array_base.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 mplied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#pragma once
 
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <ranges>
#include <utility>
 
#include "sparrow/arrow_interface/arrow_array_schema_proxy.hpp"
#include "sparrow/buffer/dynamic_bitset/dynamic_bitset_view.hpp"
#include "sparrow/layout/array_access.hpp"
#include "sparrow/layout/layout_iterator.hpp"
#include "sparrow/utils/crtp_base.hpp"
#include "sparrow/utils/iterator.hpp"
#include "sparrow/utils/nullable.hpp"
 
namespace sparrow
{
    struct array_inner_types_base
    {
        using bitmap_type = dynamic_bitset_view<std::uint8_t>;
    };

    template <class D>
    struct array_inner_types;

    template <class D>
    class array_crtp_base : public crtp_base<D>
    {
    public:
 
        using self_type = array_crtp_base<D>;
        using derived_type = D;
 
        using inner_types = array_inner_types<derived_type>;
 
        using size_type = std::size_t;
        using difference_type = std::ptrdiff_t;
 
        using bitmap_type = typename inner_types::bitmap_type;
        using bitmap_const_reference = bitmap_type::const_reference;
        using bitmap_iterator = bitmap_type::iterator;
        using const_bitmap_iterator = bitmap_type::const_iterator;
        using const_bitmap_range = std::ranges::subrange<const_bitmap_iterator>;
 
        using inner_value_type = typename inner_types::inner_value_type;
        using value_type = nullable<inner_value_type>;
 
        using inner_const_reference = typename inner_types::inner_const_reference;
        using const_reference = nullable<inner_const_reference, bitmap_const_reference>;
 
        using const_value_iterator = typename inner_types::const_value_iterator;
        using const_value_range = std::ranges::subrange<const_value_iterator>;
 
        using iterator_tag = typename inner_types::iterator_tag;
 
        struct iterator_types
        {
            using value_type = self_type::value_type;
            using reference = self_type::const_reference;
            using value_iterator = self_type::const_value_iterator;
            using bitmap_iterator = self_type::const_bitmap_iterator;
            using iterator_tag = self_type::iterator_tag;
        };
 
        using const_iterator = layout_iterator<iterator_types>;
        using const_reverse_iterator = std::reverse_iterator<const_iterator>;

        [[nodiscard]] constexpr std::optional<std::string_view> name() const;

        [[nodiscard]] std::optional<key_value_view> metadata() const;

        [[nodiscard]] constexpr bool empty() const;

        [[nodiscard]] constexpr size_type size() const;

        [[nodiscard]] constexpr const_reference at(size_type i) const;

        [[nodiscard]] constexpr const_reference operator[](size_type i) const;

        [[nodiscard]] constexpr const_reference front() const;

        [[nodiscard]] constexpr const_reference back() const;

        [[nodiscard]] constexpr const_iterator begin() const;

        [[nodiscard]] constexpr const_iterator end() const;

        [[nodiscard]] constexpr const_iterator cbegin() const;

        [[nodiscard]] constexpr const_iterator cend() const;

        [[nodiscard]] constexpr const_reverse_iterator rbegin() const;

        [[nodiscard]] constexpr const_reverse_iterator rend() const;

        [[nodiscard]] constexpr const_reverse_iterator crbegin() const;

        [[nodiscard]] constexpr const_reverse_iterator crend() const;

        [[nodiscard]] constexpr const_bitmap_range bitmap() const;

        [[nodiscard]] constexpr const_value_range values() const;

        [[nodiscard]] constexpr D slice(size_type start, size_type end) const;

        [[nodiscard]] constexpr D slice_view(size_type start, size_type end) const;
 
    protected:

        explicit array_crtp_base(arrow_proxy);
 
        constexpr array_crtp_base(const array_crtp_base&) = default;
        constexpr array_crtp_base& operator=(const array_crtp_base&) = default;
 
        constexpr array_crtp_base(array_crtp_base&&) noexcept = default;
        constexpr array_crtp_base& operator=(array_crtp_base&&) noexcept = default;

        [[nodiscard]] constexpr arrow_proxy& get_arrow_proxy() noexcept;

        [[nodiscard]] constexpr const arrow_proxy& get_arrow_proxy() const noexcept;

        constexpr bitmap_const_reference has_value(size_type i) const;

        constexpr const_bitmap_iterator bitmap_begin() const;

        constexpr const_bitmap_iterator bitmap_end() const;

        constexpr const_bitmap_iterator bitmap_cbegin() const;

        constexpr const_bitmap_iterator bitmap_cend() const;
 
    private:
 
        arrow_proxy m_proxy;  
 
        // friend classes
        friend class layout_iterator<iterator_types>;
        friend class detail::array_access;
#if defined(__cpp_lib_format)
        friend struct std::formatter<D>;
#endif
    };
 
    template <class D>
    constexpr bool operator==(const array_crtp_base<D>& lhs, const array_crtp_base<D>& rhs);
 
