optional.hpp

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// -----------------------------------------------------------------------------------------------------
// 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 <optional>
 
#include <seqan3/core/debug_stream/debug_stream_type.hpp>
#include <seqan3/core/detail/template_inspection.hpp>
#include <seqan3/utility/type_traits/basic.hpp>
 
namespace seqan3
{
template <typename char_t>
inline debug_stream_type<char_t> & operator<<(debug_stream_type<char_t> & s, std::nullopt_t SEQAN3_DOXYGEN_ONLY(arg))
{
   s << "<VALUELESS_OPTIONAL>";
   return s;
}
 
template <typename char_t, typename optional_type>
    requires detail::is_type_specialisation_of_v<std::remove_cvref_t<optional_type>, std::optional>
inline debug_stream_type<char_t> & operator<<(debug_stream_type<char_t> & s, optional_type && arg)
{
    if (arg.has_value())
        s << *arg;
    else
        s << "<VALUELESS_OPTIONAL>";
    return s;
}
 
 
} // namespace seqan3