/* Generator_System class declaration. Copyright (C) 2001-2010 Roberto Bagnara Copyright (C) 2010-2011 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://www.cs.unipr.it/ppl/ . */ #ifndef PPL_Generator_System_defs_hh #define PPL_Generator_System_defs_hh 1 #include "Generator_System.types.hh" #include "Grid_Generator_System.types.hh" #include "Linear_Expression.types.hh" #include "Linear_System.defs.hh" #include "Generator.types.hh" #include "Constraint.types.hh" #include "Polyhedron.types.hh" #include "Poly_Con_Relation.defs.hh" #include namespace Parma_Polyhedra_Library { namespace IO_Operators { //! Output operator. /*! \relates Parma_Polyhedra_Library::Generator_System Writes false if \p gs is empty. Otherwise, writes on \p s the generators of \p gs, all in one row and separated by ", ". */ std::ostream& operator<<(std::ostream& s, const Generator_System& gs); } // namespace IO_Operators // Put it in the namespace here to declare it friend later. /*! \relates Polyhedron */ bool operator==(const Polyhedron& x, const Polyhedron& y); } // namespace Parma_Polyhedra_Library namespace std { //! Specializes std::swap. /*! \relates Parma_Polyhedra_Library::Generator_System */ void swap(Parma_Polyhedra_Library::Generator_System& x, Parma_Polyhedra_Library::Generator_System& y); } // namespace std //! A system of generators. /*! \ingroup PPL_CXX_interface An object of the class Generator_System is a system of generators, i.e., a multiset of objects of the class Generator (lines, rays, points and closure points). When inserting generators in a system, space dimensions are automatically adjusted so that all the generators in the system are defined on the same vector space. A system of generators which is meant to define a non-empty polyhedron must include at least one point: the reason is that lines, rays and closure points need a supporting point (lines and rays only specify directions while closure points only specify points in the topological closure of the NNC polyhedron). \par In all the examples it is assumed that variables x and y are defined as follows: \code Variable x(0); Variable y(1); \endcode \par Example 1 The following code defines the line having the same direction as the \f$x\f$ axis (i.e., the first Cartesian axis) in \f$\Rset^2\f$: \code Generator_System gs; gs.insert(line(x + 0*y)); \endcode As said above, this system of generators corresponds to an empty polyhedron, because the line has no supporting point. To define a system of generators that does correspond to the \f$x\f$ axis, we can add the following code which inserts the origin of the space as a point: \code gs.insert(point(0*x + 0*y)); \endcode Since space dimensions are automatically adjusted, the following code obtains the same effect: \code gs.insert(point(0*x)); \endcode In contrast, if we had added the following code, we would have defined a line parallel to the \f$x\f$ axis through the point \f$(0, 1)^\transpose \in \Rset^2\f$. \code gs.insert(point(0*x + 1*y)); \endcode \par Example 2 The following code builds a ray having the same direction as the positive part of the \f$x\f$ axis in \f$\Rset^2\f$: \code Generator_System gs; gs.insert(ray(x + 0*y)); \endcode To define a system of generators indeed corresponding to the set \f[ \bigl\{\, (x, 0)^\transpose \in \Rset^2 \bigm| x \geq 0 \,\bigr\}, \f] one just has to add the origin: \code gs.insert(point(0*x + 0*y)); \endcode \par Example 3 The following code builds a system of generators having four points and corresponding to a square in \f$\Rset^2\f$ (the same as Example 1 for the system of constraints): \code Generator_System gs; gs.insert(point(0*x + 0*y)); gs.insert(point(0*x + 3*y)); gs.insert(point(3*x + 0*y)); gs.insert(point(3*x + 3*y)); \endcode \par Example 4 By using closure points, we can define the \e kernel (i.e., the largest open set included in a given set) of the square defined in the previous example. Note that a supporting point is needed and, for that purpose, any inner point could be considered. \code Generator_System gs; gs.insert(point(x + y)); gs.insert(closure_point(0*x + 0*y)); gs.insert(closure_point(0*x + 3*y)); gs.insert(closure_point(3*x + 0*y)); gs.insert(closure_point(3*x + 3*y)); \endcode \par Example 5 The following code builds a system of generators having two points and a ray, corresponding to a half-strip in \f$\Rset^2\f$ (the same as Example 2 for the system of constraints): \code Generator_System gs; gs.insert(point(0*x + 0*y)); gs.insert(point(0*x + 1*y)); gs.insert(ray(x - y)); \endcode \note After inserting a multiset of generators in a generator system, there are