Extracted a constant and deleted a no longer used method.

Signed-off-by: Dimitar Dobrev <dpldobrev@yahoo.com>

src/Generator/AST/VTables.cs

@@ -6,6 +6,8 @@ namespace CppSharp.AST
 {
     public static class VTables
     {
+        public const int ItaniumOffsetToTopAndRTTI = 2;
+
         public static List<VTableComponent> GatherVTableMethodEntries(Class @class)
         {
             switch (@class.Layout.ABI)
@@ -52,26 +54,6 @@ namespace CppSharp.AST
             return GatherVTableMethodEntries(@class.Layout.Layout);
         }
 
-        public static int GetVTableComponentIndex(Class @class, VTableComponent entry)
-        {
-            switch (@class.Layout.ABI)
-            {
-            case CppAbi.Microsoft:
-                foreach (var vfptr in @class.Layout.VFTables)
-                {
-                    var index = vfptr.Layout.Components.IndexOf(entry);
-                    if (index >= 0)
-                        return index;
-                }
-                break;
-            default:
-                // ignore offset to top and RTTI
-                return @class.Layout.Layout.Components.IndexOf(entry) - 2;
-            }
-
-            throw new NotSupportedException();
-        }
-
 
         public static int GetVTableIndex(Function function, Class @class)
         {
@@ -83,8 +65,7 @@ namespace CppSharp.AST
                             where j >= 0
                             select j).First();
                 default:
-                    // ignore offset to top and RTTI
-                    return @class.Layout.Layout.Components.FindIndex(m => m.Method == function) - 2;
+                    return @class.Layout.Layout.Components.FindIndex(m => m.Method == function) - ItaniumOffsetToTopAndRTTI;
             }
         }
 

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -1407,8 +1407,7 @@ namespace CppSharp.Generators.CSharp
             var pointerSize = Driver.TargetInfo.PointerWidth / 8;
             WriteLine("var vtptr = Marshal.AllocHGlobal({0} * {1});", size, pointerSize);
 
-            const int offsetToTopAndRTTI = 2;
-            WriteLine("var vfptr0 = vtptr + {0} * {1};", offsetToTopAndRTTI, pointerSize);
+            WriteLine("var vfptr0 = vtptr + {0} * {1};", VTables.ItaniumOffsetToTopAndRTTI, pointerSize);
             WriteLine("__ManagedVTables[0] = vfptr0.ToPointer();");
 
             AllocateNewVTableEntries(@class.Layout.Layout.Components,
@@ -1423,12 +1422,12 @@ namespace CppSharp.Generators.CSharp
         private void AllocateNewVTableEntries(IList<VTableComponent> entries,
             IList<VTableComponent> wrappedEntries, int tableIndex)
         {
-            const int offsetToTopAndRTTI = 2;
             var pointerSize = Driver.TargetInfo.PointerWidth / 8;
             for (int i = 0; i < entries.Count; i++)
             {
                 var entry = entries[i];
-                var offsetInBytes = (i - (Options.IsMicrosoftAbi ? 0 : offsetToTopAndRTTI)) * pointerSize;
+                var offsetInBytes = pointerSize
+                    * (i - (Options.IsMicrosoftAbi ? 0 : VTables.ItaniumOffsetToTopAndRTTI));
 
                 if ((entry.Kind == VTableComponentKind.FunctionPointer ||
                      entry.Kind == VTableComponentKind.DeletingDtorPointer) &&