return(text); }

// WDiffDetectBlocks: detect block borders and moved blocks // input: text object, block object

window.WDiffDetectBlocks = function(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 (wDiffShowBlockMoves) { var j = 0; var 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 (var i = 0; i < blockNumber; i ++) { currMin = null; for (var 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 (var 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 (var 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 (var 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 (var i = 0; i < blockNumber; i ++) { for (var 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; }

// WDiffShortenOutput: remove unchanged parts from final output // input: the output of WDiffString // returns: the text with removed unchanged passages indicated by (...)

window.WDiffShortenOutput = function(diffText) {

// html to newlines diffText = diffText.replace(/]*>/g, '\n');

// scan for diff html tags var regExpDiff = new RegExp('<\\w+ class=\\"(\\w+)\\"[^>]*>(.|\\n)*?', 'g'); var tagStart = []; var tagEnd = []; var i = 0; var found; while ( (found = regExpDiff.exec(diffText)) != null ) {

// combine consecutive diff tags if ( (i > 0) && (tagEnd[i - 1] == found.index) ) { tagEnd[i - 1] = found.index + found[0].length; }		else { tagStart[i] = found.index; tagEnd[i] = found.index + found[0].length; i ++; }	}

// no diff tags detected if (tagStart.length == 0) { return(wDiffNoChange); }

// define regexps var regExpHeading = new RegExp('\\n=+.+?=+ *\\n|\\n\\{\\||\\n\\|\\}', 'g'); var regExpParagraph = new RegExp('\\n\\n+', 'g'); var regExpLine = new RegExp('\\n+', 'g'); var regExpBlank = new RegExp('(<[^>]+>)*\\s+', 'g');

// determine fragment border positions around diff tags var rangeStart = []; var rangeEnd = []; var rangeStartType = []; var rangeEndType = []; for (var i = 0; i < tagStart.length; i ++) { var found;

// find last heading before diff tag var lastPos = tagStart[i] - wDiffHeadingBefore; if (lastPos < 0) { lastPos = 0; }		regExpHeading.lastIndex = lastPos; while ( (found = regExpHeading.exec(diffText)) != null ) { if (found.index > tagStart[i]) { break; }			rangeStart[i] = found.index; rangeStartType[i] = 'heading'; }

// find last paragraph before diff tag if (rangeStart[i] == null) { lastPos = tagStart[i] - wDiffParagraphBefore; if (lastPos < 0) { lastPos = 0; }			regExpParagraph.lastIndex = lastPos; while ( (found = regExpParagraph.exec(diffText)) != null ) { if (found.index > tagStart[i]) { break; }				rangeStart[i] = found.index; rangeStartType[i] = 'paragraph'; }		}

// find line break before diff tag if (rangeStart[i] == null) { lastPos = tagStart[i] - wDiffLineBeforeMax; if (lastPos < 0) { lastPos = 0; }			regExpLine.lastIndex = lastPos; while ( (found = regExpLine.exec(diffText)) != null ) { if (found.index > tagStart[i] - wDiffLineBeforeMin) { break; }				rangeStart[i] = found.index; rangeStartType[i] = 'line'; }		}

// find blank before diff tag if (rangeStart[i] == null) { lastPos = tagStart[i] - wDiffBlankBeforeMax; if (lastPos < 0) { lastPos = 0; }			regExpBlank.lastIndex = lastPos; while ( (found = regExpBlank.exec(diffText)) != null ) { if (found.index > tagStart[i] - wDiffBlankBeforeMin) { break; }				rangeStart[i] = found.index; rangeStartType[i] = 'blank'; }		}

// fixed number of chars before diff tag if (rangeStart[i] == null) { rangeStart[i] = tagStart[i] - wDiffCharsBefore; rangeStartType[i] = 'chars'; if (rangeStart[i] < 0) { rangeStart[i] = 0; }		}

