/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2021, Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include <iterator>
#include <type_traits>
#include <utility>


///////////////////////////////////////////////////////////////////////////////
namespace cruft::iterator {
    /// An output iterator that calls placement new on a supplied pointer
    /// during assignment.
    ///
    /// This simplifies usage of uninitialised arrays with STL algorithms.
    template <typename PointerT>
    struct placement_output {
    public:
        static_assert (std::is_pointer_v<PointerT>);

        using iterator_category = std::output_iterator_tag;
        using value_type      = void;
        using difference_type = void;
        using pointer 	      = void;
        using reference 	  = void;

        placement_output (PointerT _cursor)
            : m_cursor (_cursor)
        { ; }

        placement_output& operator++ () { ++m_cursor; return *this; }
        placement_output& operator * () { return *this; }
        placement_output& operator-> () { return  this; }

        template <typename ValueT>
        placement_output&
        operator= (ValueT &&val)
        {
            new (m_cursor) bare_type (std::forward<ValueT> (val));
            return *this;
        }

    private:
        using bare_type = std::remove_pointer_t<PointerT>;

        PointerT m_cursor;
    };


    template <typename PointerT>
    placement_output (PointerT) -> placement_output<std::remove_reference_t<PointerT>>;
}