no guarantees that an exact copy of them can be retrieved: in general, only an equivalent generator system will be available, where original generators may have been reordered, removed (if they are duplicate or redundant), etc. */ class Parma_Polyhedra_Library::Generator_System : protected Linear_System { public: //! Default constructor: builds an empty system of generators. Generator_System(); //! Builds the singleton system containing only generator \p g. explicit Generator_System(const Generator& g); //! Ordinary copy constructor. Generator_System(const Generator_System& gs); //! Destructor. ~Generator_System(); //! Assignment operator. Generator_System& operator=(const Generator_System& y); //! Returns the maximum space dimension a Generator_System can handle. static dimension_type max_space_dimension(); //! Returns the dimension of the vector space enclosing \p *this. dimension_type space_dimension() const; /*! \brief Removes all the generators from the generator system and sets its space dimension to 0. */ void clear(); /*! \brief Inserts in \p *this a copy of the generator \p g, increasing the number of space dimensions if needed. */ void insert(const Generator& g); //! Initializes the class. static void initialize(); //! Finalizes the class. static void finalize(); /*! \brief Returns the singleton system containing only Generator::zero_dim_point(). */ static const Generator_System& zero_dim_univ(); //! An iterator over a system of generators /*! \ingroup PPL_CXX_interface A const_iterator is used to provide read-only access to each generator contained in an object of Generator_System. \par Example The following code prints the system of generators of the polyhedron ph: \code const Generator_System& gs = ph.generators(); for (Generator_System::const_iterator i = gs.begin(), gs_end = gs.end(); i != gs_end; ++i) cout << *i << endl; \endcode The same effect can be obtained more concisely by using more features of the STL: \code const Generator_System& gs = ph.generators(); copy(gs.begin(), gs.end(), ostream_iterator(cout, "\n")); \endcode */ class const_iterator : public std::iterator { public: //! Default constructor. const_iterator(); //! Ordinary copy constructor. const_iterator(const const_iterator& y); //! Destructor. ~const_iterator(); //! Assignment operator. const_iterator& operator=(const const_iterator& y); //! Dereference operator. const Generator& operator*() const; //! Indirect member selector. const Generator* operator->() const; //! Prefix increment operator. const_iterator& operator++(); //! Postfix increment operator. const_iterator operator++(int); /*! \brief Returns true if and only if \p *this and \p y are identical. */ bool operator==(const const_iterator& y) const; /*! \brief Returns true if and only if \p *this and \p y are different. */ bool operator!=(const const_iterator& y) const; private: friend class Generator_System; //! The const iterator over the Linear_System. Linear_System::const_iterator i; //! A const pointer to the Linear_System. const Linear_System* gsp; //! Constructor. const_iterator(const Linear_System::const_iterator& iter, const Generator_System& gsys); /*! \brief \p *this skips to the next generator, skipping those closure points that are immediately followed by a matching point. */ void skip_forward(); }; //! Returns true if and only if \p *this has no generators. bool empty() const; /*! \brief Returns the const_iterator pointing to the first generator, if \p *this is not empty; otherwise, returns the past-the-end const_iterator. */ const_iterator begin() const; //! Returns the past-the-end const_iterator. const_iterator end() const; //! Checks if all the invariants are satisfied. /*! Returns true if and only if \p *this is a valid Linear_System and each row in the system is a valid Generator. */ bool OK() const; PPL_OUTPUT_DECLARATIONS /*! \brief Loads from \p s an ASCII representation (as produced by ascii_dump(std::ostream&) const) and sets \p *this accordingly. Returns true if successful, false otherwise. Resizes the matrix of generators using the numbers of rows and columns read from \p s, then initializes the coordinates of each generator and its type reading the contents from \p s. */ bool ascii_load(std::istream& s); //! Returns the total size in bytes of the memory occupied by \p *this. memory_size_type total_memory_in_bytes() const; //! Returns the size in bytes of the memory managed by \p *this. memory_size_type external_memory_in_bytes() const; //! Swaps \p *this with \p y. void swap(Generator_System& y); private: /*! \brief Holds (between class initialization and