init

2026-03-05 14:45:43 +00:00 · 2015-04-09 07:47:57 +00:00
commit 32da2df9be
809 changed files with 119606 additions and 0 deletions
--- a/lib/knockout/src/binding/editDetection/compareArrays.js
+++ b/lib/knockout/src/binding/editDetection/compareArrays.js
@@ -0,0 +1,102 @@
+// Go through the items that have been added and deleted and try to find matches between them.
+ko.utils.findMovesInArrayComparison = function (left, right, limitFailedCompares) {
+    if (left.length && right.length) {
+        var failedCompares, l, r, leftItem, rightItem;
+        for (failedCompares = l = 0; (!limitFailedCompares || failedCompares < limitFailedCompares) && (leftItem = left[l]); ++l) {
+            for (r = 0; rightItem = right[r]; ++r) {
+                if (leftItem['value'] === rightItem['value']) {
+                    leftItem['moved'] = rightItem['index'];
+                    rightItem['moved'] = leftItem['index'];
+                    right.splice(r, 1);         // This item is marked as moved; so remove it from right list
+                    failedCompares = r = 0;     // Reset failed compares count because we're checking for consecutive failures
+                    break;
+                }
+            }
+            failedCompares += r;
+        }
+    }
+};
+
+ko.utils.compareArrays = (function () {
+    var statusNotInOld = 'added', statusNotInNew = 'deleted';
+
+    // Simple calculation based on Levenshtein distance.
+    function compareArrays(oldArray, newArray, options) {
+        // For backward compatibility, if the third arg is actually a bool, interpret
+        // it as the old parameter 'dontLimitMoves'. Newer code should use { dontLimitMoves: true }.
+        options = (typeof options === 'boolean') ? { 'dontLimitMoves': options } : (options || {});
+        oldArray = oldArray || [];
+        newArray = newArray || [];
+
+        if (oldArray.length <= newArray.length)
+            return compareSmallArrayToBigArray(oldArray, newArray, statusNotInOld, statusNotInNew, options);
+        else
+            return compareSmallArrayToBigArray(newArray, oldArray, statusNotInNew, statusNotInOld, options);
+    }
+
+    function compareSmallArrayToBigArray(smlArray, bigArray, statusNotInSml, statusNotInBig, options) {
+        var myMin = Math.min,
+            myMax = Math.max,
+            editDistanceMatrix = [],
+            smlIndex, smlIndexMax = smlArray.length,
+            bigIndex, bigIndexMax = bigArray.length,
+            compareRange = (bigIndexMax - smlIndexMax) || 1,
+            maxDistance = smlIndexMax + bigIndexMax + 1,
+            thisRow, lastRow,
+            bigIndexMaxForRow, bigIndexMinForRow;
+
+        for (smlIndex = 0; smlIndex <= smlIndexMax; smlIndex++) {
+            lastRow = thisRow;
+            editDistanceMatrix.push(thisRow = []);
+            bigIndexMaxForRow = myMin(bigIndexMax, smlIndex + compareRange);
+            bigIndexMinForRow = myMax(0, smlIndex - 1);
+            for (bigIndex = bigIndexMinForRow; bigIndex <= bigIndexMaxForRow; bigIndex++) {
+                if (!bigIndex)
+                    thisRow[bigIndex] = smlIndex + 1;
+                else if (!smlIndex)  // Top row - transform empty array into new array via additions
+                    thisRow[bigIndex] = bigIndex + 1;
+                else if (smlArray[smlIndex - 1] === bigArray[bigIndex - 1])
+                    thisRow[bigIndex] = lastRow[bigIndex - 1];                  // copy value (no edit)
+                else {
+                    var northDistance = lastRow[bigIndex] || maxDistance;       // not in big (deletion)
+                    var westDistance = thisRow[bigIndex - 1] || maxDistance;    // not in small (addition)
+                    thisRow[bigIndex] = myMin(northDistance, westDistance) + 1;
+                }
+            }
+        }
+
+        var editScript = [], meMinusOne, notInSml = [], notInBig = [];
+        for (smlIndex = smlIndexMax, bigIndex = bigIndexMax; smlIndex || bigIndex;) {
+            meMinusOne = editDistanceMatrix[smlIndex][bigIndex] - 1;
+            if (bigIndex && meMinusOne === editDistanceMatrix[smlIndex][bigIndex-1]) {
+                notInSml.push(editScript[editScript.length] = {     // added
+                    'status': statusNotInSml,
+                    'value': bigArray[--bigIndex],
+                    'index': bigIndex });
+            } else if (smlIndex && meMinusOne === editDistanceMatrix[smlIndex - 1][bigIndex]) {
+                notInBig.push(editScript[editScript.length] = {     // deleted
+                    'status': statusNotInBig,
+                    'value': smlArray[--smlIndex],
+                    'index': smlIndex });
+            } else {
+                --bigIndex;
+                --smlIndex;
+                if (!options['sparse']) {
+                    editScript.push({
+                        'status': "retained",
+                        'value': bigArray[bigIndex] });
+                }
+            }
+        }
+
+        // Set a limit on the number of consecutive non-matching comparisons; having it a multiple of
+        // smlIndexMax keeps the time complexity of this algorithm linear.
+        ko.utils.findMovesInArrayComparison(notInSml, notInBig, smlIndexMax * 10);
+
+        return editScript.reverse();
+    }
+
+    return compareArrays;
+})();
+
+ko.exportSymbol('utils.compareArrays', ko.utils.compareArrays);