From 453502b4f29aa759ad28a32077fe5f7a948cd324 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Mon, 13 Oct 2014 14:45:15 +1100
Subject: [PATCH] add Transformer class that deals with running a transformer
 against a File

---
 lib/6to5/file.js        | 48 ++-----------------------------
 lib/6to5/transform.js   | 18 ++++++------
 lib/6to5/transformer.js | 62 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+), 56 deletions(-)
 create mode 100644 lib/6to5/transformer.js

diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index 3f3e813b5a..5ab96ea05e 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -1,7 +1,6 @@
 module.exports = File;
 
 var transform = require("./transform");
-var traverse  = require("./traverse");
 var util      = require("./util");
 var _         = require("lodash");
 
@@ -50,8 +49,8 @@ File.prototype.transform = function (ast) {
   var self = this;
   var opts = this.opts;
 
-  _.each(transform.transformers, function (transformer, name) {
-    self.runTransformer(name, transformer);
+  _.each(transform.transformers, function (transformer) {
+    transformer.transform(self);
   });
 
   var result = util.generate(ast, opts);
@@ -75,46 +74,3 @@ File.prototype.generateUid = function (name) {
   uids[name] = i + 1;
   return "_" + id;
 };
-
-File.prototype.canRunTransformer = function (name) {
-  var opts = this.opts;
-
-  var blacklist = opts.blacklist;
-  if (blacklist.length && _.contains(blacklist, name)) return false;
-
-  var whitelist = opts.whitelist;
-  if (whitelist.length && !_.contains(whitelist, name)) return false;
-
-  return true;
-};
-
-File.prototype.runTransformer = function (name, transformer) {
-  if (!this.canRunTransformer(name)) return;
-
-  var self = this;
-
-  var build = function (exit) {
-    return function (node, parent) {
-      var types = [node.type].concat(traverse.aliases[node.type] || []);
-
-      var fns = transformer.all;
-
-      _.each(types, function (type) {
-        fns = transformer[type] || fns;
-      });
-
-      if (!fns) return;
-
-      var fn = fns.enter;
-      if (exit) fn = fns.exit;
-      if (!fn) return;
-
-      return fn(node, parent, self);
-    };
-  };
-
-  traverse(this.ast, {
-    enter: build(),
-    exit:  build(true)
-  });
-};
diff --git a/lib/6to5/transform.js b/lib/6to5/transform.js
index 0ebb89f1f3..bac4f7f8ca 100644
--- a/lib/6to5/transform.js
+++ b/lib/6to5/transform.js
@@ -1,10 +1,11 @@
 module.exports = transform;
 
-var sourceMap = require("source-map");
-var recast    = require("recast");
-var File      = require("./file");
-var util      = require("./util");
-var _         = require("lodash");
+var Transformer = require("./transformer");
+var sourceMap   = require("source-map");
+var recast      = require("recast");
+var File        = require("./file");
+var util        = require("./util");
+var _           = require("lodash");
 
 function transform(code, opts) {
   opts = opts || {};
@@ -87,9 +88,6 @@ transform.transformers = {
   _aliasFunctions:          require("./transformers/_alias-functions")
 };
 
-_.each(transform.transformers, function (transformer) {
-  _.each(transformer, function (fns, type) {
-    if (_.isFunction(fns)) fns = { enter: fns };
-    transformer[type] = fns;
-  });
+_.each(transform.transformers, function (transformer, key) {
+  transform.transformers[key] = new Transformer(key, transformer);
 });
diff --git a/lib/6to5/transformer.js b/lib/6to5/transformer.js
new file mode 100644
index 0000000000..3ec3652374
--- /dev/null
+++ b/lib/6to5/transformer.js
@@ -0,0 +1,62 @@
+module.exports = Transformer;
+
+var traverse = require("./traverse");
+var _        = require("lodash");
+
+function Transformer(key, transformer) {
+  this.transformer = Transformer.normalise(transformer);
+  this.key         = key;
+}
+
+Transformer.normalise = function (transformer) {
+  _.each(transformer, function (fns, type) {
+    if (_.isFunction(fns)) fns = { enter: fns };
+    transformer[type] = fns;
+  });
+  return transformer;
+};
+
+Transformer.prototype.transform = function (file) {
+  if (!this.canRun(file)) return;
+
+  var transformer = this.transformer;
+
+  var build = function (exit) {
+    return function (node, parent) {
+      // add any node type aliases that exist
+      var types = [node.type].concat(traverse.aliases[node.type] || []);
+
+      var fns = transformer.all;
+
+      _.each(types, function (type) {
+        fns = transformer[type] || fns;
+      });
+
+      // this transformer cannot deal with this node type
+      if (!fns) return;
+
+      var fn = fns.enter;
+      if (exit) fn = fns.exit;
+      if (!fn) return;
+
+      return fn(node, parent, file);
+    };
+  };
+
+  traverse(file.ast, {
+    enter: build(),
+    exit:  build(true)
+  });
+};
+
+Transformer.prototype.canRun = function (file) {
+  var opts = file.opts;
+
+  var blacklist = opts.blacklist;
+  if (blacklist.length && _.contains(blacklist, this.key)) return false;
+
+  var whitelist = opts.whitelist;
+  if (whitelist.length && !_.contains(whitelist, this.key)) return false;
+
+  return true;
+};