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index.js
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/* See license.txt for terms of usage */
/*
* Text diff implementation.
*
* This library supports the following APIS:
* JsDiff.diffChars: Character by character diff
* JsDiff.diffWords: Word (as defined by \b regex) diff which ignores whitespace
* JsDiff.diffLines: Line based diff
*
* JsDiff.diffCss: Diff targeted at CSS content
*
* These methods are based on the implementation proposed in
* "An O(ND) Difference Algorithm and its Variations" (Myers, 1986).
* http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.4.6927
*/
var JsDiff = (function() {
function clonePath(path) {
return { newPos: path.newPos, components: path.components.slice(0) };
}
function removeEmpty(array) {
var ret = [];
for (var i = 0; i < array.length; i++) {
if (array[i]) {
ret.push(array[i]);
}
}
return ret;
}
function escapeHTML(s) {
var n = s;
n = n.replace(/&/g, "&");
n = n.replace(/</g, "<");
n = n.replace(/>/g, ">");
n = n.replace(/"/g, """);
return n;
}
var fbDiff = function(ignoreWhitespace) {
this.ignoreWhitespace = ignoreWhitespace;
};
fbDiff.prototype = {
diff: function(oldString, newString) {
// Handle the identity case (this is due to unrolling editLength == 0
if (newString == oldString) {
return [{ value: newString }];
}
if (!newString) {
return [{ value: oldString, removed: true }];
}
if (!oldString) {
return [{ value: newString, added: true }];
}
newString = this.tokenize(newString);
oldString = this.tokenize(oldString);
var newLen = newString.length, oldLen = oldString.length;
var maxEditLength = newLen + oldLen;
var bestPath = [{ newPos: -1, components: [] }];
// Seed editLength = 0
var oldPos = this.extractCommon(bestPath[0], newString, oldString, 0);
if (bestPath[0].newPos+1 >= newLen && oldPos+1 >= oldLen) {
return bestPath[0].components;
}
for (var editLength = 1; editLength <= maxEditLength; editLength++) {
for (var diagonalPath = -1*editLength; diagonalPath <= editLength; diagonalPath+=2) {
var basePath;
var addPath = bestPath[diagonalPath-1],
removePath = bestPath[diagonalPath+1];
oldPos = (removePath ? removePath.newPos : 0) - diagonalPath;
if (addPath) {
// No one else is going to attempt to use this value, clear it
bestPath[diagonalPath-1] = undefined;
}
var canAdd = addPath && addPath.newPos+1 < newLen;
var canRemove = removePath && 0 <= oldPos && oldPos < oldLen;
if (!canAdd && !canRemove) {
bestPath[diagonalPath] = undefined;
continue;
}
// Select the diagonal that we want to branch from. We select the prior
// path whose position in the new string is the farthest from the origin
// and does not pass the bounds of the diff graph
if (!canAdd || (canRemove && addPath.newPos < removePath.newPos)) {
basePath = clonePath(removePath);
this.pushComponent(basePath.components, oldString[oldPos], undefined, true);
} else {
basePath = clonePath(addPath);
basePath.newPos++;
this.pushComponent(basePath.components, newString[basePath.newPos], true, undefined);
}
var oldPos = this.extractCommon(basePath, newString, oldString, diagonalPath);
if (basePath.newPos+1 >= newLen && oldPos+1 >= oldLen) {
return basePath.components;
} else {
bestPath[diagonalPath] = basePath;
}
}
}
},
pushComponent: function(components, value, added, removed) {
var last = components[components.length-1];
if (last && last.added === added && last.removed === removed) {
// We need to clone here as the component clone operation is just
// as shallow array clone
components[components.length-1] =
{value: this.join(last.value, value), added: added, removed: removed };
} else {
components.push({value: value, added: added, removed: removed });
}
},
extractCommon: function(basePath, newString, oldString, diagonalPath) {
var newLen = newString.length,
oldLen = oldString.length,
newPos = basePath.newPos,
oldPos = newPos - diagonalPath;
while (newPos+1 < newLen && oldPos+1 < oldLen && this.equals(newString[newPos+1], oldString[oldPos+1])) {
newPos++;
oldPos++;
this.pushComponent(basePath.components, newString[newPos], undefined, undefined);
}
basePath.newPos = newPos;
return oldPos;
},
equals: function(left, right) {
var reWhitespace = /\S/;
if (this.ignoreWhitespace && !reWhitespace.test(left) && !reWhitespace.test(right)) {
return true;
} else {
return left == right;
}
},
join: function(left, right) {
return left + right;
},
tokenize: function(value) {
return value;
}
};
var CharDiff = new fbDiff();
var WordDiff = new fbDiff(true);
WordDiff.tokenize = function(value) {
return removeEmpty(value.split(/(\s+|\b)/));
};
var CssDiff = new fbDiff(true);
CssDiff.tokenize = function(value) {
return removeEmpty(value.split(/([{}:;,]|\s+)/));
};
var LineDiff = new fbDiff();
