///////////////////////////////////////////////////////////////////////////////
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// Copyright 2018 John Maddock. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MP_PRECISION_HPP
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#define BOOST_MP_PRECISION_HPP
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#include <boost/multiprecision/traits/is_variable_precision.hpp>
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#include <boost/multiprecision/detail/number_base.hpp>
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#include <boost/multiprecision/detail/digits.hpp>
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namespace boost { namespace multiprecision { namespace detail {
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template <class B, boost::multiprecision::expression_template_option ET>
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inline BOOST_CONSTEXPR unsigned current_precision_of_last_chance_imp(const boost::multiprecision::number<B, ET>&, const mpl::false_&)
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{
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return std::numeric_limits<boost::multiprecision::number<B, ET> >::digits10;
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}
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template <class B, boost::multiprecision::expression_template_option ET>
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inline BOOST_MP_CXX14_CONSTEXPR unsigned current_precision_of_last_chance_imp(const boost::multiprecision::number<B, ET>& val, const mpl::true_&)
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{
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//
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// We have an arbitrary precision integer, take it's "precision" as the
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// location of the most-significant-bit less the location of the
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// least-significant-bit, ie the number of bits required to represent the
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// the value assuming we will have an exponent to shift things by:
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//
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return val.is_zero() ? 1 : digits2_2_10(msb(abs(val)) - lsb(abs(val)) + 1);
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}
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template <class B, boost::multiprecision::expression_template_option ET>
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inline BOOST_MP_CXX14_CONSTEXPR unsigned current_precision_of_imp(const boost::multiprecision::number<B, ET>& n, const mpl::true_&)
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{
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return n.precision();
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}
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template <class B, boost::multiprecision::expression_template_option ET>
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inline BOOST_CONSTEXPR unsigned current_precision_of_imp(const boost::multiprecision::number<B, ET>& val, const mpl::false_&)
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{
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return current_precision_of_last_chance_imp(val,
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mpl::bool_ <
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std::numeric_limits<boost::multiprecision::number<B, ET> >::is_specialized &&
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std::numeric_limits<boost::multiprecision::number<B, ET> >::is_integer && std::numeric_limits<boost::multiprecision::number<B, ET> >::is_exact && !std::numeric_limits<boost::multiprecision::number<B, ET> >::is_modulo > ());
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}
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template <class Terminal>
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inline BOOST_CONSTEXPR unsigned current_precision_of(const Terminal&)
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{
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return std::numeric_limits<Terminal>::digits10;
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}
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template <class Terminal, std::size_t N>
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inline BOOST_CONSTEXPR unsigned current_precision_of(const Terminal (&)[N])
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{ // For string literals:
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return 0;
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}
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template <class B, boost::multiprecision::expression_template_option ET>
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inline BOOST_CONSTEXPR unsigned current_precision_of(const boost::multiprecision::number<B, ET>& n)
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{
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return current_precision_of_imp(n, boost::multiprecision::detail::is_variable_precision<boost::multiprecision::number<B, ET> >());
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}
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template <class tag, class Arg1>
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inline BOOST_CONSTEXPR unsigned current_precision_of(const expression<tag, Arg1, void, void, void>& expr)
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{
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return current_precision_of(expr.left_ref());
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}
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template <class Arg1>
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inline BOOST_CONSTEXPR unsigned current_precision_of(const expression<terminal, Arg1, void, void, void>& expr)
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{
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return current_precision_of(expr.value());
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}
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template <class tag, class Arg1, class Arg2>
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inline BOOST_CONSTEXPR unsigned current_precision_of(const expression<tag, Arg1, Arg2, void, void>& expr)
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{
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return (std::max)(current_precision_of(expr.left_ref()), current_precision_of(expr.right_ref()));
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}
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template <class tag, class Arg1, class Arg2, class Arg3>
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inline BOOST_CONSTEXPR unsigned current_precision_of(const expression<tag, Arg1, Arg2, Arg3, void>& expr)
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{
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return (std::max)((std::max)(current_precision_of(expr.left_ref()), current_precision_of(expr.right_ref())), current_precision_of(expr.middle_ref()));
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}
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#ifdef BOOST_MSVC
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#pragma warning(push)
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#pragma warning(disable : 4130)
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#endif
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template <class R, bool = boost::multiprecision::detail::is_variable_precision<R>::value>
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struct scoped_default_precision
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{
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template <class T>
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BOOST_CONSTEXPR scoped_default_precision(const T&) {}
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template <class T, class U>
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BOOST_CONSTEXPR scoped_default_precision(const T&, const U&) {}
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template <class T, class U, class V>
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BOOST_CONSTEXPR scoped_default_precision(const T&, const U&, const V&) {}
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//
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// This function is never called: in C++17 it won't be compiled either:
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//
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unsigned precision() const
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{
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BOOST_ASSERT("This function should never be called!!" == 0);
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return 0;
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}
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};
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#ifdef BOOST_MSVC
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#pragma warning(pop)
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#endif
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template <class R>
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struct scoped_default_precision<R, true>
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{
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template <class T>
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BOOST_MP_CXX14_CONSTEXPR scoped_default_precision(const T& a)
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{
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init(current_precision_of(a));
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}
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template <class T, class U>
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BOOST_MP_CXX14_CONSTEXPR scoped_default_precision(const T& a, const U& b)
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{
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init((std::max)(current_precision_of(a), current_precision_of(b)));
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}
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template <class T, class U, class V>
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BOOST_MP_CXX14_CONSTEXPR scoped_default_precision(const T& a, const U& b, const V& c)
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{
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init((std::max)((std::max)(current_precision_of(a), current_precision_of(b)), current_precision_of(c)));
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}
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~scoped_default_precision()
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{
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if(m_new_prec != m_old_prec)
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R::default_precision(m_old_prec);
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}
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BOOST_MP_CXX14_CONSTEXPR unsigned precision() const
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{
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return m_new_prec;
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}
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private:
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BOOST_MP_CXX14_CONSTEXPR void init(unsigned p)
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{
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m_old_prec = R::default_precision();
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if (p && (p != m_old_prec))
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{
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R::default_precision(p);
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m_new_prec = p;
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}
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else
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m_new_prec = m_old_prec;
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}
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unsigned m_old_prec, m_new_prec;
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};
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template <class T>
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inline BOOST_MP_CXX14_CONSTEXPR void maybe_promote_precision(T*, const mpl::false_&) {}
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template <class T>
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inline BOOST_MP_CXX14_CONSTEXPR void maybe_promote_precision(T* obj, const mpl::true_&)
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{
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if (obj->precision() != T::default_precision())
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{
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obj->precision(T::default_precision());
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}
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}
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template <class T>
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inline BOOST_MP_CXX14_CONSTEXPR void maybe_promote_precision(T* obj)
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{
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maybe_promote_precision(obj, mpl::bool_<boost::multiprecision::detail::is_variable_precision<T>::value>());
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}
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#ifndef BOOST_NO_CXX17_IF_CONSTEXPR
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#define BOOST_MP_CONSTEXPR_IF_VARIABLE_PRECISION(T) \
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if \
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constexpr(boost::multiprecision::detail::is_variable_precision<T>::value)
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#else
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#define BOOST_MP_CONSTEXPR_IF_VARIABLE_PRECISION(T) if (boost::multiprecision::detail::is_variable_precision<T>::value)
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#endif
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}
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}
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} // namespace boost::multiprecision::detail
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#endif // BOOST_MP_IS_BACKEND_HPP
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