Add transformBundle plugin hook

src/Bundle.js

@@ -11,6 +11,7 @@ import getExportMode from './utils/getExportMode.js';
 import getIndentString from './utils/getIndentString.js';
 import { unixizePath } from './utils/normalizePlatform.js';
 import transform from './utils/transform.js';
+import transformBundle from './utils/transformBundle.js';
 import collapseSourcemaps from './utils/collapseSourcemaps.js';
 import callIfFunction from './utils/callIfFunction.js';
 import { isRelative } from './utils/path.js';
@@ -46,6 +47,10 @@ export default class Bundle {
 			.map( plugin => plugin.transform )
 			.filter( Boolean );
 
+		this.bundleTransformers = this.plugins
+			.map( plugin => plugin.transformBundle )
+			.filter( Boolean );
+
 		this.moduleById = blank();
 		this.modules = [];
 
@@ -257,7 +262,7 @@ export default class Bundle {
 			map.sources = map.sources.map( unixizePath );
 		}
 
-		return { code, map };
+		return transformBundle( { code, map }, this.bundleTransformers );
 	}
 
 	sort () {

src/utils/transformBundle.js

@@ -0,0 +1,53 @@
+import Promise from 'es6-promise/lib/es6-promise/promise.js';
+
+export default function transformBundle ( source, transformers ) {
+	if ( typeof source === 'string' ) {
+		source = {
+			code: source,
+			map: null
+		};
+	}
+
+	return transformers.reduce( ( previous, transformer ) => {
+		let result = transformer( previous )
+
+		if ( result == null ) return previous;
+
+		if ( typeof result === 'string' ) {
+			result = {
+				code: result,
+				map: null
+			};
+		}
+		// `result.map` can only be a string if `result` isn't
+		else if ( typeof result.map === 'string' ) {
+			result.map = JSON.parse( result.map );
+		}
+
+		return result;
+
+	}, source );
+
+	// Promisified version
+	// return transformers.reduce( ( promise, transformer ) => {
+	// 	return promise.then( previous => {
+	// 		return Promise.resolve( transformer( previous ) ).then( result => {
+	// 			if ( result == null ) return previous;
+
+	// 			if ( typeof result === 'string' ) {
+	// 				result = {
+	// 					code: result,
+	// 					map: null
+	// 				};
+	// 			}
+	// 			// `result.map` can only be a string if `result` isn't
+	// 			else if ( typeof result.map === 'string' ) {
+	// 				result.map = JSON.parse( result.map );
+	// 			}
+
+	// 			return result;
+	// 		});
+	// 	});
+
+	// }, Promise.resolve( source ) );
+}

test/form/transform-bundle-plugin/_config.js

@@ -0,0 +1,21 @@
+module.exports = {
+	description: 'allows plugins to set banner and footer options',
+	options: {
+		plugins: [
+			{
+				transformBundle: function (result) {
+					return {
+						code: '/* first plugin */'
+					};
+				}
+			},
+			{
+				transformBundle: function (result) {
+					return {
+						code: result.code + '\n/* second plugin */'
+					};
+				}
+			}
+		]
+	}
+}

test/form/transform-bundle-plugin/_expected/amd.js

@@ -0,0 +1,2 @@
+/* first plugin */
+/* second plugin */

test/form/transform-bundle-plugin/_expected/cjs.js

@@ -0,0 +1,2 @@
+/* first plugin */
+/* second plugin */

test/form/transform-bundle-plugin/_expected/es6.js

@@ -0,0 +1,2 @@
+/* first plugin */
+/* second plugin */

test/form/transform-bundle-plugin/_expected/iife.js

@@ -0,0 +1,2 @@
+/* first plugin */
+/* second plugin */

test/form/transform-bundle-plugin/_expected/umd.js

@@ -0,0 +1,2 @@
+/* first plugin */
+/* second plugin */

test/form/transform-bundle-plugin/main.js

@@ -0,0 +1 @@
+console.log( 1 + 1 );