IsCharEncodingSimplyConvertibleTo.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include <type_traits>
#include "Traits/IsCharEncodingCompatibleWith.h"
#include "Traits/IsFixedWidthCharEncoding.h"
#include "Traits/IsCharType.h"
 
namespace UE::Core::Private
{
    template <typename SrcEncoding, typename DestEncoding>
    constexpr bool IsCharEncodingSimplyConvertibleToImpl()
    {
        if constexpr (TIsCharEncodingCompatibleWith_V<SrcEncoding, DestEncoding>)
        {
            // Binary-compatible conversions are always simple
            return true;
        }
        else if constexpr (TIsFixedWidthCharEncoding_V<SrcEncoding> && sizeof(DestEncoding) >= sizeof(SrcEncoding))
        {
            // Converting from a fixed-width encoding to a wider or same encoding should always be possible,
            // as should ANSICHAR->UTF8CHAR and UCS2CHAR->UTF16CHAR
            return true;
        }
        else
        {
            return false;
        }
    }
}
 
template <typename SrcEncoding, typename DestEncoding>
struct TIsCharEncodingSimplyConvertibleTo
{
    static_assert(TIsCharType<SrcEncoding >::Value, "SrcEncoding is not a character encoding type");
    static_assert(TIsCharType<DestEncoding>::Value, "DestEncoding is not a character encoding type");
 
    static constexpr bool Value = UE::Core::Private::IsCharEncodingSimplyConvertibleToImpl<SrcEncoding, DestEncoding>();
};
 
template <typename SrcEncoding, typename DestEncoding>
constexpr inline bool TIsCharEncodingSimplyConvertibleTo_V = TIsCharEncodingSimplyConvertibleTo<SrcEncoding, DestEncoding>::Value;