/*
** dobjtype.cpp
** Implements the type information class
**
**---------------------------------------------------------------------------
** Copyright 1998-2016 Randy Heit
** Copyright 2005-2016 Christoph Oelckers
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
**    notice, this list of conditions and the following disclaimer in the
**    documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
**    derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/

// HEADER FILES ------------------------------------------------------------

#include <limits>

#include "dobject.h"
#include "serializer.h"
#include "actor.h"
#include "autosegs.h"
#include "v_text.h"
#include "a_pickups.h"
#include "d_player.h"
#include "fragglescript/t_fs.h"
#include "a_keys.h"
#include "vm.h"
#include "types.h"

// MACROS ------------------------------------------------------------------

// TYPES -------------------------------------------------------------------

// EXTERNAL FUNCTION PROTOTYPES --------------------------------------------

// PUBLIC FUNCTION PROTOTYPES ----------------------------------------------

// PRIVATE FUNCTION PROTOTYPES ---------------------------------------------

// EXTERNAL DATA DECLARATIONS ----------------------------------------------
EXTERN_CVAR(Bool, strictdecorate);

// PUBLIC DATA DEFINITIONS -------------------------------------------------
FMemArena ClassDataAllocator(32768);	// use this for all static class data that can be released in bulk when the type system is shut down.

TArray<PClass *> PClass::AllClasses;
TMap<FName, PClass*> PClass::ClassMap;
TArray<VMFunction**> PClass::FunctionPtrList;
bool PClass::bShutdown;
bool PClass::bVMOperational;

// Originally this was just a bogus pointer, but with the VM performing a read barrier on every object pointer write
// that does not work anymore. WP_NOCHANGE needs to point to a vaild object to work as intended.
// This Object does not need to be garbage collected, though, but it needs to provide the proper structure so that the
// GC can process it.
AWeapon *WP_NOCHANGE;
DEFINE_GLOBAL(WP_NOCHANGE);


// PRIVATE DATA DEFINITIONS ------------------------------------------------

// A harmless non-nullptr FlatPointer for classes without pointers.
static const size_t TheEnd = ~(size_t)0;

//==========================================================================
//
// PClass :: WriteValue
//
// Similar to PStruct's version, except it also needs to traverse parent
// classes.
//
//==========================================================================

static void RecurseWriteFields(const PClass *type, FSerializer &ar, const void *addr)
{
	if (type != nullptr)
	{
		RecurseWriteFields(type->ParentClass, ar, addr);
		// Don't write this part if it has no non-transient variables
		for (unsigned i = 0; i < type->Fields.Size(); ++i)
		{
			if (!(type->Fields[i]->Flags & (VARF_Transient|VARF_Meta)))
			{
				// Tag this section with the class it came from in case
				// a more-derived class has variables that shadow a less-
				// derived class. Whether or not that is a language feature
				// that will actually be allowed remains to be seen.
				FString key;
				key.Format("class:%s", type->TypeName.GetChars());
				if (ar.BeginObject(key.GetChars()))
				{
					type->VMType->Symbols.WriteFields(ar, addr);
					ar.EndObject();
				}
				break;
			}
		}
	}
}

// Same as WriteValue, but does not create a new object in the serializer
// This is so that user variables do not contain unnecessary subblocks.
void PClass::WriteAllFields(FSerializer &ar, const void *addr) const
{
	RecurseWriteFields(this, ar, addr);
}

//==========================================================================
//
// PClass :: ReadAllFields
//
//==========================================================================

