Improve generation of C# (#1466)

src/CppParser/Bindings/CSharp/i686-pc-win32-msvc/Std.cs

@@ -8,6 +8,8 @@ using System;
 using System.Runtime.InteropServices;
 using System.Security;
 using System.Runtime.CompilerServices;
+using __CallingConvention = global::System.Runtime.InteropServices.CallingConvention;
+using __IntPtr = global::System.IntPtr;
 
 [assembly:InternalsVisibleTo("CppSharp.Parser.CSharp")]
 
@@ -304,13 +306,13 @@ namespace Std
         public unsafe partial struct __Internal
         {
             [FieldOffset(0)]
-            internal global::System.IntPtr _Myfirst;
+            internal __IntPtr _Myfirst;
 
             [FieldOffset(4)]
-            internal global::System.IntPtr _Mylast;
+            internal __IntPtr _Mylast;
 
             [FieldOffset(8)]
-            internal global::System.IntPtr _Myend;
+            internal __IntPtr _Myend;
         }
     }
 }
@@ -626,29 +628,39 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public unsafe partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.ThisCall,
-                EntryPoint="??0?$allocator@D@std@@QAE@XZ")]
-            internal static extern global::System.IntPtr ctorc__N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "??0?$allocator@D@std@@QAE@XZ", CallingConvention = __CallingConvention.ThisCall)]
+            internal static extern __IntPtr ctorc__N_std_S_allocator__C(__IntPtr __instance);
         }
     }
 
     public unsafe partial class Allocator<_Ty> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Ty>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Ty>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.Allocator<_Ty> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static Allocator<_Ty> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Ty>(native.ToPointer(), skipVTables);
+            return new Allocator<_Ty>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.Allocator<_Ty> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        internal static Allocator<_Ty> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Ty>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (Allocator<_Ty>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static Allocator<_Ty> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        {
+            return new Allocator<_Ty>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.Allocator.__Internal native)
@@ -669,7 +681,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public Allocator()
@@ -729,7 +741,7 @@ namespace Std
         public unsafe partial struct __Internal
         {
             [FieldOffset(0)]
-            internal global::System.IntPtr _Myhead;
+            internal __IntPtr _Myhead;
 
             [FieldOffset(4)]
             internal uint _Mysize;
@@ -747,34 +759,42 @@ namespace Std
             [FieldOffset(0)]
             internal global::Std.CompressedPair.__Internalc__N_std_S__Compressed_pair____N_std_S_allocator__C___N_std_S__String_val____N_std_S__Simple_types__C_Vb1 _Mypair;
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.ThisCall,
-                EntryPoint="??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@XZ")]
-            internal static extern global::System.IntPtr ctorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@XZ", CallingConvention = __CallingConvention.ThisCall)]
+            internal static extern __IntPtr ctorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.ThisCall,
-                EntryPoint="??1?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@XZ")]
-            internal static extern void dtorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "??1?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@XZ", CallingConvention = __CallingConvention.ThisCall)]
+            internal static extern void dtorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
         }
     }
 
     public unsafe partial class BasicString<_Elem, _Traits, _Alloc> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_Elem, _Traits, _Alloc>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_Elem, _Traits, _Alloc>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.BasicString<_Elem, _Traits, _Alloc> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static BasicString<_Elem, _Traits, _Alloc> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_Elem, _Traits, _Alloc>(native.ToPointer(), skipVTables);
+            return new BasicString<_Elem, _Traits, _Alloc>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.BasicString<_Elem, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
+        internal static BasicString<_Elem, _Traits, _Alloc> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_Elem, _Traits, _Alloc>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (BasicString<_Elem, _Traits, _Alloc>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static BasicString<_Elem, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
+        {
+            return new BasicString<_Elem, _Traits, _Alloc>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native)
@@ -795,7 +815,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public BasicString()
@@ -867,7 +887,7 @@ namespace Std
                 internal fixed sbyte _Buf[16];
 
                 [FieldOffset(0)]
-                internal global::System.IntPtr _Ptr;
+                internal __IntPtr _Ptr;
 
                 [FieldOffset(0)]
                 internal fixed sbyte _Alias[16];
@@ -886,20 +906,32 @@ namespace Std
 
     public unsafe partial class CharTraits<_Elem> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_Elem>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_Elem>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.CharTraits<_Elem> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static CharTraits<_Elem> __CreateInstance(__IntPtr native, bool skipVTables = false)
+        {
+            return new CharTraits<_Elem>(native.ToPointer(), skipVTables);
+        }
+
+        internal static CharTraits<_Elem> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_Elem>(native.ToPointer(), skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (CharTraits<_Elem>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
         }
 
-        internal static global::Std.CharTraits<_Elem> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
+        internal static CharTraits<_Elem> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_Elem>(native, skipVTables);
+            return new CharTraits<_Elem>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.CharTraits.__Internal native)
@@ -920,7 +952,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public void Dispose()
@@ -945,32 +977,24 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.ThisCall,
-                EntryPoint="?assign@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEAAV12@QBD@Z")]
-            internal static extern global::System.IntPtr Assign(global::System.IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string _Ptr);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "?assign@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEAAV12@QBD@Z", CallingConvention = __CallingConvention.ThisCall)]
+            internal static extern __IntPtr Assign(__IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string _Ptr);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.ThisCall,
-                EntryPoint="?data@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QBEPBDXZ")]
-            internal static extern global::System.IntPtr Data(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "?data@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QBEPBDXZ", CallingConvention = __CallingConvention.ThisCall)]
+            internal static extern __IntPtr Data(__IntPtr __instance);
         }
 
         public static global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> Assign(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this, string _Ptr)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Assign(__arg0, _Ptr);
-            global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> __result0;
-            if (__ret == IntPtr.Zero) __result0 = null;
-            else if (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap.ContainsKey(__ret))
-                __result0 = (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>) global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap[__ret];
-            else __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__CreateInstance(__ret);
+            var __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__GetOrCreateInstance(__ret, false);
             return __result0;
         }
 
         public static string Data(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Data(__arg0);
             return CppSharp.Runtime.MarshalUtil.GetString(global::System.Text.Encoding.UTF8, __ret);
         }

src/CppParser/Bindings/CSharp/x86_64-linux-gnu-cxx11abi/Std.cs

@@ -8,6 +8,8 @@ using System;
 using System.Runtime.InteropServices;
 using System.Security;
 using System.Runtime.CompilerServices;
+using __CallingConvention = global::System.Runtime.InteropServices.CallingConvention;
+using __IntPtr = global::System.IntPtr;
 
