350 lines
10 KiB
Plaintext
350 lines
10 KiB
Plaintext
// Boost.Units - A C++ library for zero-overhead dimensional analysis and
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// unit/quantity manipulation and conversion
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//
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// Copyright (C) 2003-2008 Matthias Christian Schabel
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// Copyright (C) 2008 Steven Watanabe
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_UNITS_STATIC_RATIONAL_HPP
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#define BOOST_UNITS_STATIC_RATIONAL_HPP
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#include <boost/integer/common_factor_ct.hpp>
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#include <boost/mpl/less.hpp>
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#include <boost/mpl/arithmetic.hpp>
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#ifdef __BORLANDC__
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#include <boost/mpl/eval_if.hpp>
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#include <boost/mpl/integral_c.hpp>
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#include <boost/mpl/identity.hpp>
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#endif
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#include <boost/units/config.hpp>
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#include <boost/units/operators.hpp>
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/// \file
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/// \brief Compile-time rational numbers and operators.
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namespace boost {
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namespace units {
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namespace detail {
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struct static_rational_tag {};
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}
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typedef long integer_type;
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/// Compile time absolute value.
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template<integer_type Value>
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struct static_abs
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{
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BOOST_STATIC_CONSTANT(integer_type,value = Value < 0 ? -Value : Value);
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};
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// Compile time rational number.
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/**
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This is an implementation of a compile time rational number, where @c static_rational<N,D> represents
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a rational number with numerator @c N and denominator @c D. Because of the potential for ambiguity arising
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from multiple equivalent values of @c static_rational (e.g. @c static_rational<6,2>==static_rational<3>),
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static rationals should always be accessed through @c static_rational<N,D>::type. Template specialization
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prevents instantiation of zero denominators (i.e. @c static_rational<N,0>). The following compile-time
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arithmetic operators are provided for static_rational variables only (no operators are defined between
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long and static_rational):
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- @c mpl::negate
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- @c mpl::plus
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- @c mpl::minus
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- @c mpl::times
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- @c mpl::divides
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Neither @c static_power nor @c static_root are defined for @c static_rational. This is because template types
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may not be floating point values, while powers and roots of rational numbers can produce floating point
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values.
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*/
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#ifdef __BORLANDC__
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template<integer_type X>
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struct make_integral_c {
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typedef boost::mpl::integral_c<integer_type, X> type;
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};
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template<integer_type N,integer_type D = 1>
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class static_rational
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{
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public:
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typedef static_rational this_type;
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typedef boost::mpl::integral_c<integer_type, N> N_type;
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typedef boost::mpl::integral_c<integer_type, D> D_type;
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typedef typename make_integral_c<
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(::boost::integer::static_gcd<
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::boost::units::static_abs<N>::value,
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::boost::units::static_abs<D>::value
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>::value)>::type gcd_type;
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typedef typename boost::mpl::eval_if<
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boost::mpl::less<
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D_type,
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boost::mpl::integral_c<integer_type, 0>
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>,
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boost::mpl::negate<gcd_type>,
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gcd_type
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>::type den_type;
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public:
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// for mpl arithmetic support
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typedef detail::static_rational_tag tag;
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BOOST_STATIC_CONSTANT(integer_type, Numerator =
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(::boost::mpl::divides<N_type, den_type>::value));
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BOOST_STATIC_CONSTANT(integer_type, Denominator =
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(::boost::mpl::divides<D_type, den_type>::value));
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/// INTERNAL ONLY
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typedef static_rational<N,D> this_type;
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/// static_rational<N,D> reduced by GCD
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typedef static_rational<
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(::boost::mpl::divides<N_type, den_type>::value),
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(::boost::mpl::divides<D_type, den_type>::value)
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> type;
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static integer_type numerator() { return Numerator; }
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static integer_type denominator() { return Denominator; }
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// INTERNAL ONLY
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static_rational() { }
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//~static_rational() { }
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};
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#else
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template<integer_type N,integer_type D = 1>
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class static_rational
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{
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private:
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static const integer_type nabs = static_abs<N>::value,
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dabs = static_abs<D>::value;
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/// greatest common divisor of N and D
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// need cast to signed because static_gcd returns unsigned long
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static const integer_type den =
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static_cast<integer_type>(boost::integer::static_gcd<nabs,dabs>::value) * ((D < 0) ? -1 : 1);
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public:
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// for mpl arithmetic support
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typedef detail::static_rational_tag tag;
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static const integer_type Numerator = N/den,
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Denominator = D/den;
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/// INTERNAL ONLY
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typedef static_rational<N,D> this_type;
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/// static_rational<N,D> reduced by GCD
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typedef static_rational<Numerator,Denominator> type;
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static integer_type numerator() { return Numerator; }
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static integer_type denominator() { return Denominator; }
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// INTERNAL ONLY