bool PClass::ReadAllFields(FSerializer &ar, void *addr) const
{
	bool readsomething = false;
	bool foundsomething = false;
	const char *key;
	key = ar.GetKey();
	if (strcmp(key, "classtype"))
	{
		// this does not represent a DObject
		Printf(TEXTCOLOR_RED "trying to read user variables but got a non-object (first key is '%s')\n", key);
		ar.mErrors++;
		return false;
	}
	while ((key = ar.GetKey()))
	{
		if (strncmp(key, "class:", 6))
		{
			// We have read all user variable blocks.
			break;
		}
		foundsomething = true;
		PClass *type = PClass::FindClass(key + 6);
		if (type != nullptr)
		{
			// Only read it if the type is related to this one.
			if (IsDescendantOf(type))
			{
				if (ar.BeginObject(nullptr))
				{
					readsomething |= type->VMType->Symbols.ReadFields(ar, addr, type->TypeName.GetChars());
					ar.EndObject();
				}
			}
			else
			{
				DPrintf(DMSG_ERROR, "Unknown superclass %s of class %s\n",
					type->TypeName.GetChars(), TypeName.GetChars());
			}
		}
		else
		{
			DPrintf(DMSG_ERROR, "Unknown superclass %s of class %s\n",
				key+6, TypeName.GetChars());
		}
	}
	return readsomething || !foundsomething;
}

//==========================================================================
//
// cregcmp
//
// Sorter to keep built-in types in a deterministic order. (Needed?)
//
//==========================================================================

static int cregcmp (const void *a, const void *b) NO_SANITIZE
{
	const PClass *class1 = *(const PClass **)a;
	const PClass *class2 = *(const PClass **)b;
	return strcmp(class1->TypeName, class2->TypeName);
}

//==========================================================================
//
// PClass :: StaticInit												STATIC
//
// Creates class metadata for all built-in types.
//
//==========================================================================

void PClass::StaticInit ()
{
	atterm (StaticShutdown);

	Namespaces.GlobalNamespace = Namespaces.NewNamespace(0);

	FAutoSegIterator probe(CRegHead, CRegTail);

	while (*++probe != nullptr)
	{
		((ClassReg *)*probe)->RegisterClass ();
	}
	probe.Reset();
	for(auto cls : AllClasses)
	{
		if (cls->IsDescendantOf(RUNTIME_CLASS(AActor)))
		{
			PClassActor::AllActorClasses.Push(static_cast<PClassActor*>(cls));
		}
	}

	// Keep built-in classes in consistant order. I did this before, though
	// I'm not sure if this is really necessary to maintain any sort of sync.
	qsort(&AllClasses[0], AllClasses.Size(), sizeof(AllClasses[0]), cregcmp);

	// WP_NOCHANGE must point to a valid object, although it does not need to be a weapon.
	// A simple DObject is enough to give the GC the ability to deal with it, if subjected to it.
	WP_NOCHANGE = (AWeapon*)Create<DObject>();
	WP_NOCHANGE->Release();
}

//==========================================================================
//
// PClass :: StaticShutdown											STATIC
//
// Frees all static class data.
//
//==========================================================================

void PClass::StaticShutdown ()
{
	if (WP_NOCHANGE != nullptr)
	{
		delete WP_NOCHANGE;
	}

	// delete all variables containing pointers to script functions.
	for (auto p : FunctionPtrList)
	{
		*p = nullptr;
	}
	FunctionPtrList.Clear();
	VMFunction::DeleteAll();

	// Make a full garbage collection here so that all destroyed but uncollected higher level objects 
	// that still exist are properly taken down before the low level data is deleted.
	GC::FullGC();

	// From this point onward no scripts may be called anymore because the data needed by the VM is getting deleted now.
	// This flags DObject::Destroy not to call any scripted OnDestroy methods anymore.
	bVMOperational = false;

	// PendingWeapon must be cleared manually because it is not subjected to the GC if it contains WP_NOCHANGE, which is just RUNTIME_CLASS(AWWeapon).
	// But that will get cleared here, confusing the GC if the value is left in.
	for (auto &p : players)
	{
		p.PendingWeapon = nullptr;
	}
	Namespaces.ReleaseSymbols();

	// This must be done in two steps because the native classes are not ordered by inheritance,
	// so all meta data must be gone before deleting the actual class objects.
	for (auto cls : AllClasses)	if (cls->Meta != nullptr) cls->DestroyMeta(cls->Meta);
	for (auto cls : AllClasses)	delete cls;
	// Unless something went wrong, anything left here should be class and type objects only, which do not own any scripts.
	bShutdown = true;
	TypeTable.Clear();
	ClassDataAllocator.FreeAllBlocks();
	AllClasses.Clear();
	PClassActor::AllActorClasses.Clear();
	ClassMap.Clear();

