Remove hasSelection property.

Instead of a PreviewSelection with hasSelection: false, just use null.
This makes the PreviewSelection type usable in places where we want
to only get objects with an actual selection, and is simpler overall.

Author: mstange

src/actions/profile-view.ts

@@ -1749,13 +1749,17 @@ export function changeShowJsTracerSummary(
 }
 
 export function updatePreviewSelection(
-  previewSelection: PreviewSelection
+  previewSelection: PreviewSelection | null
 ): ThunkAction<void> {
   return (dispatch, getState) => {
+    // Only dispatch if the selection changes. This function can fire in a tight loop,
+    // and this check saves a dispatch.
     const currentPreviewSelection = getPreviewSelection(getState());
-    if (!objectShallowEquals(currentPreviewSelection, previewSelection)) {
-      // Only dispatch if the selection changes. This function can fire in a tight loop,
-      // and this check saves a dispatch.
+    if (
+      !currentPreviewSelection ||
+      !previewSelection ||
+      !objectShallowEquals(currentPreviewSelection, previewSelection)
+    ) {
       dispatch({
         type: 'UPDATE_PREVIEW_SELECTION',
         previewSelection,

src/components/app/ProfileFilterNavigator.tsx

@@ -187,7 +187,7 @@ export const ProfileFilterNavigator = explicitConnect<
     const items = getCommittedRangeLabels(state);
     const previewSelection = getPreviewSelection(state);
     const profileTimelineUnit = getProfileTimelineUnit(state);
-    const uncommittedItem = previewSelection.hasSelection
+    const uncommittedItem = previewSelection
       ? getFormattedTimelineValue(
           previewSelection.selectionEnd - previewSelection.selectionStart,
           profileTimelineUnit

src/components/flame-graph/FlameGraph.tsx

@@ -74,7 +74,7 @@ type StateProps = {
   readonly ctssSampleIndexOffset: number;
   readonly maxStackDepthPlusOne: number;
   readonly timeRange: StartEndRange;
-  readonly previewSelection: PreviewSelection;
+  readonly previewSelection: PreviewSelection | null;
   readonly flameGraphTiming: FlameGraphTiming;
   readonly callTree: CallTree;
   readonly callNodeInfo: CallNodeInfo;

src/components/js-tracer/Canvas.tsx

@@ -608,7 +608,6 @@ class JsTracerCanvasImpl extends React.PureComponent<Props, State> {
     // const { markers, updatePreviewSelection } = this.props;
     // const marker = markers[eventIndex];
     // updatePreviewSelection({
-    //   hasSelection: true,
     //   isModifying: false,
     //   selectionStart: marker.start,
     //   selectionEnd: marker.start + marker.dur,

src/components/js-tracer/Chart.tsx

@@ -53,7 +53,7 @@ type StateProps = {
   readonly stringTable: StringTable;
   readonly timeRange: StartEndRange;
   readonly threadsKey: ThreadsKey;
-  readonly previewSelection: PreviewSelection;
+  readonly previewSelection: PreviewSelection | null;
 };
 
 type Props = ConnectedProps<OwnProps, StateProps, DispatchProps>;

src/components/marker-chart/Canvas.tsx

@@ -775,7 +775,6 @@ class MarkerChartCanvasImpl extends React.PureComponent<Props> {
     );
 
     updatePreviewSelection({
-      hasSelection: true,
       isModifying: false,
       selectionStart: start,
       selectionEnd: end,

src/components/marker-chart/index.tsx

@@ -56,7 +56,7 @@ type StateProps = {
   readonly markerListLength: number;
   readonly timeRange: StartEndRange;
   readonly threadsKey: ThreadsKey;
-  readonly previewSelection: PreviewSelection;
+  readonly previewSelection: PreviewSelection | null;
   readonly rightClickedMarkerIndex: MarkerIndex | null;
   readonly selectedMarkerIndex: MarkerIndex | null;
 };

src/components/shared/MarkerContextMenu.tsx

@@ -52,7 +52,7 @@ type OwnProps = {
 type StateProps = {
   readonly marker: Marker;
   readonly markerIndex: MarkerIndex;
-  readonly previewSelection: PreviewSelection;
+  readonly previewSelection: PreviewSelection | null;
   readonly committedRange: StartEndRange;
   readonly thread: Thread | null;
   readonly implementationFilter: ImplementationFilter;
@@ -74,12 +74,11 @@ class MarkerContextMenuImpl extends PureComponent<Props> {
     const { updatePreviewSelection, previewSelection, committedRange } =
       this.props;
 
-    const selectionEnd = previewSelection.hasSelection
+    const selectionEnd = previewSelection
       ? previewSelection.selectionEnd
       : committedRange.end;
 
     updatePreviewSelection({
-      hasSelection: true,
       isModifying: false,
       selectionStart,
       selectionEnd,
@@ -90,7 +89,7 @@ class MarkerContextMenuImpl extends PureComponent<Props> {
     const { updatePreviewSelection, committedRange, previewSelection } =
       this.props;
 
-    const selectionStart = previewSelection.hasSelection
+    const selectionStart = previewSelection
       ? previewSelection.selectionStart
       : committedRange.start;
 
