mt4hstcvt

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#include <hstfmt.h>
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namespace hst {
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dataset::dataset(const std::string& path)
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{
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    m.f.open(path, std::ios_base::binary);
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    if (!m.f) throw dataset_error("file open error");
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    m.f.read(reinterpret_cast<char*>(&m.hdr), sizeof(header));
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    if (!m.f) throw dataset_error("file read error");
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    if (version() != MT4_509 && version() != MT4_574)
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        throw dataset_error("file version error");
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    m.f.seekg(0, std::ios_base::end);
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    size_t flen = m.f.tellg();
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    flen -= sizeof(header);
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    m.count = flen / elem_size();
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}
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void dataset::update()
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{
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    m.f.seekg(0, std::ios_base::beg);
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    if (!m.f) throw dataset_error("file position error");
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    m.f.read(reinterpret_cast<char*>(&m.hdr), sizeof(header));
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    if (!m.f) throw dataset_error("file read error");
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    if (version() != MT4_509 && version() != MT4_574)
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        throw dataset_error("file version error");
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    m.f.seekg(0, std::ios_base::end);
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    size_t flen = m.f.tellg();
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    flen -= sizeof(header);
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    m.count = flen / elem_size();
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}
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bar dataset::at(size_t index)
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{
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    if (index >= m.count)
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        throw dataset_error("file indexing error");
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    return this->operator[](index);
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}
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bar dataset::operator[](size_t index)
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{
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    std::streamoff off = elem_size() * index + sizeof(header);
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    m.f.seekg(off, std::ios_base::beg);
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    if (!m.f) throw dataset_error("file position error");
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    bar result{};
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    if (version() == MT4_574)
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    {
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        m.f.read(reinterpret_cast<char*>(&result), sizeof(bar));
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    }
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    else
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    {
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        bar_old tmp{};
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        m.f.read(reinterpret_cast<char*>(&tmp), sizeof(bar_old));
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        result.ctm = static_cast<datetime64>(tmp.ctm);
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        result.volume = static_cast<decltype(result.volume)>(tmp.volume);
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    }
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    if (!m.f) throw dataset_error("file read error");
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    return result;
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}
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void dataset::each(std::function<void(const bar&)> f)
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{
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    m.f.seekg(sizeof(header), std::ios_base::beg);
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    if (!m.f) throw dataset_error("file position error");
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    bar result{};
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    while (!m.f.eof())
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    {
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        if (version() == MT4_574)
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        {
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            m.f.read(reinterpret_cast<char*>(&result), sizeof(bar));
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        }
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        else
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        {
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            bar_old tmp{};
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            m.f.read(reinterpret_cast<char*>(&tmp), sizeof(bar_old));
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            result.ctm = static_cast<datetime64>(tmp.ctm);
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            result.volume = static_cast<decltype(result.volume)>(tmp.volume);
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        }
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        if (m.f.eof()) break;
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        f(result);
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    }
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}
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} // namespace
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