Bug 1332105 Part 2 - Make Selection::LookUpSelection() return UniquePtr. r=dholbert

Selection::LookUpSelection()'s only caller,
nsFrameSelection::LookUpSelection(), doesn't check the return value. Let's
make it return UniquePtr directly like nsFrameSelection::LookUpSelection().

Rename aReturnDetails to aDetailsHead so that its role is clearer.
aDetailsHead is of type UniquePtr<SelectionDetails> instead of
UniquePtr<SelectionDetails>&& because the caller always wants to transfer
the ownership of SelectionDetails into the function.

MozReview-Commit-ID: 89Y7X1LTKON

--HG--
extra : rebase_source : 730d601ccb87eb2b616c0a021129752ed5301a3a

layout/generic/Selection.h

@@ -138,12 +138,15 @@ public:
   //  NS_IMETHOD   GetPrimaryFrameForRangeEndpoint(nsIDOMNode *aNode, int32_t aOffset, bool aIsEndNode, nsIFrame **aResultFrame);
   NS_IMETHOD   GetPrimaryFrameForAnchorNode(nsIFrame **aResultFrame);
   NS_IMETHOD   GetPrimaryFrameForFocusNode(nsIFrame **aResultFrame, int32_t *aOffset, bool aVisual);
-  NS_IMETHOD   LookUpSelection(nsIContent *aContent,
-                               int32_t aContentOffset,
-                               int32_t aContentLength,
-                               UniquePtr<SelectionDetails>* aReturnDetails,
-                               SelectionType aSelectionType,
-                               bool aSlowCheck);
+
+  UniquePtr<SelectionDetails> LookUpSelection(
+    nsIContent* aContent,
+    int32_t aContentOffset,
+    int32_t aContentLength,
+    UniquePtr<SelectionDetails> aDetailsHead,
+    SelectionType aSelectionType,
+    bool aSlowCheck);
+
   NS_IMETHOD   Repaint(nsPresContext* aPresContext);
 
   // Note: StartAutoScrollTimer might destroy arbitrary frames etc.

layout/generic/nsSelection.cpp

@@ -1895,10 +1895,10 @@ nsFrameSelection::LookUpSelection(nsIContent *aContent,
 
   for (size_t j = 0; j < kPresentSelectionTypeCount; j++) {
     if (mDomSelections[j]) {
-      mDomSelections[j]->LookUpSelection(aContent, aContentOffset,
-                                         aContentLength, &details,
-                                         ToSelectionType(1 << j),
-                                         aSlowCheck);
+      details = mDomSelections[j]->LookUpSelection(aContent, aContentOffset,
+                                                   aContentLength, Move(details),
+                                                   ToSelectionType(1 << j),
+                                                   aSlowCheck);
     }
   }
 
@@ -4595,29 +4595,36 @@ Selection::selectFrames(nsPresContext* aPresContext, nsRange* aRange,
 //    of this function did in the case of 1 range. This would also mean that
 //    the aSlowCheck flag would have meaning again.
 
-NS_IMETHODIMP
+UniquePtr<SelectionDetails>
 Selection::LookUpSelection(nsIContent* aContent, int32_t aContentOffset,
                            int32_t aContentLength,
-                           UniquePtr<SelectionDetails>* aReturnDetails,
+                           UniquePtr<SelectionDetails> aDetailsHead,
                            SelectionType aSelectionType,
                            bool aSlowCheck)
 {
-  nsresult rv;
-  if (!aContent || ! aReturnDetails)
-    return NS_ERROR_NULL_POINTER;
+  if (!aContent) {
+    return aDetailsHead;
+  }
 
   // it is common to have no ranges, to optimize that
-  if (mRanges.Length() == 0)
-    return NS_OK;
+  if (mRanges.Length() == 0) {
+    return aDetailsHead;
+  }
 
   nsTArray<nsRange*> overlappingRanges;
-  rv = GetRangesForIntervalArray(aContent, aContentOffset,
-                                 aContent, aContentOffset + aContentLength,
-                                 false,
-                                 &overlappingRanges);
-  NS_ENSURE_SUCCESS(rv, rv);
-  if (overlappingRanges.Length() == 0)
-    return NS_OK;
+  nsresult rv = GetRangesForIntervalArray(aContent, aContentOffset,
+                                          aContent, aContentOffset + aContentLength,
+                                          false,
+                                          &overlappingRanges);
+  if (NS_FAILED(rv)) {
+    return aDetailsHead;
+  }
+
+  if (overlappingRanges.Length() == 0) {
+    return aDetailsHead;
+  }
+
+  UniquePtr<SelectionDetails> detailsHead = Move(aDetailsHead);
 
   for (uint32_t i = 0; i < overlappingRanges.Length(); i++) {
     nsRange* range = overlappingRanges[i];
@@ -4661,19 +4668,19 @@ Selection::LookUpSelection(nsIContent* aContent, int32_t aContentOffset,
     if (start < 0)
       continue; // the ranges do not overlap the input range
 
-    auto details = MakeUnique<SelectionDetails>();
+    auto newHead = MakeUnique<SelectionDetails>();
 
-    details->mNext = Move(*aReturnDetails);
-    details->mStart = start;
-    details->mEnd = end;
-    details->mSelectionType = aSelectionType;
+    newHead->mNext = Move(detailsHead);
+    newHead->mStart = start;
+    newHead->mEnd = end;
+    newHead->mSelectionType = aSelectionType;
     RangeData *rd = FindRangeData(range);
     if (rd) {
-      details->mTextRangeStyle = rd->mTextRangeStyle;
+      newHead->mTextRangeStyle = rd->mTextRangeStyle;
     }
-    *aReturnDetails = Move(details);
+    detailsHead = Move(newHead);
   }
-  return NS_OK;
+  return detailsHead;
 }
 
 NS_IMETHODIMP