-
Notifications
You must be signed in to change notification settings - Fork 73
Expand file tree
/
Copy pathrtti.h
More file actions
75 lines (58 loc) · 2.09 KB
/
Copy pathrtti.h
File metadata and controls
75 lines (58 loc) · 2.09 KB
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
// Copyright 2022 Google LLC
//
// 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 THIRD_PARTY_CEL_CPP_INTERNAL_RTTI_H_
#define THIRD_PARTY_CEL_CPP_INTERNAL_RTTI_H_
#include <cstdint>
#include <utility>
namespace cel::internal {
class TypeInfo;
template <typename T>
TypeInfo TypeId();
// TypeInfo is an RTTI-like alternative for identifying a type at runtime. Its
// main benefit is it does not require RTTI being available, allowing CEL to
// work without RTTI.
//
// This is used to implement the runtime type system and conversion between CEL
// values and their native C++ counterparts.
class TypeInfo final {
public:
constexpr TypeInfo() = default;
TypeInfo(const TypeInfo&) = default;
TypeInfo& operator=(const TypeInfo&) = default;
friend bool operator==(const TypeInfo& lhs, const TypeInfo& rhs) {
return lhs.id_ == rhs.id_;
}
friend bool operator!=(const TypeInfo& lhs, const TypeInfo& rhs) {
return !operator==(lhs, rhs);
}
template <typename H>
friend H AbslHashValue(H state, const TypeInfo& type) {
return H::combine(std::move(state), reinterpret_cast<uintptr_t>(type.id_));
}
private:
template <typename T>
friend TypeInfo TypeId();
constexpr explicit TypeInfo(void* id) : id_(id) {}
void* id_ = nullptr;
};
template <typename T>
TypeInfo TypeId() {
// Adapted from Abseil and GTL. I believe this not being const is to ensure
// the compiler does not merge multiple constants with the same value to share
// the same address.
static char id;
return TypeInfo(&id);
}
} // namespace cel::internal
#endif // THIRD_PARTY_CEL_CPP_INTERNAL_RTTI_H_