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static_rational() { }
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//~static_rational() { }
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};
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#endif
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}
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}
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#if BOOST_UNITS_HAS_BOOST_TYPEOF
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#include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP()
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BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::static_rational, (long)(long))
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#endif
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namespace boost {
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namespace units {
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// prohibit zero denominator
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template<integer_type N> class static_rational<N,0>;
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/// get decimal value of @c static_rational
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template<class T,integer_type N,integer_type D>
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inline typename divide_typeof_helper<T,T>::type
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value(const static_rational<N,D>&)
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{
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return T(N)/T(D);
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}
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} // namespace units
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#ifndef BOOST_UNITS_DOXYGEN
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namespace mpl {
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#ifdef __BORLANDC__
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template<>
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struct plus_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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::boost::mpl::plus<
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boost::mpl::times<typename T0::N_type, typename T1::D_type>,
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boost::mpl::times<typename T1::N_type, typename T0::D_type>
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>::value,
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::boost::mpl::times<typename T0::D_type, typename T1::D_type>::value
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>::type type;
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};
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};
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template<>
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struct minus_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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::boost::mpl::minus<
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boost::mpl::times<typename T0::N_type, typename T1::D_type>,
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boost::mpl::times<typename T1::N_type, typename T0::D_type>
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>::value,
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::boost::mpl::times<typename T0::D_type, typename T1::D_type>::value
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>::type type;
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};
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};
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template<>
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struct times_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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::boost::mpl::times<typename T0::N_type, typename T1::N_type>::value,
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::boost::mpl::times<typename T0::D_type, typename T1::D_type>::value
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>::type type;
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};
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};
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template<>
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struct divides_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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::boost::mpl::times<typename T0::N_type, typename T1::D_type>::value,
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::boost::mpl::times<typename T0::D_type, typename T1::N_type>::value
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>::type type;
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};
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};
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template<>
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struct negate_impl<boost::units::detail::static_rational_tag>
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{
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template<class T0>
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struct apply {
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typedef typename boost::units::static_rational<
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::boost::mpl::negate<typename T0::N_type>::value,
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::boost::mpl::identity<T0>::type::Denominator
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>::type type;
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};
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};
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template<>
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struct less_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply
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{
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typedef mpl::bool_<((mpl::minus<T0, T1>::type::Numerator) < 0)> type;
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};
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};
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#else
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template<>
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struct plus_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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T0::Numerator*T1::Denominator+T1::Numerator*T0::Denominator,
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T0::Denominator*T1::Denominator
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>::type type;
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};
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};
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template<>
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struct minus_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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T0::Numerator*T1::Denominator-T1::Numerator*T0::Denominator,
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T0::Denominator*T1::Denominator
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>::type type;
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};
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};
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template<>
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struct times_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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T0::Numerator*T1::Numerator,
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T0::Denominator*T1::Denominator
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>::type type;
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};
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};
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template<>
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struct divides_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply {
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typedef typename boost::units::static_rational<
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T0::Numerator*T1::Denominator,
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T0::Denominator*T1::Numerator
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>::type type;
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};
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};
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template<>
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struct negate_impl<boost::units::detail::static_rational_tag>
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{
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template<class T0>
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struct apply {
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typedef typename boost::units::static_rational<-T0::Numerator,T0::Denominator>::type type;
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};
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};
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template<>
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struct less_impl<boost::units::detail::static_rational_tag, boost::units::detail::static_rational_tag>
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{
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template<class T0, class T1>
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struct apply
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{
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typedef mpl::bool_<((mpl::minus<T0, T1>::type::Numerator) < 0)> type;
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};
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};
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#endif
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}
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#endif
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} // namespace boost
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#endif // BOOST_UNITS_STATIC_RATIONAL_HPP
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