368 lines
13 KiB
C++
368 lines
13 KiB
C++
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// ratio.hpp ---------------------------------------------------------------//
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// Copyright 2008 Howard Hinnant
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// Copyright 2008 Beman Dawes
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// Copyright 2009 Vicente J. Botet Escriba
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// Distributed under the Boost Software License, Version 1.0.
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// See http://www.boost.org/LICENSE_1_0.txt
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/*
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This code was derived by Beman Dawes from Howard Hinnant's time2_demo prototype.
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Many thanks to Howard for making his code available under the Boost license.
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The original code was modified to conform to Boost conventions and to section
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20.4 Compile-time rational arithmetic [ratio], of the C++ committee working
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paper N2798.
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See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2798.pdf.
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time2_demo contained this comment:
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Much thanks to Andrei Alexandrescu,
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Walter Brown,
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Peter Dimov,
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Jeff Garland,
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Terry Golubiewski,
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Daniel Krugler,
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Anthony Williams.
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*/
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// The way overflow is managed for ratio_less is taken from llvm/libcxx/include/ratio
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#ifndef BOOST_RATIO_DETAIL_RATIO_OPERATIONS_HPP
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#define BOOST_RATIO_DETAIL_RATIO_OPERATIONS_HPP
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#include <boost/ratio/config.hpp>
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#include <boost/ratio/detail/mpl/abs.hpp>
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#include <boost/ratio/detail/mpl/sign.hpp>
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#include <cstdlib>
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#include <climits>
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#include <limits>
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#include <boost/cstdint.hpp>
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#include <boost/type_traits/integral_constant.hpp>
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#include <boost/core/enable_if.hpp>
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#include <boost/integer_traits.hpp>
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//
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// We simply cannot include this header on gcc without getting copious warnings of the kind:
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//
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// boost/integer.hpp:77:30: warning: use of C99 long long integer constant
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//
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// And yet there is no other reasonable implementation, so we declare this a system header
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// to suppress these warnings.
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//
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#if defined(__GNUC__) && (__GNUC__ >= 4)
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#pragma GCC system_header
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#endif
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namespace boost
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{
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//----------------------------------------------------------------------------//
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// helpers //
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//----------------------------------------------------------------------------//
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namespace ratio_detail
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{
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template <boost::intmax_t X, boost::intmax_t Y, boost::intmax_t = mpl::sign_c<boost::intmax_t, Y>::value>
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class br_add;
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_add<X, Y, 1>
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{
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static const boost::intmax_t min = boost::integer_traits<boost::intmax_t>::const_min;
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static const boost::intmax_t max = boost::integer_traits<boost::intmax_t>::const_max;
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BOOST_RATIO_STATIC_ASSERT(X <= max - Y , BOOST_RATIO_OVERFLOW_IN_ADD, ());
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public:
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static const boost::intmax_t value = X + Y;
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};
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_add<X, Y, 0>
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{
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public:
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static const boost::intmax_t value = X;
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};
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_add<X, Y, -1>
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{
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static const boost::intmax_t min = boost::integer_traits<boost::intmax_t>::const_min;
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static const boost::intmax_t max = boost::integer_traits<boost::intmax_t>::const_max;
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BOOST_RATIO_STATIC_ASSERT(min - Y <= X, BOOST_RATIO_OVERFLOW_IN_ADD, ());
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public:
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static const boost::intmax_t value = X + Y;
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};
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template <boost::intmax_t X, boost::intmax_t Y, boost::intmax_t = mpl::sign_c<boost::intmax_t, Y>::value>
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class br_sub;
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_sub<X, Y, 1>
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{
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static const boost::intmax_t min = boost::integer_traits<boost::intmax_t>::const_min;
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static const boost::intmax_t max = boost::integer_traits<boost::intmax_t>::const_max;
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BOOST_RATIO_STATIC_ASSERT(min + Y <= X, BOOST_RATIO_OVERFLOW_IN_SUB, ());
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public:
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static const boost::intmax_t value = X - Y;
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};
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_sub<X, Y, 0>
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{
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public:
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static const boost::intmax_t value = X;
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};
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_sub<X, Y, -1>
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{
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static const boost::intmax_t min = boost::integer_traits<boost::intmax_t>::const_min;
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static const boost::intmax_t max = boost::integer_traits<boost::intmax_t>::const_max;
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BOOST_RATIO_STATIC_ASSERT(X <= max + Y, BOOST_RATIO_OVERFLOW_IN_SUB, ());
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public:
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static const boost::intmax_t value = X - Y;
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};
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_mul
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{
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static const boost::intmax_t nan =
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boost::intmax_t(BOOST_RATIO_UINTMAX_C(1) << (sizeof(boost::intmax_t) * CHAR_BIT - 1));
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static const boost::intmax_t min = boost::integer_traits<boost::intmax_t>::const_min;
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static const boost::intmax_t max = boost::integer_traits<boost::intmax_t>::const_max;
