619 lines
21 KiB
C++
619 lines
21 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/Algebraic_structure_traits.h $
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// $Id: Algebraic_structure_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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#ifndef CGAL_ALGEBRAIC_STRUCTURE_TRAITS_H
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#define CGAL_ALGEBRAIC_STRUCTURE_TRAITS_H
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#include <functional>
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#include <CGAL/tags.h>
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#include <CGAL/type_traits.h>
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#include <CGAL/Coercion_traits.h>
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#include <CGAL/assertions.h>
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#include <CGAL/use.h>
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namespace CGAL {
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// REMARK: Some of the following comments and references are just copy & pasted
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// from EXACUS and have to be adapted/removed in the future.
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// The tags for Algebra_type corresponding to the number type concepts
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// ===================================================================
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//! corresponds to the \c IntegralDomainWithoutDiv concept.
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struct Integral_domain_without_division_tag {};
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//! corresponds to the \c IntegralDomain concept.
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struct Integral_domain_tag : public Integral_domain_without_division_tag {};
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//! corresponds to the \c UFDomain concept.
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struct Unique_factorization_domain_tag : public Integral_domain_tag {};
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//! corresponds to the \c EuclideanRing concept.
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struct Euclidean_ring_tag : public Unique_factorization_domain_tag {};
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//! corresponds to the \c Field concept.
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struct Field_tag : public Integral_domain_tag {};
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//! corresponds to the \c FieldWithSqrt concept.
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struct Field_with_sqrt_tag : public Field_tag {};
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//! corresponds to the \c FieldWithKthRoot concept
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struct Field_with_kth_root_tag : public Field_with_sqrt_tag {};
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//! corresponds to the \c FieldWithRootOF concept.
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struct Field_with_root_of_tag : public Field_with_kth_root_tag {};
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// The algebraic structure traits template
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// =========================================================================
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template< class Type_ >
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class Algebraic_structure_traits {
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public:
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typedef Type_ Type;
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typedef Null_tag Algebraic_category;
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typedef Null_tag Is_exact;
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typedef Null_tag Is_numerical_sensitive;
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typedef Null_functor Simplify;
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typedef Null_functor Unit_part;
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typedef Null_functor Integral_division;
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typedef Null_functor Is_square;
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typedef Null_functor Gcd;
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typedef Null_functor Div_mod;
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typedef Null_functor Div;
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typedef Null_functor Mod;
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typedef Null_functor Square;
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typedef Null_functor Is_zero;
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typedef Null_functor Is_one;
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typedef Null_functor Sqrt;
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typedef Null_functor Kth_root;
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typedef Null_functor Root_of;
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typedef Null_functor Divides;
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typedef Null_functor Inverse;
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};
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// The algebraic structure traits base class
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// =========================================================================
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template< class Type, class Algebra_type >
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class Algebraic_structure_traits_base;
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//! The template specialization that can be used for types that are not any
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//! of the number type concepts. All functors are set to \c Null_functor
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//! or suitable defaults. The \c Simplify functor does nothing by default.
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template< class Type_ >
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class Algebraic_structure_traits_base< Type_, Null_tag > {
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public:
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typedef Type_ Type;
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typedef Null_tag Algebraic_category;
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typedef Tag_false Is_exact;
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typedef Null_tag Is_numerical_sensitive;
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typedef Null_tag Boolean;
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// does nothing by default
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class Simplify
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: public CGAL::cpp98::unary_function< Type&, void > {
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public:
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void operator()( Type& ) const {}
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};
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typedef Null_functor Unit_part;
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typedef Null_functor Integral_division;
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typedef Null_functor Is_square;
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typedef Null_functor Gcd;
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typedef Null_functor Div_mod;
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typedef Null_functor Div;
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typedef Null_functor Mod;
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typedef Null_functor Square;
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typedef Null_functor Is_zero;
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typedef Null_functor Is_one;
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typedef Null_functor Sqrt;
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typedef Null_functor Kth_root;
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typedef Null_functor Root_of;
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typedef Null_functor Divides;
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typedef Null_functor Inverse;
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};
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//! The template specialization that is used if the number type is
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//! a model of the \c IntegralDomainWithoutDiv concept. The \c Simplify
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//! does nothing by default and the \c Unit_part is equal to
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//! \c Type(-1) for negative numbers and
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//! \c Type(1) otherwise
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template< class Type_ >
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class Algebraic_structure_traits_base< Type_,
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Integral_domain_without_division_tag >
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: public Algebraic_structure_traits_base< Type_,
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Null_tag > {
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public:
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typedef Type_ Type;
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typedef Integral_domain_without_division_tag Algebraic_category;
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typedef bool Boolean;
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// returns Type(1) by default
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class Unit_part
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: public CGAL::cpp98::unary_function< Type, Type > {
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public:
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Type operator()( const Type& x ) const {
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return( x < Type(0)) ?
