source: trunk/yat/utility/VectorConstView.h @ 1487

#ifndef _theplu_yat_utility_vector_const_view_
#define _theplu_yat_utility_vector_const_view_

// $Id: VectorConstView.h 1487 2008-09-10 08:41:36Z jari $

/*
  Copyright (C) 2003 Daniel Dalevi, Peter Johansson
  Copyright (C) 2004 Jari Häkkinen, Peter Johansson
  Copyright (C) 2005 Jari Häkkinen, Peter Johansson, Markus Ringnér
  Copyright (C) 2006 Jari Häkkinen, Markus Ringnér
  Copyright (C) 2007 Jari Häkkinen, Peter Johansson, Markus Ringnér
  Copyright (C) 2008 Peter Johansson

  This file is part of the yat library, http://dev.thep.lu.se/trac/yat

  The yat library 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.

  The yat library 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 yat. If not, see <http://www.gnu.org/licenses/>.
*/

#include "VectorBase.h"

#include <gsl/gsl_vector.h>

namespace theplu {
namespace yat {
namespace utility {

  class Matrix;

  /**
     @brief Read-only view. 

     Wrapper to gsl_vector_const_view 

     With this class you can create a view into const
     objects - either a vector or matrix. By design all functionality
     in this class is const to guarantee that the viewed object is not
     modified. 

     \note that view vectors do not own the underlying data,
     and a view is not valid if the vector/matrix owing the data is
     deallocated.
  */
  class VectorConstView : public VectorBase
  {
  public:
    /**
       \brief The copy constructor.
    */
    // needed to override compiler generated copy constructor
    VectorConstView(const VectorConstView& other);

    /**
       \brief Copy a VectorBase
    */ 
    VectorConstView(const VectorBase& other);

    /**
       \brief const view into a vector

       Create a const view of VectorBase \a v, with starting index \a offset,
       size \a n, and an optional \a stride.

       \note If the object viewed by the view goes out of scope or is
       deleted, the view becomes invalid and the result of further use
       is undefined.

       \throw GSL_error if a view cannot be set up.
    */
    VectorConstView(const VectorBase& v,size_t offset,size_t n,size_t stride=1);

    /**
       \brief Matrix row/column view constructor.
       
       Create a view into a row/column of a matrix. 

       \param m matrix to view into.
       \param i index telling which row/column to view into
       \param row if true (defult) created view is a row vector, i.e.,
       viewing into row \a i, and, naturally, a column vector
       otherwise.

       \see matrix::column_const_view(size_t) and
       matrix::row_const_view(size_t)

       @note If the object viewed by the view goes out of scope or is
       deleted, the view becomes invalid and the result of further
       use is undefined.
    */
    VectorConstView(const Matrix& m, size_t i, bool row=true);

    /**
       The destructor.
    */
    ~VectorConstView(void);

    /**
       \return true
    */
    bool isview(void) const; 

  private:
    void delete_allocated_memory(void);

    // Perhaps not needed - only used to create a gsl_vector (that is
    // stored in base class). For data access use data in base class
    // because this pointer may be NULL.
    gsl_vector_const_view* const_view_;
    
  };

}}} // of namespace utility, yat, and theplu

#endif