From bd78e3ed4dc93eef941c74653adc68a17ba0cd51 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Tue, 16 Dec 2014 08:06:38 +1100
Subject: [PATCH] add end/start user transformers

---
 lib/6to5/file.js                       | 18 +++++++++++++++---
 lib/6to5/transformation/transformer.js |  3 ++-
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index c5763f991f..b4a926745d 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -192,13 +192,25 @@ File.prototype.transform = function (ast) {
 
   var self = this;
 
-  _.each(this.opts.transformers, function (transformer) {
-    transformer.transform(self);
-  });
+  var runUserTransformers = function (end) {
+    _.each(self.opts.transformers, function (transformer) {
+      if (transformer.opts.end) {
+        if (!end) return;
+      } else if (end) {
+        return;
+      }
+
+      transformer.transform(self);
+    });
+  };
+
+  runUserTransformers();
 
   _.each(transform.transformers, function (transformer) {
     transformer.transform(self);
   });
+
+  runUserTransformers(true);
 };
 
 File.prototype.generate = function () {
diff --git a/lib/6to5/transformation/transformer.js b/lib/6to5/transformation/transformer.js
index fdac3442e9..43f5a1b7c7 100644
--- a/lib/6to5/transformation/transformer.js
+++ b/lib/6to5/transformation/transformer.js
@@ -4,8 +4,9 @@ var traverse = require("../traverse");
 var t        = require("../types");
 var _        = require("lodash");
 
-function Transformer(key, transformer) {
+function Transformer(key, transformer, opts) {
   this.transformer = Transformer.normalise(transformer);
+  this.opts        = opts || {};
   this.key         = key;
 }