integration/Source/Integration/LuaCall.h

#pragma once

#include "CoreMinimal.h"
#include "EdGraph/EdGraphPin.h"
#include "LuaCall.generated.h"


/////////////////////////////////////////////////////////////////
//
// These are the types that can actually be packed into
// an argument or return value buffer.  Any other type is
// subject to conversion before packing.
//
/////////////////////////////////////////////////////////////////

UENUM(BlueprintType)
enum class ELpxSimpleDynamicTag : uint8 {
    None,
    String,
	Name,
    Float,
    Boolean,
    Vector
};

/////////////////////////////////////////////////////////////////
//
// This is a little parser that parses Lua function 'prototypes'.
// The prototypes look like this:
//
// class.name(int arg1, int arg2) : int ret1, int ret2
//
// The return values can be omitted if the function has no return
// values.  Optionally, there can be one last return value which
// is just an ellipsis.  The class name can be asterisk.
//
// For more information about the meaning of all this, see the docs
// for the 'Call Lua' blueprint node.
//
/////////////////////////////////////////////////////////////////

class FlxParsedProto
{
public:
	struct Pin
	{
		FString Type;
		FString Name;
		Pin(const FString &T, const FString &N) : Type(T), Name(N) {}
	};

	FString ErrorMessage;
	TArray<FString> Tokens;
	int NextToken;
	FString ClassName;
	FString FunctionName;
	TArray<Pin> Arguments;
	TArray<Pin> ReturnValues;
	bool ExtraReturnValues;

private:
	// Check the next token to see if it's exactly equal to text.
	//
	bool IsLiteral(const TCHAR *text);

	// Check the next token to see if it's an identifier.
	//
	bool IsIdent();

	// Make a syntax error message, using the tokens.
	//
	void Syntax();

	// Empty out the FlxParsedProto.
	//
	void Empty();

	// Parse a function prototype.
	//
	void Parse(const FString &proto);

public:
	// Construct with a prototype.
	//
	FlxParsedProto(const FString &str) { Parse(str); }
};

/////////////////////////////////////////////////////////////////
//
// To make a Lua Call from inside of a blueprint, use the convenient "Call Lua"
// blueprint node.  This node macroexpands into a sequence of low-level
// function calls.  This library contains the low-level functions that
// "Call Lua" macroexpands into.
//
// The procedure for making a lua call using the low-level functions is as follows:
//
// * Use LuaCallBegin to put the class name and function name into the argument buffer.
// * Use LuaCallArgumentXXX to put arguments into the argument buffer.
// * Use LuaCallInvoke or LuaCallProbe to actually make the call.
// * Use LuaCallReturnValueXXX to fetch return values from the return buffer.
//
// The two buffers are basically global variables, they are part of the
// LuprexGameModeBase.  This is okay because blueprint is single-threaded.
//
// The following three libraries contain all the low-level functions.
//
/////////////////////////////////////////////////////////////////

UCLASS()
class INTEGRATION_API UlxLuaCallLibrary : public UObject
{
	GENERATED_BODY()

public:
	// Get an argument packing function or a return value unpacking function.
	//
	static UFunction *GetArgumentPacker(const FString &Type);
	static UFunction *GetReturnValueUnpacker(const FString &Type);

	// Get the types supported for arguments and return values, as a documentation string.
	//
	static FString AllFunctionsWithPrefix(const TCHAR *Prefix);
	static FString AllKnownArgumentTypes() { return AllFunctionsWithPrefix(TEXT("LuaCallArgument_")); }
	static FString AllKnownReturnValueTypes() { return AllFunctionsWithPrefix(TEXT("LuaCallReturnValue_")); }

public:
	//
	// Functions that do miscellaneous things.
	//

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallBegin(UObject *context, const FString &ClassName, const FString &FunctionName);
	
	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallInvoke(UObject *context, AActor *Place);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallProbe(UObject *context, AActor *Place);
	
	//
	// Functions that pack arguments into the call buffer.
	//

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallArgument_string(UObject *context, const FString &Value);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallArgument_name(UObject *context, const FName &Value);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallArgument_float(UObject *context, double Value);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallArgument_int(UObject *context, int Value);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallArgument_vector(UObject *context, const FVector &Value);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallArgument_vector2d(UObject *context, const FVector2D &Value);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static void LuaCallArgument_boolean(UObject *context, bool Value);

	//
	// Functions that extract return values from the return buffer.
	//

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static FString LuaCallReturnValue_string(UObject *context);
	
	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static FName LuaCallReturnValue_name(UObject *context);
	
	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static double LuaCallReturnValue_float(UObject *context);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static int LuaCallReturnValue_int(UObject *context);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static FVector LuaCallReturnValue_vector(UObject *context);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static FVector2D LuaCallReturnValue_vector2d(UObject *context);

	UFUNCTION(BlueprintCallable, meta = (WorldContext = "context", BlueprintInternalUseOnly = "true"), Category = "Luprex|Call Lua Function")
	static bool LuaCallReturnValue_boolean(UObject *context);
};