add if_eq handlebars helper

Author: yyx990803

lib/generate.js

@@ -1,11 +1,19 @@
 var Metalsmith = require('metalsmith')
+var Handlebars = require('handlebars')
 var async = require('async')
 var render = require('consolidate').handlebars.render
 var path = require('path')
 var getOptions = require('./options')
 var ask = require('./ask')
 var filter = require('./filter')
 
+// register hendlebars helper
+Handlebars.registerHelper('if_eq', function (a, b, opts) {
+  return a === b
+    ? opts.fn(this)
+    : opts.inverse(this)
+})
+
 /**
  * Generate a template given a `src` and `dest`.
  *