NativeString.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#ifdef _WIN32
    #include "trio/utils/PlatformWindows.h"
#endif
 
#include <pma/TypeDefs.h>
 
#ifdef _MSC_VER
    #pragma warning(push)
    #pragma warning(disable : 4365 4987)
#endif
#include <clocale>
#include <cstddef>
#include <cstring>
#include <cwchar>
#ifdef _MSC_VER
    #pragma warning(pop)
#endif
 
namespace trio {
 
template<typename TCharacter>
struct StringConverter;
 
template<>
struct StringConverter<char> {
    using CharacterType = char;
    using StringType = pma::String<CharacterType>;
 
    static StringType from(const char* source, pma::MemoryResource* memRes) {
        return StringType{source, memRes};
    }
 
};
 
template<>
struct StringConverter<wchar_t> {
    using CharacterType = wchar_t;
    using StringType = pma::String<CharacterType>;
 
    static StringType from(const char* source, pma::MemoryResource* memRes) {
        #ifdef _WIN32
            const std::size_t length = std::strlen(source);
            const int neededSize = MultiByteToWideChar(CP_UTF8, 0, source, static_cast<int>(length), nullptr, 0);
            StringType result{static_cast<std::size_t>(neededSize), 0, memRes};
            MultiByteToWideChar(CP_UTF8, 0, source, static_cast<int>(length), &result[0], neededSize);
            return result;
        #else
            const char* current = std::setlocale(LC_ALL, nullptr);
            std::setlocale(LC_ALL, "en_US.utf8");  // Any UTF-8 locale will work
 
            std::mbstate_t state{};
            const std::size_t neededSize = std::mbsrtowcs(nullptr, &source, 0, &state) + 1ul;
            StringType result{neededSize, 0, memRes};
            std::mbsrtowcs(&result[0], &source, result.size(), &state);
 
            if (current != nullptr) {
                std::setlocale(LC_ALL, current);
            }
 
            return result;
        #endif
    }
 
};
 
#if defined(_WIN32) && defined(UNICODE)
    using NativeCharacter = wchar_t;
#else
    using NativeCharacter = char;
#endif
 
using NativeString = pma::String<NativeCharacter>;
using NativeStringConverter = StringConverter<NativeCharacter>;
 
}  // namespace trio