/* -*- c++ -*- (enables emacs c++ mode) */
/*===========================================================================

 Copyright (C) 2002-2017 Yves Renard

 This file is a part of GetFEM++

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===========================================================================*/

/**@file gmm_sub_matrix.h
   @author Yves Renard <Yves.Renard@insa-lyon.fr>
   @date October 13, 2002.
   @brief Generic sub-matrices.
*/

#ifndef GMM_SUB_MATRIX_H__
#define GMM_SUB_MATRIX_H__

#include "gmm_sub_vector.h"

namespace gmm {

  /* ********************************************************************* */
  /*		sub row matrices type                                      */
  /* ********************************************************************* */

  template <typename PT, typename SUBI1, typename SUBI2>
  struct gen_sub_row_matrix {
    typedef gen_sub_row_matrix<PT, SUBI1, SUBI2> this_type;
    typedef typename std::iterator_traits<PT>::value_type M;
    typedef M * CPT;
    typedef typename std::iterator_traits<PT>::reference ref_M;
    typedef typename select_ref<typename linalg_traits<M>
            ::const_row_iterator, typename linalg_traits<M>::row_iterator,
	    PT>::ref_type iterator;
    typedef typename linalg_traits<this_type>::reference reference;
    typedef typename linalg_traits<this_type>::porigin_type porigin_type;

    SUBI1 si1;
    SUBI2 si2;
    iterator begin_;
    porigin_type origin;
    
    reference operator()(size_type i, size_type j) const 
    { return linalg_traits<M>::access(begin_ + si1.index(i), si2.index(j)); }
   
    size_type nrows(void) const { return si1.size(); }
    size_type ncols(void) const { return si2.size(); }
    
    gen_sub_row_matrix(ref_M m, const SUBI1 &s1, const SUBI2 &s2)
      : si1(s1), si2(s2), begin_(mat_row_begin(m)),
	origin(linalg_origin(m)) {}
    gen_sub_row_matrix() {}
    gen_sub_row_matrix(const gen_sub_row_matrix<CPT, SUBI1, SUBI2> &cr) :
      si1(cr.si1), si2(cr.si2), begin_(cr.begin_),origin(cr.origin) {}
  };

  template <typename PT, typename SUBI1, typename SUBI2>
  struct gen_sub_row_matrix_iterator {
    typedef gen_sub_row_matrix<PT, SUBI1, SUBI2> this_type;
    typedef typename modifiable_pointer<PT>::pointer MPT;
    typedef typename std::iterator_traits<PT>::value_type M;
    typedef typename select_ref<typename linalg_traits<M>
            ::const_row_iterator, typename linalg_traits<M>::row_iterator,
	    PT>::ref_type ITER;
    typedef ITER value_type;
    typedef ITER *pointer;
    typedef ITER &reference;
    typedef ptrdiff_t difference_type;
    typedef size_t size_type;
    typedef std::random_access_iterator_tag  iterator_category;
    typedef gen_sub_row_matrix_iterator<PT, SUBI1, SUBI2> iterator;

    ITER it;
    SUBI1 si1;
    SUBI2 si2;
    size_type ii;
    
    iterator operator ++(int) { iterator tmp = *this; ii++; return tmp; }
    iterator operator --(int) { iterator tmp = *this; ii--; return tmp; }
    iterator &operator ++()   { ii++; return *this; }
    iterator &operator --()   { ii--; return *this; }
    iterator &operator +=(difference_type i) { ii += i; return *this; }
    iterator &operator -=(difference_type i) { ii -= i; return *this; }
    iterator operator +(difference_type i) const 
    { iterator itt = *this; return (itt += i); }
    iterator operator -(difference_type i) const
    { iterator itt = *this; return (itt -= i); }
    difference_type operator -(const iterator &i) const { return ii - i.ii; }

