User:Armandeh/diff.js

/* */

/*

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

two common words at the end of sequences of common words
 * Word types have been optimized for Wikipedia 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

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 || ''; var htmlMovedLeft = htmlMovedLeft  || ''; var htmlBlockStart = htmlBlockStart || ''; var htmlBlockEnd  = htmlBlockEnd   || ' ';

// 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 += '\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 += ' \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 = ''; }

// 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, '&para; '); blockText += '<' + delTag + ' class="diffDelete">' + Escape(str) + ''; }

// 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) + ''; delText = delText.replace(/\n/g, '&para; '); outText += delText; }		if (insText != '') { insText = '<' + insTag + ' class="diffInsert">' + Escape(insText) + ''; insText = insText.replace(/\n/g, '&para; '); outText += insText; }		outText += postText;

} while (i <= text.newWords.length);

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

return(outText); }

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

function Escape(text) {

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

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; }

/* */