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- implemented handling for virtual function.

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Syntax-wise I chose to make it as strict as possible to reduce the chance of errors: Virtual base functions must be declared with the 'virtual' keyword, and overrides in child classes with the 'override' keyword. This way any mismatch in parameters that otherwise would cause silent failure will outright produce a compile error.
This commit is contained in:
Christoph Oelckers 2016-11-11 20:05:07 +01:00
parent a1aceaf04f
commit 72e77a6c65
15 changed files with 222 additions and 47 deletions
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1
src/d_dehacked.cpp
View file

@ -3030,7 +3030,6 @@ void FinishDehPatch ()
while (subclass == nullptr);
AActor *defaults2 = GetDefaultByType (subclass);
memcpy ((void *)defaults2, (void *)defaults1, sizeof(AActor));
// Make a copy of the replaced class's state labels
FStateDefinitions statedef;

88
src/dobjtype.cpp
View file

@ -156,14 +156,14 @@ PClassType::PClassType()
//==========================================================================
//
// PClassType :: Derive
// PClassType :: DeriveData
//
//==========================================================================
void PClassType::Derive(PClass *newclass)
void PClassType::DeriveData(PClass *newclass)
{
assert(newclass->IsKindOf(RUNTIME_CLASS(PClassType)));
Super::Derive(newclass);
Super::DeriveData(newclass);
static_cast<PClassType *>(newclass)->TypeTableType = TypeTableType;
}
@ -3030,12 +3030,14 @@ void PClass::DestroySpecials(void *addr) const
//
//==========================================================================
void PClass::Derive(PClass *newclass)
void PClass::Derive(PClass *newclass, FName name)
{
newclass->bRuntimeClass = true;
newclass->ParentClass = this;
newclass->ConstructNative = ConstructNative;
newclass->Symbols.SetParentTable(&this->Symbols);
newclass->InitializeDefaults();
newclass->TypeName = name;
newclass->mDescriptiveName.Format("Class<%s>", name.GetChars());
}
//==========================================================================
@ -3082,6 +3084,18 @@ void PClass::InitializeDefaults()
}
}
//==========================================================================
//
// PClass :: DeriveData
//
// Copies inheritable data to the child class.
//
//==========================================================================
void PClass::DeriveData(PClass *newclass)
{
}
//==========================================================================
//
// PClass :: CreateDerivedClass
@ -3126,11 +3140,10 @@ PClass *PClass::CreateDerivedClass(FName name, unsigned int size)
// Create a new type object of the same type as us. (We may be a derived class of PClass.)
type = static_cast<PClass *>(GetClass()->CreateNew());
type->TypeName = name;
type->Size = size;
type->bRuntimeClass = true;
type->mDescriptiveName.Format("Class<%s>", name.GetChars());
Derive(type);
Derive(type, name);
type->InitializeDefaults();
type->Virtuals = Virtuals;
DeriveData(type);
if (!notnew)
{
@ -3178,8 +3191,7 @@ PField *PClass::AddField(FName name, PType *type, DWORD flags)
// PClass :: FindClassTentative
//
// Like FindClass but creates a placeholder if no class is found.
// CreateDerivedClass will automatically fill in the placeholder when the
// actual class is defined.
// This will be filled in when the actual class is constructed.
//
//==========================================================================
@ -3201,17 +3213,59 @@ PClass *PClass::FindClassTentative(FName name, bool fatal)
PClass *type = static_cast<PClass *>(GetClass()->CreateNew());
DPrintf(DMSG_SPAMMY, "Creating placeholder class %s : %s\n", name.GetChars(), TypeName.GetChars());
type->TypeName = name;
type->ParentClass = this;
type->ConstructNative = ConstructNative;
Derive(type, name);
type->Size = TentativeClass;
type->bRuntimeClass = true;
type->mDescriptiveName.Format("Class<%s>", name.GetChars());
type->Symbols.SetParentTable(&Symbols);
TypeTable.AddType(type, RUNTIME_CLASS(PClass), (intptr_t)type->Outer, name, bucket);
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;
}
//==========================================================================
//
// PClass :: BuildFlatPointers

