1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
// This file was modified by Oracle on 2014.
// Modifications copyright (c) 2014 Oracle and/or its affiliates.
// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_GEOMETRY_UTIL_SELECT_MOST_PRECISE_HPP
#define BOOST_GEOMETRY_UTIL_SELECT_MOST_PRECISE_HPP
#include <boost/mpl/if.hpp>
#include <boost/type_traits.hpp>
namespace boost { namespace geometry
{
#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace select_most_precise
{
// At least one of the types is non-fundamental. Take that one.
// if both are non-fundamental, the type-to-be-selected
// is unknown, it should be defined by explicit specialization.
template <bool Fundamental1, bool Fundamental2, typename T1, typename T2>
struct select_non_fundamental
{
typedef T1 type;
};
template <typename T1, typename T2>
struct select_non_fundamental<true, false, T1, T2>
{
typedef T2 type;
};
template <typename T1, typename T2>
struct select_non_fundamental<false, true, T1, T2>
{
typedef T1 type;
};
// Selection of largest type (e.g. int of <short int,int>
// It defaults takes the first one, if second is larger, take the second one
template <bool SecondLarger, typename T1, typename T2>
struct select_largest
{
typedef T1 type;
};
template <typename T1, typename T2>
struct select_largest<true, T1, T2>
{
typedef T2 type;
};
// Selection of floating point and specializations:
// both FP or both !FP does never occur...
template <bool FP1, bool FP2, typename T1, typename T2>
struct select_floating_point
{
typedef char type;
};
// ... so if ONE but not both of these types is floating point, take that one
template <typename T1, typename T2>
struct select_floating_point<true, false, T1, T2>
{
typedef T1 type;
};
template <typename T1, typename T2>
struct select_floating_point<false, true, T1, T2>
{
typedef T2 type;
};
}} // namespace detail::select_most_precise
#endif // DOXYGEN_NO_DETAIL
/*!
\brief Meta-function to select, of two types, the most accurate type for
calculations
\ingroup utility
\details select_most_precise classes, compares two types on compile time.
For example, if an addition must be done with a double and an integer, the
result must be a double.
If both types are integer, the result can be an integer.
\note It is different from the "promote" class, already in boost. That
class promotes e.g. a (one) float to a double. This class selects a
type from two types. It takes the most accurate, but does not promote
afterwards.
\note This traits class is completely independant from GGL and might be a
separate addition to Boost
\note If the input is a non-fundamental type, it might be a calculation
type such as a GMP-value or another high precision value. Therefore,
if one is non-fundamental, that one is chosen.
\note If both types are non-fundamental, the result is indeterminate and
currently the first one is chosen.
*/
template <typename T1, typename T2 = void, typename T3 = void>
struct select_most_precise
{
typedef typename select_most_precise
<
typename select_most_precise<T1, T2>::type,
T3
>::type type;
};
template <typename T1, typename T2>
struct select_most_precise<T1, T2, void>
{
static const bool second_larger = sizeof(T2) > sizeof(T1);
static const bool one_not_fundamental = !
(boost::is_fundamental<T1>::type::value
&& boost::is_fundamental<T2>::type::value);
static const bool both_same =
boost::is_floating_point<T1>::type::value
== boost::is_floating_point<T2>::type::value;
typedef typename boost::mpl::if_c
<
one_not_fundamental,
typename detail::select_most_precise::select_non_fundamental
<
boost::is_fundamental<T1>::type::value,
boost::is_fundamental<T2>::type::value,
T1,
T2
>::type,
typename boost::mpl::if_c
<
both_same,
typename detail::select_most_precise::select_largest
<
second_larger,
T1,
T2
>::type,
typename detail::select_most_precise::select_floating_point
<
boost::is_floating_point<T1>::type::value,
boost::is_floating_point<T2>::type::value,
T1,
T2
>::type
>::type
>::type type;
};
template <typename T1>
struct select_most_precise<T1, void, void>
{
typedef T1 type;
};
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_UTIL_SELECT_MOST_PRECISE_HPP
|
