support multiple preprocessors, handle dependencies - fixes #1973

src/preprocess/index.ts

@@ -1,25 +1,25 @@
 import { SourceMap } from 'magic-string';
 import replaceAsync from '../utils/replaceAsync';
 
-export interface PreprocessOptions {
+export interface PreprocessorGroup {
 	markup?: (options: {
 		content: string,
 		filename: string
-	}) => { code: string, map?: SourceMap | string };
+	}) => { code: string, map?: SourceMap | string, dependencies?: string[] };
 	style?: Preprocessor;
 	script?: Preprocessor;
-	filename?: string
 }
 
 export type Preprocessor = (options: {
 	content: string,
 	attributes: Record<string, string | boolean>,
 	filename?: string
-}) => { code: string, map?: SourceMap | string };
+}) => { code: string, map?: SourceMap | string, dependencies?: string[] };
 
 interface Processed {
 	code: string;
 	map?: SourceMap | string;
+	dependencies?: string[];
 }
 
 function parseAttributeValue(value: string) {
@@ -39,28 +39,55 @@ function parseAttributes(str: string) {
 
 export default async function preprocess(
 	source: string,
-	options: PreprocessOptions
+	preprocessor: PreprocessorGroup | PreprocessorGroup[],
+	options?: { filename?: string }
 ) {
-	if (options.markup) {
-		const processed: Processed = await options.markup({
+	const filename = (options && options.filename) || preprocessor.filename; // legacy
+	const dependencies = [];
+
+	const preprocessors = Array.isArray(preprocessor) ? preprocessor : [preprocessor];
+
+	const markup = preprocessors.map(p => p.markup).filter(Boolean);
+	const script = preprocessors.map(p => p.script).filter(Boolean);
+	const style = preprocessors.map(p => p.style).filter(Boolean);
+
+	for (const fn of markup) {
+		const processed: Processed = await fn({
 			content: source,
-			filename: options.filename,
+			filename
 		});
+		if (processed && processed.dependencies) dependencies.push(...processed.dependencies);
 		source = processed ? processed.code : source;
 	}
-	if (options.style || options.script) {
+
+	for (const fn of script) {
+		source = await replaceAsync(
+			source,
+			/<script([^]*?)>([^]*?)<\/script>/gi,
+			async (match, attributes, content) => {
+				const processed: Processed = await fn({
+					content,
+					attributes: parseAttributes(attributes),
+					filename
+				});
+				if (processed && processed.dependencies) dependencies.push(...processed.dependencies);
+				return processed ? `<script${attributes}>${processed.code}</script>` : match;
+			}
+		);
+	}
+
+	for (const fn of style) {
 		source = await replaceAsync(
 			source,
-			/<(script|style)([^]*?)>([^]*?)<\/\1>/gi,
-			async (match, type, attributes, content) => {
-				const processed: Processed =
-					type in options &&
-					(await options[type]({
-						content,
-						attributes: parseAttributes(attributes),
-						filename: options.filename,
-					}));
-				return processed ? `<${type}${attributes}>${processed.code}</${type}>` : match;
+			/<style([^]*?)>([^]*?)<\/style>/gi,
+			async (match, attributes, content) => {
+				const processed: Processed = await fn({
+					content,
+					attributes: parseAttributes(attributes),
+					filename
+				});
+				if (processed && processed.dependencies) dependencies.push(...processed.dependencies);
+				return processed ? `<style${attributes}>${processed.code}</style>` : match;
 			}
 		);
 	}
@@ -71,6 +98,9 @@ export default async function preprocess(
 		// script { code: scriptCode, map: scriptMap },
 		// markup { code: markupCode, map: markupMap },
 
+		code: source,
+		dependencies: [...new Set(dependencies)],
+
 		toString() {
 			return source;
 		}

test/preprocess/index.js

@@ -16,10 +16,12 @@ describe.only('preprocess', () => {
 			const input = fs.readFileSync(`test/preprocess/samples/${dir}/input.html`, 'utf-8');
 			const expected = fs.readFileSync(`test/preprocess/samples/${dir}/output.html`, 'utf-8');
 
-			const actual = await svelte.preprocess(input, config.preprocess);
-			fs.writeFileSync(`test/preprocess/samples/${dir}/_actual.html`, actual);
+			const result = await svelte.preprocess(input, config.preprocess);
+			fs.writeFileSync(`test/preprocess/samples/${dir}/_actual.html`, result.code);
 
-			assert.equal(actual, expected);
+			assert.equal(result.code, expected);
+
+			assert.deepEqual(result.dependencies, config.dependencies || []);
 		});
 	});
 });

test/preprocess/samples/dependencies/_config.js

@@ -0,0 +1,15 @@
+export default {
+	preprocess: {
+		style: ({ content }) => {
+			const dependencies = [];
+			const code = content.replace(/@import '(.+)';/g, (match, $1) => {
+				dependencies.push($1);
+				return '/* removed */';
+			});
+
+			return { code, dependencies };
+		}
+	},
+
+	dependencies: ['./foo.css']
+};

test/preprocess/samples/dependencies/input.html

@@ -0,0 +1,3 @@
+<style>
+	@import './foo.css';
+</style>

test/preprocess/samples/dependencies/output.html

@@ -0,0 +1,3 @@
+<style>
+	/* removed */
+</style>

test/preprocess/samples/multiple-preprocessors/_config.js

@@ -0,0 +1,14 @@
+export default {
+	preprocess: [
+		{
+			markup: ({ content }) => ({ code: content.replace(/one/g, 'two') }),
+			script: ({ content }) => ({ code: content.replace(/three/g, 'four') }),
+			style:  ({ content }) => ({ code: content.replace(/four/g, 'five') })
+		},
+		{
+			markup: ({ content }) => ({ code: content.replace(/two/g, 'three') }),
+			script: ({ content }) => ({ code: content.replace(/four/g, 'five') }),
+			style:  ({ content }) => ({ code: content.replace(/three/g, 'four') })
+		}
+	]
+};

test/preprocess/samples/multiple-preprocessors/input.html

@@ -0,0 +1,11 @@
+<p>one</p>
+
+<style>
+	.one {
+		color: red;
+	}
+</style>
+
+<script>
+	console.log('one');
+</script>

test/preprocess/samples/multiple-preprocessors/output.html

@@ -0,0 +1,11 @@
+<p>three</p>
+
+<style>
+	.four {
+		color: red;
+	}
+</style>
+
+<script>
+	console.log('five');
+</script>