Chris@102: // Boost.Geometry (aka GGL, Generic Geometry Library)
Chris@102: 
Chris@102: // Copyright (c) 2015, Oracle and/or its affiliates.
Chris@102: 
Chris@102: // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
Chris@102: 
Chris@102: // Licensed under the Boost Software License version 1.0.
Chris@102: // http://www.boost.org/users/license.html
Chris@102: 
Chris@102: #ifndef BOOST_GEOMETRY_UTIL_PROMOTE_INTEGRAL_HPP
Chris@102: #define BOOST_GEOMETRY_UTIL_PROMOTE_INTEGRAL_HPP
Chris@102: 
Chris@102: // For now deactivate the use of multiprecision integers
Chris@102: // TODO: activate it later
Chris@102: #define BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER
Chris@102: 
Chris@102: #include <climits>
Chris@102: #include <cstddef>
Chris@102: 
Chris@102: #include <boost/mpl/begin.hpp>
Chris@102: #include <boost/mpl/deref.hpp>
Chris@102: #include <boost/mpl/end.hpp>
Chris@102: #include <boost/mpl/if.hpp>
Chris@102: #include <boost/mpl/list.hpp>
Chris@102: #include <boost/mpl/next.hpp>
Chris@102: #include <boost/mpl/size_t.hpp>
Chris@102: 
Chris@102: #if !defined(BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER)
Chris@102: #include <boost/multiprecision/cpp_int.hpp>
Chris@102: #endif
Chris@102: 
Chris@102: #include <boost/type_traits/integral_constant.hpp>
Chris@102: #include <boost/type_traits/is_fundamental.hpp>
Chris@102: #include <boost/type_traits/is_integral.hpp>
Chris@102: #include <boost/type_traits/is_unsigned.hpp>
Chris@102: 
Chris@102: 
Chris@102: namespace boost { namespace geometry
Chris@102: {
Chris@102: 
Chris@102: #ifndef DOXYGEN_NO_DETAIL
Chris@102: namespace detail { namespace promote_integral
Chris@102: {
Chris@102: 
Chris@102: // meta-function that returns the bit size of a type
Chris@102: template
Chris@102: <
Chris@102:     typename T,
Chris@102:     bool IsFundamental = boost::is_fundamental<T>::type::value
Chris@102: >
Chris@102: struct bit_size
Chris@102: {};
Chris@102: 
Chris@102: 
Chris@102: // for fundamental types, just return CHAR_BIT * sizeof(T)
Chris@102: template <typename T>
Chris@102: struct bit_size<T, true>
Chris@102:     : boost::mpl::size_t<(CHAR_BIT * sizeof(T))>
Chris@102: {};
Chris@102: 
Chris@102: 
Chris@102: #if !defined(BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER)
Chris@102: // partial specialization for cpp_int
Chris@102: template
Chris@102: <
Chris@102:     unsigned MinSize,
Chris@102:     unsigned MaxSize,
Chris@102:     boost::multiprecision::cpp_integer_type SignType,
Chris@102:     boost::multiprecision::cpp_int_check_type Checked,
Chris@102:     typename Allocator,
Chris@102:     boost::multiprecision::expression_template_option ExpressionTemplates
Chris@102: >
Chris@102: struct bit_size
Chris@102:     <
Chris@102:         boost::multiprecision::number
Chris@102:             <
Chris@102:                 boost::multiprecision::cpp_int_backend
Chris@102:                     <
Chris@102:                         MinSize, MaxSize, SignType, Checked, Allocator
Chris@102:                     >,
Chris@102:                 ExpressionTemplates
Chris@102:             >,
Chris@102:         false
Chris@102:     > : boost::mpl::size_t<MaxSize>
Chris@102: {};
Chris@102: #endif // BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER
Chris@102: 
Chris@102: 
Chris@102: template
Chris@102: <
Chris@102:     typename T,
Chris@102:     typename Iterator,
Chris@102:     typename EndIterator,
Chris@102:     std::size_t MinSize
Chris@102: >
Chris@102: struct promote_to_larger
Chris@102: {
Chris@102:     typedef typename boost::mpl::deref<Iterator>::type current_type;
Chris@102: 
Chris@102:     typedef typename boost::mpl::if_c
Chris@102:         <
Chris@102:             (bit_size<current_type>::type::value >= MinSize),
Chris@102:             current_type,
Chris@102:             typename promote_to_larger
Chris@102:                 <
Chris@102:                     T,
Chris@102:                     typename boost::mpl::next<Iterator>::type,
Chris@102:                     EndIterator,
Chris@102:                     MinSize
Chris@102:                 >::type
Chris@102:         >::type type;
Chris@102: };
Chris@102: 
Chris@102: // The following specialization is required to finish the loop over
Chris@102: // all list elements
Chris@102: template <typename T, typename EndIterator, std::size_t MinSize>
Chris@102: struct promote_to_larger<T, EndIterator, EndIterator, MinSize>
Chris@102: {
Chris@102:     // if promotion fails, keep the number T
Chris@102:     // (and cross fingers that overflow will not occur)
Chris@102:     typedef T type;
Chris@102: };
Chris@102: 
Chris@102: }} // namespace detail::promote_integral
Chris@102: #endif // DOXYGEN_NO_DETAIL
Chris@102: 
Chris@102: 
Chris@102: 
Chris@102: /*!
