utils.getParamNames(): get a function parameters names

Author: fengmk2

README.md

@@ -59,6 +59,9 @@ utils.getIPv4(); // "10.7.68.72"
 utils.getIP('ppp'); // "10.2.0.231"
 
 utils.getIPv6(); // "fe80::cabc:c8ff:feef:f996"
+
+// get a function parameter's names
+utils.getParamNames(function (key1, key2) {}); // ['key1', 'key2']
 ```
 
 ## benchmark

benchmark/get_paramnames.js

@@ -0,0 +1,57 @@
+/*!
+ * utility - benchmark/get_paramnames.js
+ * Copyright(c) 2013 fengmk2 <fengmk2@gmail.com>
+ * MIT Licensed
+ */
+
+"use strict";
+
+/**
+ * Module dependencies.
+ */
+
+var utils = require('../');
+var Benchmark = require('benchmark');
+var suite = new Benchmark.Suite();
+
+var foo = function (cid, startDate, endDate, rate, callback) {
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+  console.log('Date.now(): %j', Date.now());
+};
+
+console.log('cache:', utils.getParamNames(foo));
+console.log('no cache:', utils.getParamNames(foo, false));
+console.log('------------------------');
+
+suite
+.add("utils.getParamNames(foo)", function () {
+  utils.getParamNames(foo);
+})
+.add("utils.getParamNames(foo, false) no cache", function () {
+  utils.getParamNames(foo, false);
+})
+
+// add listeners
+.on('cycle', function (event) {
+  console.log(String(event.target));
+})
+.on('complete', function () {
+  console.log('Fastest is ' + this.filter('fastest').pluck('name'));
+})
+.run({ async: false });

lib/utility.js

@@ -1,6 +1,6 @@
 /*!
  * utility - lib/utility.js
- * Copyright(c) 2012 fengmk2 <fengmk2@gmail.com>
+ * Copyright(c) 2012 - 2013 fengmk2 <fengmk2@gmail.com>
  * MIT Licensed
  */
 
@@ -300,3 +300,21 @@ exports.getIP = exports.getIPv4 = function (interfaceName) {
 exports.getIPv6 = function (interfaceName) {
   return _getIP('IPv6', interfaceName);
 };
+
+/**
+ * Get a function parameter's names.
+ * 
+ * @param {Function} func
+ * @param {Boolean} [useCache], default is true
+ * @return {Array} names
+ */
+exports.getParamNames = function (func, cache) {
+  cache = cache !== false;
+  if (cache && func.__cache_names) {
+    return func.__cache_names;
+  }
+  var str = func.toString();
+  var names = str.slice(str.indexOf('(') + 1, str.indexOf(')')).match(/([^\s,]+)/g) || [];
+  func.__cache_names = names;
+  return names;
+};

test/utility.test.js

@@ -1,6 +1,6 @@
 /*!
  * utility - test/utility.test.js
- * Copyright(c) 2012 fengmk2 <fengmk2@gmail.com>
+ * Copyright(c) 2012 - 2013 fengmk2 <fengmk2@gmail.com>
  * MIT Licensed
  */
 
@@ -37,6 +37,28 @@ describe('utility.test.js', function () {
     });
   });
 
+  describe('getParamNames()', function () {
+    it('should return parameter names', function () {
+      utils.getParamNames(function () {}).should.eql([]);
+      utils.getParamNames(function (key1) {}).should.eql(['key1']);
+      utils.getParamNames(function (key1,key2) {}).should.eql(['key1', 'key2']);
+      utils.getParamNames(function (key1, key2) {}).should.eql(['key1', 'key2']);
+      utils.getParamNames(function (   key1   ,   key2, key3 
+       ,key4, callback) {
+        console.log('foo');
+      }).should.eql(['key1', 'key2', 'key3', 'key4', 'callback']);
+
+      utils.getParamNames(utils.getParamNames).should.eql(['func', 'cache']);
+      utils.getParamNames(utils.getParamNames, false).should.eql(['func', 'cache']);
+      utils.getParamNames(utils.md5).should.eql(['s']);
+      utils.getParamNames(utils.hmac).should.eql(['algorithm', 'key', 'data', 'encoding']);
+      utils.getParamNames(utils.hmac).should.eql(['algorithm', 'key', 'data', 'encoding']);
+      utils.getParamNames(utils.base64encode).should.eql(['s', 'urlsafe']);
+      utils.getParamNames(utils.base64decode).should.eql(['encode', 'urlsafe']);
+      utils.getParamNames(utils.escape).should.eql(['html']);
+    });
+  });
+
   describe('base64encode() and base64decode()', function () {
     it('should return base64 encode string', function () {
       var s = '你好￥啊!@#)(_ +/\/\\\