Change for #832: Turn TVirtualNode.LastChild into a readonly property…

Source/VirtualTrees.BaseTree.pas

@@ -5047,9 +5047,9 @@ procedure TBaseVirtualTree.SetChildCount(Node: PVirtualNode; NewChildCount: Card
             if Assigned(Node.LastChild) then
               Node.LastChild.SetNextSibling(Child);
             Child.SetParent(Node);
-            Node.LastChild := Child;
+            Node.SetLastChild(Child);
             if Node.FirstChild = nil then
-              Node.FirstChild := Child;
+              Node.SetFirstChild(Child);
             System.Dec(Remaining);
             System.Inc(Index);
 
@@ -13775,7 +13775,7 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
           Node.SetParent(Destination.Parent);
           Node.SetIndex(Destination.Index);
           if Node.PrevSibling = nil then
-            Node.Parent.FirstChild := Node
+            Node.Parent.SetFirstChild(Node)
           else
             Node.PrevSibling.SetNextSibling(Node);
 
@@ -13794,7 +13794,7 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
           Node.SetPrevSibling(Destination);
           Node.SetParent(Destination.Parent);
           if Node.NextSibling = nil then
-            Node.Parent.LastChild := Node
+            Node.Parent.SetLastChild(Node)
           else
             Node.NextSibling.SetPrevSibling(Node);
           Node.SetIndex(Destination.Index);
@@ -13814,13 +13814,13 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
             // If there's a first child then there must also be a last child.
             Destination.FirstChild.SetPrevSibling(Node);
             Node.SetNextSibling(Destination.FirstChild);
-            Destination.FirstChild := Node;
+            Destination.SetFirstChild(Node);
           end
           else
           begin
             // First child node at this location.
-            Destination.FirstChild := Node;
-            Destination.LastChild := Node;
+            Destination.SetFirstChild(Node);
+            Destination.SetLastChild(Node);
             Node.SetNextSibling(nil);
           end;
           Node.SetPrevSibling(nil);
@@ -13841,13 +13841,13 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
             // If there's a last child then there must also be a first child.
             Destination.LastChild.SetNextSibling(Node);
             Node.SetPrevSibling(Destination.LastChild);
-            Destination.LastChild := Node;
+            Destination.SetLastChild(Node);
           end
           else
           begin
             // first child node at this location
-            Destination.FirstChild := Node;
-            Destination.LastChild := Node;
+            Destination.SetFirstChild(Node);
+            Destination.SetLastChild(Node);
             Node.SetPrevSibling(nil);
           end;
           Node.SetNextSibling(nil);
@@ -13957,7 +13957,7 @@ procedure TBaseVirtualTree.InternalDisconnectNode(Node: PVirtualNode; KeepFocus:
     if Assigned(Node.PrevSibling) then
       Node.PrevSibling.SetNextSibling(Node.NextSibling)
     else
-      Parent.FirstChild := Node.NextSibling;
+      Parent.SetFirstChild(Node.NextSibling);
 
     if Assigned(Node.NextSibling) then
     begin
@@ -13976,7 +13976,7 @@ procedure TBaseVirtualTree.InternalDisconnectNode(Node: PVirtualNode; KeepFocus:
       end;
     end
     else
-      Parent.LastChild := Node.PrevSibling;
+      Parent.SetLastChild(Node.PrevSibling);
   end;
 end;
 
@@ -15132,8 +15132,8 @@ function TBaseVirtualTree.ReadChunk(Stream: TStream; Version: Integer; Node: PVi
             if Assigned(Node.LastChild) then
               Node.LastChild.SetNextSibling(Run)
             else
-              Node.FirstChild := Run;
-            Node.LastChild := Run;
+              Node.SetFirstChild(Run);
+            Node.SetLastChild(Run);
             Run.SetParent(Node);
 
