/* Declarations for the Difference_Floating_Point_Expression class and
   its constituents.
   Copyright (C) 2001-2010 Roberto Bagnara <bagnara@cs.unipr.it>
   Copyright (C) 2010-2012 BUGSENG srl (http://bugseng.com)

This file is part of the Parma Polyhedra Library (PPL).

The PPL 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 PPL 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 this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1307, USA.

For the most up-to-date information see the Parma Polyhedra Library
site: http://bugseng.com/products/ppl/ . */

#ifndef PPL_Difference_Floating_Point_Expression_defs_hh
#define PPL_Difference_Floating_Point_Expression_defs_hh 1

#include "Floating_Point_Expression.defs.hh"
#include "globals.defs.hh"
#include "Difference_Floating_Point_Expression.types.hh"
#include <map>

namespace Parma_Polyhedra_Library {

//! Swaps \p x with \p y.
/*! \relates Difference_Floating_Point_Expression */
template <typename FP_Interval_Type, typename FP_Format>
void
swap(Difference_Floating_Point_Expression<FP_Interval_Type, FP_Format>& x,
     Difference_Floating_Point_Expression<FP_Interval_Type, FP_Format>& y);

/*! \brief
  A generic Difference Floating Point Expression.
  \ingroup PPL_CXX_interface

  \par Template type parameters

  - The class template type parameter \p FP_Interval_Type represents the type
  of the intervals used in the abstract domain.
  - The class template type parameter \p FP_Format represents the floating
  point format used in the concrete domain.

  \par Linearization of difference floating-point expressions

  Let \f$i + \sum_{v \in \cV}i_{v}v \f$ and
  \f$i' + \sum_{v \in \cV}i'_{v}v \f$
  be two linear forms, \f$\aslf\f$ and \f$\adlf\f$ two sound abstract
  operators on linear form such that:
  \f[
  \left(i + \sum_{v \in \cV}i_{v}v\right)
  \aslf
  \left(i' + \sum_{v \in \cV}i'_{v}v\right)
  =
  \left(i \asifp i'\right)
  + \sum_{v \in \cV}\left(i_{v} \asifp i'_{v}\right)v,
  \f]
  \f[
  \left(i + \sum_{v \in \cV}i_{v}v\right)
  \adlf
  \left(i' + \sum_{v \in \cV}i'_{v}v\right)
  =
  \left(i \adifp i'\right)
  + \sum_{v \in \cV}\left(i_{v} \adifp i'_{v}\right)v.
  \f]
  Given an expression \f$e_{1} \ominus e_{2}\f$ and a composite
  abstract store \f$\left \llbracket \rho^{\#}, \rho^{\#}_l \right
  \rrbracket\f$,  we construct the interval linear form
  \f$\linexprenv{e_{1} \ominus e_{2}}{\rho^{\#}}{\rho^{\#}_l}\f$
  on \f$\cV\f$ as follows:
  \f[
  \linexprenv{e_{1} \ominus e_{2}}{\rho^{\#}}{\rho^{\#}_l}
  =
  \linexprenv{e_{1}}{\rho^{\#}}{\rho^{\#}_l}
  \adlf
  \linexprenv{e_{2}}{\rho^{\#}}{\rho^{\#}_l}
  \aslf
  \varepsilon_{\mathbf{f}}\left(\linexprenv{e_{1}}{\rho^{\#}}{\rho^{\#}_l}
  \right)
  \aslf
  \varepsilon_{\mathbf{f}}\left(\linexprenv{e_{2}}{\rho^{\#}}{\rho^{\#}_l}
  \right)
  \aslf
  mf_{\mathbf{f}}[-1, 1]
  \f]
  where \f$\varepsilon_{\mathbf{f}}(l)\f$ is the linear form computed by
  calling method <CODE>Floating_Point_Expression::relative_error</CODE>
  on \f$l\f$ and \f$mf_{\mathbf{f}}\f$ is a rounding error defined in
  <CODE>Floating_Point_Expression::absolute_error</CODE>.
*/
template <typename FP_Interval_Type, typename FP_Format>
class Difference_Floating_Point_Expression
  : public Floating_Point_Expression<FP_Interval_Type, FP_Format> {

public:

