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YouCompleteMe/cpp/BoostParts/boost/ratio/detail/overflow_helpers.hpp
Strahinja Val Markovic 121d88518e Updating to boost 1.52
2013-01-13 14:38:19 -08:00

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