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Type(-1) : Type(1);
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}
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};
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class Square
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: public CGAL::cpp98::unary_function< Type, Type > {
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public:
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Type operator()( const Type& x ) const {
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return x*x;
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}
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};
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class Is_zero
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: public CGAL::cpp98::unary_function< Type, bool > {
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public:
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bool operator()( const Type& x ) const {
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return x == Type(0);
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}
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};
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class Is_one
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: public CGAL::cpp98::unary_function< Type, bool > {
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public:
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bool operator()( const Type& x ) const {
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return x == Type(1);
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}
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};
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};
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//! The template specialization that is used if the number type is
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//! a model of the \c IntegralDomain concept. It is equivalent to the
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//! specialization
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//! for the \c IntegralDomainWithoutDiv concept. The additionally required
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//! \c Integral_division functor needs to be implemented in the
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//! \c Algebraic_structure_traits itself.
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template< class Type_ >
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class Algebraic_structure_traits_base< Type_,
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Integral_domain_tag >
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: public Algebraic_structure_traits_base< Type_,
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Integral_domain_without_division_tag > {
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public:
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typedef Type_ Type;
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typedef Integral_domain_tag Algebraic_category;
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};
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//! The template specialization that is used if the number type is
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//! a model of the \c UFDomain concept. It is equivalent to the specialization
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//! for the \c IntegralDomain concept. The additionally required
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//! \c Integral_div functor
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//! and \c Gcd functor need to be implemented in the
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//! \c Algebraic_structure_traits itself.
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template< class Type_ >
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class Algebraic_structure_traits_base< Type_,
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Unique_factorization_domain_tag >
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: public Algebraic_structure_traits_base< Type_,
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Integral_domain_tag > {
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public:
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typedef Type_ Type;
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typedef Unique_factorization_domain_tag Algebraic_category;
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// Default implementation of Divides functor for unique factorization domains
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// x divides y if gcd(y,x) equals x up to inverses
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class Divides
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: public CGAL::cpp98::binary_function<Type,Type,bool>{
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public:
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bool operator()( const Type& x, const Type& y) const {
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typedef CGAL::Algebraic_structure_traits<Type> AST;
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typename AST::Gcd gcd;
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typename AST::Unit_part unit_part;
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typename AST::Integral_division idiv;
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return gcd(y,x) == idiv(x,unit_part(x));
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}
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// second operator computing q = x/y
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bool operator()( const Type& x, const Type& y, Type& q) const {
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typedef CGAL::Algebraic_structure_traits<Type> AST;
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typename AST::Integral_division idiv;
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bool result = (*this)(x,y);
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if( result == true )
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q = idiv(x,y);
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return result;
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}
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR_WITH_RT(Type,bool)
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};
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};
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//! The template specialization that is used if the number type is
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//! a model of the \c EuclideanRing concept.
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template< class Type_ >
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class Algebraic_structure_traits_base< Type_,
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Euclidean_ring_tag >
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: public Algebraic_structure_traits_base< Type_,
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Unique_factorization_domain_tag > {
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public:
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typedef Type_ Type;
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typedef Euclidean_ring_tag Algebraic_category;
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// maps to \c Div by default.