  /*! \brief
     Alias for the Linear_Form<FP_Interval_Type> from
     Floating_Point_Expression
  */
  typedef typename
  Floating_Point_Expression<FP_Interval_Type, FP_Format>
  ::FP_Linear_Form FP_Linear_Form;

  /*! \brief
     Alias for the Box<FP_Interval_Type> from
     Floating_Point_Expression.
  */
  typedef typename
  Floating_Point_Expression<FP_Interval_Type, FP_Format>
  ::FP_Interval_Abstract_Store FP_Interval_Abstract_Store;

  /*! \brief
     Alias for the std::map<dimension_type, FP_Linear_Form> from
     Floating_Point_Expression.
  */
  typedef typename
  Floating_Point_Expression<FP_Interval_Type, FP_Format>
  ::FP_Linear_Form_Abstract_Store FP_Linear_Form_Abstract_Store;

  /*! \brief
     Alias for the FP_Interval_Type::boundary_type from
     Floating_Point_Expression.
  */
  typedef typename
  Floating_Point_Expression<FP_Interval_Type, FP_Format>::boundary_type
  boundary_type;

  /*! \brief
     Alias for the FP_Interval_Type::info_type from Floating_Point_Expression.
  */
  typedef typename
  Floating_Point_Expression<FP_Interval_Type, FP_Format>::info_type info_type;

  //! \name Constructors and Destructor
  //@{
  /*! \brief
    Constructor with two parameters: builds the difference floating point
    expression corresponding to \p x \f$\ominus\f$ \p y.
  */
  Difference_Floating_Point_Expression(
	   Floating_Point_Expression<FP_Interval_Type, FP_Format>* const x,
           Floating_Point_Expression<FP_Interval_Type, FP_Format>* const y);

  //! Destructor.
  ~Difference_Floating_Point_Expression();

  //@} // Constructors and Destructor

  /*! \brief
    Linearizes the expression in a given astract store.

    Makes \p result become the linearization of \p *this in the given
    composite abstract store.

    \param int_store The interval abstract store.
    \param lf_store The linear form abstract store.
    \param result The modified linear form.

    \return <CODE>true</CODE> if the linearization succeeded,
    <CODE>false</CODE> otherwise.

    Note that all variables occuring in the expressions represented
    by \p first_operand and \p second_operand MUST have an associated value in
    \p int_store. If this precondition is not met, calling the method
    causes an undefined behavior.

    See the class description for a detailed explanation of how \p result
    is computed.
  */
  bool linearize(const FP_Interval_Abstract_Store& int_store,
                 const FP_Linear_Form_Abstract_Store& lf_store,
                 FP_Linear_Form& result) const;

  //! Swaps \p *this with \p y.
  void m_swap(Difference_Floating_Point_Expression<FP_Interval_Type,
                                                   FP_Format>& y);

private:

  //! Pointer to the first operand.
  Floating_Point_Expression<FP_Interval_Type, FP_Format>* first_operand;
  //! Pointer to the second operand.
  Floating_Point_Expression<FP_Interval_Type, FP_Format>* second_operand;

  #ifdef PPL_DOXYGEN_INCLUDE_IMPLEMENTATION_DETAILS
  /*! \brief
    Inhibited copy constructor.
  */
  #endif // PPL_DOXYGEN_INCLUDE_IMPLEMENTATION_DETAILS
  Difference_Floating_Point_Expression(
         const Difference_Floating_Point_Expression<FP_Interval_Type,
                                                    FP_Format>& e);

  #ifdef PPL_DOXYGEN_INCLUDE_IMPLEMENTATION_DETAILS
  /*! \brief
    Inhibited asssignment operator.
  */
  #endif // PPL_DOXYGEN_INCLUDE_IMPLEMENTATION_DETAILS
  Difference_Floating_Point_Expression<FP_Interval_Type, FP_Format>&
  operator=(const Difference_Floating_Point_Expression<FP_Interval_Type,
	                                               FP_Format>& e);


}; // class Difference_Floating_Point_Expression

} // namespace Parma_Polyhedra_Library

#include "Difference_Floating_Point_Expression.inlines.hh"
#include "Difference_Floating_Point_Expression.templates.hh"

#endif // !defined(PPL_Difference_Floating_Point_Expression_defs_hh)
