Chris@16: // Boost.Geometry (aka GGL, Generic Geometry Library)
Chris@16: 
Chris@16: // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
Chris@16: // Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
Chris@16: // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
Chris@16: 
Chris@101: // This file was modified by Oracle on 2014.
Chris@101: // Modifications copyright (c) 2014 Oracle and/or its affiliates.
Chris@101: 
Chris@101: // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
Chris@101: 
Chris@16: // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
Chris@16: // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
Chris@16: 
Chris@16: // Use, modification and distribution is subject to the Boost Software License,
Chris@16: // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_GEOMETRY_UTIL_SELECT_MOST_PRECISE_HPP
Chris@16: #define BOOST_GEOMETRY_UTIL_SELECT_MOST_PRECISE_HPP
Chris@16: 
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: #include <boost/type_traits.hpp>
Chris@16: 
Chris@16: 
Chris@16: namespace boost { namespace geometry
Chris@16: {
Chris@16: 
Chris@16: #ifndef DOXYGEN_NO_DETAIL
Chris@16: 
Chris@16: namespace detail { namespace select_most_precise
Chris@16: {
Chris@16: 
Chris@16: 
Chris@16: // At least one of the types is non-fundamental. Take that one.
Chris@16: // if both are non-fundamental, the type-to-be-selected
Chris@16: // is unknown, it should be defined by explicit specialization.
Chris@16: template <bool Fundamental1, bool Fundamental2, typename T1, typename T2>
Chris@16: struct select_non_fundamental
Chris@16: {
Chris@16:     typedef T1 type;
Chris@16: };
Chris@16: 
Chris@16: template <typename T1, typename T2>
Chris@16: struct select_non_fundamental<true, false, T1, T2>
Chris@16: {
Chris@16:     typedef T2 type;
Chris@16: };
Chris@16: 
Chris@16: template <typename T1, typename T2>
Chris@16: struct select_non_fundamental<false, true, T1, T2>
Chris@16: {
Chris@16:     typedef T1 type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: // Selection of largest type (e.g. int of <short int,int>
Chris@16: // It defaults takes the first one, if second is larger, take the second one
Chris@16: template <bool SecondLarger, typename T1, typename T2>
Chris@16: struct select_largest
Chris@16: {
Chris@16:     typedef T1 type;
Chris@16: };
Chris@16: 
Chris@16: template <typename T1, typename T2>
Chris@16: struct select_largest<true, T1, T2>
Chris@16: {
Chris@16:     typedef T2 type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: // Selection of floating point and specializations:
Chris@16: // both FP or both !FP does never occur...
Chris@16: template <bool FP1, bool FP2, typename T1, typename T2>
Chris@16: struct select_floating_point
Chris@16: {
Chris@16:     typedef char type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: // ... so if ONE but not both of these types is floating point, take that one
Chris@16: template <typename T1, typename T2>
Chris@16: struct select_floating_point<true, false, T1, T2>
Chris@16: {
Chris@16:     typedef T1 type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: template <typename T1, typename T2>
Chris@16: struct select_floating_point<false, true, T1, T2>
Chris@16: {
Chris@16:     typedef T2 type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: }} // namespace detail::select_most_precise
Chris@16: #endif // DOXYGEN_NO_DETAIL
Chris@16: 
Chris@16: 
Chris@16: /*!
Chris@16:     \brief Meta-function to select, of two types, the most accurate type for
Chris@16:         calculations
Chris@16:     \ingroup utility
Chris@16:     \details select_most_precise classes, compares two types on compile time.
Chris@16:     For example, if an addition must be done with a double and an integer, the
Chris@16:         result must be a double.
Chris@16:     If both types are integer, the result can be an integer.
Chris@16:     \note It is different from the "promote" class, already in boost. That
Chris@16:         class promotes e.g. a (one) float to a double. This class selects a
Chris@16:         type from two types. It takes the most accurate, but does not promote
Chris@16:         afterwards.
Chris@16:     \note This traits class is completely independant from GGL and might be a
Chris@16:         separate addition to Boost
Chris@16:     \note If the input is a non-fundamental type, it might be a calculation
Chris@16:         type such as a GMP-value or another high precision value. Therefore,
Chris@16:         if one is non-fundamental, that one is chosen.
Chris@16:     \note If both types are non-fundamental, the result is indeterminate and
Chris@16:         currently the first one is chosen.
Chris@16: */
Chris@101: template <typename T1, typename T2 = void, typename T3 = void>
Chris@101: struct select_most_precise
Chris@101: {
Chris@101:     typedef typename select_most_precise
Chris@101:         <
Chris@101:             typename select_most_precise<T1, T2>::type,
Chris@101:             T3
Chris@101:         >::type type;
Chris@101: };
Chris@101: 
Chris@16: template <typename T1, typename T2>
Chris@101: struct select_most_precise<T1, T2, void>
Chris@16: {
Chris@16:     static const bool second_larger = sizeof(T2) > sizeof(T1);
Chris@16:     static const bool one_not_fundamental = !
Chris@16:         (boost::is_fundamental<T1>::type::value
Chris@16:           && boost::is_fundamental<T2>::type::value);
Chris@16: 
Chris@16:     static const bool both_same =
Chris@16:         boost::is_floating_point<T1>::type::value
Chris@16:         == boost::is_floating_point<T2>::type::value;
Chris@16: 
Chris@16:     typedef typename boost::mpl::if_c
Chris@16:         <
Chris@16:             one_not_fundamental,
Chris@16:             typename detail::select_most_precise::select_non_fundamental
Chris@16:             <
Chris@16:                 boost::is_fundamental<T1>::type::value,
Chris@16:                 boost::is_fundamental<T2>::type::value,
Chris@16:                 T1,
Chris@16:                 T2
Chris@16:             >::type,
Chris@16:             typename boost::mpl::if_c
Chris@16:             <
Chris@16:                 both_same,
Chris@16:                 typename detail::select_most_precise::select_largest
Chris@16:                 <
Chris@16:                     second_larger,
Chris@16:                     T1,
Chris@16:                     T2
Chris@16:                 >::type,
Chris@16:                 typename detail::select_most_precise::select_floating_point
Chris@16:                 <
Chris@16:                     boost::is_floating_point<T1>::type::value,
Chris@16:                     boost::is_floating_point<T2>::type::value,
Chris@16:                     T1,
Chris@16:                     T2
Chris@16:                 >::type
Chris@16:             >::type
Chris@16:         >::type type;
Chris@16: };
Chris@16: 
Chris@101: template <typename T1>
Chris@101: struct select_most_precise<T1, void, void>
Chris@101: {
Chris@101:     typedef T1 type;
Chris@101: };
Chris@16: 
Chris@16: }} // namespace boost::geometry
Chris@16: 
Chris@16: #endif // BOOST_GEOMETRY_UTIL_SELECT_MOST_PRECISE_HPP