read_composite_region()

std::optional< Kakshya::CompositeArray > MayaFlux::IO::CompositeReader::read_composite_region

(

const FileRegion &

region

)

Read an inclusive one-dimensional file region.

Parameters

region

Element bounds in start_coordinates[0] and end_coordinates[0].

Returns

Owning array, or nullopt for invalid bounds or a short read.

Note

Moves the reader position to the end of the selected region.

Definition at line 8 of file CompositeReader.cpp.

{
    if (region.start_coordinates.size() != 1
        || region.end_coordinates.size() != 1
        || region.end_coordinates[0] < region.start_coordinates[0]
        || region.end_coordinates[0] == std::numeric_limits<uint64_t>::max()) {
        m_last_error = "Composite region requires valid one-dimensional inclusive bounds";
        return std::nullopt;
    }
 
    const auto start = region.start_coordinates[0];
    const auto count = region.end_coordinates[0] - start + 1;
 
    if (start > std::numeric_limits<size_t>::max()
        || count > std::numeric_limits<size_t>::max()
        || !seek({ start })) {
        m_last_error = "Composite region is outside the file";
        return std::nullopt;
    }
 
    auto data = read_next(static_cast<size_t>(count));
    if (!data || data->size() != count) {
        if (data)
            m_last_error = "Composite region extends past the end of the file";
        return std::nullopt;
    }
 
    return data;
}

References count, MayaFlux::IO::FileRegion::end_coordinates, m_last_error, read_next(), MayaFlux::IO::FileReader::seek(), and MayaFlux::IO::FileRegion::start_coordinates.

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