Svelte with faucet-pipeline

faucet.config.js

"use strict";

let sveltify = require("./faucet_svelte");

module.exports = sveltify({
	svelte: [{
		source: "./src/index.js",
		target: "./dist/bundle.js",
		styles: "./dist/components.css",
		dev: process.env.NODE_ENV !== "production"
	}]
});

faucet_svelte.js

"use strict";

let svelte = require("rollup-plugin-svelte");
let BasicBundle = require("faucet-pipeline-js/lib/bundle/basic");

// Svelte bundles are just JavaScript bundles with additional configuration
// options (see below), so we extend the `js` section accordingly
// * `styles` is an optional file path for extracting CSS
// * `ssr` (boolean) activates server-side rendering
// * `dev` (boolean) enables run-time checks for development purposes
module.exports = config => {
	let svelteConfig = config.svelte;
	if(!svelteConfig) {
		return;
	}
	injectPlugin();

	svelteConfig = svelteConfig.map((cfg, i) => {
		let pluginConfig = { dev: !!cfg.dev };
		if(cfg.ssr) {
			pluginConfig.generate = "ssr";
		}
		let { styles } = cfg;
		if(styles) {
			// XXX: file path should be relative to config
			pluginConfig.css = css => void css.write(styles, !!cfg.sourcemaps);
		}

		// TODO: use faucet-js's `extract`?
		cfg = Object.assign({
			// XXX: hack to communicate between `BasicBundle` and individual
			//      bundle configurations (cf. `injectPlugin`)
			sourcemaps: {
				svelte: svelte(pluginConfig),
				actual: cfg.sourcemaps
			}
		}, cfg);
		delete cfg.styles;
		delete cfg.ssr;
		delete cfg.dev;
		return cfg;
	});

	config = Object.assign({}, config);
	config.js = (config.js || []).concat(svelteConfig);
	delete config.svelte;

	return config;
};

// hijacks faucet internals to inject plugin
function injectPlugin() {
	let original = BasicBundle.prototype.compile;
	BasicBundle.prototype.compile = function() {
		if(this._svelte === undefined) { // initialize
			let config = this._config;
			// XXX: hacky; relies on faucet internals
			let { sourcemap } = config.writeConfig;
			let plugin = sourcemap && sourcemap.svelte;
			if(plugin) {
				config.readConfig.plugins.unshift(plugin);
				config.writeConfig.sourcemap = sourcemap.actual;
				this._svelte = true;
			} else {
				this._svelte = false;
			}
		}
		return original.apply(this, arguments);
	};
}