    ITER operator *() const { return it + si1.index(ii); }
    ITER operator [](int i) { return it + si1.index(ii+i); }

    bool operator ==(const iterator &i) const { return (ii == i.ii); }
    bool operator !=(const iterator &i) const { return !(i == *this); }
    bool operator < (const iterator &i) const { return (ii < i.ii); }

    gen_sub_row_matrix_iterator(void) {}
    gen_sub_row_matrix_iterator(const 
	     gen_sub_row_matrix_iterator<MPT, SUBI1, SUBI2> &itm)
      : it(itm.it), si1(itm.si1), si2(itm.si2), ii(itm.ii) {}
    gen_sub_row_matrix_iterator(const ITER &iter, const SUBI1 &s1,
				const SUBI2 &s2, size_type i)
      : it(iter), si1(s1), si2(s2), ii(i) { }
    
  };

  template <typename PT, typename SUBI1, typename SUBI2>
  struct linalg_traits<gen_sub_row_matrix<PT, SUBI1, SUBI2> > {
    typedef gen_sub_row_matrix<PT, SUBI1, SUBI2> this_type;
    typedef typename std::iterator_traits<PT>::value_type M;
    typedef typename which_reference<PT>::is_reference is_reference;
    typedef abstract_matrix linalg_type;
    typedef typename linalg_traits<M>::origin_type origin_type;
    typedef typename select_ref<const origin_type *, origin_type *,
				PT>::ref_type porigin_type;
    typedef typename linalg_traits<M>::value_type value_type;
    typedef typename select_ref<value_type,
            typename linalg_traits<M>::reference, PT>::ref_type reference;
    typedef abstract_null_type sub_col_type;
    typedef abstract_null_type col_iterator;
    typedef abstract_null_type const_sub_col_type;
    typedef abstract_null_type const_col_iterator;
    typedef typename sub_vector_type<const typename org_type<typename
	    linalg_traits<M>::const_sub_row_type>::t *, SUBI2>::vector_type
            const_sub_row_type;
    typedef typename select_ref<abstract_null_type, 
	    typename sub_vector_type<typename org_type<typename linalg_traits<M>::sub_row_type>::t *,
	    SUBI2>::vector_type, PT>::ref_type sub_row_type;
    typedef gen_sub_row_matrix_iterator<typename const_pointer<PT>::pointer,
	    SUBI1, SUBI2> const_row_iterator;
    typedef typename select_ref<abstract_null_type, 
	    gen_sub_row_matrix_iterator<PT, SUBI1, SUBI2>, PT>::ref_type
            row_iterator;
    typedef typename linalg_traits<const_sub_row_type>::storage_type
            storage_type;
    typedef row_major sub_orientation;
    typedef linalg_true index_sorted;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static const_sub_row_type row(const const_row_iterator &it)
    { return const_sub_row_type(linalg_traits<M>::row(*it), it.si2); }
    static sub_row_type row(const row_iterator &it)
    { return sub_row_type(linalg_traits<M>::row(*it), it.si2); }
    static const_row_iterator row_begin(const this_type &m)
    { return const_row_iterator(m.begin_, m.si1, m.si2, 0); }
    static row_iterator row_begin(this_type &m)
    { return row_iterator(m.begin_, m.si1, m.si2, 0); }
    static const_row_iterator row_end(const this_type &m)
    { return const_row_iterator(m.begin_, m.si1, m.si2,  m.nrows()); }
    static row_iterator row_end(this_type &m)
    { return row_iterator(m.begin_, m.si1, m.si2, m.nrows()); }
    static origin_type* origin(this_type &v) { return v.origin; }
    static const origin_type* origin(const this_type &v) { return v.origin; }
    static void do_clear(this_type &m) {
      row_iterator it = mat_row_begin(m), ite = mat_row_end(m);
      for (; it != ite; ++it) clear(row(it));
    }
    static value_type access(const const_row_iterator &itrow, size_type i)
    { return linalg_traits<M>::access(*itrow, itrow.si2.index(i)); }
    static reference access(const row_iterator &itrow, size_type i)
    { return linalg_traits<M>::access(*itrow, itrow.si2.index(i)); }
  };
  
  template <typename PT, typename SUBI1, typename SUBI2>
  std::ostream &operator <<(std::ostream &o,
			    const gen_sub_row_matrix<PT, SUBI1, SUBI2>& m)
  { gmm::write(o,m); return o; }


