node_hash_policy.h
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1 // Copyright 2018 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 //
15 // Adapts a policy for nodes.
16 //
17 // The node policy should model:
18 //
19 // struct Policy {
20 // // Returns a new node allocated and constructed using the allocator, using
21 // // the specified arguments.
22 // template <class Alloc, class... Args>
23 // value_type* new_element(Alloc* alloc, Args&&... args) const;
24 //
25 // // Destroys and deallocates node using the allocator.
26 // template <class Alloc>
27 // void delete_element(Alloc* alloc, value_type* node) const;
28 // };
29 //
30 // It may also optionally define `value()` and `apply()`. For documentation on
31 // these, see hash_policy_traits.h.
32 
33 #ifndef ABSL_CONTAINER_INTERNAL_NODE_HASH_POLICY_H_
34 #define ABSL_CONTAINER_INTERNAL_NODE_HASH_POLICY_H_
35 
36 #include <cassert>
37 #include <cstddef>
38 #include <memory>
39 #include <type_traits>
40 #include <utility>
41 
42 namespace absl {
43 namespace container_internal {
44 
45 template <class Reference, class Policy>
48 
49  using slot_type = typename std::remove_cv<
50  typename std::remove_reference<Reference>::type>::type*;
51 
52  template <class Alloc, class... Args>
53  static void construct(Alloc* alloc, slot_type* slot, Args&&... args) {
54  *slot = Policy::new_element(alloc, std::forward<Args>(args)...);
55  }
56 
57  template <class Alloc>
58  static void destroy(Alloc* alloc, slot_type* slot) {
59  Policy::delete_element(alloc, *slot);
60  }
61 
62  template <class Alloc>
63  static void transfer(Alloc*, slot_type* new_slot, slot_type* old_slot) {
64  *new_slot = *old_slot;
65  }
66 
67  static size_t space_used(const slot_type* slot) {
68  if (slot == nullptr) return Policy::element_space_used(nullptr);
69  return Policy::element_space_used(*slot);
70  }
71 
72  static Reference element(slot_type* slot) { return **slot; }
73 
74  template <class T, class P = Policy>
75  static auto value(T* elem) -> decltype(P::value(elem)) {
76  return P::value(elem);
77  }
78 
79  template <class... Ts, class P = Policy>
80  static auto apply(Ts&&... ts) -> decltype(P::apply(std::forward<Ts>(ts)...)) {
81  return P::apply(std::forward<Ts>(ts)...);
82  }
83 };
84 
85 } // namespace container_internal
86 } // namespace absl
87 
88 #endif // ABSL_CONTAINER_INTERNAL_NODE_HASH_POLICY_H_
static auto apply(Ts &&... ts) -> decltype(P::apply(std::forward< Ts >(ts)...))
static size_t space_used(const slot_type *slot)
static void transfer(Alloc *, slot_type *new_slot, slot_type *old_slot)
static void destroy(Alloc *alloc, slot_type *slot)
static auto value(T *elem) -> decltype(P::value(elem))
typename std::remove_cv< typename std::remove_reference< Reference >::type >::type * slot_type
Definition: algorithm.h:29
static Reference element(slot_type *slot)
size_t value
static void construct(Alloc *alloc, slot_type *slot, Args &&... args)
std::allocator< int > alloc
MockFunction< int(int)> apply


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autogenerated on Mon Feb 28 2022 21:31:19