Implement WebWorker interface

src/worker.js

@@ -0,0 +1,70 @@
+var EventEmitter = require('events');
+var util = require('util');
+
+function VirtualMachine () {
+    if (!window.Worker) {
+        console.error('WebWorkers not supported in this environment.' +
+            ' Please use the non-worker version (vm.js or vm.min.js).');
+        return;
+    }
+    var instance = this;
+    EventEmitter.call(instance);
+    instance.vmWorker = new Worker('../vm.js');
+
+    // onmessage calls are converted into emitted events.
+    instance.vmWorker.onmessage = function (e) {
+        instance.emit(e.data.method, e.data);
+    };
+
+    instance.blockListener = function (e) {
+        // Messages from Blockly are not serializable by default.
+        // Pull out the necessary, serializable components to pass across.
+        var serializableE = {
+            blockId: e.blockId,
+            element: e.element,
+            type: e.type,
+            name: e.name,
+            newValue: e.newValue,
+            oldParentId: e.oldParentId,
+            oldInputName: e.oldInputName,
+            newParentId: e.newParentId,
+            newInputName: e.newInputName,
+            xml: {
+                outerHTML: (e.xml) ? e.xml.outerHTML : null
+            }
+        };
+        instance.vmWorker.postMessage({
+            method: 'blockListener',
+            args: serializableE
+        });
+    };
+}
+
+/**
+ * Inherit from EventEmitter
+ */
+util.inherits(VirtualMachine, EventEmitter);
+
+// For documentation, please see index.js.
+// These mirror the functionality provided there, with the worker wrapper.
+VirtualMachine.prototype.getPlaygroundData = function () {
+    this.vmWorker.postMessage({method: 'getPlaygroundData'});
+};
+
+VirtualMachine.prototype.start = function () {
+    this.vmWorker.postMessage({method: 'start'});
+};
+
+VirtualMachine.prototype.greenFlag = function () {
+    this.vmWorker.postMessage({method: 'greenFlag'});
+};
+
+VirtualMachine.prototype.stopAll = function () {
+    this.vmWorker.postMessage({method: 'stopAll'});
+};
+
+/**
+ * Export and bind to `window`
+ */
+module.exports = VirtualMachine;
+if (typeof window !== 'undefined') window.VirtualMachine = module.exports;