Introduce messagecatcher widget

core/modules/widgets/messagecatcher.js

@@ -0,0 +1,100 @@
+/*\
+title: $:/core/modules/widgets/messagecatcher.js
+type: application/javascript
+module-type: widget
+
+Message catcher widget
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var Widget = require("$:/core/modules/widgets/widget.js").widget;
+
+var MessageCatcherWidget = function(parseTreeNode,options) {
+	this.initialise(parseTreeNode,options);
+};
+
+/*
+Inherit from the base widget class
+*/
+MessageCatcherWidget.prototype = new Widget();
+
+/*
+Render this widget into the DOM
+*/
+MessageCatcherWidget.prototype.render = function(parent,nextSibling) {
+	var self = this;
+	// Remember parent
+	this.parentDomNode = parent;
+	// Compute attributes and execute state
+	this.computeAttributes();
+	this.execute();
+	// Add our message handler
+	if(this.messageType) {
+		this.addEventListeners([
+			{type: this.messageType, handler: "handleEvent"}
+		]);
+	}
+	// Render children
+	this.renderChildren(parent,null);
+};
+
+/*
+Compute the internal state of the widget
+*/
+MessageCatcherWidget.prototype.execute = function() {
+	var self = this;
+	// Get attributes that require a refresh on change
+	this.messageType = this.getAttribute("type");
+	this.messageActions = this.getAttribute("actions");
+	// Make child widgets
+	this.makeChildWidgets();
+};
+
+/*
+Handle an event
+*/
+MessageCatcherWidget.prototype.handleEvent = function(event) {
+	if(this.messageActions) {
+		// Collect all the event properties into variables
+		var collectProps = function(obj,prefix) {
+				prefix = prefix || "";
+				var props = {};
+				$tw.utils.each(obj,function(value,name) {
+					if(["string","boolean","number"].indexOf(typeof value) !== -1) {
+						props[prefix + name] = value.toString();
+					}
+				});
+				return props;
+			};
+		var variables = $tw.utils.extend(
+			{},
+			collectProps(event.paramObject,"event-paramObject-"),
+			collectProps(event,"event-"),
+			{
+				modifier: $tw.keyboardManager.getEventModifierKeyDescriptor(event)
+			});
+		this.invokeActionString(this.messageActions,this,event,variables);
+	}
+	return false;
+};
+
+/*
+Selectively refreshes the widget if needed. Returns true if the widget or any of its children needed re-rendering
+*/
+MessageCatcherWidget.prototype.refresh = function(changedTiddlers) {
+	var changedAttributes = this.computeAttributes();
+	if(changedAttributes["type"]) {
+		this.refreshSelf();
+		return true;
+	}
+	return this.refreshChildren(changedTiddlers);
+};
+
+exports.messagecatcher = MessageCatcherWidget;
+
+})();