From 33e2c74642192ca8bacd5f763a37fb0593c54258 Mon Sep 17 00:00:00 2001
From: Leonard2 <hobbax3@gmail.com>
Date: Sun, 6 Nov 2016 11:28:01 +0100
Subject: [PATCH] Provide a way to expose a native class to zscript for virtual
 functions overriding

---
 src/dobject.cpp  | 17 +++++++++--------
 src/dobject.h    | 11 ++++++++---
 src/dobjtype.cpp |  8 ++++++--
 src/dobjtype.h   |  1 +
 4 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/dobject.cpp b/src/dobject.cpp
index d057a71d3..e21d07526 100644
--- a/src/dobject.cpp
+++ b/src/dobject.cpp
@@ -57,14 +57,15 @@
 
 ClassReg DObject::RegistrationInfo =
 {
-	NULL,							// MyClass
-	"DObject",						// Name
-	NULL,							// ParentType
-	NULL,							// Pointers
-	&DObject::InPlaceConstructor,	// ConstructNative
-	&DObject::InitNativeFields,
-	sizeof(DObject),				// SizeOf
-	CLASSREG_PClass,				// MetaClassNum
+	nullptr,								// MyClass
+	"DObject",								// Name
+	nullptr,								// ParentType
+	&DVMObject<DObject>::RegistrationInfo,	// VMExport
+	nullptr,								// Pointers
+	&DObject::InPlaceConstructor,			// ConstructNative
+	&DObject::InitNativeFields,				// InitNatives
+	sizeof(DObject),						// SizeOf
+	CLASSREG_PClass,						// MetaClassNum
 };
 _DECLARE_TI(DObject)
 
diff --git a/src/dobject.h b/src/dobject.h
index fb631c91c..24ba4997c 100644
--- a/src/dobject.h
+++ b/src/dobject.h
@@ -109,6 +109,7 @@ struct ClassReg
 	PClass *MyClass;
 	const char *Name;
 	ClassReg *ParentType;
+	ClassReg *VMExport;
 	const size_t *Pointers;
 	void (*ConstructNative)(void *);
 	void(*InitNatives)();
@@ -186,11 +187,12 @@ protected: \
 #	define _DECLARE_TI(cls) ClassReg * const cls::RegistrationInfoPtr __attribute__((section(SECTION_CREG))) = &cls::RegistrationInfo;
 #endif
 
-#define _IMP_PCLASS(cls, ptrs, create, initn) \
+#define _IMP_PCLASS(cls, ptrs, create, initn, vmexport) \
 	ClassReg cls::RegistrationInfo = {\
 		nullptr, \
 		#cls, \
 		&cls::Super::RegistrationInfo, \
+		vmexport, \
 		ptrs, \
 		create, \
 		initn, \
@@ -199,9 +201,9 @@ protected: \
 	_DECLARE_TI(cls) \
 	PClass *cls::StaticType() const { return RegistrationInfo.MyClass; }
 
-#define IMPLEMENT_CLASS(cls, isabstract, ptrs, fields) \
+#define IMPLEMENT_CLASS(cls, isabstract, ptrs, fields, vmexport) \
 	_X_CONSTRUCTOR_##isabstract##(cls) \
-	_IMP_PCLASS(cls, _X_POINTERS_##ptrs##(cls), _X_ABSTRACT_##isabstract##(cls), _X_FIELDS_##fields##(cls)) 
+	_IMP_PCLASS(cls, _X_POINTERS_##ptrs##(cls), _X_ABSTRACT_##isabstract##(cls), _X_FIELDS_##fields##(cls), _X_VMEXPORT_##vmexport##(cls)) 
 
 // Taking the address of a field in an object at address 1 instead of
 // address 0 keeps GCC from complaining about possible misuse of offsetof.
@@ -218,6 +220,8 @@ protected: \
 #define _X_CONSTRUCTOR_false(cls)	void cls::InPlaceConstructor(void *mem) { new((EInPlace *)mem) cls; }
 #define _X_ABSTRACT_true(cls)		nullptr
 #define _X_ABSTRACT_false(cls)		cls::InPlaceConstructor
+#define _X_VMEXPORT_true(cls)		&DVMObject<cls>::RegistrationInfo
+#define _X_VMEXPORT_false(cls)		nullptr
 
 enum EObjectFlags
 {
@@ -643,6 +647,7 @@ ClassReg DVMObject<T>::RegistrationInfo =
 	DVMObject<T>::FormatClassName(),
 	&DVMObject<T>::Super::RegistrationInfo,
 	nullptr,
+	nullptr,
 	DVMObject<T>::InPlaceConstructor,
 	nullptr,
 	sizeof(DVMObject<T>),
diff --git a/src/dobjtype.cpp b/src/dobjtype.cpp
index 9d3022966..89b9986cc 100644
--- a/src/dobjtype.cpp
+++ b/src/dobjtype.cpp
@@ -2847,7 +2847,7 @@ PClass *ClassReg::RegisterClass()
 		assert(0 && "Class registry has an invalid meta class identifier");
 	}
 
-	if (metaclasses[MetaClassNum]->MyClass == NULL)
+	if (metaclasses[MetaClassNum]->MyClass == nullptr)
 	{ // Make sure the meta class is already registered before registering this one
 		metaclasses[MetaClassNum]->RegisterClass();
 	}
@@ -2855,10 +2855,14 @@ PClass *ClassReg::RegisterClass()
 
 	SetupClass(cls);
 	cls->InsertIntoHash();
-	if (ParentType != NULL)
+	if (ParentType != nullptr)
 	{
 		cls->ParentClass = ParentType->RegisterClass();
 	}
+	if (VMExport != nullptr)
+	{
+		cls->VMExported = VMExport->RegisterClass();
+	}
 	return cls;
 }
 
diff --git a/src/dobjtype.h b/src/dobjtype.h
index d907feeeb..e1f95a828 100644
--- a/src/dobjtype.h
+++ b/src/dobjtype.h
@@ -769,6 +769,7 @@ public:
 
 	// Per-class information -------------------------------------
 	PClass				*ParentClass;	// the class this class derives from
+	PClass				*VMExported;	// this is here to allow script classes to override native virtual functions
 	const size_t		*Pointers;		// object pointers defined by this class *only*
 	const size_t		*FlatPointers;	// object pointers defined by this class and all its superclasses; not initialized by default
 	BYTE				*Defaults;