// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
// 
// 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.
// ------------------------------------------------------------------------


//! \addtogroup diagview
//! @{


//! Class for storing data required to extract and set the diagonals of a matrix
template<typename eT>
class diagview : public Base<eT, diagview<eT> >
  {
  public:
  
  typedef eT                                elem_type;
  typedef typename get_pod_type<eT>::result pod_type;
  
  arma_aligned const Mat<eT>& m;
  
  static const bool is_row  = false;
  static const bool is_col  = true;
  static const bool is_xvec = false;
  
  const uword row_offset;
  const uword col_offset;
  
  const uword n_rows;     // equal to n_elem
  const uword n_elem;
  
  static const uword n_cols = 1;
  
  
  protected:
  
  arma_inline diagview(const Mat<eT>& in_m, const uword in_row_offset, const uword in_col_offset, const uword len);
  
  
  public:
  
  inline ~diagview();
  
  inline void operator=(const diagview& x);
  
  inline void operator+=(const eT val);
  inline void operator-=(const eT val);
  inline void operator*=(const eT val);
  inline void operator/=(const eT val);
  
  template<typename T1> inline void operator= (const Base<eT,T1>& x);
  template<typename T1> inline void operator+=(const Base<eT,T1>& x);
  template<typename T1> inline void operator-=(const Base<eT,T1>& x);
  template<typename T1> inline void operator%=(const Base<eT,T1>& x);
  template<typename T1> inline void operator/=(const Base<eT,T1>& x);
  
  
  arma_inline eT  at_alt    (const uword ii) const;
  
  arma_inline eT& operator[](const uword ii);
  arma_inline eT  operator[](const uword ii) const;
  
  arma_inline eT&         at(const uword ii);
  arma_inline eT          at(const uword ii) const;
  
  arma_inline eT& operator()(const uword ii);
  arma_inline eT  operator()(const uword ii) const;
  
  arma_inline eT&         at(const uword in_n_row, const uword);
  arma_inline eT          at(const uword in_n_row, const uword) const;
   
  arma_inline eT& operator()(const uword in_n_row, const uword in_n_col);
  arma_inline eT  operator()(const uword in_n_row, const uword in_n_col) const;
  
  
  arma_inline const Op<diagview<eT>,op_htrans>  t() const;
  arma_inline const Op<diagview<eT>,op_htrans> ht() const;
  arma_inline const Op<diagview<eT>,op_strans> st() const;
  
  inline void replace(const eT old_val, const eT new_val);
  
  inline void fill(const eT val);
  inline void zeros();
  inline void ones();
  inline void randu();
  inline void randn();
    
  inline static void extract(Mat<eT>& out, const diagview& in);
  
  inline static void  plus_inplace(Mat<eT>& out, const diagview& in);
  inline static void minus_inplace(Mat<eT>& out, const diagview& in);
  inline static void schur_inplace(Mat<eT>& out, const diagview& in);
  inline static void   div_inplace(Mat<eT>& out, const diagview& in);
  
  
  private:
  
  friend class Mat<eT>;
  friend class subview<eT>;
  
  diagview();
  //diagview(const diagview&);  // making this private causes an error under gcc 4.1/4.2, but not 4.3
  };


//! @}
