Merge pull request #41 from Conduitry/gh-40

Pass through dependencies from preprocessor

README.md

@@ -65,6 +65,11 @@ export default {
 ```
 
 
+## Preprocessing and dependencies
+
+If you are using the `preprocess` feature, then your callback responses may — in addition to the `code` and `map` values described in the Svelte compile docs — also optionally include a `dependencies` array. This should be the paths of additional files that the preprocessor result in some way depends upon. In Rollup 0.61+ in watch mode, any changes to these additional files will also trigger re-builds.
+
+
 ## `pkg.svelte`
 
 If you're importing a component from your node_modules folder, and that component's package.json has a `"svelte"` property...

index.js

@@ -198,9 +198,28 @@ module.exports = function svelte(options = {}) {
 
 			if (!~extensions.indexOf(extension)) return null;
 
-			return (options.preprocess ? preprocess(code, Object.assign({}, options.preprocess, { filename : id })) : Promise.resolve(code)).then(code => {
+			const dependencies = [];
+			let preprocessPromise;
+			if (options.preprocess) {
+				const preprocessOptions = {};
+				for (const key in options.preprocess) {
+					preprocessOptions[key] = (...args) => {
+						return Promise.resolve(options.preprocess[key](...args)).then(resp => {
+							if (resp && resp.dependencies) {
+								dependencies.push(...resp.dependencies);
+							}
+							return resp;
+						});
+					};
+				}
+				preprocessPromise = preprocess(code, Object.assign(preprocessOptions, { filename: id })).then(code => code.toString());
+			} else {
+				preprocessPromise = Promise.resolve(code);
+			}
+
+			return preprocessPromise.then(code => {
 				const compiled = compile(
-					code.toString(),
+					code,
 					Object.assign({}, {
 						onwarn: warning => {
 							if ((options.css || !options.emitCss) && warning.code === 'css-unused-selector') return;
@@ -225,6 +244,8 @@ module.exports = function svelte(options = {}) {
 					cssLookup.set(fname, compiled.css);
 				}
 
+				compiled.js.dependencies = dependencies;
+
 				return compiled.js;
 			});
 		},

test/test.js

@@ -40,10 +40,10 @@ describe('rollup-plugin-svelte', () => {
 		);
 	});
 
-	it('creates a {code, map} object, excluding the AST etc', () => {
+	it('creates a {code, map, dependencies} object, excluding the AST etc', () => {
 		const { transform } = plugin();
 		return transform('', 'test.html').then(compiled => {
-			assert.deepEqual(Object.keys(compiled), ['code', 'map']);
+			assert.deepEqual(Object.keys(compiled), ['code', 'map', 'dependencies']);
 		});
 	});
 
@@ -141,18 +141,22 @@ describe('rollup-plugin-svelte', () => {
 					return {
 						code: content
 							.replace('__REPLACEME__', 'replaced')
-							.replace('__FILENAME__', filename)
+							.replace('__FILENAME__', filename),
+						dependencies: ['foo'],
 					};
-				}
+				},
+				style: () => null,
 			}
 		});
 
 		return transform(`
 			<h1>Hello __REPLACEME__!</h1>
 			<h2>file: __FILENAME__</h2>
-		`, 'test.html').then(({ code }) => {
+			<style>h1 { color: red; }</style>
+		`, 'test.html').then(({ code, dependencies }) => {
 			assert.equal(code.indexOf('__REPLACEME__'), -1, 'content not modified');
 			assert.notEqual(code.indexOf('file: test.html'), -1, 'filename not replaced');
+			assert.deepEqual(dependencies, ['foo']);
 		});
 	});