aaac7fed
 liuqimichale
add
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// Myers' Diff Algorithm
// Modified from https://github.com/kpdecker/jsdiff/blob/master/src/diff/base.js
function Diff() {}
Diff.prototype = {
diff: function (oldArr, newArr, equals) {
if (!equals) {
equals = function (a, b) {
return a === b;
};
}
this.equals = equals;
var self = this;
oldArr = oldArr.slice();
newArr = newArr.slice(); // Allow subclasses to massage the input prior to running
var newLen = newArr.length;
var oldLen = oldArr.length;
var editLength = 1;
var maxEditLength = newLen + oldLen;
var bestPath = [{
newPos: -1,
components: []
}]; // Seed editLength = 0, i.e. the content starts with the same values
var oldPos = this.extractCommon(bestPath[0], newArr, oldArr, 0);
if (bestPath[0].newPos + 1 >= newLen && oldPos + 1 >= oldLen) {
var indices = [];
for (var i = 0; i < newArr.length; i++) {
indices.push(i);
} // Identity per the equality and tokenizer
return [{
indices: indices,
count: newArr.length
}];
} // Main worker method. checks all permutations of a given edit length for acceptance.
function execEditLength() {
for (var diagonalPath = -1 * editLength; diagonalPath <= editLength; diagonalPath += 2) {
var basePath;
var addPath = bestPath[diagonalPath - 1];
var removePath = bestPath[diagonalPath + 1];
var 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) {
// If this path is a terminal then prune
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);
self.pushComponent(basePath.components, undefined, true);
} else {
basePath = addPath; // No need to clone, we've pulled it from the list
basePath.newPos++;
self.pushComponent(basePath.components, true, undefined);
}
oldPos = self.extractCommon(basePath, newArr, oldArr, diagonalPath); // If we have hit the end of both strings, then we are done
if (basePath.newPos + 1 >= newLen && oldPos + 1 >= oldLen) {
return buildValues(self, basePath.components, newArr, oldArr);
} else {
// Otherwise track this path as a potential candidate and continue.
bestPath[diagonalPath] = basePath;
}
}
editLength++;
}
while (editLength <= maxEditLength) {
var ret = execEditLength();
if (ret) {
return ret;
}
}
},
pushComponent: function (components, 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] = {
count: last.count + 1,
added: added,
removed: removed
};
} else {
components.push({
count: 1,
added: added,
removed: removed
});
}
},
extractCommon: function (basePath, newArr, oldArr, diagonalPath) {
var newLen = newArr.length;
var oldLen = oldArr.length;
var newPos = basePath.newPos;
var oldPos = newPos - diagonalPath;
var commonCount = 0;
while (newPos + 1 < newLen && oldPos + 1 < oldLen && this.equals(newArr[newPos + 1], oldArr[oldPos + 1])) {
newPos++;
oldPos++;
commonCount++;
}
if (commonCount) {
basePath.components.push({
count: commonCount
});
}
basePath.newPos = newPos;
return oldPos;
},
tokenize: function (value) {
return value.slice();
},
join: function (value) {
return value.slice();
}
};
function buildValues(diff, components, newArr, oldArr) {
var componentPos = 0;
var componentLen = components.length;
var newPos = 0;
var oldPos = 0;
for (; componentPos < componentLen; componentPos++) {
var component = components[componentPos];
if (!component.removed) {
var indices = [];
for (var i = newPos; i < newPos + component.count; i++) {
indices.push(i);
}
component.indices = indices;
newPos += component.count; // Common case
if (!component.added) {
oldPos += component.count;
}
} else {
var indices = [];
for (var i = oldPos; i < oldPos + component.count; i++) {
indices.push(i);
}
component.indices = indices;
oldPos += component.count;
}
}
return components;
}
function clonePath(path) {
return {
newPos: path.newPos,
components: path.components.slice(0)
};
}
var arrayDiff = new Diff();
function _default(oldArr, newArr, callback) {
return arrayDiff.diff(oldArr, newArr, callback);
}
module.exports = _default;
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