matrix-view.hpp

//
// libsemigroups - C++ library for semigroups and monoids
// Copyright (C) 2026 James D. Mitchell
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
 
#ifndef LIBSEMIGROUPS_MATRIX_VIEW_HPP_
#define LIBSEMIGROUPS_MATRIX_VIEW_HPP_
 
#include <cstddef>  // for size_t
 
#include "detail/matrix-common.hpp"  // for RowViewCommon
 
namespace libsemigroups {
#ifndef LIBSEMIGROUPS_PARSED_BY_DOXYGEN
  template <typename PlusOp,
            typename ProdOp,
            typename ZeroOp,
            typename OneOp,
            size_t R,
            size_t C,
            typename Scalar>
  class StaticMatrix;
 
  template <typename... Args>
  class DynamicMatrix;
#endif

  // StaticRowViews - static arithmetic

  template <typename PlusOp,
            typename ProdOp,
            typename ZeroOp,
            typename OneOp,
            size_t C,
            typename Scalar>
  class StaticRowView
      : public detail::RowViewCommon<
            StaticMatrix<PlusOp, ProdOp, ZeroOp, OneOp, 1, C, Scalar>,
            StaticRowView<PlusOp, ProdOp, ZeroOp, OneOp, C, Scalar>>,
        public detail::
            MatrixStaticArithmetic<PlusOp, ProdOp, ZeroOp, OneOp, Scalar> {
   private:
    using RowViewCommon = detail::RowViewCommon<
        StaticMatrix<PlusOp, ProdOp, ZeroOp, OneOp, 1, C, Scalar>,
        StaticRowView<PlusOp, ProdOp, ZeroOp, OneOp, C, Scalar>>;
    friend RowViewCommon;
 
    template <size_t R>
    using StaticMatrix_ = ::libsemigroups::
        StaticMatrix<PlusOp, ProdOp, ZeroOp, OneOp, R, C, Scalar>;
 
   public:
    using const_iterator = typename RowViewCommon::const_iterator;

    using iterator = typename RowViewCommon::iterator;

    using scalar_type = Scalar;

    using scalar_reference = typename RowViewCommon::scalar_reference;

    // clang-format off
    // NOLINTNEXTLINE(whitespace/line_length)
    using scalar_const_reference = typename RowViewCommon::scalar_const_reference;
    // clang-format on

    using matrix_type = typename RowViewCommon::matrix_type;

    using Row = typename matrix_type::Row;

    StaticRowView() = default;

    StaticRowView(StaticRowView const&) = default;

    StaticRowView(StaticRowView&&) = default;

    StaticRowView& operator=(StaticRowView const&) = default;

    StaticRowView& operator=(StaticRowView&&) = default;
 
#ifndef LIBSEMIGROUPS_PARSED_BY_DOXYGEN
    using RowViewCommon::RowViewCommon;
 
    // TODO(2) This constructor should be private
    template <size_t R>
    StaticRowView(StaticMatrix_<R> const*,
                  typename RowViewCommon::iterator it,
                  size_t)
        : RowViewCommon(it) {}
 
    using RowViewCommon::size;
#else
    explicit StaticRowView(Row const& r);

    static constexpr size_t size() const noexcept;

    iterator begin() noexcept;

    iterator end();

    const_iterator cbegin() const noexcept;

    iterator cend();

    scalar_reference operator()(size_t i);

    scalar_const_reference operator()(size_t i) const;

    scalar_reference operator[](size_t i);

    scalar_const_reference operator[](size_t i) const;

    template <typename U>
    bool operator==(U const& that) const;

    template <typename U>
    bool operator!=(U const& that) const;

    // clang-format off
    // NOLINTNEXTLINE(whitespace/line_length)
    // clang-format on
    template <typename U>
    bool operator<(U const& that) const;

    template <typename U>
    bool operator<(U const& that) const;

    Row plus_no_checks(StaticRowView const& that) const;

    Row operator+(StaticRowView const& that);

    void plus_inplace_no_checks(StaticRowView const& that);

    void operator+=(StaticRowView const& that);

    void operator+=(scalar_type a);

    Row operator*(scalar_type a) const;

    void operator*=(scalar_type a);
#endif
 
   private:
    static constexpr size_t length_impl() noexcept {
      return C;
    }
  };

  // DynamicRowViews - static arithmetic
 
#ifndef LIBSEMIGROUPS_PARSED_BY_DOXYGEN
  // Doxygen needs to ignore this so that the actual implementation of
  // DynamicRowView gets documented.
  template <typename... Args>
  class DynamicRowView;
#endif

  template <typename PlusOp,
            typename ProdOp,
            typename ZeroOp,
            typename OneOp,
            typename Scalar>
  class DynamicRowView<PlusOp, ProdOp, ZeroOp, OneOp, Scalar>
      : public detail::RowViewCommon<
            DynamicMatrix<PlusOp, ProdOp, ZeroOp, OneOp, Scalar>,
            DynamicRowView<PlusOp, ProdOp, ZeroOp, OneOp, Scalar>>,
        public detail::
            MatrixStaticArithmetic<PlusOp, ProdOp, ZeroOp, OneOp, Scalar> {
   private:
    using DynamicMatrix_ = DynamicMatrix<PlusOp, ProdOp, ZeroOp, OneOp, Scalar>;
    using RowViewCommon  = detail::RowViewCommon<
        DynamicMatrix_,
        DynamicRowView<PlusOp, ProdOp, ZeroOp, OneOp, Scalar>>;
    friend RowViewCommon;
 
   public:
    using const_iterator = typename RowViewCommon::const_iterator;

    using iterator = typename RowViewCommon::iterator;

    using scalar_type = Scalar;

    using scalar_reference = typename RowViewCommon::scalar_reference;

