get()

template<typename T >
requires ArithmeticData<T>

std::optional< T > MayaFlux::Kakshya::Composite::get ( std::string_view  field_name ) const

noexcept

Read a present arithmetic field by exact value type.

Template Parameters

T	Declared arithmetic type, or int64_t/double for a dynamic field.

Parameters

field_name

Field to read.

Returns

Copied value, or std::nullopt for an absent field or type mismatch.

Definition at line 352 of file Composite.hpp.

{
    const auto field_index = m_layout->find_field(field_name);
    if (!field_index || !has(field_name))
        return std::nullopt;
 
    const auto& field = m_layout->fields()[*field_index];
    if (field.type == typeid(detail::CompositeDynamic)) {
        if constexpr (std::same_as<T, int64_t> || std::same_as<T, double>) {
            const auto dynamic = value(field_name);
            if (dynamic) {
                if (const auto* typed = std::get_if<T>(&*dynamic))
                    return *typed;
            }
        }
        return std::nullopt;
    }
    if (field.type != std::type_index(typeid(T)))
        return std::nullopt;
 
    const auto& rows = std::get<std::vector<uint8_t>>(*m_rows);
    T value {};
 
    std::memcpy(&value,
        rows.data() + m_index * m_layout->stride_bytes() + field.offset_bytes,
        sizeof(T));
 
    return value;
}

References rows, and value.