CSS extraction and code-splitting

closes #388

src/core/create_compilers/index.ts

@@ -0,0 +1,37 @@
+import * as fs from 'fs';
+import { Dirs } from '../../interfaces';
+import RollupCompiler from './RollupCompiler';
+import { WebpackCompiler } from './WebpackCompiler';
+
+export type Compiler = RollupCompiler | WebpackCompiler;
+
+export type Compilers = {
+	client: Compiler;
+	server: Compiler;
+	serviceworker?: Compiler;
+}
+
+export default function create_compilers(bundler: string, dirs: Dirs): Compilers {
+	if (bundler === 'rollup') {
+		const sw = `${dirs.rollup}/service-worker.config.js`;
+
+		return {
+			client: new RollupCompiler(`${dirs.rollup}/client.config.js`),
+			server: new RollupCompiler(`${dirs.rollup}/server.config.js`),
+			serviceworker: fs.existsSync(sw) && new RollupCompiler(sw)
+		};
+	}
+
+	if (bundler === 'webpack') {
+		const sw = `${dirs.webpack}/service-worker.config.js`;
+
+		return {
+			client: new WebpackCompiler(`${dirs.webpack}/client.config.js`),
+			server: new WebpackCompiler(`${dirs.webpack}/server.config.js`),
+			serviceworker: fs.existsSync(sw) && new WebpackCompiler(sw)
+		};
+	}
+
+	// this shouldn't be possible...
+	throw new Error(`Invalid bundler option '${bundler}'`);
+}