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Sacado_mpl_is_convertible.hpp
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1// @HEADER
2// ***********************************************************************
3//
4// Sacado Package
5// Copyright (2006) Sandia Corporation
6//
7// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
8// the U.S. Government retains certain rights in this software.
9//
10// This library is free software; you can redistribute it and/or modify
11// it under the terms of the GNU Lesser General Public License as
12// published by the Free Software Foundation; either version 2.1 of the
13// License, or (at your option) any later version.
14//
15// This library is distributed in the hope that it will be useful, but
16// WITHOUT ANY WARRANTY; without even the implied warranty of
17// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18// Lesser General Public License for more details.
19//
20// You should have received a copy of the GNU Lesser General Public
21// License along with this library; if not, write to the Free Software
22// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
23// USA
24// Questions? Contact David M. Gay (dmgay@sandia.gov) or Eric T. Phipps
25// (etphipp@sandia.gov).
26//
27// ***********************************************************************
28// @HEADER
29
30#ifndef SACADO_MPL_IS_CONVERTIBLE_HPP
31#define SACADO_MPL_IS_CONVERTIBLE_HPP
32
33#include "Sacado_ConfigDefs.h"
34
35#ifdef HAVE_SACADO_CXX11
36
37#include <type_traits>
38namespace Sacado {
39 namespace mpl {
40 using std::is_convertible;
41 }
42}
43
44#else
45
46namespace Sacado {
47
48 namespace mpl {
49
50 //
51 // A simplified implementation of boost type-trait
52 // is_convertible<From,To>. We use this in a much more limited context
53 // within Sacado, and so the easy implementation should always work.
54 // We assume From and To are "scalar" types, e.g., are not pointer or
55 // reference types.
56 //
57
59 typedef char yes; // sizeof(yes) == 1
60 typedef char (&no)[2]; // sizeof(no) == 2
61
62 // A function that takes anything convertible to a To
63 template <typename To> static yes tester(To);
64
65 // Overload resolution prefers anything over ...
66 template <typename To> static no tester(...);
67
68 // Check if From is convertible to To
69 template <typename From, typename To>
70 struct checker {
71 static From& f;
72 static const bool value = sizeof(tester<To>(f)) == sizeof(yes);
73 };
74 };
75
76 template <typename From, typename To>
79 };
80
81 }
82
83}
84
85#endif
86
87#endif // SACADO_MPL_IS_CONVERTIBLE_HPP