IsFixedWidthCharEncoding.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include <type_traits>
#include "Traits/IsCharType.h"
 
#ifndef PLATFORM_TCHAR_IS_CHAR16
    #error "Traits/IsFixedWidthCharEncoding.h should be included after platform headers"
#endif
 
namespace UE::Core::Private
{
    template <typename Encoding>
    constexpr bool IsFixedWidthEncodingImpl()
    {
        return
            std::is_same_v<Encoding, ANSICHAR> ||
            std::is_same_v<Encoding, UCS2CHAR> || // this may not be true when PLATFORM_UCS2CHAR_IS_UTF16CHAR == 1, but this is the legacy behavior
            std::is_same_v<Encoding, WIDECHAR> || // the UCS2CHAR comment also applies to WIDECHAR
#if PLATFORM_TCHAR_IS_CHAR16
            std::is_same_v<Encoding, wchar_t> || // the UCS2CHAR comment also applies to wchar_t
#endif
            std::is_same_v<Encoding, UTF32CHAR>;
    }
}
 
template <typename Encoding>
struct TIsFixedWidthCharEncoding
{
    static_assert(TIsCharType_V<Encoding>, "Encoding is not a character encoding type");
 
    static constexpr bool Value = UE::Core::Private::IsFixedWidthEncodingImpl<std::remove_cv_t<Encoding>>();
};
 
template <typename Encoding>
constexpr inline bool TIsFixedWidthCharEncoding_V = TIsFixedWidthCharEncoding<Encoding>::Value;