  /* ********************************************************************* */
  /*		sub column matrices type                                   */
  /* ********************************************************************* */

  template <typename PT, typename SUBI1, typename SUBI2>
  struct gen_sub_col_matrix {
    typedef gen_sub_col_matrix<PT, SUBI1, SUBI2> this_type;
    typedef typename std::iterator_traits<PT>::value_type M;
    typedef M * CPT;
    typedef typename std::iterator_traits<PT>::reference ref_M;
    typedef typename select_ref<typename linalg_traits<M>
            ::const_col_iterator, typename linalg_traits<M>::col_iterator,
	    PT>::ref_type iterator;
    typedef typename linalg_traits<this_type>::reference reference;
    typedef typename linalg_traits<this_type>::porigin_type porigin_type;

    SUBI1 si1;
    SUBI2 si2;
    iterator begin_;
    porigin_type origin;
    
    reference operator()(size_type i, size_type j) const
    { return linalg_traits<M>::access(begin_ + si2.index(j), si1.index(i)); }

    size_type nrows(void) const { return si1.size(); }
    size_type ncols(void) const { return si2.size(); }
    
    gen_sub_col_matrix(ref_M m, const SUBI1 &s1, const SUBI2 &s2)
      : si1(s1), si2(s2), begin_(mat_col_begin(m)),
        origin(linalg_origin(m)) {}
    gen_sub_col_matrix() {}
    gen_sub_col_matrix(const gen_sub_col_matrix<CPT, SUBI1, SUBI2> &cr) :
      si1(cr.si1), si2(cr.si2), begin_(cr.begin_),origin(cr.origin) {}
  };

  template <typename PT, typename SUBI1, typename SUBI2>
  struct gen_sub_col_matrix_iterator {
    typedef gen_sub_col_matrix<PT, SUBI1, SUBI2> this_type;
    typedef typename modifiable_pointer<PT>::pointer MPT;
    typedef typename std::iterator_traits<PT>::value_type M;
    typedef typename select_ref<typename linalg_traits<M>::const_col_iterator,
				typename linalg_traits<M>::col_iterator,
				PT>::ref_type ITER;
    typedef ITER value_type;
    typedef ITER *pointer;
    typedef ITER &reference;
    typedef ptrdiff_t difference_type;
    typedef size_t size_type;
    typedef std::random_access_iterator_tag  iterator_category;
    typedef gen_sub_col_matrix_iterator<PT, SUBI1, SUBI2> iterator;

    ITER it;
    SUBI1 si1;
    SUBI2 si2;
    size_type ii;
    
    iterator operator ++(int) { iterator tmp = *this; ii++; return tmp; }
    iterator operator --(int) { iterator tmp = *this; ii--; return tmp; }
    iterator &operator ++()   { ii++; return *this; }
    iterator &operator --()   { ii--; return *this; }
    iterator &operator +=(difference_type i) { ii += i; return *this; }
    iterator &operator -=(difference_type i) { ii -= i; return *this; }
    iterator operator +(difference_type i) const 
    { iterator itt = *this; return (itt += i); }
    iterator operator -(difference_type i) const
    { iterator itt = *this; return (itt -= i); }
    difference_type operator -(const iterator &i) const { return ii - i.ii; }

