Add support for module-specific context with 'moduleContext' option

browser/path.js

@@ -78,3 +78,9 @@ export function resolve ( ...paths ) {
 
 	return resolvedParts.join( '/' ); // TODO windows...
 }
+
+export function join ( ...parts ) {
+	const separator = '/';
+	const replaceExp = new RegExp(separator+'{1,}', 'g');
+	return parts.join(separator).replace(replaceExp, separator);
+}

src/Bundle.js

@@ -17,7 +17,7 @@ import transformBundle from './utils/transformBundle.js';
 import collapseSourcemaps from './utils/collapseSourcemaps.js';
 import SOURCEMAPPING_URL from './utils/sourceMappingURL.js';
 import callIfFunction from './utils/callIfFunction.js';
-import { dirname, isRelative, isAbsolute, normalize, relative, resolve } from './utils/path.js';
+import { dirname, isRelative, isAbsolute, normalize, relative, resolve, join } from './utils/path.js';
 import BundleScope from './ast/scopes/BundleScope.js';
 
 export default class Bundle {
@@ -72,6 +72,33 @@ export default class Bundle {
 		this.externalModules = [];
 
 		this.context = String( options.context );
+		if (options.moduleContext) {
+			if (typeof options.moduleContext === 'object') {
+				const moduleContext = {};
+				for (const key in options.moduleContext) {
+					let resolvedKey;
+					if (isAbsolute(key)) {
+						resolvedKey = normalize(key);
+					} else {
+						const useWorkingDir = key.substring(0, 2) === `./` ? true : false;
+						let absoluteKey;
+						if (useWorkingDir) {
+							absoluteKey = join(process.cwd(), key.substring(2));
+						} else {
+							absoluteKey = join(dirname(options.entry), key);
+						}
+
+						resolvedKey = normalize(absoluteKey);
+					}
+						
+					moduleContext[resolvedKey] = options.moduleContext[key];
+				}
+
+				this.moduleContext = moduleContext;
+			} else {
+				throw new Error('options.moduleContext must be an object');
+			}
+		}
 
 		if ( typeof options.external === 'function' ) {
 			this.isExternal = options.external;

src/ast/nodes/ThisExpression.js

@@ -1,11 +1,29 @@
 import Node from '../Node.js';
+import {normalize} from '../../utils/path';
+
+function getContext (module) {
+	let context = module.bundle.context;
+	const moduleContext = module.bundle.moduleContext;
+	if (moduleContext) {
+		const moduleId = normalize(module.id);
+		const candidates = Object.keys(moduleContext)
+			.map(relPath => moduleId.indexOf(relPath) >= 0 ? moduleContext[relPath] : undefined)
+			.filter(context => !!context);
+
+		if (candidates.length) {
+			context = String( candidates[candidates.length - 1] );
+		} 
+	}
+
+	return context;
+}
 
 export default class ThisExpression extends Node {
 	initialise ( scope ) {
 		const lexicalBoundary = scope.findLexicalBoundary();
 
 		if ( lexicalBoundary.isModuleScope ) {
-			this.alias = this.module.bundle.context;
+			this.alias = getContext(this.module);
 			if ( this.alias === 'undefined' ) {
 				this.module.bundle.onwarn( 'The `this` keyword is equivalent to `undefined` at the top level of an ES module, and has been rewritten' );
 			}

src/rollup.js

@@ -24,6 +24,7 @@ const ALLOWED_KEYS = [
 	'indent',
 	'interop',
 	'intro',
+	'moduleContext',
 	'moduleId',
 	'moduleName',
 	'noConflict',

src/utils/path.js

@@ -13,4 +13,4 @@ export function normalize ( path ) {
 	return path.replace( /\\/g, '/' );
 }
 
-export { basename, dirname, extname, relative, resolve } from 'path';
+export { basename, dirname, extname, relative, resolve, join} from 'path';

test/form/custom-module-context/_config.js

@@ -0,0 +1,8 @@
+module.exports = {
+	description: 'allows custom module-specific context',
+	options: {
+		moduleContext: {
+			'main.js': 'lolwut'
+		} 
+	}
+};

test/form/custom-module-context/_expected/amd.js

@@ -0,0 +1,5 @@
+define(function () { 'use strict';
+
+	lolwut.prop = '???';
+
+});

test/form/custom-module-context/_expected/cjs.js

@@ -0,0 +1,3 @@
+'use strict';
+
+lolwut.prop = '???';

test/form/custom-module-context/_expected/es.js

@@ -0,0 +1 @@
+lolwut.prop = '???';

test/form/custom-module-context/_expected/iife.js

@@ -0,0 +1,6 @@
+(function () {
+	'use strict';
+
+	lolwut.prop = '???';
+
+}());

test/form/custom-module-context/_expected/umd.js

@@ -0,0 +1,9 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, (function () { 'use strict';
+
+	lolwut.prop = '???';
+
+})));

test/form/custom-module-context/main.js

@@ -0,0 +1 @@
+this.prop = '???';

test/test.js

@@ -90,7 +90,7 @@ describe( 'rollup', function () {
 			return rollup.rollup({ entry: 'x', plUgins: [] }).then( () => {
 				throw new Error( 'Missing expected error' );
 			}, err => {
-				assert.equal( err.message, 'Unexpected key \'plUgins\' found, expected one of: acorn, banner, cache, context, dest, entry, exports, external, footer, format, globals, indent, interop, intro, moduleId, moduleName, noConflict, onwarn, outro, paths, plugins, preferConst, sourceMap, sourceMapFile, targets, treeshake, useStrict' );
+				assert.equal( err.message, 'Unexpected key \'plUgins\' found, expected one of: acorn, banner, cache, context, dest, entry, exports, external, footer, format, globals, indent, interop, intro, moduleContext, moduleId, moduleName, noConflict, onwarn, outro, paths, plugins, preferConst, sourceMap, sourceMapFile, targets, treeshake, useStrict' );
 			});
 		});