157 lines
5.0 KiB
C++
157 lines
5.0 KiB
C++
// Copyright (c) 2006-2007 Max-Planck-Institute Saarbruecken (Germany).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org)
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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Algebraic_foundations/include/CGAL/Scalar_factor_traits.h $
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// $Id: Scalar_factor_traits.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
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// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
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//
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//
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// Author(s) : Michael Hemmer <hemmer@mpi-inf.mpg.de>
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//
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// =============================================================================
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// TODO: The comments are all original EXACUS comments and aren't adapted. So
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// they may be wrong now.
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#ifndef CGAL_SCALAR_FACTOR_TRAITS_H
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#define CGAL_SCALAR_FACTOR_TRAITS_H
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#include <CGAL/assertions.h>
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#include <CGAL/Algebraic_structure_traits.h>
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/*! \file NiX/Scalar_factor_traits.h
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* \brief Definition of traits class NiX::Scalar_factor_traits.
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*/
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namespace CGAL {
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/*! \nosubgrouping
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* \ingroup NiX_Scalar_factor_traits_spec
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* \brief traits class for scalar factor extraction
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*
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* A model of the concept ScalarFactorTraits.
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*
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* This is the default implementation of NiX::Scalar_factor_traits.
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* It is valid for most basic number types as Integer, Rational etc.
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*/
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template< class NT >
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class Scalar_factor_traits {
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public:
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// the supported number type
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typedef NT Type;
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// NT is also
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typedef NT Scalar;
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// functor computing the scalar factor of a basic number type.
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class Scalar_factor {
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static Scalar scalar_factor(const NT& a, Integral_domain_tag) {
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typename Algebraic_structure_traits<NT>::Unit_part upart;
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typename Algebraic_structure_traits<NT>::Integral_division idiv;
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return idiv(a, upart(a));
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}
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static Scalar scalar_factor(const NT& a, Field_tag) {
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return (a == NT(0)) ? NT(0) : NT(1);
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}
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static Scalar scalar_factor(const NT& /* a */,
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const Scalar& /* d */,
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Integral_domain_tag) {
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return Scalar(1);
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}
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static Scalar scalar_factor(const NT& a,
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const Scalar& d,
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Field_tag) {
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return (a == NT(0) && d == Scalar(0)) ? NT(0) : NT(1);
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}
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static Scalar scalar_factor(const NT& a,
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const Scalar& d,
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Unique_factorization_domain_tag) {
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if( d == Scalar(0)) {
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return a;
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} else {
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typename Algebraic_structure_traits<NT>::Gcd gcd;
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return gcd(a,d);
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}
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}
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public:
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// argument type
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typedef NT argument_type;
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// first argument type
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typedef NT first_argument_type;
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// second argument type
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typedef Scalar second_argument_type;
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// result type
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typedef Scalar result_type;
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// determine extractable scalar factor
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Scalar operator () (const NT& a) {
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CGAL_static_assertion(( ::boost::is_same< NT,Scalar >::value));
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typedef typename Algebraic_structure_traits<NT>::Algebraic_category SAT;
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return scalar_factor(a, SAT());
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}
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// determine extractable scalar factor
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Scalar operator () (const NT& a, const Scalar& d) {
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CGAL_static_assertion(( ::boost::is_same< NT,Scalar >::value));
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typedef typename Algebraic_structure_traits<NT>::Algebraic_category SAT;
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return scalar_factor(a,d,SAT());
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}
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};
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class Scalar_div {
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public:
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// first argument type
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typedef NT& first_argument_type;
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// second argument type
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typedef Scalar second_argument_type;
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// result type
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typedef void result_type;
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// divide \a a in place by scalar factor \a b
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void operator () (NT& a, const Scalar& b) {
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CGAL_precondition(b != Scalar(0));
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typename Algebraic_structure_traits<NT>::Integral_division idiv;
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a = idiv(a, b);
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}
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};
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};
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/*! \ingroup NiX_Scalar_factor_traits
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* \brief removes the scalar factor
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*
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* Removes the scalar factor provided by NiX::Scalar_factor_traits
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*/
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template <class NT>
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void remove_scalar_factor(NT& x){
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typedef CGAL::Scalar_factor_traits<NT> SFT;
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typedef typename SFT::Scalar Scalar;
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typename SFT::Scalar_factor sfac;
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typename SFT::Scalar_div sdiv;
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Scalar scalar=sfac(x);
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if(scalar != Scalar(0))
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sdiv(x,scalar);
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}
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template <class NT>
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inline
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typename CGAL::Scalar_factor_traits<NT>::Scalar
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scalar_factor(const NT& x){
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typename CGAL::Scalar_factor_traits<NT>::Scalar_factor scalar_factor;
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return scalar_factor(x);
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}
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template <class NT>
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inline
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typename CGAL::Scalar_factor_traits<NT>::Scalar
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scalar_factor(const NT& x,
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const typename CGAL::Scalar_factor_traits<NT>::Scalar& d)
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{
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typename CGAL::Scalar_factor_traits<NT>::Scalar_factor scalar_factor;
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return scalar_factor(x,d);
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}
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} //namespace CGAL
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#endif // NiX_SCALAR_FACTOR_TRAITS_H
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// EOF
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