// find first heading after diff tag regExpHeading.lastIndex = tagEnd[i]; if ( (found = regExpHeading.exec(diffText)) != null ) { if (found.index < tagEnd[i] + wDiffHeadingAfter) { rangeEnd[i] = found.index + found[0].length; rangeEndType[i] = 'heading'; }		}

// find first paragraph after diff tag if (rangeEnd[i] == null) { regExpParagraph.lastIndex = tagEnd[i]; if ( (found = regExpParagraph.exec(diffText)) != null ) { if (found.index < tagEnd[i] + wDiffParagraphAfter) { rangeEnd[i] = found.index; rangeEndType[i] = 'paragraph'; }			}		}

// find first line break after diff tag if (rangeEnd[i] == null) { regExpLine.lastIndex = tagEnd[i] + wDiffLineAfterMin; if ( (found = regExpLine.exec(diffText)) != null ) { if (found.index < tagEnd[i] + wDiffLineAfterMax) { rangeEnd[i] = found.index; rangeEndType[i] = 'break'; }			}		}

// find blank after diff tag if (rangeEnd[i] == null) { regExpBlank.lastIndex = tagEnd[i] + wDiffBlankAfterMin; if ( (found = regExpBlank.exec(diffText)) != null ) { if (found.index < tagEnd[i] + wDiffBlankAfterMax) { rangeEnd[i] = found.index; rangeEndType[i] = 'blank'; }			}		}

// fixed number of chars after diff tag if (rangeEnd[i] == null) { rangeEnd[i] = tagEnd[i] + wDiffCharsAfter; if (rangeEnd[i] > diffText.length) { rangeEnd[i] = diffText.length; rangeEndType[i] = 'chars'; }		}	}

// remove overlaps, join close fragments var fragmentStart = []; var fragmentEnd = []; var fragmentStartType = []; var fragmentEndType = []; fragmentStart[0] = rangeStart[0]; fragmentEnd[0] = rangeEnd[0]; fragmentStartType[0] = rangeStartType[0]; fragmentEndType[0] = rangeEndType[0]; var j = 1; for (var i = 1; i < rangeStart.length; i ++) { if (rangeStart[i] > fragmentEnd[j - 1] + wDiffFragmentJoin) { fragmentStart[j] = rangeStart[i]; fragmentEnd[j] = rangeEnd[i]; fragmentStartType[j] = rangeStartType[i]; fragmentEndType[j] = rangeEndType[i]; j ++; }		else { fragmentEnd[j - 1] = rangeEnd[i]; fragmentEndType[j - 1] = rangeEndType[i]; }	}

// assemble the fragments var outText = ''; for (var i = 0; i < fragmentStart.length; i ++) {

// get text fragment var fragment = diffText.substring(fragmentStart[i], fragmentEnd[i]); var fragment = fragment.replace(/^\n+|\n+$/g, '');

// add inline marks for omitted chars and words if (fragmentStart[i] > 0) { if (fragmentStartType[i] == 'chars') { fragment = wDiffOmittedChars + fragment; }			else if (fragmentStartType[i] == 'blank') { fragment = wDiffOmittedChars + ' ' + fragment; }		}		if (fragmentEnd[i] < diffText.length) { if (fragmentStartType[i] == 'chars') { fragment = fragment + wDiffOmittedChars; }			else if (fragmentStartType[i] == 'blank') { fragment = fragment + ' ' + wDiffOmittedChars; }		}

// add omitted line separator if (fragmentStart[i] > 0) { outText += wDiffOmittedLines; }

// encapsulate span errors outText += ' ' + fragment + ' '; }

// add trailing omitted line separator if (fragmentEnd[i - 1] < diffText.length) { outText = outText + wDiffOmittedLines; }

// remove leading and trailing empty lines outText = outText.replace(/^\n+|\n+(<\/div>)$/g, '$1$2');

// convert to html linebreaks outText = outText.replace(/\n/g, ' ');

return(outText); }

/* */