Bug 1627175 - part 36: Make `EditorBase::CreateTransactionForCollapsedRange()` use `EditorBase::GetNextContent()` and `EditorBase::GetPreviousContent()` only when it's an `HTMLEditor` r=m_kato

If the editor instance is a `TextEditor`, the root element has to be
anonymous `<div>` element and it has only one text node when it has non-empty
value.  Therefore, if it's in `TextEditor`, the method does not need to use
the complicated APIs for finding a text node from the anonymous `<div>` element
or padding `<br>` element since it can adjust the given point into the text
node without such API.

Differential Revision: https://phabricator.services.mozilla.com/D113240

editor/libeditor/EditorBase.cpp

@@ -3462,6 +3462,45 @@ EditorBase::CreateTransactionForCollapsedRange(
   if (NS_WARN_IF(!point.IsSet())) {
     return nullptr;
   }
+  if (IsTextEditor()) {
+    // There should be only one text node in the anonymous `<div>` (but may
+    // be followed by a padding `<br>`).  We should adjust the point into
+    // the text node (or return nullptr if there is no text to delete) for
+    // avoiding finding the text node with complicated API.
+    if (!point.IsInTextNode()) {
+      const Element* anonymousDiv = GetRoot();
+      if (NS_WARN_IF(!anonymousDiv)) {
+        return nullptr;
+      }
+      if (!anonymousDiv->GetFirstChild() ||
+          !anonymousDiv->GetFirstChild()->IsText()) {
+        return nullptr;  // The value is empty.
+      }
+      if (point.GetContainer() == anonymousDiv) {
+        if (point.IsStartOfContainer()) {
+          point.Set(anonymousDiv->GetFirstChild(), 0);
+        } else {
+          point.SetToEndOf(anonymousDiv->GetFirstChild());
+        }
+      } else {
+        // Must be referring a padding `<br>` element or after the text node.
+        point.SetToEndOf(anonymousDiv->GetFirstChild());
+      }
+    }
+    MOZ_ASSERT(!point.ContainerAsText()->GetPreviousSibling());
+    MOZ_ASSERT(!point.ContainerAsText()->GetNextSibling() ||
+               !point.ContainerAsText()->GetNextSibling()->IsText());
+    if (aHowToHandleCollapsedRange ==
+            HowToHandleCollapsedRange::ExtendBackward &&
+        point.IsStartOfContainer()) {
+      return nullptr;
+    }
+    if (aHowToHandleCollapsedRange ==
+            HowToHandleCollapsedRange::ExtendForward &&
+        point.IsEndOfContainer()) {
+      return nullptr;
+    }
+  }
 
   // XXX: if the container of point is empty, then we'll need to delete the node
   //      as well as the 1 child
@@ -3470,11 +3509,12 @@ EditorBase::CreateTransactionForCollapsedRange(
   // XXX: this has to come from rule section
   if (aHowToHandleCollapsedRange == HowToHandleCollapsedRange::ExtendBackward &&
       point.IsStartOfContainer()) {
+    MOZ_ASSERT(IsHTMLEditor());
     // We're backspacing from the beginning of a node.  Delete the last thing
     // of previous editable content.
     nsIContent* previousEditableContent = EditorBase::GetPreviousContent(
         *point.GetContainer(), {WalkTreeOption::IgnoreNonEditableNode},
-        GetEditorType(), GetEditorRoot());
+        EditorType::HTML, GetEditorRoot());
     if (!previousEditableContent) {
       NS_WARNING("There was no editable content before the collapsed range");
       return nullptr;
@@ -3513,11 +3553,12 @@ EditorBase::CreateTransactionForCollapsedRange(
 
   if (aHowToHandleCollapsedRange == HowToHandleCollapsedRange::ExtendForward &&
       point.IsEndOfContainer()) {
+    MOZ_ASSERT(IsHTMLEditor());
     // We're deleting from the end of a node.  Delete the first thing of
     // next editable content.
     nsIContent* nextEditableContent = EditorBase::GetNextContent(
         *point.GetContainer(), {WalkTreeOption::IgnoreNonEditableNode},
-        GetEditorType(), GetEditorRoot());
+        EditorType::HTML, GetEditorRoot());
     if (!nextEditableContent) {
       NS_WARNING("There was no editable content after the collapsed range");
       return nullptr;
@@ -3574,14 +3615,16 @@ EditorBase::CreateTransactionForCollapsedRange(
     return deleteTextTransaction.forget();
   }
 
-  nsIContent* editableContent =
+  nsIContent* editableContent = nullptr;
+  if (IsHTMLEditor()) {
+    editableContent =
         aHowToHandleCollapsedRange == HowToHandleCollapsedRange::ExtendBackward
             ? EditorBase::GetPreviousContent(
-                point, {WalkTreeOption::IgnoreNonEditableNode}, GetEditorType(),
+                  point, {WalkTreeOption::IgnoreNonEditableNode},
-                GetEditorRoot())
+                  EditorType::HTML, GetEditorRoot())
-          : EditorBase::GetNextContent(point,
+            : EditorBase::GetNextContent(
-                                       {WalkTreeOption::IgnoreNonEditableNode},
+                  point, {WalkTreeOption::IgnoreNonEditableNode},
-                                       GetEditorType(), GetEditorRoot());
+                  EditorType::HTML, GetEditorRoot());
     if (!editableContent) {
       NS_WARNING("There was no editable content around the collapsed range");
       return nullptr;
@@ -3590,20 +3633,29 @@ EditorBase::CreateTransactionForCollapsedRange(
            !editableContent->Length()) {
       // Can't delete an empty text node (bug 762183)
       editableContent =
-        aHowToHandleCollapsedRange == HowToHandleCollapsedRange::ExtendBackward
+          aHowToHandleCollapsedRange ==
+                  HowToHandleCollapsedRange::ExtendBackward
               ? EditorBase::GetPreviousContent(
                     *editableContent, {WalkTreeOption::IgnoreNonEditableNode},
-                  GetEditorType(), GetEditorRoot())
+                    EditorType::HTML, GetEditorRoot())
               : EditorBase::GetNextContent(
                     *editableContent, {WalkTreeOption::IgnoreNonEditableNode},
-                  GetEditorType(), GetEditorRoot());
+                    EditorType::HTML, GetEditorRoot());
     }
-  if (NS_WARN_IF(!editableContent)) {
+    if (!editableContent) {
       NS_WARNING(
-        "There was no editable content which is not empty around the collapsed "
+          "There was no editable content which is not empty around the "
-        "range");
+          "collapsed range");
       return nullptr;
     }
+  } else {
+    MOZ_ASSERT(point.IsInTextNode());
+    editableContent = point.GetContainerAsContent();
+    if (!editableContent) {
+      NS_WARNING("If there was no text node, should've been handled first");
+      return nullptr;
+    }
+  }
 
   if (editableContent->IsText()) {
     if (aHowToHandleCollapsedRange ==
@@ -3626,6 +3678,7 @@ EditorBase::CreateTransactionForCollapsedRange(
     return deleteTextTransaction.forget();
   }
 
+  MOZ_ASSERT(IsHTMLEditor());
   RefPtr<DeleteNodeTransaction> deleteNodeTransaction =
       DeleteNodeTransaction::MaybeCreate(*this, *editableContent);
   NS_WARNING_ASSERTION(deleteNodeTransaction,