             ReadNode(Stream, Version, Run);
@@ -16912,8 +16912,8 @@ procedure TBaseVirtualTree.DeleteChildren(Node: PVirtualNode; ResetHasChildren:
         AdjustTotalHeight(Node, NodeHeight[Node]);
         AdjustTotalCount(Node, 1);
       end;
-      Node.FirstChild := nil;
-      Node.LastChild := nil;
+      Node.SetFirstChild(nil);
+      Node.SetLastChild(nil);
     finally
       System.Dec(FUpdateCount);
     end;
@@ -22463,9 +22463,9 @@ procedure TBaseVirtualTree.Sort(Node: PVirtualNode; Column: TColumnIndex; Direct
         try
           // Sort the linked list, check direction flag only once.
           if Direction = sdAscending then
-            Node.FirstChild := MergeSortAscending(Node.FirstChild, Node.ChildCount)
+            Node.SetFirstChild(MergeSortAscending(Node.FirstChild, Node.ChildCount))
           else
-            Node.FirstChild := MergeSortDescending(Node.FirstChild, Node.ChildCount);
+            Node.SetFirstChild(MergeSortDescending(Node.FirstChild, Node.ChildCount));
         finally
           EndOperation(okSortNode);
         end;
@@ -22481,7 +22481,7 @@ procedure TBaseVirtualTree.Sort(Node: PVirtualNode; Column: TColumnIndex; Direct
           Run.NextSibling.SetPrevSibling(Run);
           Run := Run.NextSibling;
         until False;
-        Node.LastChild := Run;
+        Node.SetLastChild(Run);
 
         InvalidateCache;
       end;

Source/VirtualTrees.Types.pas

@@ -904,18 +904,23 @@   TScrollBarOptions = class(TPersistent)
   private
     fParent:  PVirtualNode;     // reference to the node's parent (for the root this contains the treeview)
     fPrevSibling: PVirtualNode; // link to the node's previous sibling or nil if it is the first node
-    fNextSibling: PVirtualNode;  // link to the node's next sibling or nil if it is the last node
+    fNextSibling: PVirtualNode; // link to the node's next sibling or nil if it is the last node
+  public // still public as it is used as var parameter in MergeSortAscending()
+    FirstChild: PVirtualNode;  // link to the node's first child...
+  private
+    fLastChild: PVirtualNode;   // link to the node's last child...
   public
-    FirstChild,              // link to the node's first child...
-    LastChild: PVirtualNode; // link to the node's last child...
     procedure SetParent(const pParent: PVirtualNode); inline; //internal method, do not call directly but use Parent[Node] := x on tree control.
     procedure SetPrevSibling(const pPrevSibling: PVirtualNode); inline; //internal method, do not call directly
     procedure SetNextSibling(const pNextSibling: PVirtualNode); inline; //internal method, do not call directly
+    procedure SetFirstChild(const pFirstChild: PVirtualNode); inline; //internal method, do not call directly
+    procedure SetLastChild(const pLastChild: PVirtualNode); inline; //internal method, do not call directly
     procedure SetIndex(const pIndex: Cardinal); inline;       //internal method, do not call directly.
     property Index: Cardinal read fIndex;
     property Parent: PVirtualNode read fParent;
     property PrevSibling: PVirtualNode read fPrevSibling;
     property NextSibling: PVirtualNode read fNextSibling;
+    property LastChild: PVirtualNode read fLastChild;
   private
     Data: record end;        // this is a placeholder, each node gets extra data determined by NodeDataSize
   public
@@ -1182,6 +1187,16 @@ procedure TVirtualNode.SetData<T>(pUserData: T);
   Include(Self.States, vsOnFreeNodeCallRequired);
 end;
 
+procedure TVirtualNode.SetFirstChild(const pFirstChild: PVirtualNode);
+begin
+  FirstChild := pFirstChild;
+end;
+
+procedure TVirtualNode.SetLastChild(const pLastChild: PVirtualNode);
+begin
+  fLastChild := pLastChild;
+end;
+
 procedure TVirtualNode.SetIndex(const pIndex: Cardinal);
 begin
   fIndex := pIndex;