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

    #include "matrix_mat_abstract.h"
    #include "../stl_checked.h"
    #include <vector>
    #include "matrix_op.h"
    #include "../array2d.h"
    #include "../array.h"

    namespace dlib
    {

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

        template <
            typename EXP
            >
        const matrix_exp<EXP>& mat (
            const matrix_exp<EXP>& m
        )
        {
            return m;
        }

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

        template <typename T>
        struct op_array2d_to_mat : does_not_alias
        {
            op_array2d_to_mat( const T& array_) : array(array_){}

            const T& array;

            const static long cost = 1;
            const static long NR = 0;
            const static long NC = 0;
            typedef typename T::type type;
            typedef const typename T::type& const_ret_type;
            typedef typename T::mem_manager_type mem_manager_type;
            typedef row_major_layout layout_type;

            const_ret_type apply (long r, long c ) const { return array[r][c]; }

            long nr () const { return array.nr(); }
            long nc () const { return array.nc(); }
        };

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

        template <
            typename T,
            typename MM
            >
        const matrix_op<op_array2d_to_mat<array2d<T,MM> > > mat (
            const array2d<T,MM>& array
        )
        {
            typedef op_array2d_to_mat<array2d<T,MM> > op;
            return matrix_op<op>(op(array));
        }

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

        template <typename T>
        struct op_array_to_mat : does_not_alias
        {
            op_array_to_mat( const T& vect_) : vect(vect_){}

            const T& vect;

            const static long cost = 1;
            const static long NR = 0;
            const static long NC = 1;
            typedef typename T::type type;
            typedef const typename T::type& const_ret_type;
            typedef typename T::mem_manager_type mem_manager_type;
            typedef row_major_layout layout_type;

            const_ret_type apply (long r, long  ) const { return vect[r]; }

            long nr () const { return vect.size(); }
            long nc () const { return 1; }
        };

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

        template <
            typename T,
            typename MM
            >
        const matrix_op<op_array_to_mat<array<T,MM> > > mat (
            const array<T,MM>& m
        )
        {
            typedef op_array_to_mat<array<T,MM> > op;
            return matrix_op<op>(op(m));
        }

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

        template <typename T>
        struct op_std_vect_to_mat : does_not_alias
        {
            op_std_vect_to_mat( const T& vect_) : vect(vect_){}

            const T& vect;

            const static long cost = 1;
            const static long NR = 0;
            const static long NC = 1;
            typedef typename T::value_type type;
            typedef const typename T::value_type& const_ret_type;
            typedef default_memory_manager mem_manager_type;
            typedef row_major_layout layout_type;

            const_ret_type apply (long r, long ) const { return vect[r]; }

            long nr () const { return vect.size(); }
            long nc () const { return 1; }
        };

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

        template <
            typename value_type,
            typename alloc
            >
        const matrix_op<op_std_vect_to_mat<std::vector<value_type,alloc> > > mat (
            const std::vector<value_type,alloc>& vector
        )
        {
            typedef op_std_vect_to_mat<std::vector<value_type,alloc> > op;
            return matrix_op<op>(op(vector));
        }

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

        template <
            typename value_type,
            typename alloc
            >
        const matrix_op<op_std_vect_to_mat<std_vector_c<value_type,alloc> > > mat (
            const std_vector_c<value_type,alloc>& vector
        )
        {
            typedef op_std_vect_to_mat<std_vector_c<value_type,alloc> > op;
            return matrix_op<op>(op(vector));
        }

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

        template <typename T>
        struct op_pointer_to_col_vect : does_not_alias
        {
            op_pointer_to_col_vect(
                const T* ptr_,
                const long size_
            ) : ptr(ptr_), size(size_){}

            const T* ptr;
            const long size;

            const static long cost = 1;
            const static long NR = 0;
            const static long NC = 1;
            typedef T type;
            typedef const T& const_ret_type;
            typedef default_memory_manager mem_manager_type;
            typedef row_major_layout layout_type;

            const_ret_type apply (long r, long ) const { return ptr[r]; }

            long nr () const { return size; }
            long nc () const { return 1; }
        };

