allow postcss options to be a function and close issue #106

Author: terence-zh

lib/style-rewriter.js

@@ -36,9 +36,13 @@ module.exports = function (css, map) {
   var query = loaderUtils.parseQuery(this.query)
   var options = this.options.vue || {}
   var autoprefixOptions = options.autoprefixer
+
+  // plugins
   var plugins = options.postcss
-    ? options.postcss.slice() // make sure to copy it
-    : []
+  if (typeof plugins === 'function') {
+    plugins = plugins.call(this, this)
+  }
+  plugins = plugins ? plugins.slice() : [] // make sure to copy it
 
   // scoped css
   if (query.scoped) {