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DiagArray2.h

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// Template array classes
/*

Copyright (C) 1996, 1997, 2000, 2002, 2003, 2004, 2005, 2006, 2007
              John W. Eaton
Copyright (C) 2008, 2009 Jaroslav Hajek

This file is part of Octave.

Octave 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.

Octave 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 Octave; see the file COPYING.  If not, see
<http://www.gnu.org/licenses/>.

*/

#if !defined (octave_DiagArray2_h)
#define octave_DiagArray2_h 1

#include <cassert>
#include <cstdlib>

#include "Array.h"
#include "Array2.h"
#include "lo-error.h"

// A two-dimensional array with diagonal elements only.
// Idea and example code for Proxy class and functions from:
//
// From: kanze@us-es.sel.de (James Kanze)
// Subject: Re: How to overload [] to do READ/WRITE differently ?
// Message-ID: <KANZE.93Nov29151407@slsvhdt.us-es.sel.de>
// Sender: news@us-es.sel.de
// Date: 29 Nov 1993 14:14:07 GMT
// --
// James Kanze                             email: kanze@us-es.sel.de
// GABI Software, Sarl., 8 rue du Faisan, F-67000 Strasbourg, France

// Array<T> is inherited privately so that some methods, like index, don't
// produce unexpected results.

template <class T>
class
DiagArray2 : protected Array<T>
{
private:

  T get (octave_idx_type i) { return Array<T>::xelem (i); }

  void set (const T& val, octave_idx_type i) { Array<T>::xelem (i) = val; }

  class Proxy
  {
  public:

    Proxy (DiagArray2<T> *ref, octave_idx_type r, octave_idx_type c)
      : i (r), j (c), object (ref) { } 

    const Proxy& operator = (const T& val) const;

    operator T () const;

  private:

    // FIXME -- this is declared private to keep the user from
    // taking the address of a Proxy.  Maybe it should be implemented
    // by means of a companion function in the DiagArray2 class.

    T *operator& () const { assert (0); return 0; }

    octave_idx_type i;
    octave_idx_type j;

    DiagArray2<T> *object;

  };

  friend class Proxy;

protected:
  octave_idx_type d1, d2;

  DiagArray2 (T *d, octave_idx_type r, octave_idx_type c) 
    : Array<T> (d, std::min (r, c)), d1 (r), d2 (c) { }

public:

  using Array<T>::element_type;

  DiagArray2 (void) 
    : Array<T> (), d1 (0), d2 (0) { }

  DiagArray2 (octave_idx_type r, octave_idx_type c) 
    : Array<T> (std::min (r, c)), d1 (r), d2 (c) { }

  DiagArray2 (octave_idx_type r, octave_idx_type c, const T& val) 
    : Array<T> (std::min (r, c), val), d1 (r), d2 (c) { }

  DiagArray2 (const dim_vector& dv)
    : Array<T> (std::min (dv(0), dv(1))), d1 (dv(0)), d2 (dv(0))
    {
      if (dv.length () != 2)
        (*current_liboctave_error_handler) ("too many dimensions");
    }

  DiagArray2 (const Array<T>& a) 
    : Array<T> (a), d1 (a.numel ()), d2 (a.numel ()) { }

  DiagArray2 (const DiagArray2<T>& a) 
    : Array<T> (a), d1 (a.d1), d2 (a.d2) { }

  template <class U>
  DiagArray2 (const DiagArray2<U>& a) 
  : Array<T> (a.diag ()), d1 (a.dim1 ()), d2 (a.dim2 ()) { }

  ~DiagArray2 (void) { }

  DiagArray2<T>& operator = (const DiagArray2<T>& a)
    {
      if (this != &a)
        {
          Array<T>::operator = (a);
          d1 = a.d1;
          d2 = a.d2;
        }

      return *this;
    }

  octave_idx_type dim1 (void) const { return d1; }
  octave_idx_type dim2 (void) const { return d2; }

  octave_idx_type rows (void) const { return dim1 (); }
  octave_idx_type cols (void) const { return dim2 (); }
  octave_idx_type columns (void) const { return dim2 (); }

  octave_idx_type diag_length (void) const { return Array<T>::length (); }
  // FIXME: a dangerous ambiguity?
  octave_idx_type length (void) const { return Array<T>::length (); }
  octave_idx_type nelem (void) const { return dim1 () * dim2 (); }
  octave_idx_type numel (void) const { return nelem (); }

  size_t byte_size (void) const { return length () * sizeof (T); }

  dim_vector dims (void) const { return dim_vector (d1, d2); }

  Array<T> diag (octave_idx_type k = 0) const;

  // Warning: the non-const two-index versions will silently ignore assignments
  // to off-diagonal elements. 

  T elem (octave_idx_type r, octave_idx_type c) const
    {
      return (r == c) ? Array<T>::elem (r) : T (0);
    }

  T& elem (octave_idx_type r, octave_idx_type c)
    {
      static T zero (0);
      return (r == c) ? Array<T>::elem (r) : zero;
    }

  T dgelem (octave_idx_type i) const
    { return Array<T>::elem (i); }

  T& dgelem (octave_idx_type i) 
    { return Array<T>::elem (i); }

  T checkelem (octave_idx_type r, octave_idx_type c) const;
  Proxy checkelem (octave_idx_type r, octave_idx_type c);

  T operator () (octave_idx_type r, octave_idx_type c) const
    {
#if defined (BOUNDS_CHECKING)
      return checkelem (r, c);
#else
      return elem (r, c);
#endif
    }

  // FIXME: can this cause problems?
#if defined (BOUNDS_CHECKING)
  Proxy operator () (octave_idx_type r, octave_idx_type c)
    {
      return checkelem (r, c);
    }
#else
  T& operator () (octave_idx_type r, octave_idx_type c) 
    {
      return elem (r, c);
    }
#endif

  // No checking.

  T xelem (octave_idx_type r, octave_idx_type c) const
    {
      return (r == c) ? Array<T>::xelem (r) : T (0);
    }

  T& dgxelem (octave_idx_type i)
    { return Array<T>::xelem (i); }

  T dgxelem (octave_idx_type i) const
    { return Array<T>::xelem (i); }

  void resize (octave_idx_type n, octave_idx_type m);
  void resize_fill (octave_idx_type n, octave_idx_type m, const T& val);

  DiagArray2<T> transpose (void) const;
  DiagArray2<T> hermitian (T (*fcn) (const T&) = 0) const;

  operator Array2<T> (void) const;

  const T *data (void) const { return Array<T>::data (); }

  const T *fortran_vec (void) const { return Array<T>::fortran_vec (); }

  T *fortran_vec (void) { return Array<T>::fortran_vec (); }

  void print_info (std::ostream& os, const std::string& prefix) const
    { Array<T>::print_info (os, prefix); }
};

#endif

/*
;;; Local Variables: ***
;;; mode: C++ ***
;;; End: ***
*/