[api] Added `nconf.stores.System`

lib/nconf/provider.js

@@ -17,10 +17,10 @@ var async = require('async'),
 //
 var Provider = exports.Provider = function (options) {
   options        = options           || {};
-  this.overrides = options.overrides || null
+  this.overrides = options.overrides || null;
   this.useArgv   = options.useArgv   || false;
-
-  this.store = stores.create(options.type || 'memory', options);
+  this.useEnv    = options.useEnv    || false;
+  this.store     = stores.create(options.type || 'memory', options);
 };
 
 //

lib/nconf/stores/system.js

@@ -0,0 +1,72 @@
+/*
+ * system.js: Simple memory-based store for process environment variables and
+ *            command-line arguments.
+ *
+ * (C) 2011, Charlie Robbins
+ *
+ */
+ 
+var util = require('util'),
+    Memory = require('./memory').Memory;
+ 
+//
+// ### function System (options)
+// #### @options {Object} Options for this instance.
+// Constructor function for the System nconf store, a simple abstraction
+// around the Memory store that can read process environment variables
+// and command-line arguments.
+//
+var System = exports.System = function (options) {
+  Memory.call(this, options);
+
+  this.type = 'system';
+  this.only = options.only || [];
+  this.argv = options.argv || {};
+};
+
+// Inherit from the Memory store
+util.inherits(System, Memory);
+
+//
+// ### function loadSync ()
+// Loads the data passed in from `process.env` into this instance.
+//
+System.prototype.loadSync = function () {
+  this.loadEnv();
+  this.loadArgv();
+  
+  return this.store;
+};
+
+//
+// ### function loadEnv ()
+// Loads the data passed in from `process.env` into this instance.
+//
+System.prototype.loadEnv = function () {
+  var self = this;
+  
+  Object.keys(process.env).filter(function (key) {
+    return !self.only.length || self.only.indexOf(key) !== -1;
+  }).forEach(function (key) {
+    self.set(key, process.env[key]);
+  });
+    
+  return this.store;
+};
+
+//
+// ### function loadSync ()
+// Loads the data passed in from the command-line arguments 
+// into this instance.
+//
+Argv.prototype.loadArgv = function () {
+  var self = this, argv = Object.keys(this.argv) > 0
+    ? require('optimist').options(this.argv).argv
+    : require('optimist').argv;
+    
+  Object.keys(argv).forEach(function (key) {
+    self.set(key, argv[key])
+  });
+    
+  return this.store;
+};