spot  2.12.2
casts.hh
1 // -*- coding: utf-8 -*-
2 // Copyright (C) by the Spot authors, see the AUTHORS file for details.
3 //
4 // This file is part of Spot, a model checking library.
5 //
6 // Spot is free software; you can redistribute it and/or modify it
7 // under the terms of the GNU General Public License as published by
8 // the Free Software Foundation; either version 3 of the License, or
9 // (at your option) any later version.
10 //
11 // Spot is distributed in the hope that it will be useful, but WITHOUT
12 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 // or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 // License for more details.
15 //
16 // You should have received a copy of the GNU General Public License
17 // along with this program. If not, see <http://www.gnu.org/licenses/>.
18 
19 #pragma once
20 
21 #include <memory>
22 #include <type_traits>
23 
24 // We usually write code like
25 // subtypename* i = down_cast<subtypename*>(m);
26 // ... use i ...
27 // When NDEBUG is set, the down_cast is a fast static_cast.
28 // Otherwise, the down_cast is a dynamic_cast and may return 0
29 // on error, which is caught by an assert in the down_cast function.
30 //
31 // NB: It is valid to use down_cast with non-pointer template argument:
32 // subtypename& i = down_cast<subtypename&>(m);
33 // If an error occurs during the cast, an exception is thrown.
34 //
35 // NB: down_cast can also be used on shared_ptr.
36 namespace spot
37 {
38  template<typename T, typename U>
39  inline
40  T down_cast(U* u) noexcept
41  {
42  SPOT_ASSERT(dynamic_cast<T>(u));
43  return static_cast<T>(u);
44  }
45 
46  template<typename T, typename U>
47  inline
48  T down_cast(const std::shared_ptr<U>& u) noexcept
49  {
50  SPOT_ASSERT(std::dynamic_pointer_cast<typename T::element_type>(u));
51  return std::static_pointer_cast<typename T::element_type>(u);
52  }
53 
54  template<typename T, typename U>
55  inline
56  T down_cast(U u)
57 #ifdef NDEBUG
58  noexcept
59 #endif
60  {
61 #ifdef NDEBUG
62  return static_cast<T>(u);
63 #else
64  return dynamic_cast<T>(u);
65 #endif
66  }
67 
68 } // namespace spot
Definition: automata.hh:26

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