actions are a list, to reduce garbage

js-assembler/runtime-src/baselib-lists.js

@@ -121,7 +121,7 @@
                 break;
             }
         }
-        if (p !== Empty.EMPTY) {
+        if (p !== EMPTY) {
             texts.push('.');
             texts.push(baselib.format.toDisplayedString(p, cache));
         }
@@ -138,14 +138,14 @@
         while (p instanceof Cons) {
             node.appendChild(baselib.format.toDomNode(p.first, cache));
             p = p.rest;
-            if (p !== Empty.EMPTY) {
+            if (p !== EMPTY) {
                 node.appendChild(document.createTextNode(" "));
             }
             if (typeof (p) === 'object' && cache.containsKey(p)) {
                 break;
             }
         }
-        if (p !== Empty.EMPTY) {
+        if (p !== EMPTY) {
             node.appendChild(document.createTextNode("."));
             node.appendChild(document.createTextNode(" "));
             node.appendChild(baselib.format.toDomNode(p, cache));
@@ -157,13 +157,13 @@
 
 
     var isPair = function (x) { return x instanceof Cons; };
-    var isEmpty = function (x) { return x === Empty.EMPTY; };
+    var isEmpty = function (x) { return x === EMPTY; };
 
 
     var makePair = Cons.makeInstance;
 
     var makeList = function () {
-        var result = Empty.EMPTY, i;
+        var result = EMPTY, i;
         for (i = arguments.length - 1; i >= 0; i--) {
             result = Cons.makeInstance(arguments[i], result);
         }
@@ -171,10 +171,21 @@
     };
 
 
+    // Coerse a list back into a JavaScript array.
+    var listToArray = function(lst) {
+        var result = [];
+        while (lst !== EMPTY) {
+            result.push(lst.first);
+            lst = lst.rest;
+        }
+        return result;
+    };
+
+
     // isList: Any -> Boolean
     // Returns true if x is a list (a chain of pairs terminated by EMPTY).
     var isList = function (x) { 
-        while (x !== Empty.EMPTY) {
+        while (x !== EMPTY) {
             if (x instanceof Cons) {
                 x = x.rest;
             } else {
@@ -229,6 +240,6 @@
     exports.reverse = reverse;
     exports.length = length;
     exports.listRef = listRef;
-
+    exports.listToArray = listToArray;
 
 }(this.plt.baselib));

web-world/js-impl.js

@@ -80,6 +80,8 @@
         }
     };
 
+    var EMPTY_PENDING_ACTIONS = plt.baselib.lists.EMPTY;
+
 
     //////////////////////////////////////////////////////////////////////
     // A MockView provides a functional interface to the DOM.  It
@@ -88,17 +90,25 @@
     // freshness of the MockView.
     var MockView = function(cursor, pendingActions, eventHandlers, nonce) {
         this.cursor = cursor;
+
+        // (listof (view -> void))
         this.pendingActions = pendingActions;
+
         this.eventHandlers = eventHandlers;
         this.nonce = nonce;
     };
 
     var isMockView = plt.baselib.makeClassPredicate(MockView);
 
+    MockView.prototype.getPendingActions = function() {
+        return plt.baselib.lists.listToArray(this.pendingActions).reverse();
+    };
+
+
     MockView.prototype.act = function(actionForCursor, actionForEventHandlers, actionForReal) {
         if (arguments.length !== 3) { throw new Error("act: insufficient arguments"); }
         return new MockView(actionForCursor(this.cursor),
-                            this.pendingActions.concat([actionForReal]),
+                            plt.baselib.lists.makePair(actionForReal, this.pendingActions),
                             actionForEventHandlers(this.eventHandlers),
                             this.nonce);
     };
@@ -441,7 +451,7 @@
     View.prototype.getMockAndResetFocus = function(nonce) {
         this.focus = this.top;
         return new MockView(domToCursor($(this.top).get(0)),
-                            [],
+                            EMPTY_PENDING_ACTIONS,
                             this.eventHandlers.slice(0),
                             nonce);
     };
@@ -512,14 +522,14 @@
             } catch (exn1) {
                 return onFail(exn1);
             }
-            return onSuccess(new MockView(domToCursor(dom.get(0)), [], [], undefined));
+            return onSuccess(new MockView(domToCursor(dom.get(0)), EMPTY_PENDING_ACTIONS, [], undefined));
         } else {
             try {
                 dom = $(plt.baselib.format.toDomNode(x));
             } catch (exn2) {
                 return onFail(exn2);
             }
-            return onSuccess(new MockView(domToCursor(dom.get(0)), [], [], undefined));
+            return onSuccess(new MockView(domToCursor(dom.get(0)), EMPTY_PENDING_ACTIONS, [], undefined));
         }
     };
 
@@ -1086,7 +1096,7 @@
                        function(newMockView) {
                            if (newMockView.nonce === nonce) {
                                var i;
-                               var actions = newMockView.pendingActions;
+                               var actions = newMockView.getPendingActions();
                                for (i = 0; i < actions.length; i++) {
                                    actions[i](view);
                                }