 [assembly:InternalsVisibleTo("CppSharp.Parser.CSharp")]
 
@@ -20,34 +22,42 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public unsafe partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSaIcEC2Ev")]
-            internal static extern void ctorc__N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSaIcEC2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void ctorc__N_std_S_allocator__C(__IntPtr __instance);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSaIcED2Ev")]
-            internal static extern void dtorc__N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSaIcED2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void dtorc__N_std_S_allocator__C(__IntPtr __instance);
         }
     }
 
     public unsafe partial class Allocator<_Tp> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Tp>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Tp>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.Allocator<_Tp> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static Allocator<_Tp> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Tp>(native.ToPointer(), skipVTables);
+            return new Allocator<_Tp>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.Allocator<_Tp> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        internal static Allocator<_Tp> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Tp>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (Allocator<_Tp>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static Allocator<_Tp> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        {
+            return new Allocator<_Tp>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.Allocator.__Internal native)
@@ -68,7 +78,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public Allocator()
@@ -686,13 +696,13 @@ namespace Std
             public unsafe partial struct __Internal
             {
                 [FieldOffset(0)]
-                internal global::System.IntPtr _M_start;
+                internal __IntPtr _M_start;
 
                 [FieldOffset(8)]
-                internal global::System.IntPtr _M_finish;
+                internal __IntPtr _M_finish;
 
                 [FieldOffset(16)]
-                internal global::System.IntPtr _M_end_of_storage;
+                internal __IntPtr _M_end_of_storage;
             }
 
         }
@@ -703,13 +713,13 @@ namespace Std
             public unsafe partial struct __Internal
             {
                 [FieldOffset(0)]
-                internal global::System.IntPtr _M_start;
+                internal __IntPtr _M_start;
 
                 [FieldOffset(8)]
-                internal global::System.IntPtr _M_finish;
+                internal __IntPtr _M_finish;
 
                 [FieldOffset(16)]
-                internal global::System.IntPtr _M_end_of_storage;
+                internal __IntPtr _M_end_of_storage;
             }
         }
 
@@ -768,13 +778,13 @@ namespace Std
             internal global::Std.RbTreeColor _M_color;
 
             [FieldOffset(8)]
-            internal global::System.IntPtr _M_parent;
+            internal __IntPtr _M_parent;
 
             [FieldOffset(16)]
-            internal global::System.IntPtr _M_left;
+            internal __IntPtr _M_left;
 
             [FieldOffset(24)]
-            internal global::System.IntPtr _M_right;
+            internal __IntPtr _M_right;
         }
     }
 }
@@ -812,20 +822,32 @@ namespace Std
 
     public unsafe partial class CharTraits<_CharT> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_CharT>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_CharT>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.CharTraits<_CharT> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static CharTraits<_CharT> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_CharT>(native.ToPointer(), skipVTables);
+            return new CharTraits<_CharT>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.CharTraits<_CharT> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
+        internal static CharTraits<_CharT> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_CharT>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (CharTraits<_CharT>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static CharTraits<_CharT> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
+        {
+            return new CharTraits<_CharT>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.CharTraits.__Internal native)
@@ -846,7 +868,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public void Dispose()
@@ -886,15 +908,11 @@ namespace Std
             [FieldOffset(16)]
             internal ulong _M_allocated_capacity;
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEC2Ev")]
-            internal static extern void ctorc__N_std_N___cxx11_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEC2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void ctorc__N_std_N___cxx11_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEED2Ev")]
-            internal static extern void dtorc__N_std_N___cxx11_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEED2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void dtorc__N_std_N___cxx11_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
         }
 
         namespace AllocHider
@@ -903,7 +921,7 @@ namespace Std
             public unsafe partial struct __Internal
             {
                 [FieldOffset(0)]
-                internal global::System.IntPtr _M_p;
+                internal __IntPtr _M_p;
             }
 
         }
@@ -925,20 +943,32 @@ namespace Std
 
     public unsafe partial class BasicString<_CharT, _Traits, _Alloc> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_CharT, _Traits, _Alloc>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_CharT, _Traits, _Alloc>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.BasicString<_CharT, _Traits, _Alloc> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static BasicString<_CharT, _Traits, _Alloc> __CreateInstance(__IntPtr native, bool skipVTables = false)
+        {
+            return new BasicString<_CharT, _Traits, _Alloc>(native.ToPointer(), skipVTables);
+        }
+
+        internal static BasicString<_CharT, _Traits, _Alloc> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_CharT, _Traits, _Alloc>(native.ToPointer(), skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (BasicString<_CharT, _Traits, _Alloc>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
         }
 
-        internal static global::Std.BasicString<_CharT, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_N___cxx11_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
+        internal static BasicString<_CharT, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_N___cxx11_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_CharT, _Traits, _Alloc>(native, skipVTables);
+            return new BasicString<_CharT, _Traits, _Alloc>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.BasicString.__Internalc__N_std_N___cxx11_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native)
@@ -959,7 +989,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public BasicString()
@@ -1012,32 +1042,24 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE6assignEPKc")]
-            internal static extern global::System.IntPtr Assign(global::System.IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string __s);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE6assignEPKc", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr Assign(__IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string __s);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE4dataEv")]
-            internal static extern global::System.IntPtr Data(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE4dataEv", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr Data(__IntPtr __instance);
         }
 
         public static global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> Assign(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this, string __s)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Assign(__arg0, __s);
-            global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> __result0;
-            if (__ret == IntPtr.Zero) __result0 = null;
-            else if (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap.ContainsKey(__ret))
-                __result0 = (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>) global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap[__ret];
-            else __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__CreateInstance(__ret);
+            var __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__GetOrCreateInstance(__ret, false);
             return __result0;
         }
 
         public static string Data(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Data(__arg0);
             return CppSharp.Runtime.MarshalUtil.GetString(global::System.Text.Encoding.UTF8, __ret);
         }

src/CppParser/Bindings/CSharp/x86_64-linux-gnu/Std.cs

@@ -8,6 +8,8 @@ using System;
 using System.Runtime.InteropServices;
 using System.Security;
 using System.Runtime.CompilerServices;
+using __CallingConvention = global::System.Runtime.InteropServices.CallingConvention;
+using __IntPtr = global::System.IntPtr;
 
