Clone 3.5.1 from github

vendors/knockout/src/subscribables/dependencyDetection.js

@@ -0,0 +1,76 @@
+
+ko.computedContext = ko.dependencyDetection = (function () {
+    var outerFrames = [],
+        currentFrame,
+        lastId = 0;
+
+    // Return a unique ID that can be assigned to an observable for dependency tracking.
+    // Theoretically, you could eventually overflow the number storage size, resulting
+    // in duplicate IDs. But in JavaScript, the largest exact integral value is 2^53
+    // or 9,007,199,254,740,992. If you created 1,000,000 IDs per second, it would
+    // take over 285 years to reach that number.
+    // Reference http://blog.vjeux.com/2010/javascript/javascript-max_int-number-limits.html
+    function getId() {
+        return ++lastId;
+    }
+
+    function begin(options) {
+        outerFrames.push(currentFrame);
+        currentFrame = options;
+    }
+
+    function end() {
+        currentFrame = outerFrames.pop();
+    }
+
+    return {
+        begin: begin,
+
+        end: end,
+
+        registerDependency: function (subscribable) {
+            if (currentFrame) {
+                if (!ko.isSubscribable(subscribable))
+                    throw new Error("Only subscribable things can act as dependencies");
+                currentFrame.callback.call(currentFrame.callbackTarget, subscribable, subscribable._id || (subscribable._id = getId()));
+            }
+        },
+
+        ignore: function (callback, callbackTarget, callbackArgs) {
+            try {
+                begin();
+                return callback.apply(callbackTarget, callbackArgs || []);
+            } finally {
+                end();
+            }
+        },
+
+        getDependenciesCount: function () {
+            if (currentFrame)
+                return currentFrame.computed.getDependenciesCount();
+        },
+
+        getDependencies: function () {
+            if (currentFrame)
+                return currentFrame.computed.getDependencies();
+        },
+
+        isInitial: function() {
+            if (currentFrame)
+                return currentFrame.isInitial;
+        },
+
+        computed: function() {
+            if (currentFrame)
+                return currentFrame.computed;
+        }
+    };
+})();
+
+ko.exportSymbol('computedContext', ko.computedContext);
+ko.exportSymbol('computedContext.getDependenciesCount', ko.computedContext.getDependenciesCount);
+ko.exportSymbol('computedContext.getDependencies', ko.computedContext.getDependencies);
+ko.exportSymbol('computedContext.isInitial', ko.computedContext.isInitial);
+ko.exportSymbol('computedContext.registerDependency', ko.computedContext.registerDependency);
+
+ko.exportSymbol('ignoreDependencies', ko.ignoreDependencies = ko.dependencyDetection.ignore);