    // Copyright (C) 2006  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #undef DLIB_ARRAY2D_KERNEl_ABSTRACT_
    #ifdef DLIB_ARRAY2D_KERNEl_ABSTRACT_

    #include "../interfaces/enumerable.h"
    #include "../serialize.h"
    #include "../algs.h"
    #include "../geometry/rectangle_abstract.h"

    namespace dlib
    {

        template <
            typename T,
            typename mem_manager = default_memory_manager
            >
        class array2d : public enumerable<T>
        {

            /*!
                REQUIREMENTS ON T
                    T must have a default constructor.

                REQUIREMENTS ON mem_manager
                    must be an implementation of memory_manager/memory_manager_kernel_abstract.h or
                    must be an implementation of memory_manager_global/memory_manager_global_kernel_abstract.h or
                    must be an implementation of memory_manager_stateless/memory_manager_stateless_kernel_abstract.h
                    mem_manager::type can be set to anything.

                POINTERS AND REFERENCES TO INTERNAL DATA
                    No member functions in this object will invalidate pointers
                    or references to internal data except for the set_size()
                    and clear() member functions.

                INITIAL VALUE
                    nr() == 0
                    nc() == 0

                ENUMERATION ORDER
                    The enumerator will iterate over the elements of the array starting
                    with row 0 and then proceeding to row 1 and so on.  Each row will be
                    fully enumerated before proceeding on to the next row and the elements
                    in a row will be enumerated beginning with the 0th column, then the 1st
                    column and so on.

                WHAT THIS OBJECT REPRESENTS
                    This object represents a 2-Dimensional array of objects of
                    type T.

                    Also note that unless specified otherwise, no member functions
                    of this object throw exceptions.

                    Finally, note that this object stores its data contiguously and in
                    row major order.  Moreover, there is no padding at the end of each row.
                    This means that its width_step() value is always equal to sizeof(type)*nc().
            !*/

        public:

            // ----------------------------------------

            typedef T type;
            typedef mem_manager mem_manager_type;
            typedef T*          iterator;
            typedef const T*    const_iterator;

            // ----------------------------------------

            class row
            {
                /*!
                    POINTERS AND REFERENCES TO INTERNAL DATA
                        No member functions in this object will invalidate pointers
                        or references to internal data.

                    WHAT THIS OBJECT REPRESENTS
                        This object represents a row of Ts in an array2d object.
                !*/
            public:
                long nc (
                ) const;
                /*!
                    ensures
                        - returns the number of columns in this row
                !*/

                const T& operator[] (
                    long column
                ) const;
                /*!
                    requires
                        - 0 <= column < nc()
                    ensures
                        - returns a const reference to the T in the given column
                !*/

                T& operator[] (
                    long column
                );
                /*!
                    requires
                        - 0 <= column < nc()
                    ensures
                        - returns a non-const reference to the T in the given column
                !*/

            private:
                // restricted functions
                row();
                row& operator=(row&);
            };

            // ----------------------------------------

            array2d (
            );
            /*!
                ensures
                    - #*this is properly initialized
                throws
                    - std::bad_alloc
            !*/

            array2d(const array2d&) = delete;        // copy constructor
            array2d& operator=(const array2d&) = delete;    // assignment operator

            array2d(
                array2d&& item
            );
            /*!
                ensures
                    - Moves the state of item into *this.
                    - #item is in a valid but unspecified state.
            !*/

            array2d (
                long rows,
                long cols
            );
            /*!
                requires
                    - rows >= 0 && cols >= 0
                ensures
                    - #nc() == cols
                    - #nr() == rows
                    - #at_start() == true
                    - all elements in this array have initial values for their type
                throws
                    - std::bad_alloc
            !*/

            virtual ~array2d (
            );
            /*!
                ensures
                    - all resources associated with *this has been released
            !*/

            void clear (
            );
            /*!
                ensures
                    - #*this has an initial value for its type
            !*/

            long nc (
            ) const;
            /*!
                ensures
                    - returns the number of elements there are in a row.  i.e. returns
                      the number of columns in *this
            !*/

            long nr (
            ) const;
            /*!
                ensures
                    - returns the number of rows in *this
            !*/

            void set_size (
                long rows,
                long cols
            );
            /*!
                requires
                    - rows >= 0 && cols >= 0
                ensures
                    - #nc() == cols
                    - #nr() == rows
                    - #at_start() == true
                    - if (the call to set_size() doesn't change the dimensions of this array) then
                        - all elements in this array retain their values from before this function was called
                    - else
                        - all elements in this array have initial values for their type
                throws
                    - std::bad_alloc
                        If this exception is thrown then #*this will have an initial
                        value for its type.
            !*/

            row operator[] (
                long row_index
            );
            /*!
                requires
                    - 0 <= row_index < nr()
                ensures
                    - returns a non-const row of nc() elements that represents the
                      given row_index'th row in *this.
            !*/

            const row operator[] (
                long row_index
            ) const;
            /*!
                requires
                    - 0 <= row_index < nr()
                ensures
                    - returns a const row of nc() elements that represents the
                      given row_index'th row in *this.
            !*/

            void swap (
                array2d& item
            );
            /*!
                ensures
                    - swaps *this and item
            !*/

            array2d& operator= (
                array2d&& rhs
            );
            /*!
                ensures
                    - Moves the state of item into *this.
                    - #item is in a valid but unspecified state.
                    - returns #*this
            !*/

            long width_step (
            ) const;
            /*!
                ensures
                    - returns the size of one row of the image, in bytes.
                      More precisely, return a number N such that:
                      (char*)&item[0][0] + N == (char*)&item[1][0].
                    - for dlib::array2d objects, the returned value
                      is always equal to sizeof(type)*nc().  However,
                      other objects which implement dlib::array2d style
                      interfaces might have padding at the ends of their
                      rows and therefore might return larger numbers.
                      An example of such an object is the dlib::cv_image.
            !*/

            iterator begin(
            );
            /*!
                ensures
                    - returns a random access iterator pointing to the first element in this
                      object.
                    - The iterator will iterate over the elements of the object in row major
                      order.
            !*/

            iterator end(
            );
            /*!
                ensures
                    - returns a random access iterator pointing to one past the end of the last
                      element in this object.
            !*/

            const_iterator begin(
            ) const;
            /*!
                ensures
                    - returns a random access iterator pointing to the first element in this
                      object.
                    - The iterator will iterate over the elements of the object in row major
                      order.
            !*/

            const_iterator end(
            ) const;
            /*!
                ensures
                    - returns a random access iterator pointing to one past the end of the last
                      element in this object.
            !*/

        };

        template <
            typename T,
            typename mem_manager
            >
        inline void swap (
            array2d<T,mem_manager>& a,
            array2d<T,mem_manager>& b
        ) { a.swap(b); }
        /*!
            provides a global swap function
        !*/

        template <
            typename T,
            typename mem_manager
            >
        void serialize (
            const array2d<T,mem_manager>& item,
            std::ostream& out
        );
        /*!
            Provides serialization support.  Note that the serialization formats used by the
            dlib::matrix and dlib::array2d objects are compatible.  That means you can load the
            serialized data from one into another and it will work properly.
        !*/

        template <
            typename T,
            typename mem_manager
            >
        void deserialize (
            array2d<T,mem_manager>& item,
            std::istream& in
        );
        /*!
            provides deserialization support
        !*/

    }

    #endif // DLIB_ARRAY2D_KERNEl_ABSTRACT_