Dune Core Modules (2.8.0)

overloadset.hh
1// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
2// vi: set et ts=4 sw=2 sts=2:
3#ifndef DUNE_COMMON_OVERLOADSET_HH
4#define DUNE_COMMON_OVERLOADSET_HH
5
6#include <utility>
7#include <type_traits>
9
10namespace Dune {
11
12namespace Impl {
13
14 template<typename... F>
15 class OverloadSet
16 : public F...
17 {
18
19 public:
20
21 template<typename... FF>
22 OverloadSet(FF&&... ff)
23 : F(std::forward<FF>(ff))...
24 {}
25
26 using F::operator()...;
27
28 };
29
30} // end namespace Impl
31
32
33
58template<class... F>
59auto overload(F&&... f)
60{
61 return Impl::OverloadSet<std::decay_t<F>...>(std::forward<F>(f)...);
62}
63
64
65
66namespace Impl {
67
68 template<class F0, class... F>
69 class OrderedOverloadSet: public OrderedOverloadSet<F...>, F0
70 {
71 using Base = OrderedOverloadSet<F...>;
72 public:
73
74 template<class FF0, class... FF>
75 OrderedOverloadSet(FF0&& f0, FF&&... ff) :
76 Base(std::forward<FF>(ff)...),
77 F0(std::forward<FF0>(f0))
78 {}
79
80 // Forward to operator() of F0 if it can be called with the given arguments.
81 template<class... Args,
82 std::enable_if_t<IsCallable<F0(Args&&...)>::value, int> = 0>
83 decltype(auto) operator()(Args&&... args)
84 {
85 return F0::operator()(std::forward<Args>(args)...);
86 }
87
88 // Forward to operator() of base class if F0 cannot be called with the given
89 // arguments. In this case the base class will successively try operator()
90 // of all F... .
91 template<class... Args,
92 std::enable_if_t<not IsCallable<F0(Args&&...)>::value, int> = 0>
93 decltype(auto) operator()(Args&&... args)
94 {
95 return Base::operator()(std::forward<Args>(args)...);
96 }
97
98 };
99
100 template<class F0>
101 class OrderedOverloadSet<F0>: public F0
102 {
103 public:
104
105 template<class FF0>
106 OrderedOverloadSet(FF0&& f0) :
107 F0(std::forward<FF0>(f0))
108 {}
109
110 // Forward to operator() of F0. If it cannot be called with
111 // the given arguments a static assertion will fail.
112 template<class... Args>
113 decltype(auto) operator()(Args&&... args)
114 {
115 static_assert(IsCallable<F0(Args&&...)>::value,
116 "No matching overload found in OrderedOverloadSet");
117 return F0::operator()(std::forward<Args>(args)...);
118 }
119 };
120
121} // end namespace Impl
122
123
124
147template<class... F>
148auto orderedOverload(F&&... f)
149{
150 return Impl::OrderedOverloadSet<std::decay_t<F>...>(std::forward<F>(f)...);
151}
152
153
154
155} // end namespace Dune
156
157#endif // DUNE_COMMON_OVERLOADSET_HH
Traits for type conversions and type information.
auto orderedOverload(F &&... f)
Create an ordered overload set.
Definition: overloadset.hh:148
auto overload(F &&... f)
Create an overload set.
Definition: overloadset.hh:59
Dune namespace.
Definition: alignedallocator.hh:11
STL namespace.
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