add replace plugin (#128)

packages/repl/src/lib/workers/bundler/index.js

@@ -2,6 +2,7 @@ import * as rollup from 'rollup/dist/es/rollup.browser.js';
 import commonjs from './plugins/commonjs.js';
 import glsl from './plugins/glsl.js';
 import json from './plugins/json.js';
+import replace from './plugins/replace.js';
 
 self.window = self; // egregious hack to get magic-string to work in a worker
 
@@ -229,7 +230,15 @@ async function get_bundle(uid, mode, cache, lookup) {
 	try {
 		bundle = await rollup.rollup({
 			input: './App.svelte',
-			plugins: [repl_plugin, commonjs, json, glsl],
+			plugins: [
+				repl_plugin,
+				commonjs,
+				json,
+				glsl,
+				replace({
+					'process.env.NODE_ENV': JSON.stringify('production')
+				})
+			],
 			inlineDynamicImports: true,
 			onwarn(warning) {
 				all_warnings.push({

packages/repl/src/lib/workers/bundler/plugins/replace.js

@@ -0,0 +1,58 @@
+function escape(str) {
+	return str.replace(/[-[\]/{}()*+?.\\^$|]/g, '\\$&');
+}
+
+function ensureFunction(functionOrValue) {
+	if (typeof functionOrValue === 'function') {
+		return functionOrValue;
+	}
+	return function () {
+		return functionOrValue;
+	};
+}
+
+function longest(a, b) {
+	return b.length - a.length;
+}
+
+function mapToFunctions(object) {
+	return Object.keys(object).reduce(function (functions, key) {
+		functions[key] = ensureFunction(object[key]);
+		return functions;
+	}, {});
+}
+
+function replace(options) {
+	const functionValues = mapToFunctions(options);
+	const keys = Object.keys(functionValues).sort(longest).map(escape);
+
+	const pattern = new RegExp('\\b(' + keys.join('|') + ')\\b', 'g');
+
+	return {
+		name: 'replace',
+
+		transform: function transform(code, id) {
+			let hasReplacements = false;
+			let match;
+			let start;
+			let end;
+			let replacement;
+
+			code = code.replace(pattern, (_, key) => {
+				hasReplacements = true;
+				return String(functionValues[key](id));
+			});
+
+			if (!hasReplacements) {
+				return null;
+			}
+
+			return {
+				code,
+				map: null
+			};
+		}
+	};
+}
+
+export default replace;