Chris@102:     \brief Meta-function to define an integral type with size
Chris@102:     than is (roughly) twice the bit size of T
Chris@102:     \ingroup utility
Chris@102:     \details
Chris@102:     This meta-function tries to promote the fundamental integral type T
Chris@102:     to a another integral type with size (roughly) twice the bit size of T.
Chris@102: 
Chris@102:     To do this, two times the bit size of T is tested against the bit sizes of:
Chris@102:          short, int, long, boost::long_long_type, boost::int128_t
Chris@102:     and the one that first matches is chosen.
Chris@102: 
Chris@102:     For unsigned types the bit size of T is tested against the bit
Chris@102:     sizes of the types above, if T is promoted to a signed type, or
Chris@102:     the bit sizes of
Chris@102:          unsigned short, unsigned int, unsigned long, std::size_t,
Chris@102:          boost::ulong_long_type, boost::uint128_t
Chris@102:     if T is promoted to an unsigned type.
Chris@102: 
Chris@102:     By default an unsigned type is promoted to a signed type.
Chris@102:     This behavior is controlled by the PromoteUnsignedToUnsigned
Chris@102:     boolean template parameter, whose default value is "false".
Chris@102:     To promote an unsigned type to an unsigned type set the value of
Chris@102:     this template parameter to "true".
Chris@102: 
Chris@102:     If the macro BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER is not
Chris@102:     defined, boost's multiprecision integer cpp_int<> is used as a
Chris@102:     last resort.
Chris@102: 
Chris@102:     If BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER is defined and an
Chris@102:     appropriate type cannot be detected, the input type is returned as is.
Chris@102: 
Chris@102:     Finally, if the passed type is either a floating-point type or a
Chris@102:     user-defined type it is returned as is.
Chris@102: 
Chris@102:     \note boost::long_long_type and boost::ulong_long_type are
Chris@102:     considered only if the macro BOOST_HAS_LONG_LONG is defined
Chris@102: 
Chris@102:     \note boost::int128_type and boost::uint128_type are considered
Chris@102:     only if the macros BOOST_HAS_INT128 and BOOST_GEOMETRY_ENABLE_INT128
Chris@102:     are defined
Chris@102: */
Chris@102: template
Chris@102: <
Chris@102:     typename T,
Chris@102:     bool PromoteUnsignedToUnsigned = false,
Chris@102:     bool UseCheckedInteger = false,
Chris@102:     bool IsIntegral = boost::is_integral<T>::type::value
Chris@102: >
Chris@102: class promote_integral
Chris@102: {
Chris@102: private:
Chris@102:     static bool const is_unsigned = boost::is_unsigned<T>::type::value;
Chris@102: 
Chris@102:     typedef detail::promote_integral::bit_size<T> bit_size_type;
Chris@102: 
Chris@102: #if !defined(BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER)
Chris@102:     // Define the proper check policy for the multiprecision integer
Chris@102:     typedef typename boost::mpl::if_c
Chris@102:         <
Chris@102:             UseCheckedInteger,
Chris@102:             boost::integral_constant
Chris@102:                 <
Chris@102:                     boost::multiprecision::cpp_int_check_type,
Chris@102:                     boost::multiprecision::checked
Chris@102:                 >,
Chris@102:             boost::integral_constant
Chris@102:                 <
Chris@102:                     boost::multiprecision::cpp_int_check_type,
Chris@102:                     boost::multiprecision::unchecked
Chris@102:                 >
Chris@102:         >::type check_policy_type;
Chris@102: 
Chris@102:     // Meta-function to get the multiprecision integer type for the
Chris@102:     // given size and sign type (signed/unsigned)
Chris@102:     template
Chris@102:     <
Chris@102:         unsigned int Size,
Chris@102:         boost::multiprecision::cpp_integer_type SignType
Chris@102:     >
Chris@102:     struct multiprecision_integer_type
Chris@102:     {
Chris@102:         typedef boost::multiprecision::number
Chris@102:             <
Chris@102:                 boost::multiprecision::cpp_int_backend
Chris@102:                     <
Chris@102:                         Size,
Chris@102:                         Size,
Chris@102:                         SignType,
Chris@102:                         check_policy_type::value,
