Command.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#if defined(UE_WITH_IAS_TOOL)
 
#include <Containers/Array.h>
#include <Containers/StringConv.h>
#include <Containers/StringView.h>
#include <String/LexFromString.h>
 
#include <initializer_list>
 
namespace UE::IoStore::Tool {
 
struct FArgument
{
    static const uint32 ValueAlign = 16;
    static const uint32 ValueSize = 16;
    FStringView         Name;
    FStringView         Desc;
    PTRINT              Inner;
};
 
using FArguments = TArray<FArgument>;
 
struct FArgumentSet
{
                FArgumentSet(std::initializer_list<FArgument>);
                operator FArgument () const;
    FArguments  Arguments;
};
 
template <typename Type> FArgument TArgument(FStringView Name, FStringView Desc);
 
#define TARGUMENT_DECL(t) \
    template <> FArgument TArgument<t>(FStringView Name, FStringView Desc);
 
TARGUMENT_DECL(FStringView)
TARGUMENT_DECL(bool)
TARGUMENT_DECL(uint8)   TARGUMENT_DECL(int8)
TARGUMENT_DECL(uint16)  TARGUMENT_DECL(int16)
TARGUMENT_DECL(uint32)  TARGUMENT_DECL(int32)
TARGUMENT_DECL(uint64)  TARGUMENT_DECL(int64)
TARGUMENT_DECL(float)   TARGUMENT_DECL(double)
#undef TARGUMENT_DECL
 
class FContext
{
public:
    template <typename Type> Type   Get(FStringView Name) const;
    template <typename Type> Type   Get(FStringView Name, Type Default) const;
    [[noreturn]] void               Abort(const TCHAR* Reason) const;
 
private:
    struct alignas(FArgument::ValueAlign) FValue
    {
        uint8           Buffer[FArgument::ValueSize] = {};
    };
 
    friend              class FCommand;
                        FContext(const FArguments& InArguments, int32 ArgC, const TCHAR* const* ArgV);
    void                SetArguments(const FArguments& Input);
    uint32              FindArgument(FStringView Name) const;
    [[noreturn]] void   OnMissingValue(FStringView Name) const;
    bool                IsSet(uint32 Index) const { return !!((1ull << Index) & SetMask); }
    FArguments          Arguments;
    TArray<FValue>      Values;
    uint64              SetMask = 0;
};
 
template <typename Type>
Type FContext::Get(FStringView Name) const
{
    if (Name.GetData()[0] == '-')
    {
        return Get(Name, Type{});
    }
 
    uint32 Index = FindArgument(Name);
    if (IsSet(Index))
    {
        return *(Type*)(Values[Index].Buffer);
    }
 
    OnMissingValue(Name);
}
 
template <typename Type>
Type FContext::Get(FStringView Name, Type Default) const
{
    uint32 Index = FindArgument(Name);
    return IsSet(Index) ? *(Type*)(Values[Index].Buffer) : Default;
}
 
 
 
class FCommand
{
public:
    using               EntryFunc = int32 (const FContext&);
                        FCommand(EntryFunc* InEntry, FStringView InName, FStringView InDesc, FArguments&& InArguments);
    static int32        Main(int32 ArgC, const TCHAR* const* ArgV);
 
private:
    friend void         CommandTest();
                        FCommand() = default;
    void                Initialize(EntryFunc* InEntry, FStringView InName, FStringView InDesc, FArguments&& InArguments);
    FContext            GetContext(int32 ArgC, const TCHAR* const* ArgV) const;
    static FCommand*&   Head();
    static int32        MainInner(int32 ArgC, const TCHAR* const* ArgV);
    void                Usage() const;
    int32               Call(int32 ArgC, const TCHAR* const* ArgV);
    FCommand*           Next = FCommand::Head();
    FStringView         Name;
    FStringView         Desc;
    FArguments          Arguments;
    EntryFunc*          Entry;
};
 
} // namespace UE::IoStore::Tool
 
#endif // UE_WITH_IAS_TOOL