record.hpp

// -----------------------------------------------------------------------------------------------------
// Copyright (c) 2006-2021, Knut Reinert & Freie Universität Berlin
// Copyright (c) 2016-2021, Knut Reinert & MPI für molekulare Genetik
// This file may be used, modified and/or redistributed under the terms of the 3-clause BSD-License
// shipped with this file and also available at: https://github.com/seqan/seqan3/blob/master/LICENSE.md
// -----------------------------------------------------------------------------------------------------
 
#pragma once
 
#include <seqan3/std/ranges>
 
#include <seqan3/io/record.hpp>
#include <seqan3/utility/tuple/concept.hpp>
#include <seqan3/utility/type_list/traits.hpp>
#include <seqan3/utility/views/repeat.hpp>
 
namespace seqan3::detail
{
 
// ----------------------------------------------------------------------------
// Fields
// ----------------------------------------------------------------------------
 
template <typename t>
SEQAN3_CONCEPT fields_specialisation = is_value_specialisation_of_v<t, fields>;
 
// ----------------------------------------------------------------------------
// select_types_with_ids
// ----------------------------------------------------------------------------
 
template <typename field_types,
          typename field_types_as_ids,
          typename selected_field_ids,
          size_t field_no = 0,
          typename ...return_types>
struct select_types_with_ids                               // unconstrained template is recursion anchor
{
    using type = type_list<return_types...>;
};
 
template <typename field_types,
          typename field_types_as_ids,
          typename selected_field_ids,
          size_t field_no = 0,
          typename ...return_types>
using select_types_with_ids_t = typename select_types_with_ids<field_types,
                                                               field_types_as_ids,
                                                               selected_field_ids,
                                                               field_no,
                                                               return_types...>::type;
template <typename field_types,
          typename field_types_as_ids,
          typename selected_field_ids,
          size_t field_no,
          typename ...return_types>
    requires (field_no < selected_field_ids::as_array.size()) // perform recursion while not at end
struct select_types_with_ids<field_types, field_types_as_ids, selected_field_ids, field_no, return_types...>
{
    static_assert(field_types_as_ids::contains(selected_field_ids::as_array[field_no]),
                  "You selected a field that was not in field_types_as_ids.");
 
    // call this type trait again, but increase index by one and append a type to the returned type list.
    using type = select_types_with_ids_t<field_types,
                                         field_types_as_ids,
                                         selected_field_ids,
                                         field_no + 1,
                                         return_types ...,
                                         list_traits::at<field_types_as_ids::index_of(
                                             selected_field_ids::as_array[field_no]), field_types>>;
 
};
 
 
// ----------------------------------------------------------------------------
// get_or_ignore
// ----------------------------------------------------------------------------
 
template <field f, typename field_types, typename field_ids>
auto & get_or_ignore(record<field_types, field_ids> & r)
{
    if constexpr (field_ids::contains(f))
        return std::get<field_ids::index_of(f)>(r);
    else
        return std::ignore;
}
 
template <field f, typename field_types, typename field_ids>
auto const & get_or_ignore(record<field_types, field_ids> const & r)
{
    if constexpr (field_ids::contains(f))
        return std::get<field_ids::index_of(f)>(r);
    else
        return std::ignore;
}
 
template <size_t i, tuple_like tuple_t>
auto & get_or_ignore(tuple_t & t)
{
    if constexpr (i < std::tuple_size_v<tuple_t>)
        return std::get<i>(t);
    else
        return std::ignore;
}
 
template <size_t i, tuple_like tuple_t>
auto const & get_or_ignore(tuple_t const & t)
{
    if constexpr (i < std::tuple_size_v<tuple_t>)
        return std::get<i>(t);
    else
        return std::ignore;
}
 
 
// ----------------------------------------------------------------------------
// get_or
// ----------------------------------------------------------------------------
 
template <field f, typename field_types, typename field_ids, typename or_type>
decltype(auto) get_or(record<field_types, field_ids> & r, or_type && or_value)
{
    if constexpr (field_ids::contains(f))
        return std::get<field_ids::index_of(f)>(r);
    else
        return std::forward<or_type>(or_value);
}
 
template <field f, typename field_types, typename field_ids, typename or_type>
decltype(auto) get_or(record<field_types, field_ids> const & r, or_type && or_value)
{
    if constexpr (field_ids::contains(f))
        return std::get<field_ids::index_of(f)>(r);
    else
        return std::forward<or_type>(or_value);
}
 
template <size_t i, typename or_type, typename ...types>
decltype(auto) get_or(std::tuple<types...> & t, or_type && or_value)
{
    if constexpr (i < sizeof...(types))
        return std::get<i>(t);
    else
        return std::forward<or_type>(or_value);
}
 
template <size_t i, typename or_type, typename ...types>
decltype(auto) get_or(std::tuple<types...> const & t, or_type && or_value)
{
    if constexpr (i < sizeof...(types))
        return std::get<i>(t);
    else
        return std::forward<or_type>(or_value);
}
 
// ----------------------------------------------------------------------------
// range_wrap_ignore
// ----------------------------------------------------------------------------
 
template <std::ranges::input_range rng_t>
inline auto & range_wrap_ignore(rng_t & range)
{
    return range;
}
 
inline auto range_wrap_ignore(ignore_t const &)
{
    return views::repeat(std::ignore);
}
 
} // namespace seqan3::detail