9
src/dobjtype.h
View file

@ -31,6 +31,7 @@ enum
VARF_Implicit = (1<<12), // implicitly created parameters (i.e. do not compare types when checking function signatures)
VARF_Static = (1<<13), // static class data (by necessity read only.)
VARF_InternalAccess = (1<<14), // overrides VARF_ReadOnly for internal script code.
VARF_Override = (1<<15), // overrides a virtual function from the parent class.
};
// Symbol information -------------------------------------------------------
@ -756,7 +757,7 @@ protected:
// We unravel _WITH_META here just as we did for PType.
enum { MetaClassNum = CLASSREG_PClassClass };
TArray<FTypeAndOffset> SpecialInits;
virtual void Derive(PClass *newclass);
void Derive(PClass *newclass, FName name);
void InitializeSpecials(void *addr) const;
void SetSuper();
public:
@ -768,8 +769,9 @@ public:
bool ReadValue(FSerializer &ar, const char *key,void *addr) const override;
bool ReadAllFields(FSerializer &ar, void *addr) const;
void InitializeDefaults();
int FindVirtualIndex(FName name, PPrototype *proto);
virtual void DeriveData(PClass *newclass);
virtual void DeriveData(PClass *newclass) {}
static void StaticInit();
static void StaticShutdown();
static void StaticBootstrap();
@ -782,6 +784,7 @@ public:
BYTE *Defaults;
bool bRuntimeClass; // class was defined at run-time, not compile-time
bool bExported; // This type has been declared in a script
TArray<VMFunction*> Virtuals; // virtual function table
void (*ConstructNative)(void *);
@ -838,7 +841,7 @@ class PClassType : public PClass
protected:
public:
PClassType();
virtual void Derive(PClass *newclass);
virtual void DeriveData(PClass *newclass);
PClass *TypeTableType; // The type to use for hashing into the type table
};

1
src/sc_man_scanner.re
View file

@ -168,6 +168,7 @@ std2:
'optional' { RET(TK_Optional); }
'export' { RET(TK_Export); }
'virtual' { RET(TK_Virtual); }
'override' { RET(TK_Override); }
'super' { RET(TK_Super); }
'global' { RET(TK_Global); }
'stop' { RET(TK_Stop); }

1
src/sc_man_tokens.h
View file

@ -105,6 +105,7 @@ xx(TK_Iterator, "'iterator'")
xx(TK_Optional, "'optional'")
xx(TK_Export, "'expert'")
xx(TK_Virtual, "'virtual'")
xx(TK_Override, "'override'")
xx(TK_Super, "'super'")
xx(TK_Null, "'null'")
xx(TK_Global, "'global'")

