From 0e9b227114e77fe7bc81cef3195859b614cf0755 Mon Sep 17 00:00:00 2001
From: Ingvar Stepanyan <me@rreverser.com>
Date: Thu, 30 Jan 2014 20:12:02 +0200
Subject: [PATCH] Added transformation support (closes #1).

---
 README.md       |  7 ++++++-
 lib/pure-cjs.js | 42 ++++++++++++++++++++++++++++++++----------
 package.json    |  6 +++---
 3 files changed, 41 insertions(+), 14 deletions(-)

diff --git a/README.md b/README.md
index 25ee1e7..881897c 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,12 @@ cjs.transform({
 	input: 'superLib/topModule.js' /* String|Function(): input file */,
 	output: function (input) { return input.replace(/(\.js)?$/, '.out.js') } /* [?] String|Function(input): output file */,
 	map: function (input, output) { return output + '.map' } /* [?] String|Function(input, output): source map file */,
-	exports: 'window.SuperLib' /* [?] String|Function(input, output): Object to wrap and put exports from top module into */
+	exports: 'window.SuperLib' /* [?] String|Function(input, output): Object to wrap and put exports from top module into */,
+	transform: [] /* [?] Array|Function(input): Array of or single function that returns transformation [through](https://github.com/dominictarr/through)-stream to be used against input files.
+}).then(function (options) {
+	// handle successful result with calculated paths
+}, function (err) {
+	// handle error
 });
 ```
 
diff --git a/lib/pure-cjs.js b/lib/pure-cjs.js
index a796ee8..1307e39 100644
--- a/lib/pure-cjs.js
+++ b/lib/pure-cjs.js
@@ -5,12 +5,12 @@ var fs = require('fs'),
 	pathUtils = require('path'),
 	nodeResolve = require('resolve'),
 	Promise = require('davy'),
+	es = require('event-stream'),
 
 	types = recast.types,
 	b = types.builders,
 	n = types.namedTypes,
 
-	whenReadFile = Promise.wrap(fs.readFile),
 	whenWriteFile = Promise.wrap(fs.writeFile),
 	
 	jsExtRegExp = /(\.js)?$/,
@@ -34,9 +34,10 @@ function toValue(value) {
 	return value instanceof Function ? value.apply(null, Array.prototype.slice.call(arguments, 1)) : value;
 }
 
-function ReplacerMap() {
+function ReplacerMap(options) {
 	this.replacers = {};
 	this.promises = [];
+	this.transform = options.transform;
 }
 
 ReplacerMap.prototype.get = function (path) {
@@ -45,7 +46,11 @@ ReplacerMap.prototype.get = function (path) {
 	}
 
 	var id = this.promises.length++,
-		replacer = this.replacers[path] = new Replacer(path, this, id);
+		replacer = this.replacers[path] = new Replacer({
+			id: id,
+			map: this,
+			path: path
+		});
 
 	this.promises[id] = replacer.promise;
 
@@ -67,15 +72,29 @@ ReplacerMap.prototype.whenAll = function (startIndex) {
 };
 
 var Replacer = recast.Visitor.extend({
-	init: function (path, map, id) {
-		this.id = id;
-		this.map = map;
-		this.path = path;
-		this.promise = whenReadFile(path, {encoding: 'utf-8'}).then(function (js) {
-			var ast = recast.parse(js, {sourceFileName: path}).program;
+	init: function (options) {
+		this.id = options.id;
+		this.map = options.map;
+		this.path = options.path;
+
+		var pipeline = [fs.createReadStream(this.path, {encoding: 'utf-8'})];
+		
+		this.map.transform.forEach(function (transform) {
+			pipeline.push(transform(this.path));
+		}, this);
+
+		var promise = new Promise();
+		pipeline.push(es.wait(function (err, js) {
+			err ? promise.reject(err) : promise.fulfill(js);
+		}));
+
+		this.promise = promise.then(function (js) {
+			var ast = recast.parse(js, {sourceFileName: this.path}).program;
 			this.visit(ast);
 			return b.functionExpression(null, astModuleArgs, b.blockStatement(ast.body));
 		}.bind(this));
+
+		es.pipeline.apply(es, pipeline);
 	},
 
 	getDependency: function (path) {
@@ -127,7 +146,10 @@ exports.transform = function (inOptions) {
 
 	options.exports = toValue(inOptions.exports, options.input, options.output);
 
-	var map = new ReplacerMap(),
+	var transform = inOptions.transform;
+	options.transform = transform ? (transform instanceof Array ? transform : [transform]) : [];
+    
+	var map = new ReplacerMap(options),
 		replacer = map.get(options.input);
 
 	return map.whenAll().then(function (modules) {
diff --git a/package.json b/package.json
index 6af36bc..a026e70 100644
--- a/package.json
+++ b/package.json
@@ -1,10 +1,9 @@
 {
   "name": "pure-cjs",
-  "version": "1.6.0",
+  "version": "1.7.0",
   "description": "Pure minimalistic CommonJS builder",
   "bin": "./bin/pure-cjs",
   "main": "./lib/pure-cjs",
-  "preferGlobal": true,
   "scripts": {
     "test": "node ./bin/pure-cjs -i sample/a.js -m -e window.A"
   },
@@ -21,6 +20,7 @@
     "commander": "~2.1.0",
     "resolve": "~0.6.1",
     "davy": "0.0.8",
-    "recast": "~0.5.7"
+    "recast": "~0.5.7",
+    "event-stream": "~3.1.0"
   }
 }