	FAutoSegIterator probe(CRegHead, CRegTail);

	while (*++probe != nullptr)
	{
		auto cr = ((ClassReg *)*probe);
		cr->MyClass = nullptr;
	}
	
}

//==========================================================================
//
// PClass Constructor
//
//==========================================================================

PClass::PClass()
{
	PClass::AllClasses.Push(this);
}

//==========================================================================
//
// PClass Destructor
//
//==========================================================================

PClass::~PClass()
{
	if (Defaults != nullptr)
	{
		M_Free(Defaults);
		Defaults = nullptr;
	}
	if (Meta != nullptr)
	{
		M_Free(Meta);
		Meta = nullptr;
	}
}

//==========================================================================
//
// ClassReg :: RegisterClass
//
// Create metadata describing the built-in class this struct is intended
// for.
//
//==========================================================================

PClass *ClassReg::RegisterClass()
{
	// Skip classes that have already been registered
	if (MyClass != nullptr)
	{
		return MyClass;
	}

	// Add type to list
	PClass *cls = new PClass;

	SetupClass(cls);
	cls->InsertIntoHash(true);
	if (ParentType != nullptr)
	{
		cls->ParentClass = ParentType->RegisterClass();
	}
	return cls;
}

//==========================================================================
//
// ClassReg :: SetupClass
//
// Copies the class-defining parameters from a ClassReg to the Class object
// created for it.
//
//==========================================================================

void ClassReg::SetupClass(PClass *cls)
{
	assert(MyClass == nullptr);
	MyClass = cls;
	cls->TypeName = FName(Name+1);
	cls->Size = SizeOf;
	cls->Pointers = Pointers;
	cls->ConstructNative = ConstructNative;
}

//==========================================================================
//
// PClass :: InsertIntoHash
//
// Add class to the type table.
//
//==========================================================================

void PClass::InsertIntoHash (bool native)
{
	auto k = ClassMap.CheckKey(TypeName);
	if (k != nullptr)
	{ // This type has already been inserted
		I_Error("Tried to register class '%s' more than once.\n", TypeName.GetChars());
	}
	else
	{
		ClassMap[TypeName] = this;
	}
	if (!native && IsDescendantOf(RUNTIME_CLASS(AActor)))
	{
		PClassActor::AllActorClasses.Push(static_cast<PClassActor*>(this));
	}
}

//==========================================================================
//
// PClass :: FindParentClass
//
// Finds a parent class that matches the given name, including itself.
//
//==========================================================================

const PClass *PClass::FindParentClass(FName name) const
{
	for (const PClass *type = this; type != nullptr; type = type->ParentClass)
	{
		if (type->TypeName == name)
		{
			return type;
		}
	}
	return nullptr;
}

//==========================================================================
//
// PClass :: FindClass
//
// Find a type, passed the name as a name.
//
//==========================================================================

PClass *PClass::FindClass (FName zaname)
{
	if (zaname == NAME_None)
	{
		return nullptr;
	}
	auto k = ClassMap.CheckKey(zaname);
	return k ? *k : nullptr;
}

//==========================================================================
//
// PClass :: CreateNew
//
// Create a new object that this class represents
//
//==========================================================================

DObject *PClass::CreateNew()
{
	uint8_t *mem = (uint8_t *)M_Malloc (Size);
	assert (mem != nullptr);

	// Set this object's defaults before constructing it.
	if (Defaults != nullptr)
		memcpy (mem, Defaults, Size);
	else
		memset (mem, 0, Size);

	if (ConstructNative == nullptr)
	{
		M_Free(mem);
		I_Error("Attempt to instantiate abstract class %s.", TypeName.GetChars());
	}
	ConstructNative (mem);
	((DObject *)mem)->SetClass (const_cast<PClass *>(this));
	InitializeSpecials(mem, Defaults, &PClass::SpecialInits);
	return (DObject *)mem;
}