    ITER operator *() const { return it + si2.index(ii); }
    ITER operator [](int i) { return it + si2.index(ii+i); }

    bool operator ==(const iterator &i) const { return (ii == i.ii); }
    bool operator !=(const iterator &i) const { return !(i == *this); }
    bool operator < (const iterator &i) const { return (ii < i.ii); }

    gen_sub_col_matrix_iterator(void) {}
    gen_sub_col_matrix_iterator(const 
	gen_sub_col_matrix_iterator<MPT, SUBI1, SUBI2> &itm)
      : it(itm.it), si1(itm.si1), si2(itm.si2), ii(itm.ii) {}
    gen_sub_col_matrix_iterator(const ITER &iter, const SUBI1 &s1,
				const SUBI2 &s2, size_type i)
      : it(iter), si1(s1), si2(s2), ii(i) { }
  };

  template <typename PT, typename SUBI1, typename SUBI2>
  struct linalg_traits<gen_sub_col_matrix<PT, SUBI1, SUBI2> > {
    typedef gen_sub_col_matrix<PT, SUBI1, SUBI2> this_type;
    typedef typename std::iterator_traits<PT>::value_type M;
    typedef typename linalg_traits<M>::origin_type origin_type;
    typedef typename select_ref<const origin_type *, origin_type *,
			        PT>::ref_type porigin_type;
    typedef typename which_reference<PT>::is_reference is_reference;
    typedef abstract_matrix linalg_type;
    typedef typename linalg_traits<M>::value_type value_type;
    typedef typename select_ref<value_type,
            typename linalg_traits<M>::reference, PT>::ref_type reference;
    typedef abstract_null_type sub_row_type;
    typedef abstract_null_type row_iterator;
    typedef abstract_null_type const_sub_row_type;
    typedef abstract_null_type const_row_iterator;
    typedef typename sub_vector_type<const typename org_type<typename linalg_traits<M>::const_sub_col_type>::t *, SUBI1>::vector_type const_sub_col_type;
    typedef typename select_ref<abstract_null_type, typename sub_vector_type<typename org_type<typename linalg_traits<M>::sub_col_type>::t *, SUBI1>::vector_type, PT>::ref_type sub_col_type;
    typedef gen_sub_col_matrix_iterator<typename const_pointer<PT>::pointer,
	    SUBI1, SUBI2> const_col_iterator;
    typedef typename select_ref<abstract_null_type, 
	    gen_sub_col_matrix_iterator<PT, SUBI1, SUBI2>, PT>::ref_type
            col_iterator;
    typedef col_major sub_orientation;
    typedef linalg_true index_sorted;
    typedef typename linalg_traits<const_sub_col_type>::storage_type
    storage_type;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static const_sub_col_type col(const const_col_iterator &it)
    { return const_sub_col_type(linalg_traits<M>::col(*it), it.si1); }
    static sub_col_type col(const col_iterator &it)
    { return sub_col_type(linalg_traits<M>::col(*it), it.si1); }
    static const_col_iterator col_begin(const this_type &m)
    { return const_col_iterator(m.begin_, m.si1, m.si2, 0); }
    static col_iterator col_begin(this_type &m)
    { return col_iterator(m.begin_, m.si1, m.si2, 0); }
    static const_col_iterator col_end(const this_type &m)
    { return const_col_iterator(m.begin_, m.si1, m.si2,  m.ncols()); }
    static col_iterator col_end(this_type &m)
    { return col_iterator(m.begin_, m.si1, m.si2, m.ncols()); } 
    static origin_type* origin(this_type &v) { return v.origin; }
    static const origin_type* origin(const this_type &v) { return v.origin; }
    static void do_clear(this_type &m) {
      col_iterator it = mat_col_begin(m), ite = mat_col_end(m);
      for (; it != ite; ++it) clear(col(it));
    }
    static value_type access(const const_col_iterator &itcol, size_type i)
    { return linalg_traits<M>::access(*itcol, itcol.si1.index(i)); }
    static reference access(const col_iterator &itcol, size_type i)
    { return linalg_traits<M>::access(*itcol, itcol.si1.index(i)); }
  };

  template <typename PT, typename SUBI1, typename SUBI2> std::ostream &operator <<
  (std::ostream &o, const gen_sub_col_matrix<PT, SUBI1, SUBI2>& m)
  { gmm::write(o,m); return o; }