 [assembly:InternalsVisibleTo("CppSharp.Parser.CSharp")]
 
@@ -20,34 +22,42 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public unsafe partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSaIcEC2Ev")]
-            internal static extern void ctorc__N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSaIcEC2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void ctorc__N_std_S_allocator__C(__IntPtr __instance);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSaIcED2Ev")]
-            internal static extern void dtorc__N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSaIcED2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void dtorc__N_std_S_allocator__C(__IntPtr __instance);
         }
     }
 
     public unsafe partial class Allocator<_Tp> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Tp>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Tp>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.Allocator<_Tp> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static Allocator<_Tp> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Tp>(native.ToPointer(), skipVTables);
+            return new Allocator<_Tp>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.Allocator<_Tp> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        internal static Allocator<_Tp> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Tp>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (Allocator<_Tp>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static Allocator<_Tp> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        {
+            return new Allocator<_Tp>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.Allocator.__Internal native)
@@ -68,7 +78,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public Allocator()
@@ -686,13 +696,13 @@ namespace Std
             public unsafe partial struct __Internal
             {
                 [FieldOffset(0)]
-                internal global::System.IntPtr _M_start;
+                internal __IntPtr _M_start;
 
                 [FieldOffset(8)]
-                internal global::System.IntPtr _M_finish;
+                internal __IntPtr _M_finish;
 
                 [FieldOffset(16)]
-                internal global::System.IntPtr _M_end_of_storage;
+                internal __IntPtr _M_end_of_storage;
             }
 
         }
@@ -703,13 +713,13 @@ namespace Std
             public unsafe partial struct __Internal
             {
                 [FieldOffset(0)]
-                internal global::System.IntPtr _M_start;
+                internal __IntPtr _M_start;
 
                 [FieldOffset(8)]
-                internal global::System.IntPtr _M_finish;
+                internal __IntPtr _M_finish;
 
                 [FieldOffset(16)]
-                internal global::System.IntPtr _M_end_of_storage;
+                internal __IntPtr _M_end_of_storage;
             }
         }
 
@@ -768,13 +778,13 @@ namespace Std
             internal global::Std.RbTreeColor _M_color;
 
             [FieldOffset(8)]
-            internal global::System.IntPtr _M_parent;
+            internal __IntPtr _M_parent;
 
             [FieldOffset(16)]
-            internal global::System.IntPtr _M_left;
+            internal __IntPtr _M_left;
 
             [FieldOffset(24)]
-            internal global::System.IntPtr _M_right;
+            internal __IntPtr _M_right;
         }
     }
 }
@@ -812,20 +822,32 @@ namespace Std
 
     public unsafe partial class CharTraits<_CharT> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_CharT>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_CharT>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.CharTraits<_CharT> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static CharTraits<_CharT> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_CharT>(native.ToPointer(), skipVTables);
+            return new CharTraits<_CharT>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.CharTraits<_CharT> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
+        internal static CharTraits<_CharT> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_CharT>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (CharTraits<_CharT>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static CharTraits<_CharT> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
+        {
+            return new CharTraits<_CharT>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.CharTraits.__Internal native)
@@ -846,7 +868,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public void Dispose()
@@ -877,15 +899,11 @@ namespace Std
             [FieldOffset(0)]
             internal global::Std.BasicString.AllocHider.__Internal _M_dataplus;
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSsC2Ev")]
-            internal static extern void ctorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSsC2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void ctorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSsD2Ev")]
-            internal static extern void dtorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSsD2Ev", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void dtorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
         }
 
         namespace AllocHider
@@ -894,7 +912,7 @@ namespace Std
             public unsafe partial struct __Internal
             {
                 [FieldOffset(0)]
-                internal global::System.IntPtr _M_p;
+                internal __IntPtr _M_p;
             }
         }
 
@@ -902,20 +920,32 @@ namespace Std
 
     public unsafe partial class BasicString<_CharT, _Traits, _Alloc> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_CharT, _Traits, _Alloc>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_CharT, _Traits, _Alloc>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.BasicString<_CharT, _Traits, _Alloc> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static BasicString<_CharT, _Traits, _Alloc> __CreateInstance(__IntPtr native, bool skipVTables = false)
+        {
+            return new BasicString<_CharT, _Traits, _Alloc>(native.ToPointer(), skipVTables);
+        }
+
+        internal static BasicString<_CharT, _Traits, _Alloc> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_CharT, _Traits, _Alloc>(native.ToPointer(), skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (BasicString<_CharT, _Traits, _Alloc>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
         }
 
-        internal static global::Std.BasicString<_CharT, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
+        internal static BasicString<_CharT, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_CharT, _Traits, _Alloc>(native, skipVTables);
+            return new BasicString<_CharT, _Traits, _Alloc>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native)
@@ -936,7 +966,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public BasicString()
@@ -989,32 +1019,24 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNSs6assignEPKc")]
-            internal static extern global::System.IntPtr Assign(global::System.IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string __s);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNSs6assignEPKc", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr Assign(__IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string __s);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="_ZNKSs4dataEv")]
-            internal static extern global::System.IntPtr Data(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "_ZNKSs4dataEv", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr Data(__IntPtr __instance);
         }
 
         public static global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> Assign(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this, string __s)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Assign(__arg0, __s);
-            global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> __result0;
-            if (__ret == IntPtr.Zero) __result0 = null;
-            else if (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap.ContainsKey(__ret))
-                __result0 = (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>) global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap[__ret];
-            else __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__CreateInstance(__ret);
+            var __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__GetOrCreateInstance(__ret, false);
             return __result0;
         }
 
         public static string Data(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Data(__arg0);
             return CppSharp.Runtime.MarshalUtil.GetString(global::System.Text.Encoding.UTF8, __ret);
         }

src/CppParser/Bindings/CSharp/x86_64-pc-win32-msvc/Std.cs

@@ -8,6 +8,8 @@ using System;
 using System.Runtime.InteropServices;
 using System.Security;
 using System.Runtime.CompilerServices;
+using __CallingConvention = global::System.Runtime.InteropServices.CallingConvention;
+using __IntPtr = global::System.IntPtr;
 