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class Integral_division
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: public CGAL::cpp98::binary_function< Type, Type,
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Type > {
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public:
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Type operator()(
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const Type& x,
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const Type& y) const {
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typedef Algebraic_structure_traits<Type> AST;
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typedef typename AST::Is_exact Is_exact;
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CGAL_USE_TYPE(Is_exact);
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typename AST::Div actual_div;
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CGAL_precondition_msg(
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!Is_exact::value || actual_div( x, y) * y == x,
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"'x' must be divisible by 'y' in "
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"Algebraic_structure_traits<...>::Integral_div()(x,y)" );
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return actual_div( x, y);
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}
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR( Type )
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};
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// Algorithm from NiX/euclids_algorithm.h
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class Gcd
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: public CGAL::cpp98::binary_function< Type, Type,
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Type > {
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public:
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Type operator()(
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const Type& x,
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const Type& y) const {
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typedef Algebraic_structure_traits<Type> AST;
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typename AST::Mod mod;
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typename AST::Unit_part unit_part;
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typename AST::Integral_division integral_div;
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// First: the extreme cases and negative sign corrections.
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if (x == Type(0)) {
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if (y == Type(0))
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return Type(0);
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return integral_div( y, unit_part(y) );
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}
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if (y == Type(0))
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return integral_div(x, unit_part(x) );
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Type u = integral_div( x, unit_part(x) );
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Type v = integral_div( y, unit_part(y) );
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// Second: assuming mod is the most expensive op here,
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// we don't compute it unnecessarily if u < v
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if (u < v) {
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v = mod(v,u);
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// maintain invariant of v > 0 for the loop below
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if ( v == Type(0) )
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return u;
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}
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// Third: generic case of two positive integer values and u >= v.
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// The standard loop would be:
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// while ( v != 0) {
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// int tmp = mod(u,v);
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// u = v;
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// v = tmp;
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// }
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// return u;
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//
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// But we want to save us all the variable assignments and unroll
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// the loop. Before that, we transform it into a do {...} while()
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// loop to reduce branching statements.
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Type w;
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do {
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w = mod(u,v);
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if ( w == Type(0))
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return v;
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u = mod(v,w);
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if ( u == Type(0))
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return w;
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v = mod(w,u);
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} while (v != Type(0));
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return u;
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}
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR( Type )
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};
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// based on \c Div and \c Mod.
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class Div_mod {
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public:
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typedef Type first_argument_type;
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typedef Type second_argument_type;
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typedef Type& third_argument_type;
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typedef Type& fourth_argument_type;
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typedef void result_type;
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void operator()( const Type& x,
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const Type& y,
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Type& q, Type& r) const {
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typedef Algebraic_structure_traits<Type> Traits;
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typename Traits::Div actual_div;
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typename Traits::Mod actual_mod;
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q = actual_div( x, y );
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r = actual_mod( x, y );
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return;
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}
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template < class NT1, class NT2 >
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void operator()(
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const NT1& x,
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const NT2& y,
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Type& q,
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Type& r ) const {
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typedef Coercion_traits< NT1, NT2 > CT;
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typedef typename CT::Type Coercion_type_NT1_NT2;
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CGAL_USE_TYPE(Coercion_type_NT1_NT2);
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CGAL_static_assertion((
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::boost::is_same<Coercion_type_NT1_NT2 , Type >::value));
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typename Coercion_traits< NT1, NT2 >::Cast cast;
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operator()( cast(x), cast(y), q, r );
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}
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};
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// based on \c Div_mod.
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class Div
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: public CGAL::cpp98::binary_function< Type, Type,
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Type > {
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public:
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Type operator()( const Type& x,
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const Type& y) const {
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typename Algebraic_structure_traits<Type>
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::Div_mod actual_div_mod;
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Type q;
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Type r;
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actual_div_mod( x, y, q, r );
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return q;
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};
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR( Type )
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};
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// based on \c Div_mod.