//==========================================================================
//
// PClass :: InitializeSpecials
//
// Initialize special fields (e.g. strings) of a newly-created instance.
//
//==========================================================================

void PClass::InitializeSpecials(void *addr, void *defaults, TArray<FTypeAndOffset> PClass::*Inits)
{
	// Once we reach a native class, we can stop going up the family tree,
	// since native classes handle initialization natively.
	if ((!bRuntimeClass && Inits == &PClass::SpecialInits) || ParentClass == nullptr)
	{
		return;
	}
	ParentClass->InitializeSpecials(addr, defaults, Inits);
	for (auto tao : (this->*Inits))
	{
		tao.first->InitializeValue((char*)addr + tao.second, defaults == nullptr? nullptr : ((char*)defaults) + tao.second);
	}
}

//==========================================================================
//
// PClass :: DestroySpecials
//
// Destroy special fields (e.g. strings) of an instance that is about to be
// deleted.
//
//==========================================================================

void PClass::DestroySpecials(void *addr)
{
	if (!bRuntimeClass)
	{
		return;
	}
	assert(ParentClass != nullptr);
	ParentClass->DestroySpecials(addr);
	for (auto tao : SpecialInits)
	{
		tao.first->DestroyValue((uint8_t *)addr + tao.second);
	}
}

//==========================================================================
//
// PClass :: DestroyMeta
//
// Same for meta data
//
//==========================================================================

void PClass::DestroyMeta(void *addr)
{
	if (ParentClass != nullptr) ParentClass->DestroyMeta(addr);
	for (auto tao : MetaInits)
	{
		tao.first->DestroyValue((uint8_t *)addr + tao.second);
	}
}

//==========================================================================
//
// PClass :: Derive
//
// Copies inheritable values into the derived class and other miscellaneous setup.
//
//==========================================================================

void PClass::Derive(PClass *newclass, FName name)
{
	newclass->bRuntimeClass = true;
	newclass->ParentClass = this;
	newclass->ConstructNative = ConstructNative;
	newclass->TypeName = name;
	newclass->MetaSize = MetaSize;

}

//==========================================================================
//
// PClassActor :: InitializeNativeDefaults
//
//==========================================================================

void PClass::InitializeDefaults()
{
	if (IsDescendantOf(RUNTIME_CLASS(AActor)))
	{
		assert(Defaults == nullptr);
		Defaults = (uint8_t *)M_Malloc(Size);

		// run the constructor on the defaults to set the vtbl pointer which is needed to run class-aware functions on them.
		// Temporarily setting bSerialOverride prevents linking into the thinker chains.
		auto s = DThinker::bSerialOverride;
		DThinker::bSerialOverride = true;
		ConstructNative(Defaults);
		DThinker::bSerialOverride = s;
		// We must unlink the defaults from the class list because it's just a static block of data to the engine.
		DObject *optr = (DObject*)Defaults;
		GC::Root = optr->ObjNext;
		optr->ObjNext = nullptr;
		optr->SetClass(this);

		// Copy the defaults from the parent but leave the DObject part alone because it contains important data.
		if (ParentClass->Defaults != nullptr)
		{
			memcpy(Defaults + sizeof(DObject), ParentClass->Defaults + sizeof(DObject), ParentClass->Size - sizeof(DObject));
			if (Size > ParentClass->Size)
			{
				memset(Defaults + ParentClass->Size, 0, Size - ParentClass->Size);
			}
		}
		else
		{
			memset(Defaults + sizeof(DObject), 0, Size - sizeof(DObject));
		}

		assert(MetaSize >= ParentClass->MetaSize);
		if (MetaSize != 0)
		{
			Meta = (uint8_t*)M_Malloc(MetaSize);

