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
|
/*
* GridTools
*
* Copyright (c) 2014-2019, ETH Zurich
* All rights reserved.
*
* Please, refer to the LICENSE file in the root directory.
* SPDX-License-Identifier: BSD-3-Clause
*/
#pragma once
#include <memory>
#include <type_traits>
#include <typeinfo>
#include <utility>
namespace cpp_bindgen {
struct bad_any_cast : std::bad_cast {
const char *what() const noexcept override { return "cpp_bindgen::bad_any_cast"; }
};
/**
* this class implements the subset of std::any interface and can hold move only objects.
*
* TODO(anstaf): implement missing std::any components: piecewise ctors, emplace, reset, swap, make_any
*/
class any_moveable {
struct iface {
virtual ~iface() = default;
virtual std::type_info const &type() const noexcept = 0;
};
template <class T>
struct impl : iface {
T m_obj;
impl(T const &obj) : m_obj(obj) {}
impl(T &&obj) : m_obj(std::move(obj)) {}
std::type_info const &type() const noexcept override { return typeid(T); }
};
std::unique_ptr<iface> m_impl;
public:
any_moveable() = default;
template <class Arg, class Decayed = typename std::decay<Arg>::type>
any_moveable(Arg &&arg) : m_impl(new impl<Decayed>(std::forward<Arg>(arg))) {}
any_moveable(any_moveable &&) = default;
template <class Arg, class Decayed = typename std::decay<Arg>::type>
any_moveable &operator=(Arg &&obj) {
m_impl.reset(new impl<Decayed>(std::forward<Arg>(obj)));
return *this;
}
any_moveable &operator=(any_moveable &&) = default;
bool has_value() const noexcept { return !!m_impl; }
std::type_info const &type() const noexcept { return m_impl->type(); }
template <class T>
friend T *any_cast(any_moveable *src) noexcept {
return src && src->type() == typeid(T) ? &static_cast<impl<T> *>(src->m_impl.get())->m_obj : nullptr;
}
};
template <class T>
T const *any_cast(any_moveable const *src) noexcept {
return any_cast<T>(const_cast<any_moveable *>(src));
}
template <class T>
T any_cast(any_moveable &src) {
auto *ptr = any_cast<typename std::remove_reference<T>::type>(&src);
if (!ptr)
throw bad_any_cast{};
using ref_t = typename std::
conditional<std::is_reference<T>::value, T, typename std::add_lvalue_reference<T>::type>::type;
return static_cast<ref_t>(*ptr);
}
template <class T>
T any_cast(any_moveable const &src) {
return any_cast<T>(const_cast<any_moveable &>(src));
}
template <class T>
T any_cast(any_moveable &&src) {
static_assert(
std::is_rvalue_reference<T &&>::value || std::is_const<typename std::remove_reference<T>::type>::value,
"any_cast shall not be used for getting nonconst references to temporary objects");
return any_cast<T>(src);
}
} // namespace cpp_bindgen
|