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class Mod
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: public CGAL::cpp98::binary_function< Type, Type,
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Type > {
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public:
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Type operator()( const Type& x,
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const Type& y) const {
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typename Algebraic_structure_traits<Type>
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::Div_mod actual_div_mod;
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Type q;
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Type r;
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actual_div_mod( x, y, q, r );
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return r;
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};
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR( Type )
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};
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// Divides for Euclidean Ring
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class Divides
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: public CGAL::cpp98::binary_function<Type, Type, bool>{
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public:
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bool operator()( const Type& x, const Type& y) const {
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typedef Algebraic_structure_traits<Type> AST;
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typename AST::Mod mod;
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CGAL_precondition(typename AST::Is_zero()(x) == false );
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return typename AST::Is_zero()(mod(y,x));
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}
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// second operator computing q
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bool operator()( const Type& x, const Type& y, Type& q) const {
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typedef Algebraic_structure_traits<Type> AST;
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typename AST::Div_mod div_mod;
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CGAL_precondition(typename AST::Is_zero()(x) == false );
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Type r;
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div_mod(y,x,q,r);
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return (typename AST::Is_zero()(r));
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}
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR_WITH_RT(Type,bool)
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};
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};
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//! The template specialization that is used if the number type is
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//! a model of the \c Field concept. \c Unit_part ()(x)
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//! returns \c NT(1) if the value \c x is equal to \c NT(0) and
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//! otherwise the value \c x itself. The \c Integral_div
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//! maps to the \c operator/.
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//! See also \link NiX_NT_traits_functors concept NT_traits \endlink .
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//! \ingroup NiX_NT_traits_bases
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//
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template< class Type_ >
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class Algebraic_structure_traits_base< Type_, Field_tag >
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: public Algebraic_structure_traits_base< Type_,
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Integral_domain_tag > {
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public:
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typedef Type_ Type;
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typedef Field_tag Algebraic_category;
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// returns the argument \a a by default
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class Unit_part
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: public CGAL::cpp98::unary_function< Type, Type > {
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public:
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Type operator()( const Type& x ) const {
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return( x == Type(0)) ? Type(1) : x;
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}
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};
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// maps to \c operator/ by default.
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class Integral_division
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: public CGAL::cpp98::binary_function< Type, Type,
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Type > {
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public:
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Type operator()( const Type& x,
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const Type& y) const {
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typedef Algebraic_structure_traits<Type> AST;
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typedef typename AST::Is_exact Is_exact;
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CGAL_USE_TYPE(Is_exact);
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CGAL_precondition_code( bool ie = Is_exact::value; )
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CGAL_precondition_msg( !ie || (x / y) * y == x,
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"'x' must be divisible by 'y' in "
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"Algebraic_structure_traits<...>::Integral_div()(x,y)" );
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return x / y;
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}
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR( Type )
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};
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// maps to \c 1/x by default.
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class Inverse
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: public CGAL::cpp98::unary_function< Type, Type > {
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public:
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Type operator()( const Type& x ) const {
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return Type(1)/x;
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}
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};
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// Default implementation of Divides functor for Field:
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// returns always true
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// \pre: x != 0
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class Divides
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: public CGAL::cpp98::binary_function< Type, Type, bool > {
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public:
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bool operator()( const Type& CGAL_precondition_code(x), const Type& /* y */) const {
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CGAL_precondition_code( typedef Algebraic_structure_traits<Type> AST);
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CGAL_precondition( typename AST::Is_zero()(x) == false );
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return true;
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}
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// second operator computing q
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bool operator()( const Type& x, const Type& y, Type& q) const {
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CGAL_precondition_code(typedef Algebraic_structure_traits<Type> AST);
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CGAL_precondition( typename AST::Is_zero()(x) == false );
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q = y/x;
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return true;
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}
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CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR_WITH_RT(Type,bool)
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};
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};
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//! The template specialization that is used if the number type is a model
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//! of the \c FieldWithSqrt concept. It is equivalent to the
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//! specialization for the \c Field concept. The additionally required
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//! \c NiX::NT_traits::Sqrt functor need to be
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//! implemented in the \c NT_traits itself.
