Adds Polymer.ArraySplice.calculateSplices to externs.
Closes
@@ -168,7 +168,7 @@ PolymerElement.prototype.domHost;
/**
* Notifies the event binding system of a change to a property.
* @param {string} path The path to set.
- * @param {*=} value The value to send in the update notification.
+ * @param {*} value The value to send in the update notification.
* @param {boolean=} fromAbove When true, specifies that the change came from
* above this element and thus upward notification is not necessary.
* @return {boolean} True if notification actually took place, based on a dirty
@@ -1473,3 +1473,38 @@ Polymer.AppLayout.ElementWithBackground.prototype = {
/** @return {?Element} Element in local dom by id. */
_getDOMRef: function(title){}
}
+
+/** @const */
+Polymer.ArraySplice = {};
+
+/**
+ * Returns an array of splice records indicating the minimum edits required
+ * to transform the `previous` array into the `current` array.
+ *
+ * Splice records are ordered by index and contain the following fields:
+ * - `index`: index where edit started
+ * - `removed`: array of removed items from this index
+ * - `addedCount`: number of items added at this index
+ *
+ * This function is based on the Levenshtein "minimum edit distance"
+ * algorithm. Note that updates are treated as removal followed by addition.
+ *
+ * The worst-case time complexity of this algorithm is `O(l * p)`
+ * l: The length of the current array
+ * p: The length of the previous array
+ *
+ * However, the worst-case complexity is reduced by an `O(n)` optimization
+ * to detect any shared prefix & suffix between the two arrays and only
+ * perform the more expensive minimum edit distance calculation over the
+ * non-shared portions of the arrays.
+ *
+ * @param {!Array} current The "changed" array for which splices will be
+ * calculated.
+ * @param {!Array} previous The "unchanged" original array to compare
+ * `current` against to determine the splices.
+ * @return {!Array} Returns an array of splice record objects. Each of these
+ * contains: `index` the location where the splice occurred; `removed`
+ * the array of removed items from this location; `addedCount` the number
+ * of items added at this location.
+ */
+Polymer.ArraySplice.calculateSplices = function(current, previous) {};
