160 lines
4.2 KiB
C++
Executable File
160 lines
4.2 KiB
C++
Executable File
/****************************************************************************
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* Core Library Version 1.7, August 2004
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* Copyright (c) 1995-2004 Exact Computation Project
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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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* You can redistribute it and/or modify it under the terms of the GNU
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* Lesser General Public License as published by the Free Software Foundation,
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* either version 3 of the License, or (at your option) any later version.
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*
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* Licensees holding a valid commercial license may use this file in
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* accordance with the commercial license agreement provided with the
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* software.
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*
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* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*
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*
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* File: Expr.h
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* Synopsis: a class of Expression in Level 3
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*
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* Written by
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* Koji Ouchi <ouchi@simulation.nyu.edu>
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* Chee Yap <yap@cs.nyu.edu>
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* Igor Pechtchanski <pechtcha@cs.nyu.edu>
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* Vijay Karamcheti <vijayk@cs.nyu.edu>
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* Chen Li <chenli@cs.nyu.edu>
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* Zilin Du <zilin@cs.nyu.edu>
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* Sylvain Pion <pion@cs.nyu.edu>
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* Vikram Sharma<sharma@cs.nyu.edu>
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*
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* WWW URL: http://cs.nyu.edu/exact/
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* Email: exact@cs.nyu.edu
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*
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* $URL$
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* $Id$
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* SPDX-License-Identifier: LGPL-3.0+
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***************************************************************************/
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#ifndef __PROMOTE_H__
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#define __PROMOTE_H__
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#include <CGAL/CORE/Impl.h>
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namespace CORE {
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/// hasExactDivision()
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/// CHECKING if NT has exact division
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/// NOTE: it is important that the compiler does not try to
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/// prove theorems about arithmetic identities like "x*(y/x) == y"
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/// USAGE: If you want to check if a number type NT has exact division, do for example,
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/// if (hasExactDivision< NT >::check()) ...
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/// We use this in Polynomial<NT> class.
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template < class NT >
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struct hasExactDivision {
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static bool check() { // This default function is supposed to work for NT other than BigRat or Expr
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return false;
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}
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};
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template<> struct hasExactDivision<Expr> {
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static bool check() {
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return true;
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}
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};
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template<> struct hasExactDivision<BigRat> {
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static bool check() {
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return true;
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}
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};
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template<typename T1, typename T2>
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class Promotion;
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template<typename T>
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class Promotion<T, T> {
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public:
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typedef T ResultT;
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};
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#define MAX_TYPE(T1, T2) \
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typename Promotion<T1, T2>::ResultT
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#define DEFINE_MAX_TYPE(T1, T2, Tr) \
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template<> class Promotion<T1, T2> { \
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public: \
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typedef Tr ResultT; \
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}; \
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template<> class Promotion<T2, T1> { \
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public: \
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typedef Tr ResultT; \
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};
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/*
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* For example:
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*
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* DEFINE_MAX_TYPE(BigInt, BigRat, BigRat) // define the promotion
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*
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* template<typename T1, typename T2> // define function f with type templates
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* MAX_TYPE(T1, T2) f(T1& , T2& );
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*
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* or
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*
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* template<typename T1, typename T2> // define function f with type templates
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* const MAX_TYPE(T1, T2)& f(T1& , T2& );
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*
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* BigInt a = 1;
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* BigRat b = "1/3";
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* BigRat c = f(a, b); // or, typename Promotion<BigInt, BigRat>::ResultT c = f(a,b);
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*
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* REMARK: this mechanism is used by the eval function for polynomial evaluation (see Poly.tcc)
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* where the two types are NT (type of coefficients) and N (type of evaluation point).
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*/
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/*
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* primary types: (11)
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*
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* bool,
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* char, unsigned char,
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* short, unsigned short,
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* int, unsigned int,
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* long, unsigned long,
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* float, double
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*
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* CORE types: (5)
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*
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* BigInt < BigFloat < BigRat < Real < Expr
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*
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* (NOTE: BigFloat here must be error-free)
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*
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*/
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class BigInt;
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class BigFloat;
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class BigRat;
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class Expr;
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DEFINE_MAX_TYPE(long, BigInt, BigInt)
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DEFINE_MAX_TYPE(long, BigFloat, BigFloat)
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DEFINE_MAX_TYPE(long, BigRat, BigRat)
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DEFINE_MAX_TYPE(long, Expr, Expr)
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DEFINE_MAX_TYPE(int, BigInt, BigInt)
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DEFINE_MAX_TYPE(int, BigFloat, BigFloat)
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DEFINE_MAX_TYPE(int, BigRat, BigRat)
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DEFINE_MAX_TYPE(int, Expr, Expr)
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DEFINE_MAX_TYPE(BigInt, BigFloat, BigFloat)
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DEFINE_MAX_TYPE(BigInt, BigRat, BigRat)
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DEFINE_MAX_TYPE(BigInt, Expr, Expr)
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DEFINE_MAX_TYPE(BigFloat, BigRat, BigRat)
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DEFINE_MAX_TYPE(BigFloat, Expr, Expr)
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DEFINE_MAX_TYPE(BigRat, Expr, Expr)
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} //namespace CORE
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#endif //__PROMOTE_H__
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