Add methods to manipulate Repl context

Each invokes a Repl with some necessary context

lib/cylon.js

@@ -13,6 +13,7 @@ var Async = require("async");
 var Logger = require("./logger"),
     Robot = require("./robot"),
     Config = require("./config"),
+    Repl = require("./repl"),
     Utils = require("./utils"),
     _ = require("./utils/helpers");
 
@@ -143,6 +144,20 @@ Cylon.config = function(opts) {
   return Config;
 };
 
+/**
+ * Starts a new REPL in the context of the MCP.
+ *
+ * @return {void}
+ */
+Cylon.repl = function repl() {
+  var instance = new Repl(
+    { prompt: "mcp > " },
+    { robots: this.robots }
+  );
+
+  instance.start();
+};
+
 // Public: Halts the API and the robots
 //
 // callback - callback to be triggered when Cylon is ready to shutdown

lib/repl.js

@@ -0,0 +1,82 @@
+"use strict";
+
+var util = require("util"),
+    createRepl = require("repl").start,
+    EventEmitter = require("events").EventEmitter;
+
+var _ = require("./utils/helpers");
+
+// asserts that a constructor was called with 'new'
+function classCallCheck(instance, constructor) {
+  if (!instance instanceof constructor) {
+    throw new TypeError("Cannot call a class as a function");
+  }
+}
+
+var Repl = module.exports = function Repl(opts, context) {
+  classCallCheck(this, Repl);
+
+  opts = opts || {};
+  context = context || {};
+
+  opts.prompt = opts.prompt || "repl > ";
+  opts.stdin = opts.stdin || process.stdin;
+  opts.stdout = opts.stdout || process.stdout;
+
+  this.repl = null;
+  this.options = opts;
+  this.context = context;
+};
+
+Repl.active = false;
+
+util.inherits(Repl, EventEmitter);
+
+Repl.prototype.start = function() {
+  // don't try to start two repls at once
+  if (Repl.active) {
+    return false;
+  }
+
+  Repl.active = true;
+
+  this.repl = createRepl(this.options);
+  _.extend(this.repl.context, this.context);
+
+  this.repl.on("exit", function() {
+    Repl.active = false;
+    this.emit("exit");
+  }.bind(this));
+
+  this.repl.on("reset", function(context) {
+    _.extend(context, this.context);
+    this.emit("reset");
+  }.bind(this));
+};
+
+// add a value to the context
+Repl.prototype.addContext = function(key, value) {
+  this.context[key] = value;
+  this.repl.context[key] = value;
+};
+
+// remove a value from the context
+Repl.prototype.removeContext = function(key) {
+  delete this.context[key];
+  delete this.repl.context[key];
+};
+
+// set the context to the provided object
+Repl.prototype.setContext = function(object) {
+  _.each(this.context, function(value, key) {
+    if (this.context.hasOwnProperty(key)) {
+      this.removeContext(key);
+    }
+  }.bind(this));
+
+  _.each(object, function(value, key) {
+    if (object.hasOwnProperty(key)) {
+      this.addContext(key, value);
+    }
+  }.bind(this));
+};

lib/robot.js

@@ -11,6 +11,7 @@
 var initializer = require("./initializer"),
     Logger = require("./logger"),
     Utils = require("./utils"),
+    Repl = require("./repl"),
     Config = require("./config"),
     _ = require("./utils/helpers");
 
@@ -421,6 +422,22 @@ Robot.prototype.halt = function(callback) {
   this.running = false;
 };
 
+/**
+ * Starts a new REPL in the context of the Robot.
+ *
+ * @return {void}
+ */
+Robot.prototype.repl = function() {
+  var context = {};
+
+  _.extend(context, this.connections);
+  _.extend(context, this.devices);
+
+  var repl = new Repl({ prompt: this.name + " > " }, context);
+
+  repl.start();
+};
+
 // Public: Returns basic info about the robot as a String
 //
 // Returns a String