 [assembly:InternalsVisibleTo("CppSharp.Parser.CSharp")]
 
@@ -304,13 +306,13 @@ namespace Std
         public unsafe partial struct __Internal
         {
             [FieldOffset(0)]
-            internal global::System.IntPtr _Myfirst;
+            internal __IntPtr _Myfirst;
 
             [FieldOffset(8)]
-            internal global::System.IntPtr _Mylast;
+            internal __IntPtr _Mylast;
 
             [FieldOffset(16)]
-            internal global::System.IntPtr _Myend;
+            internal __IntPtr _Myend;
         }
     }
 }
@@ -626,29 +628,39 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public unsafe partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="??0?$allocator@D@std@@QEAA@XZ")]
-            internal static extern global::System.IntPtr ctorc__N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "??0?$allocator@D@std@@QEAA@XZ", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr ctorc__N_std_S_allocator__C(__IntPtr __instance);
         }
     }
 
     public unsafe partial class Allocator<_Ty> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Ty>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.Allocator<_Ty>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.Allocator<_Ty> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static Allocator<_Ty> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Ty>(native.ToPointer(), skipVTables);
+            return new Allocator<_Ty>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.Allocator<_Ty> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        internal static Allocator<_Ty> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.Allocator<_Ty>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (Allocator<_Ty>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static Allocator<_Ty> __CreateInstance(global::Std.Allocator.__Internal native, bool skipVTables = false)
+        {
+            return new Allocator<_Ty>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.Allocator.__Internal native)
@@ -669,7 +681,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public Allocator()
@@ -729,7 +741,7 @@ namespace Std
         public unsafe partial struct __Internal
         {
             [FieldOffset(0)]
-            internal global::System.IntPtr _Myhead;
+            internal __IntPtr _Myhead;
 
             [FieldOffset(8)]
             internal ulong _Mysize;
@@ -747,34 +759,42 @@ namespace Std
             [FieldOffset(0)]
             internal global::Std.CompressedPair.__Internalc__N_std_S__Compressed_pair____N_std_S_allocator__C___N_std_S__String_val____N_std_S__Simple_types__C_Vb1 _Mypair;
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEAA@XZ")]
-            internal static extern global::System.IntPtr ctorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEAA@XZ", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr ctorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="??1?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEAA@XZ")]
-            internal static extern void dtorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "??1?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEAA@XZ", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern void dtorc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C(__IntPtr __instance);
         }
     }
 
     public unsafe partial class BasicString<_Elem, _Traits, _Alloc> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_Elem, _Traits, _Alloc>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.BasicString<_Elem, _Traits, _Alloc>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.BasicString<_Elem, _Traits, _Alloc> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static BasicString<_Elem, _Traits, _Alloc> __CreateInstance(__IntPtr native, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_Elem, _Traits, _Alloc>(native.ToPointer(), skipVTables);
+            return new BasicString<_Elem, _Traits, _Alloc>(native.ToPointer(), skipVTables);
         }
 
-        internal static global::Std.BasicString<_Elem, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
+        internal static BasicString<_Elem, _Traits, _Alloc> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.BasicString<_Elem, _Traits, _Alloc>(native, skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (BasicString<_Elem, _Traits, _Alloc>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
+        }
+
+        internal static BasicString<_Elem, _Traits, _Alloc> __CreateInstance(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native, bool skipVTables = false)
+        {
+            return new BasicString<_Elem, _Traits, _Alloc>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.BasicString.__Internalc__N_std_S_basic_string__C___N_std_S_char_traits__C___N_std_S_allocator__C native)
@@ -795,7 +815,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public BasicString()
@@ -867,7 +887,7 @@ namespace Std
                 internal fixed sbyte _Buf[16];
 
                 [FieldOffset(0)]
-                internal global::System.IntPtr _Ptr;
+                internal __IntPtr _Ptr;
 
                 [FieldOffset(0)]
                 internal fixed sbyte _Alias[16];
@@ -886,20 +906,32 @@ namespace Std
 
     public unsafe partial class CharTraits<_Elem> : IDisposable
     {
-        public global::System.IntPtr __Instance { get; protected set; }
+        public __IntPtr __Instance { get; protected set; }
 
         internal static readonly global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_Elem>> NativeToManagedMap = new global::System.Collections.Concurrent.ConcurrentDictionary<IntPtr, global::Std.CharTraits<_Elem>>();
 
         protected bool __ownsNativeInstance;
 
-        internal static global::Std.CharTraits<_Elem> __CreateInstance(global::System.IntPtr native, bool skipVTables = false)
+        internal static CharTraits<_Elem> __CreateInstance(__IntPtr native, bool skipVTables = false)
+        {
+            return new CharTraits<_Elem>(native.ToPointer(), skipVTables);
+        }
+
+        internal static CharTraits<_Elem> __GetOrCreateInstance(__IntPtr native, bool saveInstance = false, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_Elem>(native.ToPointer(), skipVTables);
+            if (native == __IntPtr.Zero)
+                return null;
+            if (NativeToManagedMap.TryGetValue(native, out var managed))
+                return (CharTraits<_Elem>)managed;
+            var result = __CreateInstance(native, skipVTables);
+            if (saveInstance)
+                NativeToManagedMap[native] = result;
+            return result;
         }
 
