1 | // Copyright 2019 Google LLC |
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 | #ifndef dap_any_h |
16 | #define dap_any_h |
17 | |
18 | #include "typeinfo.h" |
19 | |
20 | #include <assert.h> |
21 | #include <stdint.h> |
22 | |
23 | namespace dap { |
24 | |
25 | template <typename T> |
26 | struct TypeOf; |
27 | |
28 | // any provides a type-safe container for values of any of dap type (boolean, |
29 | // integer, number, array, variant, any, null, dap-structs). |
30 | class any { |
31 | public: |
32 | // constructors |
33 | inline any() = default; |
34 | inline any(const any& other) noexcept; |
35 | inline any(any&& other) noexcept; |
36 | |
37 | template <typename T> |
38 | inline any(const T& val); |
39 | |
40 | // destructors |
41 | inline ~any(); |
42 | |
43 | // replaces the contained value with a null. |
44 | inline void reset(); |
45 | |
46 | // assignment |
47 | inline any& operator=(const any& rhs); |
48 | inline any& operator=(any&& rhs) noexcept; |
49 | template <typename T> |
50 | inline any& operator=(const T& val); |
51 | |
52 | // get() returns the contained value of the type T. |
53 | // If the any does not contain a value of type T, then get() will assert. |
54 | template <typename T> |
55 | inline T& get() const; |
56 | |
57 | // is() returns true iff the contained value is of type T. |
58 | template <typename T> |
59 | inline bool is() const; |
60 | |
61 | private: |
62 | static inline void* alignUp(void* val, size_t alignment); |
63 | inline void alloc(size_t size, size_t align); |
64 | inline void free(); |
65 | inline bool isInBuffer(void* ptr) const; |
66 | |
67 | void* value = nullptr; |
68 | const TypeInfo* type = nullptr; |
69 | void* heap = nullptr; // heap allocation |
70 | uint8_t buffer[32]; // or internal allocation |
71 | }; |
72 | |
73 | inline any::~any() { |
74 | reset(); |
75 | } |
76 | |
77 | template <typename T> |
78 | inline any::any(const T& val) { |
79 | *this = val; |
80 | } |
81 | |
82 | any::any(const any& other) noexcept : type(other.type) { |
83 | if (other.value != nullptr) { |
84 | alloc(type->size(), type->alignment()); |
85 | type->copyConstruct(value, other.value); |
86 | } |
87 | } |
88 | |
89 | any::any(any&& other) noexcept : type(other.type) { |
90 | if (other.isInBuffer(other.value)) { |
91 | alloc(type->size(), type->alignment()); |
92 | type->copyConstruct(value, other.value); |
93 | } else { |
94 | value = other.value; |
95 | } |
96 | other.value = nullptr; |
97 | other.type = nullptr; |
98 | } |
99 | |
100 | void any::reset() { |
101 | if (value != nullptr) { |
102 | type->destruct(value); |
103 | free(); |
104 | } |
105 | value = nullptr; |
106 | type = nullptr; |
107 | } |
108 | |
109 | any& any::operator=(const any& rhs) { |
110 | reset(); |
111 | type = rhs.type; |
112 | if (rhs.value != nullptr) { |
113 | alloc(type->size(), type->alignment()); |
114 | type->copyConstruct(value, rhs.value); |
115 | } |
116 | return *this; |
117 | } |
118 | |
119 | any& any::operator=(any&& rhs) noexcept { |
120 | reset(); |
121 | type = rhs.type; |
122 | if (rhs.isInBuffer(rhs.value)) { |
123 | alloc(type->size(), type->alignment()); |
124 | type->copyConstruct(value, rhs.value); |
125 | } else { |
126 | value = rhs.value; |
127 | } |
128 | rhs.value = nullptr; |
129 | rhs.type = nullptr; |
130 | return *this; |
131 | } |
132 | |
133 | template <typename T> |
134 | any& any::operator=(const T& val) { |
135 | if (!is<T>()) { |
136 | reset(); |
137 | type = TypeOf<T>::type(); |
138 | alloc(type->size(), type->alignment()); |
139 | type->copyConstruct(value, &val); |
140 | } else { |
141 | *reinterpret_cast<T*>(value) = val; |
142 | } |
143 | return *this; |
144 | } |
145 | |
146 | template <typename T> |
147 | T& any::get() const { |
148 | assert(is<T>()); |
149 | return *reinterpret_cast<T*>(value); |
150 | } |
151 | |
152 | template <typename T> |
153 | bool any::is() const { |
154 | return type == TypeOf<T>::type(); |
155 | } |
156 | |
157 | template <> |
158 | inline bool any::is<std::nullptr_t>() const { |
159 | return value == nullptr; |
160 | } |
161 | |
162 | void* any::alignUp(void* val, size_t alignment) { |
163 | auto ptr = reinterpret_cast<uintptr_t>(val); |
164 | return reinterpret_cast<void*>(alignment * |
165 | ((ptr + alignment - 1) / alignment)); |
166 | } |
167 | |
168 | void any::alloc(size_t size, size_t align) { |
169 | assert(value == nullptr); |
170 | value = alignUp(buffer, align); |
171 | if (isInBuffer(reinterpret_cast<uint8_t*>(value) + size - 1)) { |
172 | return; |
173 | } |
174 | heap = new uint8_t[size + align]; |
175 | value = alignUp(heap, align); |
176 | } |
177 | |
178 | void any::free() { |
179 | assert(value != nullptr); |
180 | if (heap != nullptr) { |
181 | delete[] reinterpret_cast<uint8_t*>(heap); |
182 | heap = nullptr; |
183 | } |
184 | value = nullptr; |
185 | } |
186 | |
187 | bool any::isInBuffer(void* ptr) const { |
188 | auto addr = reinterpret_cast<uintptr_t>(ptr); |
189 | return addr >= reinterpret_cast<uintptr_t>(buffer) && |
190 | addr < reinterpret_cast<uintptr_t>(buffer + sizeof(buffer)); |
191 | } |
192 | |
193 | } // namespace dap |
194 | |
195 | #endif // dap_any_h |
196 | |