layout_iterator.hpp

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// Copyright 2024 Man Group Operations Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#pragma once
 
#include "sparrow/utils/iterator.hpp"
 
namespace sparrow
{
    template <class T>
    concept iterator_types = requires {
        typename T::value_type;
        typename T::reference;
        typename T::value_iterator;
        typename T::bitmap_iterator;
        typename T::iterator_tag;
    };

    template <iterator_types Iterator_types>
    class layout_iterator : public iterator_base<
                                layout_iterator<Iterator_types>,
                                typename Iterator_types::value_type,
                                typename Iterator_types::iterator_tag,
                                typename Iterator_types::reference>
    {
    public:
 
        using self_type = layout_iterator<Iterator_types>;
        using base_type = iterator_base<
            self_type,
            typename Iterator_types::value_type,
            typename Iterator_types::iterator_tag,
            typename Iterator_types::reference>;
 
        using reference = typename base_type::reference;
        using difference_type = typename base_type::difference_type;
 
        using value_iterator = Iterator_types::value_iterator;
 
        using bitmap_iterator = Iterator_types::bitmap_iterator;
 
        constexpr layout_iterator() noexcept = default;
        constexpr layout_iterator(value_iterator value_iter, bitmap_iterator bitmap_iter);
 
    private:
 
        [[nodiscard]] constexpr reference dereference() const;
        [[nodiscard]] constexpr reference dereference();
        constexpr void increment();
        constexpr void decrement();
        constexpr void advance(difference_type n);
        [[nodiscard]] constexpr difference_type distance_to(const self_type& rhs) const;
        [[nodiscard]] constexpr bool equal(const self_type& rhs) const;
        [[nodiscard]] constexpr bool less_than(const self_type& rhs) const;
 
        value_iterator m_value_iter;
        bitmap_iterator m_bitmap_iter;
 
        friend class iterator_access;
    };
 
    /**********************************
     * layout_iterator implementation *
     **********************************/
 
    template <iterator_types Iterator_types>
    constexpr layout_iterator<Iterator_types>::layout_iterator(value_iterator value_iter, bitmap_iterator bitmap_iter)
        : m_value_iter(value_iter)
        , m_bitmap_iter(bitmap_iter)
    {
    }
 
    template <iterator_types Iterator_types>
    constexpr auto layout_iterator<Iterator_types>::dereference() const -> reference
    {
        return reference(*m_value_iter, *m_bitmap_iter);
    }
 
    template <iterator_types Iterator_types>
    constexpr auto layout_iterator<Iterator_types>::dereference() -> reference
    {
        return reference(*m_value_iter, *m_bitmap_iter);
    }
 
    template <iterator_types Iterator_types>
    constexpr void layout_iterator<Iterator_types>::increment()
    {
        ++m_value_iter;
        ++m_bitmap_iter;
    }
 
    template <iterator_types Iterator_types>
    constexpr void layout_iterator<Iterator_types>::decrement()
    {
        --m_value_iter;
        --m_bitmap_iter;
    }
 
    template <iterator_types Iterator_types>
    constexpr void layout_iterator<Iterator_types>::advance(difference_type n)
    {
        m_value_iter += n;
        m_bitmap_iter += n;
    }
 
    template <iterator_types Iterator_types>
    constexpr auto layout_iterator<Iterator_types>::distance_to(const self_type& rhs) const -> difference_type
    {
        return rhs.m_value_iter - m_value_iter;
    }
 
    template <iterator_types Iterator_types>
    constexpr bool layout_iterator<Iterator_types>::equal(const self_type& rhs) const
    {
        return m_value_iter == rhs.m_value_iter && m_bitmap_iter == rhs.m_bitmap_iter;
    }
 
    template <iterator_types Iterator_types>
    constexpr bool layout_iterator<Iterator_types>::less_than(const self_type& rhs) const
    {
        return m_value_iter < rhs.m_value_iter && m_bitmap_iter < rhs.m_bitmap_iter;
    }
}