From f2cbf11cc20d47b9df3816b0060d3080d8026706 Mon Sep 17 00:00:00 2001
From: Timothy Johnson <timothy@idioticdev.com>
Date: Sat, 24 Nov 2018 14:01:43 -0800
Subject: [PATCH] Consume sourcemaps

---
 src/cli/compile.ts   |  1 +
 src/compile/index.ts | 17 ++++++++++++++++-
 src/interfaces.ts    |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/cli/compile.ts b/src/cli/compile.ts
index 47141f2346..54f7286479 100644
--- a/src/cli/compile.ts
+++ b/src/cli/compile.ts
@@ -107,6 +107,7 @@ function compileFile(input, output, options) {
 	let compiled;
 
 	try {
+		delete options.sourceMap; // compiler doesn't use this option
 		compiled = svelte.compile(source, options);
 	} catch (err) {
 		error(err);
diff --git a/src/compile/index.ts b/src/compile/index.ts
index 59e204b816..4418de4081 100644
--- a/src/compile/index.ts
+++ b/src/compile/index.ts
@@ -1,3 +1,4 @@
+import { SourceMapGenerator, SourceMapConsumer } from 'source-map';
 import { assign } from '../shared';
 import Stats from '../Stats';
 import parse from '../parse/index';
@@ -89,7 +90,21 @@ export default function compile(source: string, options: CompileOptions = {}) {
 			return renderSSR(component, options);
 		}
 
-		return renderDOM(component, options);
+		const result = renderDOM(component, options);
+
+		if (options.sourceMap) {
+			const inputConsumer = new SourceMapConsumer(options.sourceMap);
+
+			const jsSourceMap = SourceMapGenerator.fromSourceMap(new SourceMapConsumer(result.js.map));
+			jsSourceMap.applySourceMap(inputConsumer);
+			result.js.map = jsSourceMap.toJSON();
+
+			const cssSourceMap = SourceMapGenerator.fromSourceMap(new SourceMapConsumer(result.css.map));
+			cssSourceMap.applySourceMap(inputConsumer);
+			result.css.map = cssSourceMap.toJSON();
+		}
+
+		return result;
 	} catch (err) {
 		onerror(err);
 	}
diff --git a/src/interfaces.ts b/src/interfaces.ts
index b637a727bb..8609576841 100644
--- a/src/interfaces.ts
+++ b/src/interfaces.ts
@@ -57,6 +57,7 @@ export interface CompileOptions {
 	legacy?: boolean;
 	customElement?: CustomElementOptions | true;
 	css?: boolean;
+	sourceMap?: string | object;
 
 	preserveComments?: boolean | false;