@@ -102,7 +101,6 @@ class MarkerContextMenuImpl extends PureComponent<Props> {
     }
 
     updatePreviewSelection({
-      hasSelection: true,
       isModifying: false,
       selectionStart,
       selectionEnd,
@@ -137,7 +135,6 @@ class MarkerContextMenuImpl extends PureComponent<Props> {
     }
 
     updatePreviewSelection({
-      hasSelection: true,
       isModifying: false,
       selectionStart: marker.start,
       selectionEnd: marker.end,
@@ -385,11 +382,11 @@ class MarkerContextMenuImpl extends PureComponent<Props> {
     const { marker, previewSelection, committedRange } = this.props;
     const { data } = marker;
 
-    const selectionEnd = previewSelection.hasSelection
+    const selectionEnd = previewSelection
       ? previewSelection.selectionEnd
       : committedRange.end;
 
-    const selectionStart = previewSelection.hasSelection
+    const selectionStart = previewSelection
       ? previewSelection.selectionStart
       : committedRange.start;
 

src/components/shared/chart/Viewport.tsx

@@ -145,7 +145,7 @@ type ViewportProps<ChartProps> = {
   // The "committed range", whose endpoints correspond to 0 and 1.
   readonly timeRange: StartEndRange;
   // The preview selection, whose endpoints correspond to viewportLeft and viewportRight.
-  readonly previewSelection: PreviewSelection;
+  readonly previewSelection: PreviewSelection | null;
   // The left margin. Margins are outside the viewport but inside containerWidth.
   readonly marginLeft: CssPixels;
   // The right margin. Margins are outside the viewport but inside containerWidth.
@@ -214,7 +214,7 @@ class ChartViewportImpl<OwnProps> extends React.PureComponent<
 > {
   zoomScrollId: number = 0;
   _pendingPreviewSelectionUpdates: Array<
-    (horizontalViewport: HorizontalViewport) => PreviewSelection
+    (horizontalViewport: HorizontalViewport) => PreviewSelection | null
   > = [];
   _container: HTMLDivElement | null = null;
   _takeContainerRef = (container: HTMLDivElement) => {
@@ -235,10 +235,10 @@ class ChartViewportImpl<OwnProps> extends React.PureComponent<
   }
 
   getHorizontalViewport(
-    previewSelection: PreviewSelection,
+    previewSelection: PreviewSelection | null,
     timeRange: StartEndRange
   ) {
-    if (previewSelection.hasSelection) {
+    if (previewSelection) {
       const { selectionStart, selectionEnd } = previewSelection;
       const timeRangeLength = timeRange.end - timeRange.start;
       return {
@@ -433,7 +433,7 @@ class ChartViewportImpl<OwnProps> extends React.PureComponent<
    * processes all queued updates from a requestAnimationFrame callback.
    */
   _addBatchedPreviewSelectionUpdate(
-    callback: (param: HorizontalViewport) => PreviewSelection
+    callback: (param: HorizontalViewport) => PreviewSelection | null
   ) {
     if (this._pendingPreviewSelectionUpdates.length === 0) {
       requestAnimationFrame(() => this._flushPendingPreviewSelectionUpdates());
@@ -532,14 +532,10 @@ class ChartViewportImpl<OwnProps> extends React.PureComponent<
           viewportProps: { timeRange },
         } = this.props;
         if (newViewportLeft === 0 && newViewportRight === 1) {
-          return {
-            hasSelection: false,
-            isModifying: false,
-          };
+          return null;
         }
         const timeRangeLength = timeRange.end - timeRange.start;
         return {
-          hasSelection: true,
           isModifying: false,
           selectionStart: timeRange.start + timeRangeLength * newViewportLeft,
           selectionEnd: timeRange.start + timeRangeLength * newViewportRight,
@@ -722,10 +718,7 @@ class ChartViewportImpl<OwnProps> extends React.PureComponent<
           // Calculate left and right in terms of the unit interval of the profile range.
           const viewportLength = viewportRight - viewportLeft;
           if (viewportLength >= 1) {
-            return {
-              hasSelection: false,
-              isModifying: false,
-            };
+            return null;
           }
           const viewportPixelWidth = containerWidth - marginLeft - marginRight;
           const unitOffsetX = offsetX * (viewportLength / viewportPixelWidth);
@@ -742,7 +735,6 @@ class ChartViewportImpl<OwnProps> extends React.PureComponent<
 
           const timeRangeLength = timeRange.end - timeRange.start;
           return {
-            hasSelection: true,
             isModifying: false,
             selectionStart: timeRange.start + timeRangeLength * newViewportLeft,
             selectionEnd: timeRange.start + timeRangeLength * newViewportRight,

src/components/stack-chart/Canvas.tsx

@@ -641,7 +641,6 @@ class StackChartCanvasImpl extends React.PureComponent<Props> {
     const { depth, stackTimingIndex } = hoveredItem;
     const { combinedTimingRows, updatePreviewSelection } = this.props;
     updatePreviewSelection({
-      hasSelection: true,
       isModifying: false,
       selectionStart: combinedTimingRows[depth].start[stackTimingIndex],
       selectionEnd: combinedTimingRows[depth].end[stackTimingIndex],