finalization) a pointer to the singleton system containing only Generator::zero_dim_point(). */ static const Generator_System* zero_dim_univ_p; friend class const_iterator; friend class Parma_Polyhedra_Library::Polyhedron; friend class Parma_Polyhedra_Library::Grid_Generator_System; friend bool operator==(const Polyhedron& x, const Polyhedron& y); //! Builds an empty system of generators having the specified topology. explicit Generator_System(Topology topol); /*! \brief Builds a system of \p n_rows rays/points on a \p n_columns - 1 dimensional space (including the \f$\epsilon\f$ dimension, if \p topol is NOT_NECESSARILY_CLOSED). */ Generator_System(Topology topol, dimension_type n_rows, dimension_type n_columns); /*! \brief Adjusts \p *this so that it matches the topology and the number of space dimensions given as parameters (adding or removing columns if needed). Returns false if and only if \p topol is equal to NECESSARILY_CLOSED and \p *this contains closure points. */ bool adjust_topology_and_space_dimension(Topology topol, dimension_type num_dimensions); /*! \brief For each unmatched closure point in \p *this, adds the corresponding point. It is assumed that the topology of \p *this is NOT_NECESSARILY_CLOSED. */ void add_corresponding_points(); /*! \brief Returns true if and only if \p *this contains one or more points. */ bool has_points() const; /*! \brief For each unmatched point in \p *this, adds the corresponding closure point. It is assumed that the topology of \p *this is NOT_NECESSARILY_CLOSED. */ void add_corresponding_closure_points(); /*! \brief Returns true if and only if \p *this contains one or more closure points. Note: the check for the presence of closure points is done under the point of view of the user. Namely, we scan the generator system using high-level iterators, so that closure points that are matching the corresponding points will be disregarded. */ bool has_closure_points() const; //! Returns the \p k- th generator of the system. Generator& operator[](dimension_type k); //! Returns a constant reference to the \p k- th generator of the system. const Generator& operator[](dimension_type k) const; /*! \brief Returns the relations holding between the generator system and the constraint \p c. */ Parma_Polyhedra_Library::Poly_Con_Relation relation_with(const Constraint& c) const; //! Returns true if all the generators satisfy \p c. bool satisfied_by_all_generators(const Constraint& c) const; //! Returns true if all the generators satisfy \p c. /*! It is assumed that c.is_necessarily_closed() holds. */ bool satisfied_by_all_generators_C(const Constraint& c) const; //! Returns true if all the generators satisfy \p c. /*! It is assumed that c.is_necessarily_closed() does not hold. */ bool satisfied_by_all_generators_NNC(const Constraint& c) const; //! Assigns to a given variable an affine expression. /*! \param v Index of the column to which the affine transformation is assigned; \param expr The numerator of the affine transformation: \f$\sum_{i = 0}^{n - 1} a_i x_i + b\f$; \param denominator The denominator of the affine transformation. We want to allow affine transformations (see the Introduction) having any rational coefficients. Since the coefficients of the constraints are integers we must also provide an integer \p denominator that will be used as denominator of the affine transformation. The denominator is required to be a positive integer. The affine transformation assigns to each element of \p v -th column the follow expression: \f[ \frac{\sum_{i = 0}^{n - 1} a_i x_i + b} {\mathrm{denominator}}. \f] \p expr is a constant parameter and unaltered by this computation. */ void affine_image(dimension_type v, const Linear_Expression& expr, Coefficient_traits::const_reference denominator); //! Returns the number of lines of the system. dimension_type num_lines() const; //! Returns the number of rays of the system. dimension_type num_rays() const; //! Removes all the invalid lines and rays. /*! The invalid lines and rays are those with all the homogeneous terms set to zero. */ void remove_invalid_lines_and_rays(); /*! \brief Applies Gaussian elimination and back-substitution so as to provide a partial simplification of the system of generators. It is assumed that the system has no pending generators. */ void simplify(); /*! \brief Inserts in \p *this a copy of the generator \p g, increasing the number of space dimensions if needed. It is a pending generator. */ void insert_pending(const Generator& g); }; // Generator_System.inlines.hh is not included here on purpose. #endif // !defined(PPL_Generator_System_defs_hh)