iceoryx_hoofs  2.0.2
variant.hpp
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16 // SPDX-License-Identifier: Apache-2.0
17 #ifndef IOX_HOOFS_CXX_VARIANT_HPP
18 #define IOX_HOOFS_CXX_VARIANT_HPP
19 
20 #include "iceoryx_hoofs/cxx/algorithm.hpp"
21 #include "iceoryx_hoofs/internal/cxx/variant_internal.hpp"
22 
23 #include <cstdint>
24 #include <iostream>
25 #include <limits>
26 #include <type_traits>
27 
28 #include "iceoryx_hoofs/platform/platform_correction.hpp"
29 
30 namespace iox
31 {
32 namespace cxx
33 {
40 template <uint64_t N>
42 {
43  static constexpr uint64_t value = N;
44 };
45 
52 template <typename T>
54 {
55  using type = T;
56 };
57 
70 static constexpr uint64_t INVALID_VARIANT_INDEX = std::numeric_limits<uint64_t>::max();
71 
105 template <typename... Types>
106 class variant
107 {
108  private:
110  static constexpr uint64_t TYPE_SIZE = algorithm::max(sizeof(Types)...);
111 
112  public:
115  constexpr variant() noexcept = default;
116 
125  template <uint64_t N, typename... CTorArguments>
126  constexpr variant(const in_place_index<N>& index, CTorArguments&&... args) noexcept;
127 
135  template <typename T, typename... CTorArguments>
136  constexpr variant(const in_place_type<T>& type, CTorArguments&&... args) noexcept;
137 
141  template <typename T,
142  typename = std::enable_if_t<!std::is_same<std::decay_t<T>, variant>::value>,
143  typename std::enable_if_t<!internal::is_in_place_index<std::decay_t<T>>::value, bool> = false,
144  typename std::enable_if_t<!internal::is_in_place_type<std::decay_t<T>>::value, bool> = false>
145  constexpr variant(T&& arg) noexcept;
146 
150  constexpr variant(const variant& rhs) noexcept;
151 
156  constexpr variant& operator=(const variant& rhs) noexcept;
157 
161  constexpr variant(variant&& rhs) noexcept;
162 
167  constexpr variant& operator=(variant&& rhs) noexcept;
168 
171  ~variant() noexcept;
172 
179  template <typename T>
180  typename std::enable_if<!std::is_same<T, variant<Types...>&>::value, variant<Types...>>::type&
181  operator=(T&& rhs) noexcept;
182 
190  template <uint64_t TypeIndex, typename... CTorArguments>
191  bool emplace_at_index(CTorArguments&&... args) noexcept;
192 
199  template <typename T, typename... CTorArguments>
200  bool emplace(CTorArguments&&... args) noexcept;
201 
211  template <uint64_t TypeIndex>
212  typename internal::get_type_at_index<0, TypeIndex, Types...>::type* get_at_index() noexcept;
213 
223  template <uint64_t TypeIndex>
224  const typename internal::get_type_at_index<0, TypeIndex, Types...>::type* get_at_index() const noexcept;
225 
231  template <typename T>
232  const T* get() const noexcept;
233 
239  template <typename T>
240  T* get() noexcept;
241 
245  template <typename T>
246  T* get_if(T* defaultValue) noexcept;
247 
253  template <typename T>
254  const T* get_if(const T* defaultValue) const noexcept;
255 
259  constexpr uint64_t index() const noexcept;
260 
261  private:
262  alignas(algorithm::max(alignof(Types)...)) internal::byte_t m_storage[TYPE_SIZE]{0u};
263  uint64_t m_type_index = INVALID_VARIANT_INDEX;
264 
265  private:
266  template <typename T>
267  bool has_bad_variant_element_access() const noexcept;
268  static void error_message(const char* source, const char* msg) noexcept;
269 
270  void call_element_destructor() noexcept;
271 };
272 
274 template <typename T, typename... Types>
275 constexpr bool holds_alternative(const variant<Types...>& variant) noexcept;
276 
277 } // namespace cxx
278 } // namespace iox
279 
280 #include "iceoryx_hoofs/internal/cxx/variant.inl"
281 
282 #endif // IOX_HOOFS_CXX_VARIANT_HPP
Variant implementation from the C++17 standard with C++11. The interface is inspired by the C++17 sta...
Definition: variant.hpp:107
internal::get_type_at_index< 0, TypeIndex, Types... >::type * get_at_index() noexcept
returns a pointer to the type stored at index TypeIndex. (not stl compliant)
const T * get() const noexcept
returns a pointer to the type T stored in the variant. (not stl compliant)
bool emplace_at_index(CTorArguments &&... args) noexcept
calls the constructor of the type at index TypeIndex and perfectly forwards the arguments to this con...
constexpr uint64_t index() const noexcept
returns the index of the stored type in the variant. if the variant does not contain any type it retu...
T * get_if(T *defaultValue) noexcept
returns a pointer to the type T if its stored in the variant otherwise it returns the provided defaul...
constexpr variant() noexcept=default
the default constructor constructs a variant which does not contain an element and returns INVALID_VA...
bool emplace(CTorArguments &&... args) noexcept
calls the constructor of the type T and perfectly forwards the arguments to the constructor of T.
building block to easily create free function for logging in a library context
Definition: lockfree_queue.hpp:29
helper struct to perform an emplacement at a predefined index in the constructor of a variant
Definition: variant.hpp:42
helper struct to perform an emplacement of a predefined type in in the constructor of a variant
Definition: variant.hpp:54