translation.h

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// Copyright (c) 2019-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef BITCOIN_UTIL_TRANSLATION_H
#define BITCOIN_UTIL_TRANSLATION_H
 
#include <tinyformat.h>
 
#include <functional>
#include <string>
 
const extern std::function<std::string(const char*)> G_TRANSLATION_FUN;
 
struct bilingual_str {
    std::string original;
    std::string translated;
 
    bilingual_str& operator+=(const bilingual_str& rhs)
    {
        original += rhs.original;
        translated += rhs.translated;
        return *this;
    }
 
    bool empty() const
    {
        return original.empty();
    }
 
    void clear()
    {
        original.clear();
        translated.clear();
    }
};
 
inline bilingual_str operator+(bilingual_str lhs, const bilingual_str& rhs)
{
    lhs += rhs;
    return lhs;
}
 
inline bilingual_str Untranslated(std::string original) { return {original, original}; }
 
// Provide an overload of tinyformat::format which can take bilingual_str arguments.
namespace tinyformat {
template <typename... Args>
bilingual_str format(const bilingual_str& fmt, const Args&... args)
{
    const auto translate_arg{[](const auto& arg, bool translated) -> const auto& {
        if constexpr (std::is_same_v<decltype(arg), const bilingual_str&>) {
            return translated ? arg.translated : arg.original;
        } else {
            return arg;
        }
    }};
    return bilingual_str{tfm::format(fmt.original, translate_arg(args, false)...),
                         tfm::format(fmt.translated, translate_arg(args, true)...)};
}
} // namespace tinyformat
 
struct ConstevalStringLiteral {
    const char* const lit;
    consteval ConstevalStringLiteral(const char* str) : lit{str} {}
    consteval ConstevalStringLiteral(std::nullptr_t) = delete;
};
 
inline bilingual_str _(ConstevalStringLiteral str)
{
    return bilingual_str{str.lit, G_TRANSLATION_FUN ? (G_TRANSLATION_FUN)(str.lit) : str.lit};
}
 
#endif // BITCOIN_UTIL_TRANSLATION_H