			// Copy the defaults from the parent but leave the DObject part alone because it contains important data.
			if (ParentClass->Meta != nullptr)
			{
				memcpy(Meta, ParentClass->Meta, ParentClass->MetaSize);
				if (MetaSize > ParentClass->MetaSize)
				{
					memset(Meta + ParentClass->MetaSize, 0, MetaSize - ParentClass->MetaSize);
				}
			}
			else
			{
				memset(Meta, 0, MetaSize);
			}

			if (MetaSize > 0) memcpy(Meta, ParentClass->Meta, ParentClass->MetaSize);
			else memset(Meta, 0, MetaSize);
		}
	}

	if (VMType != nullptr)	// purely internal classes have no symbol table
	{
		if (bRuntimeClass)
		{
			// Copy parent values from the parent defaults.
			assert(ParentClass != nullptr);
			if (Defaults != nullptr) ParentClass->InitializeSpecials(Defaults, ParentClass->Defaults, &PClass::SpecialInits);
			for (const PField *field : Fields)
			{
				if (!(field->Flags & VARF_Native) && !(field->Flags & VARF_Meta))
				{
					field->Type->SetDefaultValue(Defaults, unsigned(field->Offset), &SpecialInits);
				}
			}
		}
		if (Meta != nullptr) ParentClass->InitializeSpecials(Meta, ParentClass->Meta, &PClass::MetaInits);
		for (const PField *field : Fields)
		{
			if (!(field->Flags & VARF_Native) && (field->Flags & VARF_Meta))
			{
				field->Type->SetDefaultValue(Meta, unsigned(field->Offset), &MetaInits);
			}
		}
	}
}

//==========================================================================
//
// PClass :: CreateDerivedClass
//
// Create a new class based on an existing class
//
//==========================================================================

PClass *PClass::CreateDerivedClass(FName name, unsigned int size)
{
	assert(size >= Size);
	PClass *type;
	bool notnew;

	const PClass *existclass = FindClass(name);

	if (existclass != nullptr)
	{
		// This is a placeholder so fill it in
		if (existclass->Size == TentativeClass)
		{
			type = const_cast<PClass*>(existclass);
			if (!IsDescendantOf(type->ParentClass))
			{
				I_Error("%s must inherit from %s but doesn't.", name.GetChars(), type->ParentClass->TypeName.GetChars());
			}
			DPrintf(DMSG_SPAMMY, "Defining placeholder class %s\n", name.GetChars());
			notnew = true;
		}
		else
		{
			// a different class with the same name already exists. Let the calling code deal with this.
			return nullptr;
		}
	}
	else
	{
		type = new PClass;
		notnew = false;
	}

	type->TypeName = name;
	type->bRuntimeClass = true;
	Derive(type, name);
	type->Size = size;
	if (size != TentativeClass)
	{
		NewClassType(type);
		type->InitializeDefaults();
		type->Virtuals = Virtuals;
	}
	else
		type->bOptional = false;

	if (!notnew)
	{
		type->InsertIntoHash(false);
	}
	return type;
}

//==========================================================================
//
// PClass :: AddField
//
//==========================================================================

PField *PClass::AddField(FName name, PType *type, uint32_t flags)
{
	PField *field;
	if (!(flags & VARF_Meta))
	{
		unsigned oldsize = Size;
		field = VMType->Symbols.AddField(name, type, flags, Size);

		// Only initialize the defaults if they have already been created.
		// For ZScript this is not the case, it will first define all fields before
		// setting up any defaults for any class.
		if (field != nullptr && !(flags & VARF_Native) && Defaults != nullptr)
		{
			Defaults = (uint8_t *)M_Realloc(Defaults, Size);
			memset(Defaults + oldsize, 0, Size - oldsize);
		}
	}
	else
	{
		// Same as above, but a different data storage.
		unsigned oldsize = MetaSize;
		field = VMType->Symbols.AddField(name, type, flags, MetaSize);

		if (field != nullptr && !(flags & VARF_Native) && Meta != nullptr)
		{
			Meta = (uint8_t *)M_Realloc(Meta, MetaSize);
			memset(Meta + oldsize, 0, MetaSize - oldsize);
		}
	}
	if (field != nullptr) Fields.Push(field);
	return field;
}

//==========================================================================
//
// PClass :: FindClassTentative
//
// Like FindClass but creates a placeholder if no class is found.
// This will be filled in when the actual class is constructed.
//
//==========================================================================

