Support alternate preprocessors for assets

lib/preprocessors.js

@@ -2,37 +2,55 @@
 
 var pkg = require(process.cwd() + '/package');
 var deps = pkg['devDependencies'];
+var path = require('path');
+var Registry = require('./preprocessors/registry');
+var requireLocal = require('./utilities/require-local');
 
-function preprocessorType(preprocessor) {
-  var types = Object.keys(preprocessor.supportedPlugins);
+var registry = new Registry(deps);
 
-  return types.reduce(function(final, type) {
-    var plugin = preprocessor.supportedPlugins[type];
+registry.add('css', 'broccoli-sass', 'scss');
+registry.add('css', 'broccoli-ruby-sass', 'scss');
+registry.add('css', 'broccoli-less-single', 'less');
+registry.add('css', 'broccoli-stylus-single', 'styl');
 
-    if(deps[plugin]) {
-      return type;
-    }
+registry.add('js', 'broccoli-coffee', 'coffee');
+registry.add('js', 'broccoli-sweetjs', 'js');
 
-    return final;
-  }, preprocessor.fallback);
-}
+registry.add('template', 'broccoli-template', ['hbs', 'handlebars']);
+registry.add('template', 'broccoli-emblem-compiler', ['embl', 'emblem']);
 
-var js = require('./preprocessors/javascript');
-var css = require('./preprocessors/css');
-var templates = require('./preprocessors/templates');
+module.exports.registerPlugin = registry.add.bind(registry);
 
 module.exports.preprocessCss = function(trees, inputPath, outputPath, options) {
-  var type = preprocessorType(css);
-  return css[type].call(null, trees, inputPath, outputPath, options);
+  var plugin = registry.load('css');
+
+  if(!plugin) { return trees; }
+
+  var input = path.join(inputPath, 'app.' + plugin.ext);
+  var output = path.join(outputPath, 'app.css');
+  return requireLocal(plugin.name).call(null, trees, input, output, options);
 };
 
 module.exports.preprocessTemplates = function(tree) {
-  var type = preprocessorType(templates);
-  return templates[type].call(null, tree);
+  var plugin = registry.load('template');
+
+  return requireLocal(plugin.name).call(null, tree, {
+    extensions: plugin.ext,
+    compileFunction: 'Ember.Handlebars.compile'
+  });
 };
 
 module.exports.preprocessJs = function(tree, inputPath, outputPath, options) {
-  var type = preprocessorType(js);
-  if(!type) { return tree; }
-  return js[type].call(null, tree, inputPath, outputPath, options);
+  var plugin = registry.load('js');
+
+  if(!plugin) { return tree; }
+
+  if(plugin.name.indexOf('coffee') !== -1) {
+    options = options || {};
+    options.bare = true;
+    options.srcDir = inputPath;
+    options.destDir = outputPath;
+  }
+
+  return requireLocal(plugin.name).call(null, tree, options);
 };

lib/preprocessors/registry.js

@@ -0,0 +1,36 @@
+'use strict';
+
+var isArray = require('lodash-node/compat/objects/isArray');
+
+function Plugin(name, ext) {
+  this.name = name;
+  this.ext = ext;
+}
+
+function Registry(plugins) {
+  this.registry = {};
+  this.availablePlugins = plugins;
+}
+
+module.exports = Registry;
+
+Registry.prototype.load = function(type) {
+  return this.registry[type].reduce(function(actual, plugin) {
+    if(this.availablePlugins.hasOwnProperty(plugin.name)) {
+      return plugin;
+    } else {
+      return actual;
+    }
+  }.bind(this), null);
+};
+
+
+Registry.prototype.add = function(type, name, extension) {
+  var registered = this.registry[type];
+
+  if(isArray(registered)) {
+    registered.push(new Plugin(name, extension));
+  } else {
+    this.registry[type] = [new Plugin(name, extension)];
+  }
+};

tests/unit/preprocessors/registry-test.js

@@ -0,0 +1,44 @@
+'use strict';
+
+var assert = require('../../helpers/assert');
+var PluginRegistry = require('../../../lib/preprocessors/registry');
+
+var pkg, registry;
+
+describe('Plugin Loader', function() {
+
+  beforeEach(function() {
+    pkg = {
+      devDependencies: {
+        'broccoli-sass': 'latest',
+        'broccoli-coffee': 'latest'
+      }
+    };
+    registry = new PluginRegistry(pkg.devDependencies);
+    registry.add('css', 'broccoli-sass');
+    registry.add('css', 'broccoli-ruby-sass');
+  });
+
+  it('returns first plugin when only one', function() {
+    var plugin = registry.load('css');
+    assert.equal(plugin.name, 'broccoli-sass');
+  });
+
+  it('returns the correct plugin when there are more than one', function() {
+    registry.availablePlugins = { 'broccoli-ruby-sass': 'latest' };
+    var plugin = registry.load('css');
+    assert.equal(plugin.name, 'broccoli-ruby-sass');
+  });
+
+  it('returns plugin of the correct type', function() {
+    registry.add('js', 'broccoli-coffee');
+    var plugin = registry.load('js');
+    assert.equal(plugin.name, 'broccoli-coffee');
+  });
+
+  it('returns null when no plugin available for type', function() {
+    registry.add('blah', 'not-available');
+    var plugin = registry.load('blah');
+    assert.notOk(plugin, 'loaded a plugin that wasn\'t in dependencies');
+  });
+});