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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_CONTAINER_INTERNAL_CONTAINER_H_
#define ABSL_CONTAINER_INTERNAL_CONTAINER_H_
#include <cassert>
#include <type_traits>
#include "absl/meta/type_traits.h"
#include "absl/types/optional.h"
namespace absl {
namespace container_internal {
template <class, class = void>
struct IsTransparent : std::false_type {};
template <class T>
struct IsTransparent<T, absl::void_t<typename T::is_transparent>>
: std::true_type {};
template <bool is_transparent>
struct KeyArg {
// Transparent. Forward `K`.
template <typename K, typename key_type>
using type = K;
};
template <>
struct KeyArg<false> {
// Not transparent. Always use `key_type`.
template <typename K, typename key_type>
using type = key_type;
};
// The node_handle concept from C++17.
// We specialize node_handle for sets and maps. node_handle_base holds the
// common API of both.
template <typename PolicyTraits, typename Alloc>
class node_handle_base {
protected:
using slot_type = typename PolicyTraits::slot_type;
public:
using allocator_type = Alloc;
constexpr node_handle_base() {}
node_handle_base(node_handle_base&& other) noexcept {
*this = std::move(other);
}
~node_handle_base() { destroy(); }
node_handle_base& operator=(node_handle_base&& other) noexcept {
destroy();
if (!other.empty()) {
alloc_ = other.alloc_;
PolicyTraits::transfer(alloc(), slot(), other.slot());
other.reset();
}
return *this;
}
bool empty() const noexcept { return !alloc_; }
explicit operator bool() const noexcept { return !empty(); }
allocator_type get_allocator() const { return *alloc_; }
protected:
friend struct CommonAccess;
struct transfer_tag_t {};
node_handle_base(transfer_tag_t, const allocator_type& a, slot_type* s)
: alloc_(a) {
PolicyTraits::transfer(alloc(), slot(), s);
}
struct move_tag_t {};
node_handle_base(move_tag_t, const allocator_type& a, slot_type* s)
: alloc_(a) {
PolicyTraits::construct(alloc(), slot(), s);
}
void destroy() {
if (!empty()) {
PolicyTraits::destroy(alloc(), slot());
reset();
}
}
void reset() {
assert(alloc_.has_value());
alloc_ = absl::nullopt;
}
slot_type* slot() const {
assert(!empty());
return reinterpret_cast<slot_type*>(std::addressof(slot_space_));
}
allocator_type* alloc() { return std::addressof(*alloc_); }
private:
absl::optional<allocator_type> alloc_;
mutable absl::aligned_storage_t<sizeof(slot_type), alignof(slot_type)>
slot_space_;
};
// For sets.
template <typename Policy, typename PolicyTraits, typename Alloc,
typename = void>
class node_handle : public node_handle_base<PolicyTraits, Alloc> {
using Base = node_handle_base<PolicyTraits, Alloc>;
public:
using value_type = typename PolicyTraits::value_type;
constexpr node_handle() {}
value_type& value() const { return PolicyTraits::element(this->slot()); }
private:
friend struct CommonAccess;
using Base::Base;
};
// For maps.
template <typename Policy, typename PolicyTraits, typename Alloc>
class node_handle<Policy, PolicyTraits, Alloc,
absl::void_t<typename Policy::mapped_type>>
: public node_handle_base<PolicyTraits, Alloc> {
using Base = node_handle_base<PolicyTraits, Alloc>;
public:
using key_type = typename Policy::key_type;
using mapped_type = typename Policy::mapped_type;
constexpr node_handle() {}
auto key() const -> decltype(PolicyTraits::key(this->slot())) {
return PolicyTraits::key(this->slot());
}
mapped_type& mapped() const {
return PolicyTraits::value(&PolicyTraits::element(this->slot()));
}
private:
friend struct CommonAccess;
using Base::Base;
};
// Provide access to non-public node-handle functions.
struct CommonAccess {
template <typename Node>
static auto GetSlot(const Node& node) -> decltype(node.slot()) {
return node.slot();
}
template <typename Node>
static void Destroy(Node* node) {
node->destroy();
}
template <typename Node>
static void Reset(Node* node) {
node->reset();
}
template <typename T, typename... Args>
static T Transfer(Args&&... args) {
return T(typename T::transfer_tag_t{}, std::forward<Args>(args)...);
}
template <typename T, typename... Args>
static T Move(Args&&... args) {
return T(typename T::move_tag_t{}, std::forward<Args>(args)...);
}
};
// Implement the insert_return_type<> concept of C++17.
template <class Iterator, class NodeType>
struct InsertReturnType {
Iterator position;
bool inserted;
NodeType node;
};
} // namespace container_internal
} // namespace absl
#endif // ABSL_CONTAINER_INTERNAL_CONTAINER_H_
|