    // clang-format off
    // NOLINTNEXTLINE(whitespace/line_length)
    using scalar_const_reference = typename RowViewCommon::scalar_const_reference;
    // clang-format on

    using matrix_type = typename RowViewCommon::matrix_type;

    using Row = typename matrix_type::Row;

    DynamicRowView() = default;

    DynamicRowView(DynamicRowView const&) = default;

    DynamicRowView(DynamicRowView&&) = default;

    DynamicRowView& operator=(DynamicRowView const&) = default;

    DynamicRowView& operator=(DynamicRowView&&) = default;

    explicit DynamicRowView(Row const& r)
        : RowViewCommon(r), _length(r.number_of_cols()) {}
 
#ifndef LIBSEMIGROUPS_PARSED_BY_DOXYGEN
    using RowViewCommon::RowViewCommon;
 
    // TODO(2) This constructor should be private
    DynamicRowView(DynamicMatrix_ const*, iterator const& it, size_t N)
        : RowViewCommon(it), _length(N) {}
 
    using RowViewCommon::size;
#else
    size_t size() const noexcept;

    iterator begin() noexcept;

    iterator end();

    const_iterator cbegin() const noexcept;

    iterator cend();

    scalar_reference operator()(size_t i);

    scalar_const_reference operator()(size_t i) const;

    scalar_reference operator[](size_t i);

    scalar_const_reference operator[](size_t i) const;

    template <typename U>
    bool operator==(U const& that) const;

    template <typename U>
    bool operator!=(U const& that) const;

    template <typename U>
    bool operator<(U const& that) const;

    template <typename U>
    bool operator<(U const& that) const;

    Row plus_no_checks(DynamicRowView const& that);

    Row operator+(DynamicRowView const& that);

    void plus_inplace_no_checks(DynamicRowView const& that);

    void operator+=(DynamicRowView const& that);

    void operator+=(scalar_type a);

    Row operator*(scalar_type a) const;

    void operator*=(scalar_type a);
#endif  // LIBSEMIGROUPS_PARSED_BY_DOXYGEN
 
   private:
    size_t length_impl() const noexcept {
      return _length;
    }
    size_t _length;
  };

  // DynamicRowViews - dynamic arithmetic

  template <typename Semiring, typename Scalar>
  class DynamicRowView<Semiring, Scalar>
      : public detail::RowViewCommon<DynamicMatrix<Semiring, Scalar>,
                                     DynamicRowView<Semiring, Scalar>> {
   private:
    using DynamicMatrix_ = DynamicMatrix<Semiring, Scalar>;
    friend DynamicMatrix_;
    using RowViewCommon
        = detail::RowViewCommon<DynamicMatrix_,
                                DynamicRowView<Semiring, Scalar>>;
    friend RowViewCommon;
 
   public:
    using const_iterator = typename RowViewCommon::const_iterator;

    using iterator = typename RowViewCommon::iterator;

    using scalar_type = Scalar;

    using scalar_reference = typename RowViewCommon::scalar_reference;

    // clang-format off
    // NOLINTNEXTLINE(whitespace/line_length)
    using scalar_const_reference = typename RowViewCommon::scalar_const_reference;
    // clang-format on

    using matrix_type = typename RowViewCommon::matrix_type;

    using Row = typename matrix_type::Row;

    DynamicRowView() = default;

    DynamicRowView(DynamicRowView const&) = default;

    DynamicRowView(DynamicRowView&&) = default;

    DynamicRowView& operator=(DynamicRowView const&) = default;

    DynamicRowView& operator=(DynamicRowView&&) = default;

    explicit DynamicRowView(Row const& r) : RowViewCommon(r), _matrix(&r) {}
 
#ifndef LIBSEMIGROUPS_PARSED_BY_DOXYGEN
    using RowViewCommon::RowViewCommon;
 
    // TODO(2) This constructor should be private
    DynamicRowView(DynamicMatrix_ const* mat, iterator const& it, size_t)
        : RowViewCommon(it), _matrix(mat) {}
 
    using RowViewCommon::size;
#else
    size_t size() const noexcept;

    iterator begin() noexcept;

    iterator end();

    const_iterator cbegin() const noexcept;

    iterator cend();

    scalar_reference operator()(size_t i);

    scalar_const_reference operator()(size_t i) const;

    scalar_reference operator[](size_t i);

    scalar_const_reference operator[](size_t i) const;

    template <typename U>
    bool operator==(U const& that) const;

    template <typename U>
    bool operator!=(U const& that) const;

    template <typename U>
    bool operator<(U const& that) const;

    template <typename U>
    bool operator<(U const& that) const;

    Row plus_no_checks(DynamicRowView const& that);

    Row operator+(DynamicRowView const& that);

    void plus_inplace_no_checks(DynamicRowView const& that);

    void operator+=(DynamicRowView const& that);

    void operator+=(scalar_type a);

    Row operator*(scalar_type a) const;

    void operator*=(scalar_type a);
#endif
 
   private:
    size_t length_impl() const noexcept {
      return _matrix->number_of_cols();
    }
 
    scalar_type plus_no_checks_impl(scalar_type x,
                                    scalar_type y) const noexcept {
      return _matrix->plus_no_checks_impl(x, y);
    }
 
    scalar_type product_no_checks_impl(scalar_type x,
                                       scalar_type y) const noexcept {
      return _matrix->product_no_checks_impl(x, y);
    }
 
    DynamicMatrix_ const* _matrix;
  };
}  // namespace libsemigroups
#endif  // LIBSEMIGROUPS_MATRIX_VIEW_HPP_