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

        template <
            typename T
            >
        const matrix_op<op_pointer_to_col_vect<T> > mat (
            const T* ptr,
            long nr
        )
        {
            DLIB_ASSERT(nr > 0 ,
                        "\tconst matrix_exp mat(ptr, nr)"
                        << "\n\t nr must be bigger than 0"
                        << "\n\t nr: " << nr
            );
            typedef op_pointer_to_col_vect<T> op;
            return matrix_op<op>(op(ptr, nr));
        }

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

        template <typename T>
        struct op_pointer_to_mat : does_not_alias
        {
            op_pointer_to_mat(
                const T* ptr_,
                const long nr_,
                const long nc_
            ) : ptr(ptr_), rows(nr_), cols(nc_){}

            const T* ptr;
            const long rows;
            const long cols;

            const static long cost = 1;
            const static long NR = 0;
            const static long NC = 0;
            typedef T type;
            typedef const T& const_ret_type;
            typedef default_memory_manager mem_manager_type;
            typedef row_major_layout layout_type;

            const_ret_type apply (long r, long c) const { return ptr[r*cols + c]; }

            long nr () const { return rows; }
            long nc () const { return cols; }
        };

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

        template <
            typename T
            >
        const matrix_op<op_pointer_to_mat<T> > mat (
            const T* ptr,
            long nr,
            long nc
        )
        {
            DLIB_ASSERT(nr > 0 && nc > 0 ,
                        "\tconst matrix_exp mat(ptr, nr, nc)"
                        << "\n\t nr and nc must be bigger than 0"
                        << "\n\t nr: " << nr
                        << "\n\t nc: " << nc
            );
            typedef op_pointer_to_mat<T> op;
            return matrix_op<op>(op(ptr,nr,nc));
        }

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

    }

    namespace arma
    {
        template <typename T> class Mat;
    }
    namespace dlib
    {
        template <typename T>
        struct op_arma_Mat_to_mat : does_not_alias
        {
            op_arma_Mat_to_mat( const T& array_) : array(array_){}

            const T& array;

            const static long cost = 1;
            const static long NR = 0;
            const static long NC = 0;
            typedef typename T::elem_type type;
            typedef typename T::elem_type const_ret_type;
            typedef default_memory_manager mem_manager_type;
            typedef row_major_layout layout_type;

            const_ret_type apply (long r, long c ) const { return array(r,c); }

            long nr () const { return array.n_rows; }
            long nc () const { return array.n_cols; }
        };

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

        template <
            typename T
            >
        const matrix_op<op_arma_Mat_to_mat< ::arma::Mat<T> > > mat (
            const ::arma::Mat<T>& array
        )
        {
            typedef op_arma_Mat_to_mat< ::arma::Mat<T> > op;
            return matrix_op<op>(op(array));
        }
    }

    namespace Eigen
    {
        template<typename _Scalar, int _Rows, int _Cols, int _Options, int _MaxRows, int _MaxCols>
        class Matrix;
    }

    namespace dlib
    {
        template <typename T, int _Rows, int _Cols>
        struct op_eigen_Matrix_to_mat : does_not_alias
        {
            op_eigen_Matrix_to_mat( const T& array_) : m(array_){}

            const T& m;

            const static long cost = 1;
            const static long NR = (_Rows > 0) ? _Rows : 0;
            const static long NC = (_Cols > 0) ? _Cols : 0;
            typedef typename T::Scalar type;
            typedef typename T::Scalar const_ret_type;
            typedef default_memory_manager mem_manager_type;
            typedef row_major_layout layout_type;

            const_ret_type apply (long r, long c ) const { return m(r,c); }

            long nr () const { return m.rows(); }
            long nc () const { return m.cols(); }
        };