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static const boost::intmax_t a_x = mpl::abs_c<boost::intmax_t, X>::value;
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static const boost::intmax_t a_y = mpl::abs_c<boost::intmax_t, Y>::value;
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BOOST_RATIO_STATIC_ASSERT(X != nan, BOOST_RATIO_OVERFLOW_IN_MUL, ());
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BOOST_RATIO_STATIC_ASSERT(Y != nan, BOOST_RATIO_OVERFLOW_IN_MUL, ());
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BOOST_RATIO_STATIC_ASSERT(a_x <= max / a_y, BOOST_RATIO_OVERFLOW_IN_MUL, ());
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public:
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static const boost::intmax_t value = X * Y;
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};
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template <boost::intmax_t Y>
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class br_mul<0, Y>
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{
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public:
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static const boost::intmax_t value = 0;
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};
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template <boost::intmax_t X>
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class br_mul<X, 0>
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{
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public:
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static const boost::intmax_t value = 0;
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};
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template <>
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class br_mul<0, 0>
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{
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public:
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static const boost::intmax_t value = 0;
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};
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// Not actually used but left here in case needed in future maintenance
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template <boost::intmax_t X, boost::intmax_t Y>
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class br_div
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{
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static const boost::intmax_t nan = boost::intmax_t(BOOST_RATIO_UINTMAX_C(1) << (sizeof(boost::intmax_t) * CHAR_BIT - 1));
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static const boost::intmax_t min = boost::integer_traits<boost::intmax_t>::const_min;
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static const boost::intmax_t max = boost::integer_traits<boost::intmax_t>::const_max;
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BOOST_RATIO_STATIC_ASSERT(X != nan, BOOST_RATIO_OVERFLOW_IN_DIV, ());
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BOOST_RATIO_STATIC_ASSERT(Y != nan, BOOST_RATIO_OVERFLOW_IN_DIV, ());
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BOOST_RATIO_STATIC_ASSERT(Y != 0, BOOST_RATIO_DIVIDE_BY_0, ());
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public:
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static const boost::intmax_t value = X / Y;
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};
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// ratio arithmetic
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template <class R1, class R2> struct ratio_add;
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template <class R1, class R2> struct ratio_subtract;
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template <class R1, class R2> struct ratio_multiply;
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template <class R1, class R2> struct ratio_divide;
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template <class R1, class R2>
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struct ratio_add
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{
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//The nested typedef type shall be a synonym for ratio<T1, T2>::type where T1 has the value R1::num *
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//R2::den + R2::num * R1::den and T2 has the value R1::den * R2::den.
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// As the preceding doesn't works because of overflow on boost::intmax_t we need something more elaborated.
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private:
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static const boost::intmax_t gcd_n1_n2 = mpl::gcd_c<boost::intmax_t, R1::num, R2::num>::value;
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static const boost::intmax_t gcd_d1_d2 = mpl::gcd_c<boost::intmax_t, R1::den, R2::den>::value;
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public:
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// No need to normalize as ratio_multiply is already normalized
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typedef typename ratio_multiply
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<
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ratio<gcd_n1_n2, R1::den / gcd_d1_d2>,
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ratio
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<
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boost::ratio_detail::br_add
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<
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boost::ratio_detail::br_mul<R1::num / gcd_n1_n2, R2::den / gcd_d1_d2>::value,
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boost::ratio_detail::br_mul<R2::num / gcd_n1_n2, R1::den / gcd_d1_d2>::value
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>::value,
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R2::den
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>
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>::type type;
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};
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template <class R, boost::intmax_t D>
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struct ratio_add<R, ratio<0,D> >
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{
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typedef R type;
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};
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template <class R1, class R2>
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struct ratio_subtract
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{
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//The nested typedef type shall be a synonym for ratio<T1, T2>::type where T1 has the value
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// R1::num *R2::den - R2::num * R1::den and T2 has the value R1::den * R2::den.
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// As the preceding doesn't works because of overflow on boost::intmax_t we need something more elaborated.
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private:
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static const boost::intmax_t gcd_n1_n2 = mpl::gcd_c<boost::intmax_t, R1::num, R2::num>::value;
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static const boost::intmax_t gcd_d1_d2 = mpl::gcd_c<boost::intmax_t, R1::den, R2::den>::value;
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public:
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// No need to normalize as ratio_multiply is already normalized
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typedef typename ratio_multiply
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<
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ratio<gcd_n1_n2, R1::den / gcd_d1_d2>,
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ratio
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<
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boost::ratio_detail::br_sub
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<
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boost::ratio_detail::br_mul<R1::num / gcd_n1_n2, R2::den / gcd_d1_d2>::value,
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boost::ratio_detail::br_mul<R2::num / gcd_n1_n2, R1::den / gcd_d1_d2>::value
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>::value,
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R2::den
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>
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>::type type;
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};
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template <class R, boost::intmax_t D>
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struct ratio_subtract<R, ratio<0,D> >
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{
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typedef R type;
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};
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template <class R1, class R2>
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struct ratio_multiply
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{
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// The nested typedef type shall be a synonym for ratio<R1::num * R2::den - R2::num * R1::den, R1::den * R2::den>::type.