Chris@102:                         void
Chris@102:                     >
Chris@102:             > type;
Chris@102:     };
Chris@102: #endif
Chris@102: 
Chris@102:     // Define the minimum size (in bits) needed for the promoted type
Chris@102:     // If T is the input type and P the promoted type, then the
Chris@102:     // minimum number of bits for P are (below b stands for the number
Chris@102:     // of bits of T):
Chris@102:     // * if T is unsigned and P is unsigned: 2 * b
Chris@102:     // * if T is signed and P is signed: 2 * b - 1
Chris@102:     // * if T is unsigned and P is signed: 2 * b + 1
Chris@102:     typedef typename boost::mpl::if_c
Chris@102:         <
Chris@102:             (PromoteUnsignedToUnsigned && is_unsigned),
Chris@102:             boost::mpl::size_t<(2 * bit_size_type::value)>,
Chris@102:             typename boost::mpl::if_c
Chris@102:                 <
Chris@102:                     is_unsigned,
Chris@102:                     boost::mpl::size_t<(2 * bit_size_type::value + 1)>,
Chris@102:                     boost::mpl::size_t<(2 * bit_size_type::value - 1)>
Chris@102:                 >::type
Chris@102:         >::type min_bit_size_type;
Chris@102: 
Chris@102:     // Define the list of signed integral types we are going to use
Chris@102:     // for promotion
Chris@102:     typedef boost::mpl::list
Chris@102:         <
Chris@102:             short, int, long
Chris@102: #if defined(BOOST_HAS_LONG_LONG)
Chris@102:             , boost::long_long_type
Chris@102: #endif
Chris@102: #if defined(BOOST_HAS_INT128) && defined(BOOST_GEOMETRY_ENABLE_INT128)
Chris@102:             , boost::int128_type
Chris@102: #endif
Chris@102: #if !defined(BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER)
Chris@102:             , typename multiprecision_integer_type
Chris@102:                 <
Chris@102:                     min_bit_size_type::value,
Chris@102:                     boost::multiprecision::signed_magnitude
Chris@102:                 >::type
Chris@102: #endif
Chris@102:         > signed_integral_types;
Chris@102: 
Chris@102:     // Define the list of unsigned integral types we are going to use
Chris@102:     // for promotion
Chris@102:     typedef boost::mpl::list
Chris@102:         <
Chris@102:             unsigned short, unsigned int, unsigned long, std::size_t
Chris@102: #if defined(BOOST_HAS_LONG_LONG)
Chris@102:             , boost::ulong_long_type
Chris@102: #endif
Chris@102: #if defined(BOOST_HAS_INT128) && defined(BOOST_GEOMETRY_ENABLE_INT128)
Chris@102:             , boost::uint128_type
Chris@102: #endif
Chris@102: #if !defined(BOOST_GEOMETRY_NO_MULTIPRECISION_INTEGER)
Chris@102:             , typename multiprecision_integer_type
Chris@102:                 <
Chris@102:                     min_bit_size_type::value,
Chris@102:                     boost::multiprecision::unsigned_magnitude
Chris@102:                 >::type
Chris@102: #endif
Chris@102:         > unsigned_integral_types;
Chris@102: 
Chris@102:     // Define the list of integral types that will be used for
Chris@102:     // promotion (depending in whether we was to promote unsigned to
Chris@102:     // unsigned or not)
Chris@102:     typedef typename boost::mpl::if_c
Chris@102:         <
Chris@102:             (is_unsigned && PromoteUnsignedToUnsigned),
Chris@102:             unsigned_integral_types,
Chris@102:             signed_integral_types
Chris@102:         >::type integral_types;
Chris@102: 
Chris@102: public:
Chris@102:     typedef typename detail::promote_integral::promote_to_larger
Chris@102:         <
Chris@102:             T,
Chris@102:             typename boost::mpl::begin<integral_types>::type,
Chris@102:             typename boost::mpl::end<integral_types>::type,
Chris@102:             min_bit_size_type::value
Chris@102:         >::type type;
Chris@102: };
Chris@102: 
Chris@102: 
Chris@102: template <typename T, bool PromoteUnsignedToUnsigned, bool UseCheckedInteger>
Chris@102: class promote_integral
Chris@102:     <
Chris@102:         T, PromoteUnsignedToUnsigned, UseCheckedInteger, false
Chris@102:     >
Chris@102: {
Chris@102: public:
Chris@102:     typedef T type;
Chris@102: };
Chris@102: 
Chris@102: 
Chris@102: }} // namespace boost::geometry
Chris@102: 
Chris@102: #endif // BOOST_GEOMETRY_UTIL_PROMOTE_INTEGRAL_HPP