-        internal static global::Std.CharTraits<_Elem> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
+        internal static CharTraits<_Elem> __CreateInstance(global::Std.CharTraits.__Internal native, bool skipVTables = false)
         {
-            return new global::Std.CharTraits<_Elem>(native, skipVTables);
+            return new CharTraits<_Elem>(native, skipVTables);
         }
 
         private static void* __CopyValue(global::Std.CharTraits.__Internal native)
@@ -920,7 +952,7 @@ namespace Std
         {
             if (native == null)
                 return;
-            __Instance = new global::System.IntPtr(native);
+            __Instance = new __IntPtr(native);
         }
 
         public void Dispose()
@@ -945,32 +977,24 @@ namespace Std
         [StructLayout(LayoutKind.Explicit, Size = 0)]
         public partial struct __Internal
         {
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="?assign@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEAAAEAV12@QEBD@Z")]
-            internal static extern global::System.IntPtr Assign(global::System.IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string _Ptr);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "?assign@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEAAAEAV12@QEBD@Z", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr Assign(__IntPtr __instance, [MarshalAs(UnmanagedType.LPUTF8Str)] string _Ptr);
 
-            [SuppressUnmanagedCodeSecurity]
-            [DllImport("Std-symbols", CallingConvention = global::System.Runtime.InteropServices.CallingConvention.Cdecl,
-                EntryPoint="?data@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEBAPEBDXZ")]
-            internal static extern global::System.IntPtr Data(global::System.IntPtr __instance);
+            [SuppressUnmanagedCodeSecurity, DllImport("Std-symbols", EntryPoint = "?data@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEBAPEBDXZ", CallingConvention = __CallingConvention.Cdecl)]
+            internal static extern __IntPtr Data(__IntPtr __instance);
         }
 
         public static global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> Assign(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this, string _Ptr)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Assign(__arg0, _Ptr);
-            global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> __result0;
-            if (__ret == IntPtr.Zero) __result0 = null;
-            else if (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap.ContainsKey(__ret))
-                __result0 = (global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>) global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.NativeToManagedMap[__ret];
-            else __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__CreateInstance(__ret);
+            var __result0 = global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>>.__GetOrCreateInstance(__ret, false);
             return __result0;
         }
 
         public static string Data(this global::Std.BasicString<sbyte, global::Std.CharTraits<sbyte>, global::Std.Allocator<sbyte>> @this)
         {
-            var __arg0 = ReferenceEquals(@this, null) ? global::System.IntPtr.Zero : @this.__Instance;
+            var __arg0 = @this is null ? __IntPtr.Zero : @this.__Instance;
             var __ret = __Internal.Data(__arg0);
             return CppSharp.Runtime.MarshalUtil.GetString(global::System.Text.Encoding.UTF8, __ret);
         }

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -344,34 +344,22 @@ namespace CppSharp.Generators.CSharp
         {
             var originalClass = @class.OriginalClass ?? @class;
             var ret = Generator.GeneratedIdentifier("result") + Context.ParameterIndex;
-            var qualifiedIdentifier = @class.Visit(typePrinter);
-            Context.Before.WriteLine("{0} {1};", qualifiedIdentifier, ret);
-            Context.Before.WriteLine("if ({0} == IntPtr.Zero) {1} = {2};", Context.ReturnVarName, ret,
-                originalClass.IsRefType ? "null" : string.Format("new {0}()", qualifiedClass));
+        
             if (originalClass.IsRefType)
             {
-                Context.Before.WriteLine(
-                    "else if ({0}.NativeToManagedMap.TryGetValue({1}, out var {2}))", qualifiedClass, Context.ReturnVarName, ret + "Object");
-                Context.Before.WriteLineIndent("{0} = ({1}) {2};",
-                    ret, qualifiedIdentifier, ret + "Object");
                 var dtor = originalClass.Destructors.FirstOrDefault();
-                if (dtor != null && dtor.IsVirtual)
-                {
-                    Context.Before.WriteLine("else {0}{1} = ({2}) {3}.{4}({5}{6});",
-                        Context.Parameter != null
-                            ? string.Empty
-                            : string.Format("{0}.NativeToManagedMap[{1}] = ", qualifiedClass, Context.ReturnVarName),
-                        ret, qualifiedIdentifier, qualifiedClass, Helpers.CreateInstanceIdentifier, Context.ReturnVarName,
-                        Context.Parameter != null ? ", skipVTables: true" : string.Empty);
-                }
-                else
-                {
-                    Context.Before.WriteLine("else {0} = {1}.{2}({3});", ret, qualifiedClass,
-                        Helpers.CreateInstanceIdentifier, Context.ReturnVarName);
-                }
+                var dtorVirtual = (dtor != null && dtor.IsVirtual);
+                var cache = dtorVirtual && Context.Parameter == null;
+                var skipVTables = dtorVirtual && Context.Parameter != null;
+                Context.Before.WriteLine("var {0} = {1}.__GetOrCreateInstance({2}, {3}{4});",
+                    ret, qualifiedClass, Context.ReturnVarName, cache ? "true" : "false", skipVTables ? ", skipVTables: true" : string.Empty);
             }
             else
             {
+                var qualifiedIdentifier = @class.Visit(typePrinter);
+                Context.Before.WriteLine("{0} {1};", qualifiedIdentifier, ret);
+                Context.Before.WriteLine("if ({0} == IntPtr.Zero) {1} = {2};", Context.ReturnVarName, ret,
+                    originalClass.IsRefType ? "null" : string.Format("new {0}()", qualifiedClass));
                 Context.Before.WriteLine("else {0} = {1}.{2}({3});", ret, qualifiedClass,
                     Helpers.CreateInstanceIdentifier, Context.ReturnVarName);
             }
@@ -394,7 +382,7 @@ namespace CppSharp.Generators.CSharp
 
             Context.Before.WriteLine($"{intermediateArrayType}[] {intermediateArray};");
 
-            Context.Before.WriteLine($"if (ReferenceEquals({Context.ReturnVarName}, null))");
+            Context.Before.WriteLine($"if ({Context.ReturnVarName} is null)");
             Context.Before.WriteLineIndent($"{intermediateArray} = null;");
             Context.Before.WriteLine("else");
 