PClass *PClass::FindClassTentative(FName name)
{
	if (name == NAME_None)
	{
		return nullptr;
	}

	PClass *found = FindClass(name);
	if (found != nullptr) return found;

	PClass *type = new PClass;
	DPrintf(DMSG_SPAMMY, "Creating placeholder class %s : %s\n", name.GetChars(), TypeName.GetChars());

	Derive(type, name);
	type->Size = TentativeClass;

	type->InsertIntoHash(false);
	return type;
}

//==========================================================================
//
// PClass :: FindVirtualIndex
//
// Compares a prototype with the existing list of virtual functions
// and returns an index if something matching is found.
//
//==========================================================================

int PClass::FindVirtualIndex(FName name, PPrototype *proto)
{
	for (unsigned i = 0; i < Virtuals.Size(); i++)
	{
		if (Virtuals[i]->Name == name)
		{
			auto vproto = Virtuals[i]->Proto;
			if (vproto->ReturnTypes.Size() != proto->ReturnTypes.Size() ||
				vproto->ArgumentTypes.Size() != proto->ArgumentTypes.Size())
			{
				continue;	// number of parameters does not match, so it's incompatible
			}
			bool fail = false;
			// The first argument is self and will mismatch so just skip it.
			for (unsigned a = 1; a < proto->ArgumentTypes.Size(); a++)
			{
				if (proto->ArgumentTypes[a] != vproto->ArgumentTypes[a])
				{
					fail = true;
					break;
				}
			}
			if (fail) continue;

			for (unsigned a = 0; a < proto->ReturnTypes.Size(); a++)
			{
				if (proto->ReturnTypes[a] != vproto->ReturnTypes[a])
				{
					fail = true;
					break;
				}
			}
			if (!fail) return i;
		}
	}
	return -1;
}

PSymbol *PClass::FindSymbol(FName symname, bool searchparents) const
{
	if (VMType == nullptr) return nullptr;
	return VMType->Symbols.FindSymbol(symname, searchparents);
}

//==========================================================================
//
// PClass :: BuildFlatPointers
//
// Create the FlatPointers array, if it doesn't exist already.
// It comprises all the Pointers from superclasses plus this class's own
// Pointers. If this class does not define any new Pointers, then
// FlatPointers will be set to the same array as the super class.
//
//==========================================================================

void PClass::BuildFlatPointers ()
{
	if (FlatPointers != nullptr)
	{ // Already built: Do nothing.
		return;
	}
	else if (ParentClass == nullptr)
	{ // No parent (i.e. DObject: FlatPointers is the same as Pointers.
		if (Pointers == nullptr)
		{ // No pointers: Make FlatPointers a harmless non-nullptr.
			FlatPointers = &TheEnd;
		}
		else
		{
			FlatPointers = Pointers;
		}
	}
	else
	{
		ParentClass->BuildFlatPointers ();

		TArray<size_t> ScriptPointers;

		// Collect all pointers in scripted fields. These are not part of the Pointers list.
		for (auto field : Fields)
		{
			if (!(field->Flags & VARF_Native))
			{
				field->Type->SetPointer(Defaults, unsigned(field->Offset), &ScriptPointers);
			}
		}

		if (Pointers == nullptr && ScriptPointers.Size() == 0)
		{ // No new pointers: Just use the same FlatPointers as the parent.
			FlatPointers = ParentClass->FlatPointers;
		}
		else
		{ // New pointers: Create a new FlatPointers array and add them.
			int numPointers, numSuperPointers;

			if (Pointers != nullptr)
			{
				// Count pointers defined by this class.
				for (numPointers = 0; Pointers[numPointers] != ~(size_t)0; numPointers++)
				{
				}
			}
			else numPointers = 0;

			// Count pointers defined by superclasses.
			for (numSuperPointers = 0; ParentClass->FlatPointers[numSuperPointers] != ~(size_t)0; numSuperPointers++)
			{ }