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//! \ingroup NiX_NT_traits_bases
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//
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template< class Type_ >
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class Algebraic_structure_traits_base< Type_,
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Field_with_sqrt_tag>
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: public Algebraic_structure_traits_base< Type_,
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|
Field_tag> {
|
|
public:
|
|
typedef Type_ Type;
|
|
typedef Field_with_sqrt_tag Algebraic_category;
|
|
|
|
struct Is_square
|
|
:public CGAL::cpp98::binary_function<Type,Type&,bool>
|
|
{
|
|
bool operator()(const Type& ) const {return true;}
|
|
bool operator()(
|
|
const Type& x,
|
|
Type & result) const {
|
|
typename Algebraic_structure_traits<Type>::Sqrt sqrt;
|
|
result = sqrt(x);
|
|
return true;
|
|
}
|
|
};
|
|
};
|
|
|
|
//! The template specialization that is used if the number type is a model
|
|
//! of the \c FieldWithKthRoot concept. It is equivalent to the
|
|
//! specialization for the \c Field concept. The additionally required
|
|
//! \c NiX::NT_traits::Kth_root functor need to be
|
|
//! implemented in the \c Algebraic_structure_traits itself.
|
|
//! \ingroup NiX_NT_traits_bases
|
|
//
|
|
template< class Type_ >
|
|
class Algebraic_structure_traits_base< Type_,
|
|
Field_with_kth_root_tag>
|
|
: public Algebraic_structure_traits_base< Type_,
|
|
Field_with_sqrt_tag> {
|
|
|
|
|
|
|
|
public:
|
|
typedef Type_ Type;
|
|
typedef Field_with_kth_root_tag Algebraic_category;
|
|
};
|
|
|
|
|
|
|
|
|
|
//! The template specialization that is used if the number type is a model
|
|
//! of the \c FieldWithRootOf concept. It is equivalent to the
|
|
//! specialization for the \c FieldWithKthRoot concept. The additionally
|
|
//! required \c NiX::NT_traits::Root_of functor need to be
|
|
//! implemented in the \c NT_traits itself.
|
|
//! \ingroup NiX_NT_traits_bases
|
|
//
|
|
template< class Type_ >
|
|
class Algebraic_structure_traits_base< Type_,
|
|
Field_with_root_of_tag >
|
|
: public Algebraic_structure_traits_base< Type_,
|
|
Field_with_kth_root_tag > {
|
|
public:
|
|
typedef Type_ Type;
|
|
typedef Field_with_root_of_tag Algebraic_category;
|
|
};
|
|
|
|
// Some common functors to be used by AST specializations
|
|
namespace INTERN_AST {
|
|
template< class Type >
|
|
class Div_per_operator
|
|
: public CGAL::cpp98::binary_function< Type, Type,
|
|
Type > {
|
|
public:
|
|
Type operator()( const Type& x,
|
|
const Type& y ) const {
|
|
return x / y;
|
|
}
|
|
|
|
CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR( Type )
|
|
};
|
|
|
|
template< class Type >
|
|
class Mod_per_operator
|
|
: public CGAL::cpp98::binary_function< Type, Type,
|
|
Type > {
|
|
public:
|
|
Type operator()( const Type& x,
|
|
const Type& y ) const {
|
|
return x % y;
|
|
}
|
|
|
|
CGAL_IMPLICIT_INTEROPERABLE_BINARY_OPERATOR( Type )
|
|
};
|
|
|
|
template< class Type >
|
|
class Is_square_per_sqrt
|
|
: public CGAL::cpp98::binary_function< Type, Type&,
|
|
bool > {
|
|
public:
|
|
bool operator()( const Type& x,
|
|
Type& y ) const {
|
|
typename Algebraic_structure_traits< Type >::Sqrt
|
|
actual_sqrt;
|
|
y = actual_sqrt( x );
|
|
return y * y == x;
|
|
}
|
|
bool operator()( const Type& x) const {
|
|
Type dummy;
|
|
return operator()(x,dummy);
|
|
}
|
|
};
|
|
} // INTERN_AST
|
|
} //namespace CGAL
|
|
|
|
#endif // CGAL_ALGEBRAIC_STRUCTURE_TRAITS_H
|