1 ///////////////////////////////////////////////////////////////////////////////
2 // Copyright 2016 John Maddock. Distributed under the Boost
3 // Software License, Version 1.0. (See accompanying file
4 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
5
6 #ifndef BOOST_MP_MIN_MAX_HPP
7 #define BOOST_MP_MIN_MAX_HPP
8
9 #include <boost/multiprecision/traits/is_backend.hpp>
10
11 namespace boost{ namespace multiprecision{
12
13 //
14 // Expression template overloads for (min) and (max):
15 //
16 // Introduced in response to https://svn.boost.org/trac/boost/ticket/11149
17 // note that these can not legally be injected into namespace std, and that doing so
18 // may break future enhancements to the standard. None the less adding
19 // namespace std{ using boost::multiprecision::(min); using boost::multiprecision::(max); }
20 // to your code may get some generic code working that wouldn't work otherwise.
21 //
22 // The use of enable_if on the return type is to avoid poisoning std::min/max,
23 // otherwise attempting to make an explicit call to min<long>(a, b) when these and std
24 // versions are in scope, will cause the compiler to try to instantiate the signatures
25 // for our versions as well as the std ones, which in turn instantiates number<long>
26 // which fails to compile as "long" is not a valid backend type.
27 //
28 template <class Backend>
type(min)29 inline typename boost::enable_if_c < boost::multiprecision::detail::is_backend<Backend>::value, const number<Backend, et_on>&>::type
30 (min)(const number<Backend, et_on>& a, const number<Backend, et_on>& b)
31 {
32 return a < b ? a : b;
33 }
34 template <class Backend, class tag, class A1, class A2, class A3, class A4>
type(min)35 inline typename boost::enable_if_c < boost::multiprecision::detail::is_backend<Backend>::value, const number<Backend, et_on> >::type
36 (min)(const number<Backend, et_on>& a, const detail::expression<tag, A1, A2, A3, A4>& b)
37 {
38 number<Backend, et_on> t(b);
39 if(a < t)
40 return a;
41 return BOOST_MP_MOVE(t);
42 }
43 template <class tag, class A1, class A2, class A3, class A4, class Backend>
type(min)44 inline typename boost::enable_if_c < boost::multiprecision::detail::is_backend<Backend>::value, const number<Backend, et_on> >::type
45 (min)(const detail::expression<tag, A1, A2, A3, A4>& a, const number<Backend, et_on>& b)
46 {
47 number<Backend, et_on> t(a);
48 if(t < b)
49 return BOOST_MP_MOVE(t);
50 return b;
51 }
52 template <class tag, class A1, class A2, class A3, class A4, class tagb, class A1b, class A2b, class A3b, class A4b>
result_type(min)53 inline typename detail::expression<tag, A1, A2, A3, A4>::result_type
54 (min)(const detail::expression<tag, A1, A2, A3, A4>& a, const detail::expression<tagb, A1b, A2b, A3b, A4b>& b)
55 {
56 typename detail::expression<tag, A1, A2, A3, A4>::result_type t1(a), t2(b);
57 if(t1 < t2)
58 return BOOST_MP_MOVE(t1);
59 return BOOST_MP_MOVE(t2);
60 }
61 template <class tag, class A1, class A2, class A3, class A4>
result_type(min)62 inline typename detail::expression<tag, A1, A2, A3, A4>::result_type (min)(const detail::expression<tag, A1, A2, A3, A4>& a, const detail::expression<tag, A1, A2, A3, A4>& b)
63 {
64 typename detail::expression<tag, A1, A2, A3, A4>::result_type t1(a), t2(b);
65 if(t1 < t2)
66 return BOOST_MP_MOVE(t1);
67 return BOOST_MP_MOVE(t2);
68 }
69
70 template <class Backend>
type(max)71 inline typename boost::enable_if_c < boost::multiprecision::detail::is_backend<Backend>::value, const number<Backend, et_on>&>::type
72 (max)(const number<Backend, et_on>& a, const number<Backend, et_on>& b)
73 {
74 return a > b ? a : b;
75 }
76 template <class Backend, class tag, class A1, class A2, class A3, class A4>
type(max)77 inline typename boost::enable_if_c < boost::multiprecision::detail::is_backend<Backend>::value, const number<Backend, et_on> >::type
78 (max)(const number<Backend, et_on>& a, const detail::expression<tag, A1, A2, A3, A4>& b)
79 {
80 number<Backend, et_on> t(b);
81 if(a > t)
82 return a;
83 return BOOST_MP_MOVE(t);
84 }
85 template <class tag, class A1, class A2, class A3, class A4, class Backend>
type(max)86 inline typename boost::enable_if_c < boost::multiprecision::detail::is_backend<Backend>::value, const number<Backend, et_on> >::type
87 (max)(const detail::expression<tag, A1, A2, A3, A4>& a, const number<Backend, et_on>& b)
88 {
89 number<Backend, et_on> t(a);
90 if(t > b)
91 return BOOST_MP_MOVE(t);
92 return b;
93 }
94 template <class tag, class A1, class A2, class A3, class A4, class tagb, class A1b, class A2b, class A3b, class A4b>
result_type(max)95 inline typename detail::expression<tag, A1, A2, A3, A4>::result_type
96 (max)(const detail::expression<tag, A1, A2, A3, A4>& a, const detail::expression<tagb, A1b, A2b, A3b, A4b>& b)
97 {
98 typename detail::expression<tag, A1, A2, A3, A4>::result_type t1(a), t2(b);
99 if(t1 > t2)
100 return BOOST_MP_MOVE(t1);
101 return BOOST_MP_MOVE(t2);
102 }
103 template <class tag, class A1, class A2, class A3, class A4>
result_type(max)104 inline typename detail::expression<tag, A1, A2, A3, A4>::result_type (max)(const detail::expression<tag, A1, A2, A3, A4>& a, const detail::expression<tag, A1, A2, A3, A4>& b)
105 {
106 typename detail::expression<tag, A1, A2, A3, A4>::result_type t1(a), t2(b);
107 if(t1 > t2)
108 return BOOST_MP_MOVE(t1);
109 return BOOST_MP_MOVE(t2);
110 }
111
112 }} // namespaces
113
114 #endif
115