Parma_Polyhedra_Library::Shape_Preserving_Reduction< D1, D2 > Class Template Reference

This class provides the reduction method for the Shape_Preserving_Product domain. More...

#include <Partially_Reduced_Product_defs.hh>

Public Member Functions
	Shape_Preserving_Reduction ()
	Default constructor. More...
void	product_reduce (D1 &d1, D2 &d2)
	The congruences reduction operator for detect emptiness or any equalities implied by each of the congruences defining one of the components and the bounds of the other component. It is assumed that the components are already constraints reduced. More...
	~Shape_Preserving_Reduction ()
	Destructor. More...

Detailed Description

template<typename D1, typename D2>
class Parma_Polyhedra_Library::Shape_Preserving_Reduction< D1, D2 >

This class provides the reduction method for the Shape_Preserving_Product domain.

The reduction classes are used to instantiate the Partially_Reduced_Product domain.

This reduction method includes the congruences reduction. This class uses the minimized constraints defining each of the components. For each of the constraints, it checks the frequency and value for the same linear expression in the other component. If the constraint does not satisfy the implied congruence, the inhomogeneous term is adjusted so that it does. Note that, unless the congruences reduction adds equalities, the shapes of the domains are unaltered.

Definition at line 249 of file Partially_Reduced_Product_defs.hh.

Constructor & Destructor Documentation

template<typename D1 , typename D2 >

Parma_Polyhedra_Library::Shape_Preserving_Reduction< D1, D2 >::Shape_Preserving_Reduction ( )

inline

Default constructor.

Definition at line 801 of file Partially_Reduced_Product_inlines.hh.

                                                               {
}

template<typename D1 , typename D2 >

Parma_Polyhedra_Library::Shape_Preserving_Reduction< D1, D2 >::~Shape_Preserving_Reduction ( )

inline

Destructor.

Definition at line 806 of file Partially_Reduced_Product_inlines.hh.

                                                                {
}

Member Function Documentation

template<typename D1 , typename D2 >

void Parma_Polyhedra_Library::Shape_Preserving_Reduction< D1, D2 >::product_reduce	(	D1 &	d1,
		D2 &	d2
	)

The congruences reduction operator for detect emptiness or any equalities implied by each of the congruences defining one of the components and the bounds of the other component. It is assumed that the components are already constraints reduced.

The minimized congruence system defining the domain element d1 is used to check if d2 intersects none, one or more than one of the hyperplanes defined by the congruences: if it intersects none, then product is set empty; if it intersects one, then the equality defining this hyperplane is added to both components; otherwise, the product is unchanged. In each case, the donor domain must provide a congruence system in minimal form.

Parameters

d1	A pointset domain element;
d2	A pointset domain element;

Definition at line 677 of file Partially_Reduced_Product_templates.hh.

References Parma_Polyhedra_Library::Constraint_System::begin(), c, Parma_Polyhedra_Library::Constraint_System::clear(), Parma_Polyhedra_Library::Constraint_System::end(), Parma_Polyhedra_Library::Constraint::expression(), Parma_Polyhedra_Library::Constraint_System::insert(), Parma_Polyhedra_Library::Constraint::is_equality(), Parma_Polyhedra_Library::Boundary_NS::le(), PPL_DIRTY_TEMP_COEFFICIENT, Parma_Polyhedra_Library::Constraints_Reduction< D1, D2 >::product_reduce(), and Parma_Polyhedra_Library::Congruences_Reduction< D1, D2 >::product_reduce().

                                                                 {
  // First do the congruences reduction.
  Parma_Polyhedra_Library::Congruences_Reduction<D1, D2> cgr;
  cgr.product_reduce(d1, d2);
  if (d1.is_empty()) {
    return;
  }

  PPL_DIRTY_TEMP_COEFFICIENT(freq_n);
  PPL_DIRTY_TEMP_COEFFICIENT(freq_d);
  PPL_DIRTY_TEMP_COEFFICIENT(val_n);
  PPL_DIRTY_TEMP_COEFFICIENT(val_d);

  // Use the constraints representing d2.
  Constraint_System cs = d2.minimized_constraints();
  Constraint_System refining_cs;
  for (Constraint_System::const_iterator i = cs.begin(),
         cs_end = cs.end(); i != cs_end; ++i) {
    const Constraint& c = *i;
    if (c.is_equality()) {
      continue;
    }
    // Check the frequency and value of the linear expression for
    // the constraint `c'.
    Linear_Expression le(c.expression());
    if (!d1.frequency(le, freq_n, freq_d, val_n, val_d)) {
      // Nothing to do.
      continue;
    }
    if (val_n == 0) {
      // Nothing to do.
      continue;
    }
    // Adjust the value of the inhomogeneous term to satisfy
    // the implied congruence.
    if (val_n < 0) {
      val_n = val_n*freq_d + val_d*freq_n;
      val_d *= freq_d;
    }
    le *= val_d;
    le -= val_n;
    refining_cs.insert(le >= 0);
  }
  d2.refine_with_constraints(refining_cs);

  // Use the constraints representing d1.
  cs = d1.minimized_constraints();
  refining_cs.clear();
  for (Constraint_System::const_iterator i = cs.begin(),
         cs_end = cs.end(); i != cs_end; ++i) {
    const Constraint& c = *i;
    if (c.is_equality()) {
      // Equalities already shared.
      continue;
    }
    // Check the frequency and value of the linear expression for
    // the constraint `c'.
    Linear_Expression le(c.expression());
    if (!d2.frequency(le, freq_n, freq_d, val_n, val_d)) {
      // Nothing to do.
      continue;
    }
    if (val_n == 0) {
      // Nothing to do.
      continue;
    }
    // Adjust the value of the inhomogeneous term to satisfy
    // the implied congruence.
    if (val_n < 0) {
      val_n = val_n*freq_d + val_d*freq_n;
      val_d *= freq_d;
    }
    le *= val_d;
    le -= val_n;
    refining_cs.insert(le >= 0);
  }
  d1.refine_with_constraints(refining_cs);

  // The reduction may have introduced additional equalities
  // so these must be shared with the other component.
  Parma_Polyhedra_Library::Constraints_Reduction<D1, D2> cr;
  cr.product_reduce(d1, d2);
}

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The documentation for this class was generated from the following files:

• Partially_Reduced_Product_defs.hh
• Partially_Reduced_Product_inlines.hh
• Partially_Reduced_Product_templates.hh