Implement thread status, YieldTimer, block glow, wait

src/engine/thread.js

@@ -20,6 +20,40 @@ function Thread (firstBlock) {
      * @type {Array.<string>}
      */
     this.stack = [];
+
+    /**
+     * Status of the thread, one of three states (below)
+     * @type {number}
+     */
+    this.status = 0; /* Thread.STATUS_RUNNING */
+
+    /**
+     * Yield timer ID (for checking when the thread should unyield).
+     * @type {number}
+     */
+    this.yieldTimerId = -1;
 }
 
+/**
+ * Thread status for initialized or running thread.
+ * Threads are in this state when the primitive is called for the first time.
+ * @const
+ */
+Thread.STATUS_RUNNING = 0;
+
+/**
+ * Thread status for a yielded thread.
+ * Threads are in this state when a primitive has yielded.
+ * @const
+ */
+Thread.STATUS_YIELD = 1;
+
+/**
+ * Thread status for a finished/done thread.
+ * Thread is moved to this state when the interpreter
+ * can proceed with execution.
+ * @const
+ */
+Thread.STATUS_DONE = 2;
+
 module.exports = Thread;