support custom resolvePath functions

README.md

@@ -92,7 +92,13 @@ The example below is aspirational. It isn't yet implemented - it exists in the n
 
 ```js
 rollup.rollup( 'app.js', {
-  /* options */
+  // Override the default path resolution
+  resolvePath: function ( importee, importer ) {
+    // return a string or a falsy value - if falsy,
+    // import is kept external to the bundle.
+    // Alternative, return a Promise that fulfils
+    // with a string or falsy value
+  }
 }).then( function ( bundle ) {
   // generate code and a sourcemap
   const { code, map } = bundle.generate({

src/Bundle.js

@@ -1,5 +1,5 @@
-import { resolve } from 'path';
-import { readFile } from 'sander';
+import { dirname, resolve } from 'path';
+import { readFile, Promise } from 'sander';
 import MagicString from 'magic-string';
 import { keys, has } from './utils/object';
 import { sequence } from './utils/promise';
@@ -12,8 +12,9 @@ import { defaultResolver } from './utils/resolvePath';
 
 export default class Bundle {
 	constructor ( options ) {
-		this.base = options.base || process.cwd();
-		this.entryPath = resolve( this.base, options.entry ).replace( /\.js$/, '' ) + '.js';
+		this.entryPath = resolve( options.entry ).replace( /\.js$/, '' ) + '.js';
+		this.base = dirname( this.entryPath );
+
 		this.resolvePath = options.resolvePath || defaultResolver;
 
 		this.entryModule = null;
@@ -23,8 +24,8 @@ export default class Bundle {
 	}
 
 	fetchModule ( importee, importer ) {
-		const path = this.resolvePath( importee, importer );
-
+		return Promise.resolve( importer === null ? importee : this.resolvePath( importee, importer ) )
+			.then( path => {
 				if ( !path ) {
 					// external module
 					if ( !has( this.modulePromises, importee ) ) {
@@ -50,11 +51,12 @@ export default class Bundle {
 				}
 
 				return this.modulePromises[ path ];
+			});
 	}
 
 	build () {
 		// bring in top-level AST nodes from the entry module
-		return this.fetchModule( this.entryPath )
+		return this.fetchModule( this.entryPath, null )
 			.then( entryModule => {
 				this.entryModule = entryModule;
 

src/rollup.js

@@ -8,7 +8,7 @@ SOURCEMAPPING_URL += 'ppingURL';
 export function rollup ( entry, options = {} ) {
 	const bundle = new Bundle({
 		entry,
-		base: options.base || process.cwd()
+		resolvePath: options.resolvePath
 	});
 
 	return bundle.build().then( () => {

test/samples/custom-path-resolver-async/_config.js

@@ -0,0 +1,20 @@
+module.exports = {
+	description: 'uses a custom path resolver (synchronous)',
+	options: {
+		resolvePath: function ( importee, importer ) {
+			var Promise = require( 'sander' ).Promise;
+			var resolved;
+
+			if ( importee === 'foo' ) {
+				resolved = require( 'path' ).resolve( __dirname, 'bar.js' );
+			} else {
+				resolved = false;
+			}
+
+			return Promise.resolve( resolved );
+		}
+	},
+	exports: function ( exports, assert ) {
+		assert.strictEqual( exports.path, require( 'path' ) );
+	}
+};

test/samples/custom-path-resolver-async/bar.js

@@ -0,0 +1 @@
+export default 'bar';

test/samples/custom-path-resolver-async/main.js

@@ -0,0 +1,6 @@
+import foo from 'foo';
+import path from 'path';
+
+assert.equal( foo, 'bar' );
+
+export { path };

test/samples/custom-path-resolver-sync/_config.js

@@ -0,0 +1,15 @@
+module.exports = {
+	description: 'uses a custom path resolver (synchronous)',
+	options: {
+		resolvePath: function ( importee, importer ) {
+			if ( importee === 'foo' ) {
+				return require( 'path' ).resolve( __dirname, 'bar.js' );
+			}
+
+			return false;
+		}
+	},
+	exports: function ( exports, assert ) {
+		assert.strictEqual( exports.path, require( 'path' ) );
+	}
+};

test/samples/custom-path-resolver-sync/bar.js

@@ -0,0 +1 @@
+export default 'bar';

test/samples/custom-path-resolver-sync/main.js

@@ -0,0 +1,6 @@
+import foo from 'foo';
+import path from 'path';
+
+assert.equal( foo, 'bar' );
+
+export { path };

test/test.js

@@ -8,6 +8,16 @@ var rollup = require( '../dist/rollup' );
 
 var SAMPLES = path.resolve( __dirname, 'samples' );
 
+function extend ( target ) {
+	[].slice.call( arguments, 1 ).forEach( function ( source ) {
+		source && Object.keys( source ).forEach( function ( key ) {
+			target[ key ] = source[ key ];
+		});
+	});
+
+	return target;
+}
+
 describe( 'rollup', function () {
 	it( 'exists', function () {
 		assert.ok( !!rollup );
@@ -23,11 +33,11 @@ describe( 'rollup', function () {
 		var config = require( SAMPLES + '/' + dir + '/_config' );
 
 		( config.solo ? it.only : it )( config.description, function () {
-			return rollup.rollup( SAMPLES + '/' + dir + '/main.js' )
+			return rollup.rollup( SAMPLES + '/' + dir + '/main.js', extend( {}, config.options ) )
 				.then( function ( bundle ) {
-					var result = bundle.generate({
+					var result = bundle.generate( extend( {}, config.bundleOptions, {
 						format: 'cjs'
-					});
+					}));
 
 					try {
 						var fn = new Function( 'require', 'exports', 'assert', result.code );