MappedName.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "Containers/ArrayView.h"
#include "Containers/ContainersFwd.h"
#include "CoreMinimal.h"
#include "HAL/Platform.h"
#include "Math/NumericLimits.h"
#include "Misc/AssertionMacros.h"
#include "UObject/NameBatchSerialization.h"
#include "UObject/NameTypes.h"
#include "UObject/UnrealNames.h"
 
class FArchive;
 
/**
 * Index and name number into a name map.
 */
class FMappedName
{
    static constexpr uint32 InvalidIndex = ~uint32(0);
    static constexpr uint32 IndexBits = 30u;
    static constexpr uint32 IndexMask = (1u << IndexBits) - 1u;
    static constexpr uint32 TypeMask = ~IndexMask;
    static constexpr uint32 TypeShift = IndexBits;
 
public:
    enum class EType
    {
        Package,
        Container,
        Global
    };
 
    inline FMappedName() = default;
 
    static inline FMappedName Create(const uint32 InIndex, const uint32 InNumber, EType InType)
    {
        check(InIndex <= MAX_int32);
        return FMappedName((uint32(InType) << TypeShift) | InIndex, InNumber);
    }
 
    static inline FMappedName FromMinimalName(const FMinimalName& MinimalName)
    {
        return *reinterpret_cast<const FMappedName*>(&MinimalName);
    }
 
    static inline bool IsResolvedToMinimalName(const FMinimalName& MinimalName)
    {
        // Not completely safe, relies on that no FName will have its Index and Number equal to Max_uint32
        const FMappedName MappedName = FromMinimalName(MinimalName);
        return MappedName.IsValid();
    }
 
    static inline FName SafeMinimalNameToName(const FMinimalName& MinimalName)
    {
        return IsResolvedToMinimalName(MinimalName) ? MinimalNameToName(MinimalName) : NAME_None;
    }
 
    inline FMinimalName ToUnresolvedMinimalName() const
    {
        return *reinterpret_cast<const FMinimalName*>(this);
    }
 
    inline bool IsValid() const
    {
        return Index != InvalidIndex && Number != InvalidIndex;
    }
 
    inline EType GetType() const
    {
        return static_cast<EType>(uint32((Index & TypeMask) >> TypeShift));
    }
 
    inline bool IsGlobal() const
    {
        return ((Index & TypeMask) >> TypeShift) != 0;
    }
 
    inline uint32 GetIndex() const
    {
        return Index & IndexMask;
    }
 
    inline uint32 GetNumber() const
    {
        return Number;
    }
 
    inline bool operator!=(FMappedName Other) const
    {
        return Index != Other.Index || Number != Other.Number;
    }
 
    FName ResolveName(TConstArrayView<FDisplayNameEntryId> Names) const
    {
        return Names[GetIndex()].ToName(GetNumber());
    }
 
    friend FArchive& operator<<(FArchive& Ar, FMappedName& MappedName);
 
private:
    inline FMappedName(const uint32 InIndex, const uint32 InNumber)
        : Index(InIndex)
        , Number(InNumber) { }
 
    uint32 Index = InvalidIndex;
    uint32 Number = InvalidIndex;
};
 
/*
 * Maps serialized name entries to names.
 */
class FNameMap
{
public:
    inline int32 Num() const
    {
        return NameEntries.Num();
    }
 
    void Load(FArchive& Ar, FMappedName::EType NameMapType);
 
    FName GetName(const FMappedName& MappedName) const
    {
        check(MappedName.GetType() == NameMapType);
        check(MappedName.GetIndex() < uint32(NameEntries.Num()));
 
        return NameEntries[MappedName.GetIndex()].ToName(MappedName.GetNumber());
    }
 
    bool TryGetName(const FMappedName& MappedName, FName& OutName) const
    {
        check(MappedName.GetType() == NameMapType);
 
        uint32 Index = MappedName.GetIndex();
        if (Index < uint32(NameEntries.Num()))
        {
            OutName = NameEntries[MappedName.GetIndex()].ToName(MappedName.GetNumber());
 
            return true;
        }
 
        return false;
    }
 
    FMinimalName GetMinimalName(const FMappedName& MappedName) const
    {
        // Wasteful, looks up display name then discards it
        return NameToMinimalName(GetName(MappedName));
    }
 
private:
    TArray<FDisplayNameEntryId> NameEntries;
    FMappedName::EType NameMapType = FMappedName::EType::Global;
};