Moved the generation of a virtual table call to a separate function, for independence on back-ends.

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

src/Generator/AST/VTables.cs

@@ -1,5 +1,9 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using CppSharp.Generators;
+using CppSharp.Generators.CSharp;
 
 namespace CppSharp.AST
 {
@@ -78,5 +82,41 @@ namespace CppSharp.AST
 
             throw new NotSupportedException();
         }
+
+        public static string GetVirtualCallDelegate(INamedDecl method, Class @class, out string delegateId)
+        {
+            var virtualCallBuilder = new StringBuilder();
+            virtualCallBuilder.AppendFormat(
+                "void* vtable = *((void**) {0}.ToPointer());",
+                Helpers.InstanceIdentifier);
+            virtualCallBuilder.AppendLine();
+
+            int i;
+            switch (@class.Layout.ABI)
+            {
+                case CppAbi.Microsoft:
+                    i = (from table in @class.Layout.VFTables
+                         let j = table.Layout.Components.FindIndex(m => m.Method == method)
+                         where j >= 0
+                         select j).First();
+                    break;
+                default:
+                    i = @class.Layout.Layout.Components.FindIndex(m => m.Method == method);
+                    break;
+            }
+
+            virtualCallBuilder.AppendFormat(
+                "void* slot = *((void**) vtable + {0} * IntPtr.Size);", i);
+            virtualCallBuilder.AppendLine();
+
+            string @delegate = method.Name + "Delegate";
+            delegateId = Generator.GeneratedIdentifier(@delegate);
+
+            virtualCallBuilder.AppendFormat(
+                "var {1} = ({0}) Marshal.GetDelegateForFunctionPointer(new IntPtr(slot), typeof({0}));",
+                @delegate, delegateId);
+            virtualCallBuilder.AppendLine();
+            return virtualCallBuilder.ToString();
+        }
     }
 }

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using System.Linq;
+using System.Text;
 using CppSharp.AST;
 using CppSharp.Utils;
 using Type = CppSharp.AST.Type;
@@ -1569,26 +1570,8 @@ namespace CppSharp.Generators.CSharp
 
         private void GenerateVirtualTableFunctionCall(Function method, Class @class)
         {
-            WriteLine("void* vtable = *((void**) {0}.ToPointer());",
-                Helpers.InstanceIdentifier);
-            int i;
-            switch (Driver.Options.Abi)
-            {
-                case CppAbi.Microsoft:
-                    i = (from table in @class.Layout.VFTables
-                         let j = table.Layout.Components.FindIndex(m => m.Method == method)
-                         where j >= 0
-                         select j).First();
-                    break;
-                default:
-                    i = @class.Layout.Layout.Components.FindIndex(m => m.Method == method);
-                    break;
-            }
-            WriteLine("void* slot = *((void**) vtable + {0} * IntPtr.Size);", i);
-            string @delegate = method.Name + "Delegate";
-            string delegateId = GeneratedIdentifier(@delegate);
-            WriteLine("var {1} = ({0}) Marshal.GetDelegateForFunctionPointer(new IntPtr(slot), typeof({0}));",
-                @delegate, delegateId);
+            string delegateId;
+            Write(VTables.GetVirtualCallDelegate(method, @class, out delegateId));
             GenerateFunctionCall(delegateId, method.Parameters, method);
         }