out_file_iterator.hpp

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// -----------------------------------------------------------------------------------------------------
// Copyright (c) 2006-2020, Knut Reinert & Freie Universität Berlin
// Copyright (c) 2016-2020, 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 <cassert>
 
#include <range/v3/range_fwd.hpp>
 
#include <seqan3/core/platform.hpp>
 
#include <seqan3/std/ranges>
 
namespace seqan3::detail
{
 
template <typename file_type>
class out_file_iterator
{
    static_assert(!std::is_const_v<file_type>,
                  "You cannot iterate over const files, because the iterator changes the file.");
public:
    using value_type        = void;
    using reference         = void;
    using const_reference   = void;
    using size_type         = void;
    using difference_type   = std::ptrdiff_t;
    using pointer           = void *;
    using iterator_category = std::output_iterator_tag;
 
    constexpr out_file_iterator() = default;
    constexpr out_file_iterator(out_file_iterator const &) = default;
    constexpr out_file_iterator & operator=(out_file_iterator const &) = default;
    constexpr out_file_iterator (out_file_iterator &&) = default;
    constexpr out_file_iterator & operator=(out_file_iterator &&) = default;
    ~out_file_iterator() = default;
 
    constexpr out_file_iterator(file_type & _host) noexcept :
        host{&_host}
    {}
 
    out_file_iterator & operator++()
    {
        return *this;
    }
 
    out_file_iterator operator++(int)
    {
        return *this;
    }
 
 
    out_file_iterator & operator*() noexcept
    {
        return *this;
    }
 
    template <typename arg_t>
    out_file_iterator & operator=(arg_t && arg)
    {
        assert(host != nullptr);
        host->push_back(std::forward<arg_t>(arg));
        return *this;
    }
 
    constexpr bool operator==(std::ranges::default_sentinel_t const &) const noexcept
    {
        return false;
    }
 
    constexpr bool operator!=(std::ranges::default_sentinel_t const &) const noexcept
    {
        return true;
    }
 
    constexpr friend bool operator==(std::ranges::default_sentinel_t const &,
                                     out_file_iterator const & it) noexcept
    {
        return (it == std::ranges::default_sentinel);
    }
 
    constexpr friend bool operator!=(std::ranges::default_sentinel_t const &,
                                     out_file_iterator const & it) noexcept
    {
        return (it != std::ranges::default_sentinel);
    }
 
private:
    file_type * host{};
};
 
} // namespace seqan3::detail