LineDiff.tokenize = function(value) {
return value.split(/^/m);
};
return {
diffChars: function(oldStr, newStr) { return CharDiff.diff(oldStr, newStr); },
diffWords: function(oldStr, newStr) { return WordDiff.diff(oldStr, newStr); },
diffLines: function(oldStr, newStr) { return LineDiff.diff(oldStr, newStr); },
diffCss: function(oldStr, newStr) { return CssDiff.diff(oldStr, newStr); },
createPatch: function(fileName, oldStr, newStr, oldHeader, newHeader) {
var ret = [];
ret.push("Index: " + fileName);
ret.push("===================================================================");
ret.push("--- " + fileName + (typeof oldHeader === "undefined" ? "" : "\t" + oldHeader));
ret.push("+++ " + fileName + (typeof newHeader === "undefined" ? "" : "\t" + newHeader));
var diff = LineDiff.diff(oldStr, newStr);
if (!diff[diff.length-1].value) {
diff.pop(); // Remove trailing newline add
}
diff.push({value: "", lines: []}); // Append an empty value to make cleanup easier
function contextLines(lines) {
return lines.map(function(entry) { return ' ' + entry; });
}
function eofNL(curRange, i, current) {
var last = diff[diff.length-2],
isLast = i === diff.length-2,
isLastOfType = i === diff.length-3 && (current.added === !last.added || current.removed === !last.removed);
// Figure out if this is the last line for the given file and missing NL
if (!/\n$/.test(current.value) && (isLast || isLastOfType)) {
curRange.push('\\ No newline at end of file');
}
}
var oldRangeStart = 0, newRangeStart = 0, curRange = [],
oldLine = 1, newLine = 1;
for (var i = 0; i < diff.length; i++) {
var current = diff[i],
lines = current.lines || current.value.replace(/\n$/, "").split("\n");
current.lines = lines;
if (current.added || current.removed) {
if (!oldRangeStart) {
var prev = diff[i-1];
oldRangeStart = oldLine;
newRangeStart = newLine;
if (prev) {
curRange = contextLines(prev.lines.slice(-4));
oldRangeStart -= curRange.length;
newRangeStart -= curRange.length;
}
}
curRange.push.apply(curRange, lines.map(function(entry) { return (current.added?"+":"-") + entry; }));
eofNL(curRange, i, current);
if (current.added) {
newLine += lines.length;
} else {
oldLine += lines.length;
}
} else {
if (oldRangeStart) {
// Close out any changes that have been output (or join overlapping)
if (lines.length <= 8 && i < diff.length-2) {
// Overlapping
curRange.push.apply(curRange, contextLines(lines));
} else {
// end the range and output
var contextSize = Math.min(lines.length, 4);
ret.push(
"@@ -" + oldRangeStart + "," + (oldLine-oldRangeStart+contextSize)
+ " +" + newRangeStart + "," + (newLine-newRangeStart+contextSize)
+ " @@");
ret.push.apply(ret, curRange);
ret.push.apply(ret, contextLines(lines.slice(0, contextSize)));
if (lines.length <= 4) {
eofNL(ret, i, current);
}
oldRangeStart = 0; newRangeStart = 0; curRange = [];
}
}
oldLine += lines.length;
newLine += lines.length;
}
}
return ret.join('\n') + '\n';
},
applyPatch: function(oldStr, uniDiff) {
var diffstr = uniDiff.split("\n");
var diff = [];
var remEOFNL = false,
addEOFNL = false;
for (var i = (diffstr[0][0]=="I"?4:0); i < diffstr.length; i++) {
if(diffstr[i][0] == "@") {
var meh = diffstr[i].split(/@@ -(\d+),(\d+) \+(\d+),(\d+) @@/);
diff.unshift({
start:meh[3],
oldlength:meh[2],
oldlines:[],
newlength:meh[4],
newlines:[]
});
} else
if(diffstr[i][0] == "+") {
diff[0].newlines.push(diffstr[i].substr(1));
} else
if(diffstr[i][0] == "-") {
diff[0].oldlines.push(diffstr[i].substr(1));
} else
if(diffstr[i][0] == " ") {
diff[0].newlines.push(diffstr[i].substr(1));
diff[0].oldlines.push(diffstr[i].substr(1));
} else
if(diffstr[i][0] == "\\") {
if(diffstr[i-1][0] == "+") remEOFNL = true;
if(diffstr[i-1][0] == "-") addEOFNL = true;
}
};
var str = oldStr.split("\n");
for (var i = diff.length - 1; i >= 0; i--) {
var d = diff[i];
for (var j = 0; j < d.oldlength; j++) {
if(str[d.start-1+j] != d.oldlines[j]) {
return false;
}
};
Array.prototype.splice.apply(str,[d.start-1,+d.oldlength].concat(d.newlines));
}
if(remEOFNL) while(str[str.length-1]=="") str.pop();
else if(addEOFNL) str.push("");
return str.join("\n");
},
convertChangesToXML: function(changes){
var ret = [];
for ( var i = 0; i < changes.length; i++) {
var change = changes[i];
if (change.added) {
ret.push("<ins>");
} else if (change.removed) {
ret.push("<del>");
}
ret.push(escapeHTML(change.value));
if (change.added) {
ret.push("</ins>");
} else if (change.removed) {
ret.push("</del>");
}
}
return ret.join("");
},
convertChangesToDMP: function(changes){
var ret = [], change;
for ( var i = 0; i < changes.length; i++) {
change = changes[i];
ret.push([(change.added ? 1 : change.removed ? -1 : 0), change.value]);
}
return ret;
}
};
})();
module.exports = JsDiff;