Add support for Dart Sass (#283)

gruntfile.js

@@ -1,7 +1,12 @@
 'use strict';
+const sass = require('node-sass');
+
 module.exports = grunt => {
 	grunt.initConfig({
 		sass: {
+			options: {
+				implementation: sass
+			},
 			compile: {
 				files: {
 					'test/tmp/compile.css': 'test/fixtures/test.scss',

package.json

@@ -28,14 +28,12 @@
 		"preprocess",
 		"libsass"
 	],
-	"dependencies": {
-		"node-sass": "^4.7.2"
-	},
 	"devDependencies": {
 		"grunt": "^1.0.1",
 		"grunt-cli": "^1.2.0",
 		"grunt-contrib-clean": "^1.0.0",
 		"grunt-contrib-nodeunit": "^1.0.0",
+		"node-sass": "^4.7.2",
 		"xo": "*"
 	},
 	"peerDependencies": {

readme.md

@@ -1,18 +1,30 @@
 # grunt-sass [![Build Status](https://travis-ci.org/sindresorhus/grunt-sass.svg?branch=master)](https://travis-ci.org/sindresorhus/grunt-sass)
 
-[<img src="https://rawgit.com/sass/node-sass/master/media/logo.svg" width="150" align="right">](https://github.com/sass/node-sass)
+[<img src="https://github.com/sass/sass-site/blob/master/source/assets/img/logos/logo-seal.png" width="150" align="right">](https://sass-lang.com)
 
-> Compile Sass to CSS using [node-sass](https://github.com/sass/node-sass)
+> Compile Sass to CSS using [Dart Sass][] or [Node Sass][].
 
-*The issue tracker is disabled because of continuous abuse. Use [Stack Overflow](https://stackoverflow.com/questions/tagged/node-sass) for support questions. Issues with the output should be reported on the libsass [issue tracker](https://github.com/hcatlin/libsass/issues). Install issues should be reported on the node-sass [issue tracker](https://github.com/sass/node-sass/issues). Learn how [semver works](https://nodesource.com/blog/semver-tilde-and-caret) before opening a PR updating node-sass.*
+[Dart Sass]: http://sass-lang.com/dart-sass
+[Node Sass]: https://github.com/sass/node-sass
 
-This task uses [libsass](http://libsass.org), which is a Sass compiler in C++. It's a lot faster than the original Ruby compiler and [fully compatible](http://sass-compatibility.github.io/).
+Before filing an issue with this repository, please consider:
+
+* Asking support questions on Use [Stack Overflow][].
+
+* Reporting issues with the output on the [Dart Sass][Dart Sass issues] or [LibSass][LibSass issues] issue trackers, depending which implementation you're using.
+
+* Reporting installation issues on the [Dart Sass][Dart Sass issues] or [Node Sass][Node Sass issues] issue trackers, depending on which implementation you're using.
+
+[Stack Overflow]: https://stackoverflow.com/questions/tagged/node-sass
+[Dart Sass issues]: https://github.com/sass/dart-sass/issues/new
+[LibSass issues]: https://github.com/sass/libsass/issues/new
+[Node Sass issues]: https://github.com/sass/node-sass/issues/new
 
 
 ## Install
 
 ```
-$ npm install --save-dev grunt-sass
+$ npm install --save-dev node-sass grunt-sass
 ```
 
 <a href="https://www.patreon.com/sindresorhus">
@@ -23,11 +35,42 @@ $ npm install --save-dev grunt-sass
 ## Usage
 
 ```js
+const sass = require('node-sass');
+
+require('load-grunt-tasks')(grunt);
+
+grunt.initConfig({
+	sass: {
+		options: {
+			implementation: sass,
+			sourceMap: true
+		},
+		dist: {
+			files: {
+				'main.css': 'main.scss'
+			}
+		}
+	}
+});
+
+grunt.registerTask('default', ['sass']);
+```
+
+You can choose whether to use [Dart Sass][] or [Node Sass][] by passing the module to the `implementation` option. One implementation or the other *must* be passed.
+
+Note that when using Dart Sass, **synchronous compilation is twice as fast as asynchronous compilation** by default, due to the overhead of asynchronous callbacks. To avoid this overhead, you can use the [`fibers`](https://www.npmjs.com/package/fibers) package to call asynchronous importers from the synchronous code path. To enable this, pass the `Fiber` class to the `fiber` option:
+
+```js
+const Fiber = require('fibers');
+const sass = require('node-sass');
+
 require('load-grunt-tasks')(grunt);
 
 grunt.initConfig({
 	sass: {
 		options: {
+			implementation: sass,
+			fiber: Fiber,
 			sourceMap: true
 		},
 		dist: {
@@ -46,7 +89,7 @@ Files starting with `_` are ignored to match the expected [Sass partial behaviou
 
 ## Options
 
-See the `node-sass` [options](https://github.com/sass/node-sass#options), except for `file`, `outFile`, `success`, `error`.
+See the Node Sass [options](https://github.com/sass/node-sass#options), except for `file`, `outFile`, `success`, `error`.
 
 The default value for the `precision` option is `10`, so you don't have to change it when using Bootstrap.
 

tasks/sass.js

@@ -1,26 +1,28 @@
 'use strict';
 const util = require('util');
 const path = require('path');
-const sass = require('node-sass');
 
 module.exports = grunt => {
-	grunt.verbose.writeln(`\n${sass.info}\n`);
-
 	grunt.registerMultiTask('sass', 'Compile Sass to CSS', async function () {
 		const done = this.async();
 
 		const options = this.options({
 			precision: 10
 		});
 
+		if (!options.implementation) {
+			grunt.fatal('The implementation option must be passed to the Sass task.');
+		}
+		grunt.verbose.writeln(`\n${options.implementation.info}\n`);
+
 		await Promise.all(this.files.map(async item => {
 			const [src] = item.src;
 
 			if (!src || path.basename(src)[0] === '_') {
 				return;
 			}
 
-			const result = await util.promisify(sass.render)(Object.assign({}, options, {
+			const result = await util.promisify(options.implementation.render)(Object.assign({}, options, {
 				file: src,
 				outFile: item.dest
 			}));