IoDirectoryIndex.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "Containers/ChunkedArray.h"
#include "Containers/Map.h"
#include "Containers/StringFwd.h"
#include "Containers/StringView.h"
#include "Containers/UnrealString.h"
#include "HAL/Platform.h"
#include "Misc/AES.h"
 
class FArchive;
 
namespace IoDirectoryIndexUtils
{
    CORE_API FString GetCommonRootPath(const TArray<FStringView>& Filenames);
}
 
struct FIoDirectoryIndexEntry
{
    uint32 Name             = ~uint32(0);
    uint32 FirstChildEntry  = ~uint32(0);
    uint32 NextSiblingEntry = ~uint32(0);
    uint32 FirstFileEntry   = ~uint32(0);
 
    friend FArchive& operator<<(FArchive& Ar, FIoDirectoryIndexEntry& Entry);
};
 
struct FIoFileIndexEntry
{
    uint32 Name             = ~uint32(0);
    uint32 NextFileEntry    = ~uint32(0);
    uint32 UserData         = 0;
 
    friend FArchive& operator<<(FArchive& Ar, FIoFileIndexEntry& Entry);
};
 
struct FIoDirectoryIndexResource
{
    FString MountPoint;
    TArray<FIoDirectoryIndexEntry> DirectoryEntries;
    TArray<FIoFileIndexEntry> FileEntries;
    TArray<FString> StringTable;
 
    friend FArchive& operator<<(FArchive& Ar, FIoDirectoryIndexResource& Entry);
};
 
class FIoDirectoryIndexWriter
{
public:
    CORE_API FIoDirectoryIndexWriter();
 
    CORE_API void SetMountPoint(FString InMountPoint);
    CORE_API uint32 AddFile(const FStringView& InFileName);
    CORE_API void SetFileUserData(uint32 InFileEntryIndex, uint32 InUserData);
 
    // Flush() can be called only once, because afterwards contents of Strings member
    // will be empty as all strings have been moved away
    CORE_API void Flush(TArray<uint8>& OutBuffer, FAES::FAESKey InEncryptionKey);
 
private:
    uint32 GetDirectory(uint32 DirectoryName, uint32 Parent);
    uint32 CreateDirectory(const FStringView& DirectoryName, uint32 Parent);
    uint32 GetNameIndex(const FStringView& String);
    uint32 AddFile(const FStringView& FileName, uint32 Directory);
 
    static bool IsValid(uint32 Index)
    {
        return Index != ~uint32(0);
    }
 
    FString MountPoint;
    TArray<FIoDirectoryIndexEntry> DirectoryEntries;
    TArray<FIoFileIndexEntry> FileEntries;
 
    // These FStringView's are referencing stable FString locations inside Strings
    // member, and Strings member is only appended, never removed. It is safe to
    // use StringToIndex during lifetime of this object while Strings member is
    // populated by AddFile() until Flush() is called
    TMap<FStringView, uint32> StringToIndex;
    TChunkedArray<FString> Strings;
};