svelte/rollup.config.js

import fs from 'fs';
import replace from '@rollup/plugin-replace';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import json from '@rollup/plugin-json';
import sucrase from '@rollup/plugin-sucrase';
import typescript from '@rollup/plugin-typescript';
import pkg from './package.json';

const is_publish = !!process.env.PUBLISH;
const external = (id) => id.startsWith('svelte/');
const ts_plugin = is_publish
	? typescript({ include: 'src/**', typescript: require('typescript') })
	: sucrase({ transforms: ['typescript'] });

// documented in src/ambient.ts
const globals = (name) =>
	replace({
		'var __DEV__: boolean': 'var rollup_removes_this',
		'__DEV__': name === 'dev',
		'var __TEST__: boolean': 'var rollup_removes_this',
		'__TEST__': name === 'test',
		'var __VERSION__: string': 'var rollup_removes_this',
		'__VERSION__': `"${pkg.version}"`,
	});
/**
 *
 */
function map_outputs({ output, plugins, ...rest }) {
	return Object.keys(output).flatMap((name) =>
		['esm', 'cjs'].map((format) => ({
			external,
			...rest,
			output: {
				format,
				file: `${name !== 'default' ? name + '/' : ''}${output[name].file}.${format === 'esm' ? 'mjs' : 'js'}`,
				paths: (id) => external(id) && `${id.replace('svelte', output[name].path)}`,
			},
			plugins: [globals(name), ...(plugins || [])],
		}))
	);
}

function writeFileSync(...arr) {
	arr.filter(Boolean).forEach(({ dir, content }) => fs.writeFileSync(dir, content));
}

fs.writeFileSync(`./compiler.d.ts`, `export { compile, parse, preprocess, version } from './types/compiler/index';`);
export default [
	/* main exports */
	...map_outputs({
		input: `src/runtime/index.ts`,
		output: {
			/**
			 * Production main runtime
			 * -> 'svelte/index.js'
			 */
			default: { file: 'index', path: '.' },
			/**
			 * Development main runtime
			 * -> 'svelte/dev/index.js'
			 * redirected to by the compiler
			 */
			dev: { file: 'index', path: '.' },
		},
		plugins: [ts_plugin],
	}),
	/* 'svelte/[library]' exports */
	...fs
		.readdirSync('src/runtime')
		.filter((dir) => fs.statSync(`src/runtime/${dir}`).isDirectory())
		.flatMap((library) =>
			map_outputs({
				input: `src/runtime/${library}/index.ts`,
				output: {
					/**
					 * Production runtime
					 * -> 'svelte/[library]/index.js'
					 */
					[library]: { file: 'index', path: '..' },
					/**
					 * Development runtime
					 * -> 'svelte/dev/[library].js'
					 * Must be redirected to by user's bundler
					 */
					dev: { file: library, path: '.' },
				},
				plugins: [
					ts_plugin,
					{
						writeBundle(bundle) {
							writeFileSync(
								/* gives internal function names to the compiler */
								library === 'internal' &&
									bundle['index.mjs'] && {
										dir: `src/compiler/compile/internal_exports.ts`,
										content: `
										// This file is automatically generated
										export default new Set(${JSON.stringify(bundle['index.mjs'].exports)});`,
									},
								/* adds package.json to every svelte/[library] */
								{
									dir: `${library}/package.json`,
									content: `{
										"main": "./index",
										"module": "./index.mjs",
										"types": "./index.d.ts"
									}`,
								},
								/* exports types */
								{
									dir: `${library}/index.d.ts`,
									content: `export * from '../types/runtime/${library}/index';`,
								}
							);
						},
					},
				],
			})
		),
	/* compiler.js */
	{
		input: 'src/compiler/index.ts',
		plugins: [globals('compiler'), resolve(), commonjs({ include: ['node_modules/**'] }), json(), ts_plugin],
		output: {
			file: 'compiler.js',
			format: is_publish ? 'umd' : 'cjs',
			name: 'svelte',
			sourcemap: true,
		},
		external: is_publish ? [] : (id) => id === 'acorn' || id === 'magic-string' || id.startsWith('css-tree'),
	},
];