  /* ******************************************************************** */
  /*		sub matrices                                              */
  /* ******************************************************************** */
  
  template <typename PT, typename SUBI1, typename SUBI2, typename ST>
  struct sub_matrix_type_ {
    typedef abstract_null_type return_type;
  };
  template <typename PT, typename SUBI1, typename SUBI2>
  struct sub_matrix_type_<PT, SUBI1, SUBI2, col_major>
  { typedef gen_sub_col_matrix<PT, SUBI1, SUBI2> matrix_type; };
  template <typename PT, typename SUBI1, typename SUBI2>
  struct sub_matrix_type_<PT, SUBI1, SUBI2, row_major>
  { typedef gen_sub_row_matrix<PT, SUBI1, SUBI2> matrix_type; };
  template <typename PT, typename SUBI1, typename SUBI2>
  struct sub_matrix_type {
    typedef typename std::iterator_traits<PT>::value_type M;
    typedef typename sub_matrix_type_<PT, SUBI1, SUBI2,
        typename principal_orientation_type<typename
        linalg_traits<M>::sub_orientation>::potype>::matrix_type matrix_type;
  };

  template <typename M, typename SUBI1, typename SUBI2>  inline
    typename select_return<typename sub_matrix_type<const M *, SUBI1, SUBI2>
    ::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI2>::matrix_type,
    M *>::return_type
  sub_matrix(M &m, const SUBI1 &si1, const SUBI2 &si2) {
    GMM_ASSERT2(si1.last() <= mat_nrows(m) && si2.last() <= mat_ncols(m),
		"sub matrix too large");
    return typename select_return<typename sub_matrix_type<const M *, SUBI1,
      SUBI2>::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI2>
      ::matrix_type, M *>::return_type(linalg_cast(m), si1, si2);
  }

  template <typename M, typename SUBI1, typename SUBI2>  inline
    typename select_return<typename sub_matrix_type<const M *, SUBI1, SUBI2>
    ::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI2>::matrix_type,
    const M *>::return_type
  sub_matrix(const M &m, const SUBI1 &si1, const SUBI2 &si2) {
    GMM_ASSERT2(si1.last() <= mat_nrows(m) && si2.last() <= mat_ncols(m),
		"sub matrix too large");
    return typename select_return<typename sub_matrix_type<const M *, SUBI1,
      SUBI2>::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI2>
      ::matrix_type, const M *>::return_type(linalg_cast(m), si1, si2);
  }

  template <typename M, typename SUBI1>  inline
    typename select_return<typename sub_matrix_type<const M *, SUBI1, SUBI1>
    ::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI1>::matrix_type,
    M *>::return_type
  sub_matrix(M &m, const SUBI1 &si1) {
    GMM_ASSERT2(si1.last() <= mat_nrows(m) && si1.last() <= mat_ncols(m),
		"sub matrix too large");
    return typename select_return<typename sub_matrix_type<const M *, SUBI1,
      SUBI1>::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI1>
      ::matrix_type, M *>::return_type(linalg_cast(m), si1, si1);
  }

  template <typename M, typename SUBI1>  inline
    typename select_return<typename sub_matrix_type<const M *, SUBI1, SUBI1>
    ::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI1>::matrix_type,
    const M *>::return_type
  sub_matrix(const M &m, const SUBI1 &si1) {
    GMM_ASSERT2(si1.last() <= mat_nrows(m) && si1.last() <= mat_ncols(m),
		"sub matrix too large");
    return typename select_return<typename sub_matrix_type<const M *, SUBI1,
      SUBI1>::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI1>
      ::matrix_type, const M *>::return_type(linalg_cast(m), si1, si1);
  }

}

#endif //  GMM_SUB_MATRIX_H__