			// Concatenate them into a new array
			size_t *flat = (size_t*)ClassDataAllocator.Alloc(sizeof(size_t) * (numPointers + numSuperPointers + ScriptPointers.Size() + 1));
			if (numSuperPointers > 0)
			{
				memcpy (flat, ParentClass->FlatPointers, sizeof(size_t)*numSuperPointers);
			}
			if (numPointers > 0)
			{
				memcpy(flat + numSuperPointers, Pointers, sizeof(size_t)*numPointers);
			}
			if (ScriptPointers.Size() > 0)
			{
				memcpy(flat + numSuperPointers + numPointers, &ScriptPointers[0], sizeof(size_t) * ScriptPointers.Size());
			}
			flat[numSuperPointers + numPointers + ScriptPointers.Size()] = ~(size_t)0;
			FlatPointers = flat;
		}
	}
}

//==========================================================================
//
// PClass :: BuildArrayPointers
//
// same as above, but creates a list to dynamic object arrays
//
//==========================================================================

void PClass::BuildArrayPointers()
{
	if (ArrayPointers != nullptr)
	{ // Already built: Do nothing.
		return;
	}
	else if (ParentClass == nullptr)
	{ // No parent (i.e. DObject: FlatPointers is the same as Pointers.
		ArrayPointers = &TheEnd;
	}
	else
	{
		ParentClass->BuildArrayPointers();

		TArray<size_t> ScriptPointers;

		// Collect all arrays to pointers in scripted fields.
		for (auto field : Fields)
		{
			if (!(field->Flags & VARF_Native))
			{
				field->Type->SetPointerArray(Defaults, unsigned(field->Offset), &ScriptPointers);
			}
		}

		if (ScriptPointers.Size() == 0)
		{ // No new pointers: Just use the same ArrayPointers as the parent.
			ArrayPointers = ParentClass->ArrayPointers;
		}
		else
		{ // New pointers: Create a new FlatPointers array and add them.
			int numSuperPointers;

			// Count pointers defined by superclasses.
			for (numSuperPointers = 0; ParentClass->ArrayPointers[numSuperPointers] != ~(size_t)0; numSuperPointers++)
			{
			}

			// Concatenate them into a new array
			size_t *flat = (size_t*)ClassDataAllocator.Alloc(sizeof(size_t) * (numSuperPointers + ScriptPointers.Size() + 1));
			if (numSuperPointers > 0)
			{
				memcpy(flat, ParentClass->ArrayPointers, sizeof(size_t)*numSuperPointers);
			}
			if (ScriptPointers.Size() > 0)
			{
				memcpy(flat + numSuperPointers, &ScriptPointers[0], sizeof(size_t) * ScriptPointers.Size());
			}
			flat[numSuperPointers + ScriptPointers.Size()] = ~(size_t)0;
			ArrayPointers = flat;
		}
	}
}

//==========================================================================
//
// PClass :: NativeClass
//
// Finds the native type underlying this class.
//
//==========================================================================

const PClass *PClass::NativeClass() const
{
	const PClass *cls = this;

	while (cls && cls->bRuntimeClass)
		cls = cls->ParentClass;

	return cls;
}

VMFunction *PClass::FindFunction(FName clsname, FName funcname)
{
	auto cls = PClass::FindClass(clsname);
	if (!cls) return nullptr;
	auto func = dyn_cast<PFunction>(cls->FindSymbol(funcname, true));
	if (!func) return nullptr;
	return func->Variants[0].Implementation;
}

void PClass::FindFunction(VMFunction **pptr, FName clsname, FName funcname)
{
	auto cls = PClass::FindClass(clsname);
	if (!cls) return;
	auto func = dyn_cast<PFunction>(cls->FindSymbol(funcname, true));
	if (!func) return;
	*pptr = func->Variants[0].Implementation;
	FunctionPtrList.Push(pptr);
}

unsigned GetVirtualIndex(PClass *cls, const char *funcname)
{
	// Look up the virtual function index in the defining class because this may have gotten overloaded in subclasses with something different than a virtual override.
	auto sym = dyn_cast<PFunction>(cls->FindSymbol(funcname, false));
	assert(sym != nullptr);
	auto VIndex = sym->Variants[0].Implementation->VirtualIndex;
	return VIndex;
}