From c935a95cb0c54537fe935f6999aebfbf8c4bb698 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ricardo=20Lu=C3=ADs=20Vaz=20Silva?= <ricolvs123@gmail.com>
Date: Wed, 11 Oct 2023 13:03:32 -0300
Subject: [PATCH] Add function pointer Properties

---
 src/common/scripting/core/types.cpp        |  6 ++
 src/common/scripting/core/types.h          |  2 +
 src/scripting/zscript/zcc_compile_doom.cpp | 79 ++++++++++++++++++++++
 src/scripting/zscript/zcc_compile_doom.h   |  1 +
 4 files changed, 88 insertions(+)

diff --git a/src/common/scripting/core/types.cpp b/src/common/scripting/core/types.cpp
index 72b80482b9..efe4dfec54 100644
--- a/src/common/scripting/core/types.cpp
+++ b/src/common/scripting/core/types.cpp
@@ -2883,6 +2883,12 @@ static FString MakeFunctionPointerDescriptiveName(PPrototype * proto,const TArra
 	return mDescriptiveName;
 }
 
+
+FString PFunctionPointer::GenerateNameForError(const PFunction * from)
+{
+	return MakeFunctionPointerDescriptiveName(from->Variants[0].Proto, from->Variants[0].ArgFlags, FScopeBarrier::SideFromFlags(from->Variants[0].Flags));
+}
+
 PFunctionPointer::PFunctionPointer(PPrototype * proto, TArray<uint32_t> && argflags, int scope)
 	: PPointer(proto ? (PType*) proto : TypeVoid, false), ArgFlags(std::move(argflags)), Scope(scope)
 {
diff --git a/src/common/scripting/core/types.h b/src/common/scripting/core/types.h
index d338405961..e24bcd38bb 100644
--- a/src/common/scripting/core/types.h
+++ b/src/common/scripting/core/types.h
@@ -605,6 +605,8 @@ public:
 	//PointedType = PPrototype or TypeVoid
 	PFunctionPointer(PPrototype * proto, TArray<uint32_t> &&argflags, int scope);
 
+	static FString GenerateNameForError(const PFunction * from);
+
 	TArray<uint32_t> ArgFlags;
 	int Scope;
 
diff --git a/src/scripting/zscript/zcc_compile_doom.cpp b/src/scripting/zscript/zcc_compile_doom.cpp
index 8c21659dcd..4becfc4fe1 100644
--- a/src/scripting/zscript/zcc_compile_doom.cpp
+++ b/src/scripting/zscript/zcc_compile_doom.cpp
@@ -70,6 +70,7 @@ int ZCCDoomCompiler::Compile()
 	InitDefaults();
 	InitFunctions();
 	CompileStates();
+	InitDefaultFunctionPointers();
 	return FScriptPosition::ErrorCounter;
 }
 
@@ -395,6 +396,46 @@ void ZCCDoomCompiler::DispatchProperty(FPropertyInfo *prop, ZCC_PropertyStmt *pr
 //
 //==========================================================================
 
+PFunction * FindFunctionPointer(PClass * cls, int fn_name);
+PFunction *NativeFunctionPointerCast(PFunction *from, const PFunctionPointer *to);
+
+struct FunctionPointerProperties
+{
+	ZCC_PropertyStmt *prop;
+	PClass * cls;
+	FName name;
+	const PFunctionPointer * type;
+	PFunction ** addr;
+};
+
+TArray<FunctionPointerProperties> DefaultFunctionPointers;
+
+void ZCCDoomCompiler::InitDefaultFunctionPointers()
+{
+	for(auto &d : DefaultFunctionPointers)
+	{
+		PFunction * fn = FindFunctionPointer(d.cls, d.name.GetIndex());
+		if(!fn)
+		{
+			Error(d.prop, "Could not find function '%s' in class '%s'",d.name.GetChars(), d.cls->TypeName.GetChars());
+		}
+		else
+		{
+			PFunction * casted = NativeFunctionPointerCast(fn,d.type);
+			if(!casted)
+			{
+				FString fn_proto_name = PFunctionPointer::GenerateNameForError(fn);
+				Error(d.prop, "Function has incompatible types, cannot convert from '%s' to '%s'",fn_proto_name.GetChars(), d.type->DescriptiveName());
+			}
+			else
+			{
+				(*d.addr) = casted;
+			}
+		}
+	}
+	DefaultFunctionPointers.Clear();
+}
+
 void ZCCDoomCompiler::DispatchScriptProperty(PProperty *prop, ZCC_PropertyStmt *property, AActor *defaults, Baggage &bag)
 {
 	ZCC_ExprConstant one;
@@ -608,6 +649,44 @@ void ZCCDoomCompiler::DispatchScriptProperty(PProperty *prop, ZCC_PropertyStmt *
 				*(PClass**)addr = cls;
 			}
 		}
+		else if (f->Type->isFunctionPointer())
+		{
+			const char * fn_str = GetStringConst(ex, ctx);
+			if (*fn_str == 0 || !stricmp(fn_str, "none"))
+			{
+				*(PFunction**)addr = nullptr;
+			}
+			else
+			{
+				TArray<FString> fn_info(FString(fn_str).Split("::", FString::TOK_SKIPEMPTY));
+				if(fn_info.Size() != 2)
+				{
+					Error(property, "Malformed function pointer property \"%s\", must be \"Class::Function\"",fn_str);
+				}
+				PClass * cls = PClass::FindClass(fn_info[0]);
+				if(!cls)
+				{
+					Error(property, "Could not find class '%s'",fn_info[0].GetChars());
+					*(PFunction**)addr = nullptr;
+				}
+				else
+				{
+					FName fn_name(fn_info[1], true);
+					if(fn_name.GetIndex() == 0)
+					{
+						Error(property, "Could not find function '%s' in class '%s'",fn_info[1].GetChars(),fn_info[0].GetChars());
+						*(PFunction**)addr = nullptr;
+					}
+					else
+					{
+						DefaultFunctionPointers.Push({property, cls, fn_name, static_cast<const PFunctionPointer *>(f->Type), (PFunction**)addr});
+						*(PFunction**)addr = nullptr;
+					}
+
+				}
+			}
+
+		}
 		else
 		{
 			Error(property, "unhandled property type %s", f->Type->DescriptiveName());
diff --git a/src/scripting/zscript/zcc_compile_doom.h b/src/scripting/zscript/zcc_compile_doom.h
index 36d7a4680f..1fb8943728 100644
--- a/src/scripting/zscript/zcc_compile_doom.h
+++ b/src/scripting/zscript/zcc_compile_doom.h
@@ -25,6 +25,7 @@ private:
 	void ProcessDefaultProperty(PClassActor *cls, ZCC_PropertyStmt *prop, Baggage &bag);
 	void ProcessDefaultFlag(PClassActor *cls, ZCC_FlagStmt *flg);
 	void InitDefaults() override final;
+	void InitDefaultFunctionPointers();
 	FxExpression *SetupActionFunction(PClass *cls, ZCC_TreeNode *af, int StateFlags);
 	void CompileStates();
 	int CheckActionKeyword(ZCC_FuncDeclarator *f, uint32_t &varflags, int useflags, ZCC_StructWork *c);