@@ -764,7 +752,7 @@ namespace CppSharp.Generators.CSharp
                     Context.Return.Write("{0}{1}",
                         method != null && method.OperatorKind == CXXOperatorKind.EqualEqual
                             ? string.Empty
-                            : $"ReferenceEquals({param}, null) ? global::System.IntPtr.Zero : ",
+                            : $"{param} is null ? {typePrinter.IntPtrType}.Zero : ",
                         paramInstance);
                 }
                 return;
@@ -872,7 +860,7 @@ namespace CppSharp.Generators.CSharp
 
             Context.Before.WriteLine($"{intermediateArrayType}[] {intermediateArray};");
 
-            Context.Before.WriteLine($"if (ReferenceEquals({Context.Parameter.Name}, null))");
+            Context.Before.WriteLine($"if ({Context.Parameter.Name} is null)");
                 Context.Before.WriteLineIndent($"{intermediateArray} = null;");
             Context.Before.WriteLine("else");
 
@@ -887,12 +875,12 @@ namespace CppSharp.Generators.CSharp
             if (elementType.IsAddress())
             {
                 var intPtrZero = $"{typePrinter.IntPtrType}.Zero";
-                Context.Before.WriteLine($@"{intermediateArray}[i] = ReferenceEquals({
-                    element}, null) ? {intPtrZero} : {element}.{Helpers.InstanceIdentifier};");
+                Context.Before.WriteLine($@"{intermediateArray}[i] = {
+                    element} is null ? {intPtrZero} : {element}.{Helpers.InstanceIdentifier};");
             }
             else
-                Context.Before.WriteLine($@"{intermediateArray}[i] = ReferenceEquals({
-                    element}, null) ? new {intermediateArrayType}() : *({
+                Context.Before.WriteLine($@"{intermediateArray}[i] = {
+                    element} is null ? new {intermediateArrayType}() : *({
                     intermediateArrayType}*) {element}.{Helpers.InstanceIdentifier};");
             Context.Before.UnindentAndWriteCloseBrace();
 

src/Generator/Generators/CSharp/CSharpSources.cs

@@ -164,6 +164,10 @@ namespace CppSharp.Generators.CSharp
 
             foreach (var customUsingStatement in Options.DependentNameSpaces)
                 WriteLine("using {0};", customUsingStatement);
+
+            WriteLine("using __CallingConvention = global::System.Runtime.InteropServices.CallingConvention;");
+            WriteLine("using __IntPtr = global::System.IntPtr;");
+
             PopBlock(NewLineKind.BeforeNextBlock);
 
             foreach (var library in internalsVisibleTo)
@@ -940,8 +944,12 @@ namespace CppSharp.Generators.CSharp
                     f => f.FieldPtr == field.OriginalPtr).Name;
                 if (@class.IsValueType)
                     returnVar = $"{Helpers.InstanceField}.{name}";
-                else
-                    returnVar = $"(({TypePrinter.PrintNative(@class)}*){Helpers.InstanceIdentifier})->{name}";
+                else {
+                    var typeName = TypePrinter.PrintNative(@class);
+                    if (IsInternalClassNested(field.Class))
+                        typeName.RemoveNamespace();
+                    returnVar = $"(({typeName}*){Helpers.InstanceIdentifier})->{name}";
+                }
             }
 
             var param = new Parameter
@@ -992,6 +1000,11 @@ namespace CppSharp.Generators.CSharp
                 UnindentAndWriteCloseBrace();
         }
 
+        private static bool IsInternalClassNested(Class @class)
+        {
+            return !(@class is ClassTemplateSpecialization) && !(@class.Namespace is ClassTemplateSpecialization);
+        }
+
         private string HandleValueArray(ArrayType arrayType, Field field)
         {
             var originalType = new PointerType(new QualifiedType(arrayType.Type));
@@ -1280,7 +1293,10 @@ namespace CppSharp.Generators.CSharp
             }
             else
             {
-                returnVar = $"(({TypePrinter.PrintNative(@class)}*) {Helpers.InstanceIdentifier})->{name}";
+                var typeName = TypePrinter.PrintNative(@class);
+                if (IsInternalClassNested(field.Class))
+                    typeName.RemoveNamespace();
+                returnVar = $"(({typeName}*){Helpers.InstanceIdentifier})->{name}";
                 // Class field getter should return a reference object instead of a copy. Wrapping `returnVar` in
                 // IntPtr ensures that non-copying object constructor is invoked.
                 Class typeClass;
@@ -1909,14 +1925,8 @@ namespace CppSharp.Generators.CSharp
                 string.Join(", ", @params));
             WriteOpenBraceAndIndent();
 
-            WriteLine($"if (!NativeToManagedMap.TryGetValue({Helpers.InstanceField}, out var {Helpers.TargetIdentifier}Object))");
-            WriteLineIndent("throw new global::System.Exception(\"No managed instance was found\");");
-            NewLine();
-
             var printedClass = @class.Visit(TypePrinter);
-            WriteLine($@"var {Helpers.TargetIdentifier} = ({printedClass}){Helpers.TargetIdentifier}Object;");
-            WriteLine("if ({0}.{1})", Helpers.TargetIdentifier, Helpers.OwnsNativeInstanceIdentifier);
-            WriteLineIndent("{0}.SetupVTables();", Helpers.TargetIdentifier);
+            WriteLine($@"var {Helpers.TargetIdentifier} = {printedClass}.__GetInstance({Helpers.InstanceField});");
             GenerateVTableManagedCall(method);
 
             UnindentAndWriteCloseBrace();
@@ -1934,6 +1944,11 @@ namespace CppSharp.Generators.CSharp
             return string.Format("_{0}Delegate", nativeId);
         }
 
+        public bool HasVirtualTables(Class @class)
+        {
+            return @class.IsGenerated && @class.IsDynamic && GetUniqueVTableMethodEntries(@class).Count > 0;
+        }
+
         #endregion
 
         #region Events
@@ -1952,7 +1967,7 @@ namespace CppSharp.Generators.CSharp
             var delegateName = delegateInstance + "Delegate";
             var delegateRaise = delegateInstance + "RaiseInstance";
 
