Add WebAssets support

README.rst

@@ -41,6 +41,16 @@ To compile ES6 code to ES5 for everyday usage you can use ``dukpy.babel_compile`
     ... ''')
     '"use strict";\n\nvar _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };\n\nvar _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };\n\nvar Point = (function () {\n    function Point(x, y) {\n        _classCallCheck(this, Point);\n\n        this.x = x;\n        this.y = y;\n    }\n\n    _prototypeProperties(Point, null, {\n        toString: {\n            value: function toString() {\n                return "(" + this.x + ", " + this.y + ")";\n            },\n            writable: true,\n            configurable: true\n        }\n    });\n\n    return Point;\n})();\n'
 
+The DukPY based BabelJS compiler also provides a WebAssets ( http://webassets.readthedocs.org/en/latest/ ) filter to automatically compile ES6 code in your assets pipeline.
+You register this filter as ``babeljs`` within WebAssets using::
+
+    from webassets.filter import register_filter
+    from dukpy.webassets.babelfilter import BabelJS
+    
+    register_filter(BabelJS)
+
+Which makes the filter available with the ``babeljs`` name.
+
 **NOTE:** When using the BabelJS compiler for code that needs to run in the browser, make sure to add https://cdnjs.cloudflare.com/ajax/libs/babel-core/4.6.6/browser-polyfill.js dependency.
 
 Using the JavaScript Interpreter

webassets/babelfilter.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import absolute_import, print_function
+from webassets.filter import Filter
+
+import dukpy
+
+
+__all__ = ('BabelJS', )
+
+
+class BabelJS(Filter):
+    name = 'babeljs'
+    max_debug_level = None
+
+    def setup(self):
+        super(BabelJS, self).setup()
+
+    def input(self, _in, out, **kw):
+        src = dukpy.babel_compile(_in.read())
+        out.write(src)