add createArray function in Base class with overriden push/splice/pop…

… functions:

surveyjs#596

src/base.ts

@@ -119,7 +119,16 @@ export class Base {
     endLoadingFromJson() {
         this.isLoadingFromJsonValue = false;
     }
+    /**
+     * Returns the property value by name
+     * @param name property name
+     */
     public getPropertyValue(name: string): any { return this.propertyHash[name]; }
+    /**
+     * set property value
+     * @param name property name
+     * @param val new property value
+     */
     public setPropertyValue(name: string, val: any) { 
         var oldValue = this.propertyHash[name];
         this.propertyHash[name] = val;
@@ -131,6 +140,48 @@ export class Base {
         if(this.isLoadingFromJson) return;
         this.onPropertyChanged.fire(this, {name: name, oldValue: oldValue, newValue: newValue});
     }
+    protected createNewArray(name: string, onPush: any = null, onRemove: any = null): Array<any> {
+        var newArray = new Array<any>();
+        this.propertyHash[name] = newArray;
+        var self = this;
+        newArray.push = function (value): number { 
+            var result = Array.prototype.push.call(newArray, value);
+            if(onPush) onPush(value);
+            self.propertyValueChanged(name, newArray, newArray);
+            return result;
+        };
+        newArray.pop = function (): number { 
+            var result = Array.prototype.pop.call(newArray);
+            if(onRemove) onRemove(result);
+            self.propertyValueChanged(name, newArray, newArray);
+            return result;
+        };
+        newArray.splice = function (start?: number, deleteCount?: number, ...items: any[]): any[] {
+            if(!start) start = 0;
+            if(!deleteCount) deleteCount = 0;
+            var deletedItems = [];
+            for(var i = 0; i < deleteCount; i ++) {
+                if(i + start >= newArray.length) continue;
+                deletedItems.push(newArray[i + start]);
+            }
+            var result = Array.prototype.splice.call(newArray, start, deleteCount, ... items);
+            if(!items) items = [];
+            if(onRemove) {
+                for(var i = 0; i < deletedItems.length; i ++) {
+                    onRemove(deletedItems[i])
+                }
+            }
+            if(onPush) {
+                for(var i = 0; i < items.length; i ++) {
+                    onPush(items[i], start + i);
+                }
+            }
+            self.propertyValueChanged(name, newArray, newArray);
+            return result;
+         };
+
+        return newArray;
+    }
     protected isTwoValueEquals(x: any, y: any): boolean {
         if (x === y) return true;
         if (!(x instanceof Object) || !(y instanceof Object)) return false;

tests/basetests.ts

@@ -103,11 +103,19 @@ QUnit.test("ItemValue.getItemByValue()", function (assert) {
 });
 
 class BaseTester extends Base {
+    constructor() {
+        super();
+        var self = this;
+        this.createNewArray("items", 
+            function(newItem){newItem.owner = self;}, 
+            function(deletedItem){deletedItem.isDeleted = true;});
+    }
     public get value1(): number { return this.getPropertyValue("value1"); }
     public set value1(val: number) { this.setPropertyValue("value1", val); }
+    public get items(): Array<any> { return this.getPropertyValue("items"); }
 }
 
-QUnit.test("Base changed value", function (assert) {
+QUnit.test("Base simple propety value", function (assert) {
     var base = new BaseTester();
     var counter = 0;
     var propertyName;
@@ -125,3 +133,34 @@ QUnit.test("Base changed value", function (assert) {
     assert.notOk(oldValue, "oldValue is underfined");
     assert.equal(newValue, 5, "newValue is 5");
 });
+
+QUnit.test("Base array propety value, push/splice/pop", function (assert) {
+    var base = new BaseTester();
+    var counter = 0;
+    var propertyName;
+    base.onPropertyChanged.add(function (sender, options) {
+        counter ++;
+        propertyName = options.name;
+    });
+    base.items.push({value: 1});
+    assert.equal(base.items.length, 1, "There is one item");
+    assert.equal(base.items[0].owner, base, "Owner property is set to base")
+    assert.equal(counter, 1, "event called one time");
+    assert.equal(propertyName, "items", "items has been changed");
+    var item = base.items[0];
+    base.items.splice(0, 1, {value: 2}, {value: 3});
+    assert.equal(base.items.length, 2, "There are two items");
+    assert.equal(item.isDeleted, true, "First Item is deleted")
+    assert.equal(base.items[0].owner, base, "Item1, Owner property is set to base")
+    assert.equal(base.items[0].owner, base, "Item2, Owner property is set to base")
+    assert.equal(counter, 2, "event called two times");
+    assert.equal(propertyName, "items", "items has been changed");
+
+    item = base.items[0];
+    base.items.pop();
+    base.items.pop();
+    assert.equal(base.items.length, 0, "There is no items");
+    assert.equal(item.isDeleted, true, "Item is deleted")
+    assert.equal(counter, 4, "event called 4 times, pop is called two times");
+    assert.equal(propertyName, "items", "items has been changed");
+});