Add a block container for monitors that will run in the sequencer

src/engine/runtime.js

@@ -52,6 +52,13 @@ class Runtime extends EventEmitter {
          */
         this.flyoutBlocks = new Blocks();
 
+        /**
+         * Storage container for monitor blocks.
+         * These will execute on a target maybe
+         * @type {!Blocks}
+         */
+        this.monitorBlocks = new Blocks();
+
         /**
          * Currently known editing target for the VM.
          * @type {?Target}
@@ -416,8 +423,9 @@ class Runtime extends EventEmitter {
     /**
      * Toggle a script.
      * @param {!string} topBlockId ID of block that starts the script.
+     * @param {?string} optTarget target ID for target to run script on. If not supplied, uses editing target.
      */
-    toggleScript (topBlockId) {
+    toggleScript (topBlockId, optTarget) {
         // Remove any existing thread.
         for (let i = 0; i < this.threads.length; i++) {
             if (this.threads[i].topBlock === topBlockId) {
@@ -426,7 +434,7 @@ class Runtime extends EventEmitter {
             }
         }
         // Otherwise add it.
-        this._pushThread(topBlockId, this._editingTarget);
+        this._pushThread(topBlockId, optTarget ? optTarget : this._editingTarget);
     }
 
     /**
@@ -632,6 +640,7 @@ class Runtime extends EventEmitter {
             }
         }
         this.redrawRequested = false;
+        this._pushMonitors();
         const doneThreads = this.sequencer.stepThreads();
         this._updateGlows(doneThreads);
         this._setThreadCount(this.threads.length + doneThreads.length);
@@ -641,6 +650,13 @@ class Runtime extends EventEmitter {
         }
     }
 
+    /**
+     * Queue monitor blocks to sequencer to be run.
+     */
+    _pushMonitors () {
+        this.monitorBlocks.runAllMonitored(this);
+    }
+
     /**
      * Set the current editing target known by the runtime.
      * @param {!Target} editingTarget New editing target.