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// Copyright (c) 2005-2008 INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/Filtered_kernel/include/CGAL/Robust_construction.h $
// $Id: include/CGAL/Robust_construction.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s) : Sylvain Pion, Mariette Yvinec, Laurent Rineau
#ifndef CGAL_ROBUST_CONSTRUCTION_H
#define CGAL_ROBUST_CONSTRUCTION_H
#include <CGAL/config.h>
namespace CGAL {
// This template class is a functor adaptor targeting geometric constructions.
//
// They are "robust" in the following sense : the input and output are
// approximate (doubles), but the internal computation tries to guarantees the
// approximation quantitatively.
//
// This is especially useful in order to minimize the bad things that happen
// in close-to-degenerate cases (e.g. computing the circumcenter of an almost
// flat tetrahedron).
//
// The implementation strategy is to:
// - convert the input to Lazy kernel objects
// - perform the computation with it
// - convert back to double in a guaranteed way (since Lazy_exact_nt guarantees
// a precision on to_double).
// TODO :
// - possible improvement by avoiding the constructions of Lazy_exact_nt's.
template <class EC, class A2E, class E2A, class Result_type>
class Robust_construction
{
EC ec;
A2E a2e;
E2A e2a;
public:
typedef Result_type result_type;
typedef EC Exact_construction;
typedef A2E Approximate_to_exact_converter;
typedef E2A Exact_to_approximate_converter;
template <typename... Args>
result_type
operator()(const Args&... args) const
{ return e2a(ec(a2e(args)...)); }
};
} //namespace CGAL
#endif // CGAL_ROBUST_CONSTRUCTION_H
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