Function ToSmthRet

util/charset/wide.cpp:494–512

template <typename F>
static TUtf16String ToSmthRet(const TWtringBuf text, size_t pos, size_t count, F&& f) {
    pos = pos < text.size() ? pos : text.size();
    count = count < text.size() - pos ? count : text.size() - pos;

    auto res = TUtf16String::Uninitialized(text.size());
    auto* const resBegin = res.Detach();

    if (pos) {
        MemCopy(resBegin, text.data(), pos);
    }

    f(text.data() + pos, count, resBegin + pos);

    if (count - pos != text.size()) {
        MemCopy(resBegin + pos + count, text.data() + pos + count, text.size() - pos - count);
    }

    return res;
}

template <typename F>
static TUtf32String ToSmthRet(const TUtf32StringBuf text, size_t pos, size_t count, F&& f) {