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// As the preceding doesn't works because of overflow on boost::intmax_t we need something more elaborated.
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private:
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static const boost::intmax_t gcd_n1_d2 = mpl::gcd_c<boost::intmax_t, R1::num, R2::den>::value;
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static const boost::intmax_t gcd_d1_n2 = mpl::gcd_c<boost::intmax_t, R1::den, R2::num>::value;
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public:
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typedef typename ratio
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<
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boost::ratio_detail::br_mul<R1::num / gcd_n1_d2, R2::num / gcd_d1_n2>::value,
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boost::ratio_detail::br_mul<R2::den / gcd_n1_d2, R1::den / gcd_d1_n2>::value
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>::type type;
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};
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template <class R1, class R2>
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struct ratio_divide
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{
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// The nested typedef type shall be a synonym for ratio<R1::num * R2::den, R2::num * R1::den>::type.
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// As the preceding doesn't works because of overflow on boost::intmax_t we need something more elaborated.
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private:
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static const boost::intmax_t gcd_n1_n2 = mpl::gcd_c<boost::intmax_t, R1::num, R2::num>::value;
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static const boost::intmax_t gcd_d1_d2 = mpl::gcd_c<boost::intmax_t, R1::den, R2::den>::value;
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public:
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typedef typename ratio
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<
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boost::ratio_detail::br_mul<R1::num / gcd_n1_n2, R2::den / gcd_d1_d2>::value,
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boost::ratio_detail::br_mul<R2::num / gcd_n1_n2, R1::den / gcd_d1_d2>::value
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>::type type;
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};
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template <class R1, class R2>
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struct is_evenly_divisible_by
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{
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private:
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static const boost::intmax_t gcd_n1_n2 = mpl::gcd_c<boost::intmax_t, R1::num, R2::num>::value;
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static const boost::intmax_t gcd_d1_d2 = mpl::gcd_c<boost::intmax_t, R1::den, R2::den>::value;
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public:
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typedef integral_constant<bool,
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((R2::num / gcd_n1_n2 ==1) && (R1::den / gcd_d1_d2)==1)
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> type;
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};
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template <class T>
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struct is_ratio : public boost::false_type
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{};
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template <boost::intmax_t N, boost::intmax_t D>
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struct is_ratio<ratio<N, D> > : public boost::true_type
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{};
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template <class R1, class R2,
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boost::intmax_t Q1 = R1::num / R1::den, boost::intmax_t M1 = R1::num % R1::den,
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boost::intmax_t Q2 = R2::num / R2::den, boost::intmax_t M2 = R2::num % R2::den>
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struct ratio_less1
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{
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static const bool value = Q1 < Q2;
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};
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template <class R1, class R2, boost::intmax_t Q>
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struct ratio_less1<R1, R2, Q, 0, Q, 0>
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{
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static const bool value = false;
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};
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template <class R1, class R2, boost::intmax_t Q, boost::intmax_t M2>
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struct ratio_less1<R1, R2, Q, 0, Q, M2>
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{
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static const bool value = true;
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};
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template <class R1, class R2, boost::intmax_t Q, boost::intmax_t M1>
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struct ratio_less1<R1, R2, Q, M1, Q, 0>
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{
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static const bool value = false;
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};
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||
|
|
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||
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|
template <class R1, class R2, boost::intmax_t Q, boost::intmax_t M1, boost::intmax_t M2>
|
||
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|
struct ratio_less1<R1, R2, Q, M1, Q, M2>
|
||
|
|
{
|
||
|
|
static const bool value = ratio_less1<ratio<R2::den, M2>, ratio<R1::den, M1>
|
||
|
|
>::value;
|
||
|
|
};
|
||
|
|
|
||
|
|
template <
|
||
|
|
class R1,
|
||
|
|
class R2,
|
||
|
|
boost::intmax_t S1 = mpl::sign_c<boost::intmax_t, R1::num>::value,
|
||
|
|
boost::intmax_t S2 = mpl::sign_c<boost::intmax_t, R2::num>::value
|
||
|
|
>
|
||
|
|
struct ratio_less
|
||
|
|
{
|
||
|
|
static const bool value = S1 < S2;
|
||
|
|
};
|
||
|
|
|
||
|
|
template <class R1, class R2>
|
||
|
|
struct ratio_less<R1, R2, 1LL, 1LL>
|
||
|
|
{
|
||
|
|
static const bool value = ratio_less1<R1, R2>::value;
|
||
|
|
};
|
||
|
|
|
||
|
|
template <class R1, class R2>
|
||
|
|
struct ratio_less<R1, R2, -1LL, -1LL>
|
||
|
|
{
|
||
|
|
static const bool value = ratio_less1<ratio<-R2::num, R2::den>,
|
||
|
|
ratio<-R1::num, R1::den> >::value;
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
} // namespace ratio_detail
|
||
|
|
|
||
|
|
} // namespace boost
|
||
|
|
|
||
|
|
#endif // BOOST_RATIO_HPP
|