    /**********************************
     * array_crtp_base implementation *
     **********************************/
 
    template <class D>
    constexpr std::optional<std::string_view> array_crtp_base<D>::name() const
    {
        return get_arrow_proxy().name();
    }
 
    template <class D>
    std::optional<key_value_view> array_crtp_base<D>::metadata() const
    {
        return get_arrow_proxy().metadata();
    }
 
    template <class D>
    constexpr bool array_crtp_base<D>::empty() const
    {
        return size() == size_type(0);
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::size() const -> size_type
    {
        return static_cast<size_type>(get_arrow_proxy().length());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::at(size_type i) const -> const_reference
    {
        if (i >= size())
        {
            const std::string error_message = "Index " + std::to_string(i)
                                              + " is greater or equal to size of array ("
                                              + std::to_string(size()) + ")";
            throw std::out_of_range(error_message);
        }
        return (*this)[i];
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::operator[](size_type i) const -> const_reference
    {
        auto& derived_cast = this->derived_cast();
        SPARROW_ASSERT_TRUE(i < derived_cast.size());
        return const_reference(inner_const_reference(derived_cast.value(i)), derived_cast.has_value(i));
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::front() const -> const_reference
    {
        SPARROW_ASSERT_TRUE(!empty());
        return (*this)[size_type(0)];
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::back() const -> const_reference
    {
        SPARROW_ASSERT_TRUE(!empty());
        return (*this)[size() - 1];
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::begin() const -> const_iterator
    {
        return cbegin();
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::end() const -> const_iterator
    {
        return cend();
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::cbegin() const -> const_iterator
    {
        return const_iterator(this->derived_cast().value_cbegin(), bitmap_begin());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::cend() const -> const_iterator
    {
        return const_iterator(this->derived_cast().value_cend(), bitmap_end());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::rbegin() const -> const_reverse_iterator
    {
        return crbegin();
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::rend() const -> const_reverse_iterator
    {
        return crend();
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::crbegin() const -> const_reverse_iterator
    {
        return const_reverse_iterator(cend());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::crend() const -> const_reverse_iterator
    {
        return const_reverse_iterator(cbegin());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::bitmap() const -> const_bitmap_range
    {
        return const_bitmap_range(bitmap_begin(), bitmap_end());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::values() const -> const_value_range
    {
        return const_value_range(this->derived_cast().value_cbegin(), this->derived_cast().value_cend());
    }
 
    template <class D>
    array_crtp_base<D>::array_crtp_base(arrow_proxy proxy)
        : m_proxy(std::move(proxy))
    {
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::get_arrow_proxy() noexcept -> arrow_proxy&
    {
        return m_proxy;
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::get_arrow_proxy() const noexcept -> const arrow_proxy&
    {
        return m_proxy;
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::has_value(size_type i) const -> bitmap_const_reference
    {
        SPARROW_ASSERT_TRUE(i < size());
        return *sparrow::next(bitmap_begin(), i);
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::bitmap_begin() const -> const_bitmap_iterator
    {
        return sparrow::next(this->derived_cast().get_bitmap().cbegin(), get_arrow_proxy().offset());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::bitmap_end() const -> const_bitmap_iterator
    {
        return sparrow::next(bitmap_begin(), size());
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::bitmap_cbegin() const -> const_bitmap_iterator
    {
        return bitmap_begin();
    }
 
    template <class D>
    constexpr auto array_crtp_base<D>::bitmap_cend() const -> const_bitmap_iterator
    {
        return bitmap_end();
    }
 
    template <class D>
    constexpr D array_crtp_base<D>::slice(size_type start, size_type end) const
    {
        SPARROW_ASSERT_TRUE(start <= end);
        return D{get_arrow_proxy().slice(start, end)};
    }
 
    template <class D>
    constexpr D array_crtp_base<D>::slice_view(size_type start, size_type end) const
    {
        SPARROW_ASSERT_TRUE(start <= end);
        return D{get_arrow_proxy().slice_view(start, end)};
    }
 
    /*
     * @brief Equality comparison operator for arrays.
     *
     * Compares two arrays element-wise, including both values and validity flags.
     *
     * @tparam D Array type
     * @param lhs First array to compare
     * @param rhs Second array to compare
     * @return true if arrays are element-wise equal, false otherwise
     *
     * @post Returns true iff arrays have same size and all elements compare equal
     * @post Comparison includes both values and validity states
     */
    template <class D>
    constexpr bool operator==(const array_crtp_base<D>& lhs, const array_crtp_base<D>& rhs)
    {
        return std::ranges::equal(lhs, rhs);
    }
}
 
#if defined(__cpp_lib_format)
 
template <typename D>
    requires std::derived_from<D, sparrow::array_crtp_base<D>>
struct std::formatter<D>
{
    constexpr auto parse(std::format_parse_context& ctx)
    {
        return ctx.begin();  // Simple implementation
    }
 
    auto format(const D& ar, std::format_context& ctx) const
    {
        const auto& proxy = ar.get_arrow_proxy();
        std::string type;
        if (proxy.dictionary())
        {
            std::format_to(ctx.out(), "Dictionary<{}>", proxy.dictionary()->data_type());
        }
        else
        {
            std::format_to(ctx.out(), "{}", proxy.data_type());
        }
        std::format_to(ctx.out(), " [name={} | size={}] <", ar.name().value_or("nullptr"), proxy.length());
 
        std::for_each(
            ar.cbegin(),
            std::prev(ar.cend()),
            [&ctx](const auto& value)
            {
                std::format_to(ctx.out(), "{}, ", value);
            }
        );
        return std::format_to(ctx.out(), "{}>", ar.back());
    }
};
 
namespace sparrow
{
    template <typename D>
        requires std::derived_from<D, array_crtp_base<D>>
    std::ostream& operator<<(std::ostream& os, const D& value)
    {
        os << std::format("{}", value);
        return os;
    }
}
 
#endif