Merge branch 'add/env'

Readme.md

@@ -109,6 +109,19 @@ yields:
 
   Convert "yes", "no", "enabled", "disabled" into booleans.
 
+### eson.env([prefix])
+
+  Allow environment variables to define config values. If you have the following:
+
+```js
+{
+  "upload path": "/data/uploads"
+}
+```
+
+  You could then export `UPLOAD_PATH=/tmp` to change this value. Optionally when
+  a `prefix` is given such as "MYAPP_" then you must prefix such as `MYAPP_UPLOAD_PATH=/tmp`.
+
 ### eson.replace(str, val)
 
   The replace plugin allows you to replace arbitrary substrings, useful

lib/eson.js

@@ -22,6 +22,7 @@ exports.version = '0.0.1';
  */
 
 exports.ms = require('./plugins/ms');
+exports.env = require('./plugins/env');
 exports.glob = require('./plugins/glob');
 exports.bools = require('./plugins/bools');
 exports.replace = require('./plugins/replace');

lib/plugins/env.js

@@ -0,0 +1,13 @@
+
+/**
+ * Allow environment variables to take precedence over `val`,
+ * with optional `prefix`.
+ */
+
+module.exports = function(prefix){
+  prefix = prefix || '';
+  return function(key, val){
+    var name = prefix + key.toUpperCase().split(' ').join('_');
+    return process.env[name] || val;
+  }
+};

test/bools.js

@@ -2,7 +2,7 @@
 var Parser = require('../')
   , bools = Parser.bools;
 
-describe('ms', function(){
+describe('bools', function(){
   it('should parse string bool representations', function(){
     bools('', 'yes').should.be.true;
     bools('', 'enabled').should.be.true;

test/env.js

@@ -0,0 +1,23 @@
+
+var Parser = require('../')
+  , env = Parser.env;
+
+describe('env(prefix)', function(){
+  it('should allow setting environment variables', function(){
+    var fn = env();
+    fn('foo', 'bar').should.equal('bar');
+    process.env.FOO = 'baz';
+    fn('foo', 'bar').should.equal('baz');
+    process.env.DEV_UI = 'yes';
+    fn('dev ui', 'no').should.equal('yes');
+  })
+
+  it('should accept a prefix', function(){
+    var fn = env('NB_');
+    fn('dev ui', 'no').should.equal('no');
+    process.env.DEV_UI = 'yes';
+    fn('dev ui', 'no').should.equal('no');
+    process.env.NB_DEV_UI = 'yes';
+    fn('dev ui', 'no').should.equal('yes');
+  })
+})