76
src/scripting/codegeneration/codegen.cpp
View file

@ -6693,12 +6693,16 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
}
}
VMFunction *vmfunc = Function->Variants[0].Implementation;
bool staticcall = (vmfunc->Final || vmfunc->VirtualIndex == -1 || NoVirtual);
count = 0;
// Emit code to pass implied parameters
ExpEmit selfemit;
if (Function->Variants[0].Flags & VARF_Method)
{
assert(Self != nullptr);
ExpEmit selfemit = Self->Emit(build);
selfemit = Self->Emit(build);
assert(selfemit.RegType == REGT_POINTER);
build->Emit(OP_PARAM, 0, selfemit.RegType, selfemit.RegNum);
count += 1;
@ -6718,8 +6722,9 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
}
count += 2;
}
selfemit.Free(build);
if (staticcall) selfemit.Free(build);
}
else staticcall = true;
// Emit code to pass explicit parameters
for (unsigned i = 0; i < ArgList.Size(); ++i)
{
@ -6729,27 +6734,56 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
ArgList.ShrinkToFit();
// Get a constant register for this function
VMFunction *vmfunc = Function->Variants[0].Implementation;
int funcaddr = build->GetConstantAddress(vmfunc, ATAG_OBJECT);
// Emit the call
if (EmitTail)
{ // Tail call
build->Emit(OP_TAIL_K, funcaddr, count, 0);
ExpEmit call;
call.Final = true;
return call;
}
else if (vmfunc->Proto->ReturnTypes.Size() > 0)
{ // Call, expecting one result
ExpEmit reg(build, vmfunc->Proto->ReturnTypes[0]->GetRegType(), vmfunc->Proto->ReturnTypes[0]->GetRegCount());
build->Emit(OP_CALL_K, funcaddr, count, 1);
build->Emit(OP_RESULT, 0, EncodeRegType(reg), reg.RegNum);
return reg;
if (staticcall)
{
int funcaddr = build->GetConstantAddress(vmfunc, ATAG_OBJECT);
// Emit the call
if (EmitTail)
{ // Tail call
build->Emit(OP_TAIL_K, funcaddr, count, 0);
ExpEmit call;
call.Final = true;
return call;
}
else if (vmfunc->Proto->ReturnTypes.Size() > 0)
{ // Call, expecting one result
ExpEmit reg(build, vmfunc->Proto->ReturnTypes[0]->GetRegType(), vmfunc->Proto->ReturnTypes[0]->GetRegCount());
build->Emit(OP_CALL_K, funcaddr, count, 1);
build->Emit(OP_RESULT, 0, EncodeRegType(reg), reg.RegNum);
return reg;
}
else
{ // Call, expecting no results
build->Emit(OP_CALL_K, funcaddr, count, 0);
return ExpEmit();
}
}
else
{ // Call, expecting no results
build->Emit(OP_CALL_K, funcaddr, count, 0);
return ExpEmit();
{
selfemit.Free(build);
ExpEmit funcreg(build, REGT_POINTER);
build->Emit(OP_VTBL, funcreg.RegNum, selfemit.RegNum, vmfunc->VirtualIndex);
if (EmitTail)
{ // Tail call
build->Emit(OP_TAIL, funcreg.RegNum, count, 0);
ExpEmit call;
call.Final = true;
return call;
}
else if (vmfunc->Proto->ReturnTypes.Size() > 0)
{ // Call, expecting one result
ExpEmit reg(build, vmfunc->Proto->ReturnTypes[0]->GetRegType(), vmfunc->Proto->ReturnTypes[0]->GetRegCount());
build->Emit(OP_CALL, funcreg.RegNum, count, 1);
build->Emit(OP_RESULT, 0, EncodeRegType(reg), reg.RegNum);
return reg;
}
else
{ // Call, expecting no results
build->Emit(OP_CALL, funcreg.RegNum, count, 0);
return ExpEmit();
}
}
}

2
src/scripting/vm/vm.h
View file

@ -655,7 +655,9 @@ class VMFunction : public DObject
HAS_OBJECT_POINTERS;
public:
bool Native;
bool Final = false; // cannot be overridden
BYTE ImplicitArgs = 0; // either 0 for static, 1 for method or 3 for action
int VirtualIndex = -1;
FName Name;
TArray<VMValue> DefaultArgs;

1
src/scripting/vm/vmdisasm.cpp
View file

@ -84,6 +84,7 @@
#define RPI8 MODE_AP | MODE_BIMMZ | MODE_CUNUSED
#define KPI8 MODE_AKP | MODE_BIMMZ | MODE_CUNUSED
#define RPI8I8 MODE_AP | MODE_BIMMZ | MODE_CIMMZ
#define RPRPI8 MODE_AP | MODE_BP | MODE_CIMMZ
#define KPI8I8 MODE_AKP | MODE_BIMMZ | MODE_CIMMZ
#define I8BCP MODE_AIMMZ | MODE_BCJOINT | MODE_BCPARAM
#define THROW MODE_AIMMZ | MODE_BCTHROW

9
src/scripting/vm/vmexec.h
View file

@ -525,6 +525,15 @@ begin:
}
}
NEXTOP;
OP(VTBL):
ASSERTA(a); ASSERTA(B);
{
auto o = (DObject*)reg.a[B];
auto p = o->GetClass();
assert(C < p->Virtuals.Size());
reg.a[a] = p->Virtuals[C];
}
NEXTOP;
OP(CALL_K):
ASSERTKA(a);
assert(konstatag[a] == ATAG_OBJECT);