-            WriteLine("[UnmanagedFunctionPointer(global::System.Runtime.InteropServices.CallingConvention.Cdecl)]");
+            WriteLine("[UnmanagedFunctionPointer(__CallingConvention.Cdecl)]");
             WriteLine("delegate void {0}({1});", delegateName, args);
             WriteLine("{0} {1};", delegateName, delegateRaise);
             NewLine();
@@ -2147,7 +2162,7 @@ namespace CppSharp.Generators.CSharp
                     ClassLayout layout = (@class.IsDependent ? @class.Specializations[0] : @class).Layout;
                     for (var i = 0; i < layout.VTablePointers.Count; i++)
                         WriteLine($@"(({classInternal}*) {Helpers.InstanceIdentifier})->{
-                            layout.VTablePointers[i].Name} = new global::System.IntPtr(__OriginalVTables[{i}]);");
+                            layout.VTablePointers[i].Name} = new {TypePrinter.IntPtrType}(__OriginalVTables[{i}]);");
                 }
             }
 
@@ -2213,15 +2228,53 @@ namespace CppSharp.Generators.CSharp
             {
                 PushBlock(BlockKind.Method);
                 TypePrinterResult printedClass = @class.Visit(TypePrinter);
-                WriteLine("internal static {0}{1} {2}(global::System.IntPtr native, bool skipVTables = false)",
+                printedClass.RemoveNamespace();
+
+                WriteLine("internal static {0}{1} {2}({3} native, bool skipVTables = false)",
                     @class.NeedsBase && !@class.BaseClass.IsInterface ? "new " : string.Empty,
-                    printedClass, Helpers.CreateInstanceIdentifier);
+                    printedClass, Helpers.CreateInstanceIdentifier, TypePrinter.IntPtrType);
                 WriteOpenBraceAndIndent();
                 var suffix = @class.IsAbstract ? "Internal" : string.Empty;
                 var ctorCall = $"{printedClass.Type}{suffix}{printedClass.NameSuffix}";
                 WriteLine("return new {0}(native.ToPointer(), skipVTables);", ctorCall);
                 UnindentAndWriteCloseBrace();
                 PopBlock(NewLineKind.BeforeNextBlock);
+
+                if (@class.IsRefType)
+                {
+                    var @new = @class.HasBase && @class.HasRefBase();
+
+                    WriteLines($@"
+internal static{(@new ? " new" : string.Empty)} {printedClass} __GetOrCreateInstance({TypePrinter.IntPtrType} native, bool saveInstance = false, bool skipVTables = false)
+{{
+    if (native == {TypePrinter.IntPtrType}.Zero)
+        return null;
+    if (NativeToManagedMap.TryGetValue(native, out var managed))
+        return ({printedClass})managed;
+    var result = {Helpers.CreateInstanceIdentifier}(native, skipVTables);
+    if (saveInstance)
+        NativeToManagedMap[native] = result;
+    return result;
+}}");
+                    NewLine();
+
+                    if (HasVirtualTables(@class))
+                    {
+                        @new = @class.HasBase;
+
+                        WriteLines($@"
+internal static{(@new ? " new" : string.Empty)} {printedClass} __GetInstance({TypePrinter.IntPtrType} native)
+{{
+    if (!NativeToManagedMap.TryGetValue(native, out var managed))
+        throw new System.Exception(""No managed instance was found"");
+    var result = ({printedClass})managed;
+    if (result.{Helpers.OwnsNativeInstanceIdentifier})
+        result.SetupVTables();
+    return result;
+}}");
+                        NewLine();
+                    }
+                }
             }
 
             this.GenerateNativeConstructorsByValue(@class);
@@ -2248,7 +2301,7 @@ namespace CppSharp.Generators.CSharp
                     WriteLine("if (native == null)");
                     WriteLineIndent("return;");
                     if (!hasBaseClass)
-                        WriteLine($"{Helpers.InstanceIdentifier} = new global::System.IntPtr(native);");
+                        WriteLine($"{Helpers.InstanceIdentifier} = new {TypePrinter.IntPtrType}(native);");
                 }
                 var dtor = @class.Destructors.FirstOrDefault();
                 var setupVTables = !@class.IsAbstractImpl && hasVTables && dtor?.IsVirtual == true;
@@ -2272,9 +2325,13 @@ namespace CppSharp.Generators.CSharp
         public void GenerateNativeConstructorByValue(Class @class, TypePrinterResult returnType)
         {
             var @internal = TypePrinter.PrintNative(@class.IsAbstractImpl ? @class.BaseClass : @class);
+            
+            if (IsInternalClassNested(@class))
+                @internal.RemoveNamespace();
 
             if (!@class.IsAbstractImpl)
             {
+                returnType.RemoveNamespace();
                 PushBlock(BlockKind.Method);
                 WriteLine("internal static {0} {1}({2} native, bool skipVTables = false)",
                     returnType, Helpers.CreateInstanceIdentifier, @internal);
@@ -2298,7 +2355,7 @@ namespace CppSharp.Generators.CSharp
                     // Allocate memory for a new native object and call the ctor.
                     WriteLine($"var ret = Marshal.AllocHGlobal(sizeof({@internal}));");
                     var printed = TypePrinter.PrintNative(@class);
-                    WriteLine($"{printed}.{GetFunctionNativeIdentifier(copyCtorMethod)}(ret, new global::System.IntPtr(&native));",
+                    WriteLine($"{printed}.{GetFunctionNativeIdentifier(copyCtorMethod)}(ret, new {TypePrinter.IntPtrType}(&native));",
                         printed, GetFunctionNativeIdentifier(copyCtorMethod));
                     WriteLine("return ret.ToPointer();");
                 }
@@ -2639,8 +2696,8 @@ namespace CppSharp.Generators.CSharp
 
         private void GenerateGetHashCode(Class @class)
         {
-            WriteLine($"if ({Helpers.InstanceIdentifier} == global::System.IntPtr.Zero)");
-            WriteLineIndent("return global::System.IntPtr.Zero.GetHashCode();");
+            WriteLine($"if ({Helpers.InstanceIdentifier} == {TypePrinter.IntPtrType}.Zero)");
+            WriteLineIndent($"return {TypePrinter.IntPtrType}.Zero.GetHashCode();");
             WriteLine($@"return (*({TypePrinter.PrintNative(@class)}*) {
                 Helpers.InstanceIdentifier}).GetHashCode();");
         }
@@ -2674,23 +2731,19 @@ namespace CppSharp.Generators.CSharp
                 vtableIndex = @class.Layout.VFTables.IndexOf(@class.Layout.VFTables.First(
                     v => v.Layout.Components.Any(c => c.Method == @virtual)));
 