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

        template <
            typename _Scalar, int _Rows, int _Cols, int _Options, int _MaxRows, int _MaxCols
            >
        const matrix_op<op_eigen_Matrix_to_mat< ::Eigen::Matrix<_Scalar,_Rows,_Cols,_Options,_MaxRows,_MaxCols>,_Rows,_Cols > > mat (
            const ::Eigen::Matrix<_Scalar,_Rows,_Cols,_Options,_MaxRows,_MaxCols>& m
        )
        {
            typedef op_eigen_Matrix_to_mat< ::Eigen::Matrix<_Scalar,_Rows,_Cols,_Options,_MaxRows,_MaxCols>,_Rows,_Cols > op;
            return matrix_op<op>(op(m));
        }

    // ----------------------------------------------------------------------------------------
    // ----------------------------------------------------------------------------------------
    //                                  DEPRECATED FUNCTIONS
    // ----------------------------------------------------------------------------------------
    // ----------------------------------------------------------------------------------------

    // vector_to_matrix(), array_to_matrix(), pointer_to_matrix(), and
    // pointer_to_column_vector() have been deprecated in favor of the more uniform mat()
    // function.  But they are here for backwards compatibility.

        template <
            typename vector_type
            >
        const typename disable_if<is_matrix<vector_type>, matrix_op<op_array_to_mat<vector_type> > >::type
        vector_to_matrix (
            const vector_type& vector
        )
        {
            typedef op_array_to_mat<vector_type> op;
            return matrix_op<op>(op(vector));
        }

        template <
            typename vector_type
            >
        const typename enable_if<is_matrix<vector_type>,vector_type>::type& vector_to_matrix (
            const vector_type& vector
        )
        /*!
            This overload catches the case where the argument to this function is
            already a matrix.
        !*/
        {
            return vector;
        }

        template <
            typename value_type,
            typename alloc
            >
        const matrix_op<op_std_vect_to_mat<std::vector<value_type,alloc> > > vector_to_matrix (
            const std::vector<value_type,alloc>& vector
        )
        {
            typedef op_std_vect_to_mat<std::vector<value_type,alloc> > op;
            return matrix_op<op>(op(vector));
        }

        template <
            typename value_type,
            typename alloc
            >
        const matrix_op<op_std_vect_to_mat<std_vector_c<value_type,alloc> > > vector_to_matrix (
            const std_vector_c<value_type,alloc>& vector
        )
        {
            typedef op_std_vect_to_mat<std_vector_c<value_type,alloc> > op;
            return matrix_op<op>(op(vector));
        }

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

        template <
            typename array_type
            >
        const typename enable_if<is_matrix<array_type>,array_type>::type&
        array_to_matrix (
            const array_type& array
        )
        {
            return array;
        }

        template <
            typename array_type
            >
        const typename disable_if<is_matrix<array_type>,matrix_op<op_array2d_to_mat<array_type> > >::type
        array_to_matrix (
            const array_type& array
        )
        {
            typedef op_array2d_to_mat<array_type> op;
            return matrix_op<op>(op(array));
        }

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

        template <
            typename T
            >
        const matrix_op<op_pointer_to_mat<T> > pointer_to_matrix (
            const T* ptr,
            long nr,
            long nc
        )
        {
            DLIB_ASSERT(nr > 0 && nc > 0 ,
                        "\tconst matrix_exp pointer_to_matrix(ptr, nr, nc)"
                        << "\n\t nr and nc must be bigger than 0"
                        << "\n\t nr: " << nr
                        << "\n\t nc: " << nc
            );
            typedef op_pointer_to_mat<T> op;
            return matrix_op<op>(op(ptr,nr,nc));
        }

        template <
            typename T
            >
        const matrix_op<op_pointer_to_col_vect<T> > pointer_to_column_vector (
            const T* ptr,
            long nr
        )
        {
            DLIB_ASSERT(nr > 0 ,
                        "\tconst matrix_exp pointer_to_column_vector(ptr, nr)"
                        << "\n\t nr must be bigger than 0"
                        << "\n\t nr: " << nr
            );
            typedef op_pointer_to_col_vect<T> op;
            return matrix_op<op>(op(ptr, nr));
        }

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

    }

    #endif // DLIB_MATRIx_MAT_H__