1
src/scripting/vm/vmops.h
View file

@ -82,6 +82,7 @@ xx(PARAM, param, __BCP), // push parameter encoded in BC for function call (B=r
xx(PARAMI, parami, I24), // push immediate, signed integer for function call
xx(CALL, call, RPI8I8), // Call function pkA with parameter count B and expected result count C
xx(CALL_K, call, KPI8I8),
xx(VTBL, vtbl, RPRPI8), // dereferences a virtual method table.
xx(TAIL, tail, RPI8), // Call+Ret in a single instruction
xx(TAIL_K, tail, KPI8),
xx(RESULT, result, __BCP), // Result should go in register encoded in BC (in caller, after CALL)

2
src/scripting/zscript/zcc-parse.lemon
View file

@ -905,6 +905,8 @@ decl_flags(X) ::= decl_flags(A) META(T). { X.Int = A.Int | ZCC_Meta; X.SourceLo
decl_flags(X) ::= decl_flags(A) ACTION(T). { X.Int = A.Int | ZCC_Action; X.SourceLoc = A.SourceLoc ? A.SourceLoc : T.SourceLoc; }
decl_flags(X) ::= decl_flags(A) READONLY(T). { X.Int = A.Int | ZCC_ReadOnly; X.SourceLoc = A.SourceLoc ? A.SourceLoc : T.SourceLoc; }
decl_flags(X) ::= decl_flags(A) DEPRECATED(T). { X.Int = A.Int | ZCC_Deprecated; X.SourceLoc = A.SourceLoc ? A.SourceLoc : T.SourceLoc; }
decl_flags(X) ::= decl_flags(A) VIRTUAL(T). { X.Int = A.Int | ZCC_Virtual; X.SourceLoc = A.SourceLoc ? A.SourceLoc : T.SourceLoc; }
decl_flags(X) ::= decl_flags(A) OVERRIDE(T). { X.Int = A.Int | ZCC_Override; X.SourceLoc = A.SourceLoc ? A.SourceLoc : T.SourceLoc; }
func_const(X) ::= . { X.Int = 0; X.SourceLoc = stat->sc->GetMessageLine(); }
func_const(X) ::= CONST(T). { X.Int = ZCC_FuncConst; X.SourceLoc = T.SourceLoc; }

