1 files changed, 69 insertions, 0 deletions
diff --git a/devtools/client/debugger/src/utils/pause/frames/collapseFrames.js b/devtools/client/debugger/src/utils/pause/frames/collapseFrames.js
new file mode 100644
index 0000000000..d39a26d574
--- /dev/null
+++ b/devtools/client/debugger/src/utils/pause/frames/collapseFrames.js
@@ -0,0 +1,69 @@
+/* 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 { findIndex } from "lodash";
+
+// eslint-disable-next-line max-len
+import type { Frame } from "../../../types";
+import { getFrameUrl } from "./getFrameUrl";
+
+function collapseLastFrames(frames) {
+  const index = findIndex(frames, frame =>
+    getFrameUrl(frame).match(/webpack\/bootstrap/i)
+  );
+
+  if (index == -1) {
+    return { newFrames: frames, lastGroup: [] };
+  }
+
+  const newFrames = frames.slice(0, index);
+  const lastGroup = frames.slice(index);
+  return { newFrames, lastGroup };
+}
+
+type FrameGroup = Frame[];
+type GroupedFrames = Array<FrameGroup | Frame>;
+
+export function collapseFrames(frames: Frame[]): GroupedFrames {
+  // We collapse groups of one so that user frames
+  // are not in a group of one
+  function addGroupToList(group, list) {
+    if (!group) {
+      return list;
+    }
+
+    if (group.length > 1) {
+      list.push(group);
+    } else {
+      list = list.concat(group);
+    }
+
+    return list;
+  }
+  const { newFrames, lastGroup } = collapseLastFrames(frames);
+  frames = newFrames;
+  let items = [];
+  let currentGroup = null;
+  let prevItem = null;
+  for (const frame of frames) {
+    const prevLibrary = prevItem?.library;
+
+    if (!currentGroup) {
+      currentGroup = [frame];
+    } else if (prevLibrary && prevLibrary == frame.library) {
+      currentGroup.push(frame);
+    } else {
+      items = addGroupToList(currentGroup, items);
+      currentGroup = [frame];
+    }
+
+    prevItem = frame;
+  }
+
+  items = addGroupToList(currentGroup, items);
+  items = addGroupToList(lastGroup, items);
+  return items;
+}