-            WriteLine($@"var {Helpers.SlotIdentifier} = *(void**) ((IntPtr) {
-                (thisParam != null ? $"{thisParam.Name}."
-                : string.Empty)}__OriginalVTables[{vtableIndex}] + {i} * {
-                Context.TargetInfo.PointerWidth / 8});");
+            var vtables = $@"{ (thisParam != null ? $"{thisParam.Name}." : string.Empty)}__OriginalVTables";
+            var @delegate = GetVTableMethodDelegateName(@virtual);
+            var delegateId = Generator.GeneratedIdentifier(@delegate);
+
+            WriteLine("var {0} = CppSharp.Runtime.MarshalUtil.GetDelegate<{1}>({2}, {3}, {4});",
+                delegateId, method.FunctionType.ToString(), vtables, vtableIndex, i);
+
             if (method.IsDestructor && @class.IsAbstract)
             {
-                WriteLine("if ({0} != null)", Helpers.SlotIdentifier);
+                WriteLine("if ({0} != null)", delegateId);
                 WriteOpenBraceAndIndent();
             }
 
-            var @delegate = GetVTableMethodDelegateName(@virtual);
-            var delegateId = Generator.GeneratedIdentifier(@delegate);
-
-            WriteLine("var {0} = ({1}) Marshal.GetDelegateForFunctionPointer(new IntPtr({2}), typeof({1}));",
-                delegateId, method.FunctionType.ToString(),
-                Helpers.SlotIdentifier);
-
             return delegateId;
         }
 
@@ -2895,7 +2948,7 @@ namespace CppSharp.Generators.CSharp
 
                 if (needsFixedThis)
                 {
-                    names.Insert(instanceIndex, "new global::System.IntPtr(__instancePtr)");
+                    names.Insert(instanceIndex, $"new {TypePrinter.IntPtrType}(__instancePtr)");
                 }
                 else
                 {
@@ -3125,7 +3178,7 @@ namespace CppSharp.Generators.CSharp
                 else
                     WriteLine(
                         "[SuppressUnmanagedCodeSecurity, " +
-                        "UnmanagedFunctionPointer(global::System.Runtime.InteropServices.CallingConvention.{0})]",
+                        "UnmanagedFunctionPointer(__CallingConvention.{0})]",
                         interopCallConv);
 
                 if (functionType.ReturnType.Type.Desugar().IsPrimitiveType(PrimitiveType.Bool))
@@ -3251,14 +3304,12 @@ namespace CppSharp.Generators.CSharp
                 return;
 
             PushBlock(BlockKind.InternalsClassMethod);
-            WriteLine("[SuppressUnmanagedCodeSecurity]");
-            Write("[DllImport(\"{0}\", ", GetLibraryOf(function));
-
             var callConv = function.CallingConvention.ToInteropCallConv();
-            WriteLine("CallingConvention = global::System.Runtime.InteropServices.CallingConvention.{0},",
-                callConv);
 
-            WriteLineIndent("EntryPoint=\"{0}\")]", function.Mangled);
+            WriteLine("[SuppressUnmanagedCodeSecurity, DllImport(\"{0}\", EntryPoint = \"{1}\", CallingConvention = __CallingConvention.{2})]", 
+                GetLibraryOf(function),
+                function.Mangled,
+                callConv);
 
             if (function.ReturnType.Type.IsPrimitiveType(PrimitiveType.Bool))
                 WriteLine("[return: MarshalAs(UnmanagedType.I1)]");

src/Generator/Generators/CSharp/CSharpTypePrinter.cs

@@ -13,7 +13,7 @@ namespace CppSharp.Generators.CSharp
 {
     public class CSharpTypePrinter : TypePrinter
     {
-        public string IntPtrType => QualifiedType("System.IntPtr");
+        public string IntPtrType => "__IntPtr";
 
         public BindingContext Context { get; set; }
 

src/Generator/Generators/TypePrinter.cs

@@ -20,6 +20,13 @@ namespace CppSharp.Generators
             NameSuffix.Append(nameSuffix);
         }
 
+        public void RemoveNamespace()
+        {
+            var index = Type.LastIndexOf('.');
+            if (index != -1)
+                Type = Type.Substring(index + 1);
+        }
+
         public static implicit operator TypePrinterResult(string type) =>
             new TypePrinterResult { Type = type };
 

src/Generator/Utils/BlockGenerator.cs

@@ -239,6 +239,8 @@ namespace CppSharp
 
     public abstract class BlockGenerator : ITextGenerator
     {
+        private static string[] LineBreakSequences = new[] { "\r\n", "\r", "\n" };
+
         public Block RootBlock { get; }
         public Block ActiveBlock { get; private set; }
         public uint CurrentIndentation => ActiveBlock.Text.CurrentIndentation;
@@ -311,6 +313,12 @@ namespace CppSharp
             ActiveBlock.WriteLine(msg, args);
         }
 
+        public void WriteLines(string msg)
+        {
+            foreach(var line in msg.TrimStart().Split(LineBreakSequences, StringSplitOptions.None))
+                WriteLine(line);
+        }
+
         public void WriteLineIndent(string msg, params object[] args)
         {
             ActiveBlock.WriteLineIndent(msg, args);

src/Runtime/MarshalUtil.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.InteropServices;
 using System.Text;
 
 namespace CppSharp.Runtime
@@ -55,5 +56,11 @@ namespace CppSharp.Runtime
         {
             return GetArray<IntPtr>(array, size);
         }
+
+        public static T GetDelegate<T>(void*[] vtables, short table, int i) where T : class
+        {
+            var slot = *(void**)((IntPtr)vtables[table] + i * sizeof(IntPtr));
+            return Marshal.GetDelegateForFunctionPointer<T>(new IntPtr(slot));
+        }
     }
 }