add a --bundler option, for forcing rollup or webpack

src/cli/build.ts

@@ -1,14 +1,18 @@
 import { build as _build } from '../api/build';
-import colors from 'kleur';
+import * as colors from 'kleur';
 import { locations } from '../config';
+import validate_bundler from './utils/validate_bundler';
+
+export function build(opts: { bundler?: string }) {
+	const bundler = validate_bundler(opts.bundler);
 
-export function build() {
 	return new Promise((fulfil, reject) => {
 		try {
 			const emitter = _build({
 				dest: locations.dest(),
 				app: locations.app(),
 				routes: locations.routes(),
+				bundler,
 				webpack: 'webpack',
 				rollup: 'rollup'
 			});

src/cli/dev.ts

@@ -5,7 +5,7 @@ import prettyMs from 'pretty-ms';
 import { dev as _dev } from '../api/dev';
 import * as events from '../api/interfaces';
 
-export function dev(opts: { port: number, open: boolean }) {
+export function dev(opts: { port: number, open: boolean, bundler?: string }) {
 	try {
 		const watcher = _dev(opts);
 

src/cli/export.ts

@@ -1,5 +1,5 @@
 import { exporter as _exporter } from '../api/export';
-import colors from 'kleur';
+import * as colors from 'kleur';
 import prettyBytes from 'pretty-bytes';
 import { locations } from '../config';
 

src/cli/utils/validate_bundler.ts

@@ -0,0 +1,21 @@
+import * as fs from 'fs';
+
+export default function validate_bundler(bundler?: string) {
+	if (!bundler) {
+		bundler = (
+			fs.existsSync('rollup') ? 'rollup' :
+			fs.existsSync('webpack') ? 'webpack' :
+			null
+		);
+
+		if (!bundler) {
+			throw new Error(`Could not find a 'rollup' or 'webpack' directory`);
+		}
+	}
+
+	if (bundler !== 'rollup' && bundler !== 'webpack') {
+		throw new Error(`'${bundler}' is not a valid option for --bundler — must be either 'rollup' or 'webpack'`);
+	}
+
+	return bundler;
+}