Make this package implementation-agnostic

README.md

@@ -5,7 +5,10 @@
 [![Ember Observer Score](http://emberobserver.com/badges/ember-cli-sass.svg)](http://emberobserver.com/addons/ember-cli-sass)
 [![Dependency Status](https://david-dm.org/aexmachina/ember-cli-sass.svg)](https://david-dm.org/aexmachina/ember-cli-sass)
 
-ember-cli-sass uses libsass to preprocess your ember-cli app's files and provides support for source maps and include paths. It provides support for the common use case for Ember.js projects:
+ember-cli-sass uses [Dart Sass][] or [LibSass][] to preprocess your ember-cli app's files and provides support for source maps and include paths. It provides support for the common use case for Ember.js projects:
+
+[Dart Sass]: https://sass-lang.com/dart-sass
+[LibSass]: https://sass-lang.com/libsass
 
 - Source maps by default in development
 - Support for [`outputPaths` configuration](http://ember-cli.com/user-guide/#configuring-output-paths)
@@ -16,36 +19,43 @@ ember-cli-sass uses libsass to preprocess your ember-cli app's files and provide
 
 ```
 ember install ember-cli-sass
+npm install --save-dev sass # or node-sass to use LibSass
 ```
 
 ### Addon Development
 
 If you want to use ember-cli-sass in an addon and you want to distribute the compiled CSS it must be installed as a `dependency` so that `addon/styles/addon.scss` is compiled into `dist/assets/vendor.css`. This can be done using:
 
 ```bash
-npm install --save ember-cli-sass
+npm install --save ember-cli-sass sass
 ```
 
 ## Usage
 
-By default this addon will compile `app/styles/app.scss` into `dist/assets/app.css` and produce
-a source map for your delectation.
-
-If you want more control then you can specify options using the
-`sassOptions` config property in `ember-cli-build.js` (or in `Brocfile.js` if you are using an Ember CLI version older than 1.13):
+To use this addon, you must pass a Sass implementation to the `sassOptions`
+config property in `ember-cli-build.js` (or in `Brocfile.js` if you are using an
+Ember CLI version older than 1.13):
 
 ```javascript
+var sass = require('sass');
+
 var app = new EmberApp({
-  sassOptions: {...}
+  sassOptions: {
+    implementation: sass
+  }
 });
 ```
 
+By default this addon will compile `app/styles/app.scss` into `dist/assets/app.css` and produce
+a source map for your delectation.
+
+If you want more control, you can pass additional options to `sassOptions`:
+
 - `includePaths`: an array of include paths
 - `onlyIncluded`: true/false whether to use only what is in `app/styles` and `includePaths`. This may helps with performance, particularly when using NPM linked modules
 - `sourceMap`: controls whether to generate sourceMaps, defaults to `true` in development. The sourceMap file will be saved to `options.outputFile + '.map'`
 - `extension`: specifies the file extension for the input files, defaults to `scss`. Set to `sass` if you want to use `.sass` instead.
 - `passthrough`: an optional hash of [broccoli-funnel](https://github.com/broccolijs/broccoli-funnel) configuration for files from the styles tree to be passed through to `dist`
-- `nodeSass`: Allows a different version of [node-sass](https://www.npmjs.com/package/node-sass) to be used (see below)
 - See [broccoli-sass-source-maps](https://github.com/aexmachina/broccoli-sass-source-maps) for a list of other supported options.
 
 ### Processing multiple files
@@ -65,22 +75,6 @@ var app = new EmberApp({
 });
 ```
 
-### Choosing the version of node-sass
-
-You can specify which version of node-sass to use with the [`nodeSass` option](https://github.com/aexmachina/broccoli-sass-source-maps#usage).
-
-Add the version that you want to use to _your_ package.json and then provide that version of the module using the `nodeSass` option:
-
-```js
-var nodeSass = require('node-sass'); // loads the version in your package.json
-
-var app = new EmberApp({
-  sassOptions: {
-    nodeSass: nodeSass
-  }
-});
-```
-
 ### Source Maps
 
 Source maps work for reading with no configuration, but to edit the SASS in the Dev Tools
@@ -128,8 +122,8 @@ To compile SASS within an ember-cli addon, there are a few additional steps:
 
 1. Include your styles in `addon/styles/addon.scss`.
 
-2. Ensure you've installed `ember-cli-sass` under `dependencies` in your
-   `package.json`.
+2. Ensure you've installed `ember-cli-sass` and either `sass` or `node-sass`
+   under `dependencies` in your `package.json`.
 
 3. Define an `included` function in your app:
    ```js

ember-cli-build.js

@@ -2,6 +2,7 @@
 'use strict';
 
 const EmberAddon = require('ember-cli/lib/broccoli/ember-addon');
+const sass = require('sass');
 
 module.exports = function(defaults) {
   let app = new EmberAddon(defaults, {
@@ -14,6 +15,7 @@ module.exports = function(defaults) {
       }
     },
     sassOptions: {
+      implementation: sass,
       includePaths: [
         'bower_components/SpinKit/scss',
       ]

index.js

@@ -1,6 +1,6 @@
 'use strict';
 /* eslint-env node */
-var SassCompiler = require('broccoli-sass-source-maps');
+var SassCompilerFactory = require('broccoli-sass-source-maps');
 var path = require('path');
 var VersionChecker = require('ember-cli-version-checker');
 var Funnel = require('broccoli-funnel');
@@ -30,6 +30,15 @@ SASSPlugin.prototype.toTree = function(tree, inputPath, outputPath, inputOptions
     inputTrees = inputTrees.concat(options.includePaths);
   }
 
+  if (!options.implementation) {
+    var error = new Error(
+      'sassOptions must have an implementation option. For example:\n' +
+      '  sassOptions: {implementation: require("sass")}');
+    error.type = 'Sass Plugin Error';
+      throw error;
+  }
+
+  var SassCompiler = SassCompilerFactory(options.implementation);
   var ext = options.extension || 'scss';
   var paths = options.outputPaths;
   var trees = Object.keys(paths).map(function(file) {