72
src/scripting/zscript/zcc_compile.cpp
View file

@ -1258,7 +1258,7 @@ bool ZCCCompiler::CompileFields(PStruct *type, TArray<ZCC_VarDeclarator *> &Fiel
PType *fieldtype = DetermineType(type, field, field->Names->Name, field->Type, true, true);
// For structs only allow 'deprecated', for classes exclude function qualifiers.
int notallowed = forstruct? ~ZCC_Deprecated : ZCC_Latent | ZCC_Final | ZCC_Action | ZCC_Static | ZCC_FuncConst | ZCC_Abstract;
int notallowed = forstruct? ~ZCC_Deprecated : ZCC_Latent | ZCC_Final | ZCC_Action | ZCC_Static | ZCC_FuncConst | ZCC_Abstract | ZCC_Virtual | ZCC_Override;
if (field->Flags & notallowed)
{
@ -1894,6 +1894,7 @@ void ZCCCompiler::InitDefaults()
if (!c->Type()->IsDescendantOf(RUNTIME_CLASS(AActor)))
{
if (c->Defaults.Size()) Error(c->cls, "%s: Non-actor classes may not have defaults", c->Type()->TypeName.GetChars());
if (c->Type()->ParentClass) c->Type()->ParentClass->DeriveData(c->Type());
}
else
{
@ -1989,6 +1990,16 @@ void ZCCCompiler::InitFunctions()
for (auto c : Classes)
{
// cannot be done earlier because it requires the parent class to be processed by this code, too.
if (c->Type()->ParentClass != nullptr)
{
if (c->Type()->ParentClass->Virtuals.Size() == 0)
{
// This a VMClass which didn't get processed here.
c->Type()->ParentClass->Virtuals = c->Type()->ParentClass->ParentClass->Virtuals;
}
c->Type()->Virtuals = c->Type()->ParentClass->Virtuals;
}
for (auto f : c->Functions)
{
rets.Clear();
@ -2030,13 +2041,32 @@ void ZCCCompiler::InitFunctions()
if (f->Flags & ZCC_Private) varflags |= VARF_Private;
if (f->Flags & ZCC_Protected) varflags |= VARF_Protected;
if (f->Flags & ZCC_Deprecated) varflags |= VARF_Deprecated;
if (f->Flags & ZCC_Virtual) varflags |= VARF_Virtual;
if (f->Flags & ZCC_Override) varflags |= VARF_Override;
if (f->Flags & ZCC_Action) varflags |= VARF_Action|VARF_Final, implicitargs = 3; // Action implies Final.
if (f->Flags & ZCC_Static) varflags = (varflags & ~VARF_Method) | VARF_Final, implicitargs = 0; // Static implies Final.
if ((f->Flags & (ZCC_Action | ZCC_Static)) == (ZCC_Action | ZCC_Static))
if (varflags & VARF_Override) varflags &= ~VARF_Virtual; // allow 'virtual override'.
// Only one of these flags may be used.
static int exclude[] = { ZCC_Virtual, ZCC_Override, ZCC_Action, ZCC_Static };
static const char * print[] = { "virtual", "override", "action", "static" };
int fc = 0;
FString build;
for (int i = 0; i < 4; i++)
{
Error(f, "%s: Action and Static on the same function is not allowed.", FName(f->Name).GetChars());
if (f->Flags & exclude[i])
{
fc++;
if (build.Len() > 0) build += ", ";
build += print[i];
}
}
if (fc > 1)
{
Error(f, "Invalid combination of qualifiers %s on function %s.", FName(f->Name).GetChars(), build.GetChars() );
varflags |= VARF_Method;
}
if (varflags & VARF_Override) varflags |= VARF_Virtual; // Now that the flags are checked, make all override functions virtual as well.
if (f->Flags & ZCC_Native)
{
@ -2193,7 +2223,41 @@ void ZCCCompiler::InitFunctions()
{
sym->Variants[0].Implementation->DefaultArgs = std::move(argdefaults);
}
// todo: Check inheritance.
if (varflags & VARF_Virtual)
{
if (varflags & VARF_Final)
{
sym->Variants[0].Implementation->Final = true;
}
int vindex = c->Type()->FindVirtualIndex(sym->SymbolName, sym->Variants[0].Proto);
// specifying 'override' is necessary to prevent one of the biggest problem spots with virtual inheritance: Mismatching argument types.
if (varflags & VARF_Override)
{
if (vindex == -1)
{
Error(p, "Attempt to override non-existent virtual function %s", FName(f->Name).GetChars());
}
else
{
auto oldfunc = c->Type()->Virtuals[vindex];
if (oldfunc->Final)
{
Error(p, "Attempt to override final function %s", FName(f->Name).GetChars());
}
c->Type()->Virtuals[vindex] = sym->Variants[0].Implementation;
sym->Variants[0].Implementation->VirtualIndex = vindex;
}
}
else
{
if (vindex != -1)
{
Error(p, "Function %s attempts to override parent function without 'override' qualifier", FName(f->Name).GetChars());
}
sym->Variants[0].Implementation->VirtualIndex = c->Type()->Virtuals.Push(sym->Variants[0].Implementation);
}
}
}
}
}

2
src/scripting/zscript/zcc_parser.cpp
View file

@ -123,6 +123,8 @@ static void InitTokenMap()
TOKENDEF (TK_Private, ZCC_PRIVATE);
TOKENDEF (TK_Protected, ZCC_PROTECTED);
TOKENDEF (TK_Latent, ZCC_LATENT);
TOKENDEF (TK_Virtual, ZCC_VIRTUAL);
TOKENDEF (TK_Override, ZCC_OVERRIDE);
TOKENDEF (TK_Final, ZCC_FINAL);
TOKENDEF (TK_Meta, ZCC_META);
TOKENDEF (TK_Deprecated, ZCC_DEPRECATED);

2
src/scripting/zscript/zcc_parser.h
View file

@ -33,6 +33,8 @@ enum
ZCC_FuncConst = 1 << 10,
ZCC_Abstract = 1 << 11,
ZCC_Extension = 1 << 12,
ZCC_Virtual = 1 << 13,
ZCC_Override = 1 << 14,
};
// Function parameter modifiers

2
wadsrc/static/zscript/base.txt
View file

@ -1,6 +1,6 @@
class Object native
{
/*virtual*/ native void Destroy();
virtual native void Destroy();
native class<Object> GetClass();
}