3 files changed, 117 insertions, 0 deletions
diff --git a/devtools/client/debugger/src/workers/pretty-print/index.js b/devtools/client/debugger/src/workers/pretty-print/index.js
new file mode 100644
index 0000000000..be10314d2b
--- /dev/null
+++ b/devtools/client/debugger/src/workers/pretty-print/index.js
@@ -0,0 +1,43 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
+
+// @flow
+
+import { prefs } from "../../utils/prefs";
+import { workerUtils } from "devtools-utils";
+const { WorkerDispatcher } = workerUtils;
+
+import type { URL } from "../../types";
+
+let dispatcher;
+let workerPath;
+
+export const start = (path: string) => {
+  workerPath = path;
+};
+export const stop = () => {
+  if (dispatcher) {
+    dispatcher.stop();
+    dispatcher = null;
+    workerPath = null;
+  }
+};
+
+type PrettyPrintOpts = {
+  text: string,
+  url: URL,
+};
+
+export async function prettyPrint({ text, url }: PrettyPrintOpts) {
+  if (!dispatcher) {
+    dispatcher = new WorkerDispatcher();
+    dispatcher.start(workerPath);
+  }
+
+  return dispatcher.invoke("prettyPrint", {
+    url,
+    indent: prefs.indentSize,
+    sourceText: text,
+  });
+}
diff --git a/devtools/client/debugger/src/workers/pretty-print/moz.build b/devtools/client/debugger/src/workers/pretty-print/moz.build
new file mode 100644
index 0000000000..b7223ac81a
--- /dev/null
+++ b/devtools/client/debugger/src/workers/pretty-print/moz.build
@@ -0,0 +1,10 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += []
+
+CompiledModules(
+    "index.js",
+)
diff --git a/devtools/client/debugger/src/workers/pretty-print/worker.js b/devtools/client/debugger/src/workers/pretty-print/worker.js
new file mode 100644
index 0000000000..7697d5c88c
--- /dev/null
+++ b/devtools/client/debugger/src/workers/pretty-print/worker.js
@@ -0,0 +1,64 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
+
+// @flow
+
+import prettyFast from "pretty-fast";
+
+import { workerUtils } from "devtools-utils";
+const { workerHandler } = workerUtils;
+
+type Mappings = {
+  _array: Mapping[],
+};
+
+type Mapping = {
+  originalLine: number,
+  originalColumn: number,
+  source?: string,
+  generatedLine?: number,
+  generatedColumn?: number,
+  name?: string,
+};
+
+type InvertedMapping = {
+  generated: Object,
+  source?: any,
+  original?: any,
+  name?: string,
+};
+
+function prettyPrint({ url, indent, sourceText }) {
+  const prettified = prettyFast(sourceText, {
+    url,
+    indent: " ".repeat(indent),
+  });
+
+  return {
+    code: prettified.code,
+    mappings: invertMappings(prettified.map._mappings),
+  };
+}
+
+function invertMappings(mappings: Mappings) {
+  return mappings._array.map((m: Mapping) => {
+    const mapping: InvertedMapping = {
+      generated: {
+        line: m.originalLine,
+        column: m.originalColumn,
+      },
+    };
+    if (m.source) {
+      mapping.source = m.source;
+      mapping.original = {
+        line: m.generatedLine,
+        column: m.generatedColumn,
+      };
+      mapping.name = m.name;
+    }
+    return mapping;
+  });
+}
+
+self.onmessage = workerHandler({ prettyPrint });