/usr/include/dune/common/overloadset.hh is in libdune-common-dev 2.5.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 | // -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_COMMON_OVERLOADSET_HH
#define DUNE_COMMON_OVERLOADSET_HH
#include <utility>
#include <type_traits>
#include <dune/common/std/type_traits.hh>
namespace Dune {
namespace Impl {
// This overload set derives from
// all passed functions. Since we
// cannot do argument pack expansion
// on using statements this is done recursively.
template<class F0, class... F>
class OverloadSet: public OverloadSet<F...>, F0
{
using Base = OverloadSet<F...>;
public:
template<class FF0, class... FF>
OverloadSet(FF0&& f0, FF&&... ff) :
Base(std::forward<FF>(ff)...),
F0(std::forward<FF0>(f0))
{}
// pull in operator() of F0 and of all F... via the base class
using F0::operator();
using Base::operator();
};
template<class F0>
class OverloadSet<F0>: public F0
{
public:
template<class FF0>
OverloadSet(FF0&& f0) :
F0(std::forward<FF0>(f0))
{}
// pull in operator() of F0
using F0::operator();
};
} // end namespace Impl
/**
* \brief Create an overload set
*
* \tparam F List of function object types
* \param f List of function objects
*
* This returns an object that contains all
* operator() implementations of the passed
* functions. All those are available when
* calling operator() of the returned object.
*
* The returned object derives from
* those implementations such that it contains
* all operator() implementations in its
* overload set. When calling operator()
* this will select the best overload.
* If multiple overload are equally good this
* will lead to ambiguity.
*
* Notice that the passed function objects are
* stored by value and must be copy-constructible.
*/
template<class... F>
auto overload(F&&... f)
{
return Impl::OverloadSet<std::decay_t<F>...>(std::forward<F>(f)...);
}
namespace Impl {
template<class F0, class... F>
class OrderedOverloadSet: public OrderedOverloadSet<F...>, F0
{
using Base = OrderedOverloadSet<F...>;
public:
template<class FF0, class... FF>
OrderedOverloadSet(FF0&& f0, FF&&... ff) :
Base(std::forward<FF>(ff)...),
F0(std::forward<FF0>(f0))
{}
// Forward to operator() of F0 if it can be called with the given arguments.
template<class... Args,
std::enable_if_t<Std::is_callable<F0(Args&&...)>::value, int> = 0>
decltype(auto) operator()(Args&&... args)
{
return F0::operator()(std::forward<Args>(args)...);
}
// Forward to operator() of base class if F0 cannot be called with the given
// arguments. In this case the base class will successively try operator()
// of all F... .
template<class... Args,
std::enable_if_t< not Std::is_callable<F0(Args&&...)>::value, int> = 0>
decltype(auto) operator()(Args&&... args)
{
return Base::operator()(std::forward<Args>(args)...);
}
};
template<class F0>
class OrderedOverloadSet<F0>: public F0
{
public:
template<class FF0>
OrderedOverloadSet(FF0&& f0) :
F0(std::forward<FF0>(f0))
{}
// Forward to operator() of F0. If it cannot be called with
// the given arguments a static assertion will fail.
template<class... Args>
decltype(auto) operator()(Args&&... args)
{
static_assert(Std::is_callable<F0(Args&&...)>::value, "No matching overload found in OrderedOverloadSet");
return F0::operator()(std::forward<Args>(args)...);
}
};
} // end namespace Impl
/**
* \brief Create an ordered overload set
*
* \tparam F List of function object types
* \param f List of function objects
*
* This returns an object that contains all
* operator() implementations of the passed
* functions. All those are available when
* calling operator() of the returned object.
*
* In contrast to overload() these overloads
* are ordered in the sense that the first
* matching overload for the given arguments
* is selected and later ones are ignored.
* Hence such a call is never ambiguous.
*
* Notice that the passed function objects are
* stored by value and must be copy-constructible.
*/
template<class... F>
auto orderedOverload(F&&... f)
{
return Impl::OrderedOverloadSet<std::decay_t<F>...>(std::forward<F>(f)...);
}
} // end namespace Dune
#endif // DUNE_COMMON_OVERLOADSET_HH
|