LLVM  13.0.0git
Any.h
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1 //===- Any.h - Generic type erased holder of any type -----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file provides Any, a non-template class modeled in the spirit of
10 // std::any. The idea is to provide a type-safe replacement for C's void*.
11 // It can hold a value of any copy-constructible copy-assignable type
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_ADT_ANY_H
16 #define LLVM_ADT_ANY_H
17 
18 #include "llvm/ADT/STLExtras.h"
19 
20 #include <cassert>
21 #include <memory>
22 #include <type_traits>
23 
24 namespace llvm {
25 
27 
28  // The `Typeid<T>::Id` static data member below is a globally unique
29  // identifier for the type `T`. It is explicitly marked with default
30  // visibility so that when `-fvisibility=hidden` is used, the loader still
31  // merges duplicate definitions across DSO boundaries.
32  template <typename T> struct TypeId { static const char Id; };
33 
34  struct StorageBase {
35  virtual ~StorageBase() = default;
36  virtual std::unique_ptr<StorageBase> clone() const = 0;
37  virtual const void *id() const = 0;
38  };
39 
40  template <typename T> struct StorageImpl : public StorageBase {
41  explicit StorageImpl(const T &Value) : Value(Value) {}
42 
43  explicit StorageImpl(T &&Value) : Value(std::move(Value)) {}
44 
45  std::unique_ptr<StorageBase> clone() const override {
46  return std::make_unique<StorageImpl<T>>(Value);
47  }
48 
49  const void *id() const override { return &TypeId<T>::Id; }
50 
51  T Value;
52 
53  private:
54  StorageImpl &operator=(const StorageImpl &Other) = delete;
55  StorageImpl(const StorageImpl &Other) = delete;
56  };
57 
58 public:
59  Any() = default;
60 
61  Any(const Any &Other)
62  : Storage(Other.Storage ? Other.Storage->clone() : nullptr) {}
63 
64  // When T is Any or T is not copy-constructible we need to explicitly disable
65  // the forwarding constructor so that the copy constructor gets selected
66  // instead.
67  template <typename T,
68  std::enable_if_t<
71  // We also disable this overload when an `Any` object can be
72  // converted to the parameter type because in that case,
73  // this constructor may combine with that conversion during
74  // overload resolution for determining copy
75  // constructibility, and then when we try to determine copy
76  // constructibility below we may infinitely recurse. This is
77  // being evaluated by the standards committee as a potential
78  // DR in `std::any` as well, but we're going ahead and
79  // adopting it to work-around usage of `Any` with types that
80  // need to be implicitly convertible from an `Any`.
82  std::is_copy_constructible<std::decay_t<T>>>::value,
83  int> = 0>
84  Any(T &&Value) {
85  Storage =
86  std::make_unique<StorageImpl<std::decay_t<T>>>(std::forward<T>(Value));
87  }
88 
89  Any(Any &&Other) : Storage(std::move(Other.Storage)) {}
90 
91  Any &swap(Any &Other) {
92  std::swap(Storage, Other.Storage);
93  return *this;
94  }
95 
96  Any &operator=(Any Other) {
97  Storage = std::move(Other.Storage);
98  return *this;
99  }
100 
101  bool hasValue() const { return !!Storage; }
102 
103  void reset() { Storage.reset(); }
104 
105 private:
106  template <class T> friend T any_cast(const Any &Value);
107  template <class T> friend T any_cast(Any &Value);
108  template <class T> friend T any_cast(Any &&Value);
109  template <class T> friend const T *any_cast(const Any *Value);
110  template <class T> friend T *any_cast(Any *Value);
111  template <typename T> friend bool any_isa(const Any &Value);
112 
113  std::unique_ptr<StorageBase> Storage;
114 };
115 
116 template <typename T> const char Any::TypeId<T>::Id = 0;
117 
118 
119 template <typename T> bool any_isa(const Any &Value) {
120  if (!Value.Storage)
121  return false;
122  return Value.Storage->id() == &Any::TypeId<remove_cvref_t<T>>::Id;
123 }
124 
125 template <class T> T any_cast(const Any &Value) {
126  return static_cast<T>(*any_cast<remove_cvref_t<T>>(&Value));
127 }
128 
129 template <class T> T any_cast(Any &Value) {
130  return static_cast<T>(*any_cast<remove_cvref_t<T>>(&Value));
131 }
132 
133 template <class T> T any_cast(Any &&Value) {
134  return static_cast<T>(std::move(*any_cast<remove_cvref_t<T>>(&Value)));
135 }
136 
137 template <class T> const T *any_cast(const Any *Value) {
138  using U = remove_cvref_t<T>;
139  assert(Value && any_isa<T>(*Value) && "Bad any cast!");
140  if (!Value || !any_isa<U>(*Value))
141  return nullptr;
142  return &static_cast<Any::StorageImpl<U> &>(*Value->Storage).Value;
143 }
144 
145 template <class T> T *any_cast(Any *Value) {
146  using U = std::decay_t<T>;
147  assert(Value && any_isa<U>(*Value) && "Bad any cast!");
148  if (!Value || !any_isa<U>(*Value))
149  return nullptr;
150  return &static_cast<Any::StorageImpl<U> &>(*Value->Storage).Value;
151 }
152 
153 } // end namespace llvm
154 
155 #endif // LLVM_ADT_ANY_H
llvm::Any::hasValue
bool hasValue() const
Definition: Any.h:101
llvm
---------------------— PointerInfo ------------------------------------—
Definition: AllocatorList.h:23
llvm::Any::Any
Any(T &&Value)
Definition: Any.h:84
llvm::Any::Any
Any(Any &&Other)
Definition: Any.h:89
T
#define T
Definition: Mips16ISelLowering.cpp:341
STLExtras.h
llvm::conjunction
Definition: STLForwardCompat.h:32
llvm::Any::Any
Any(const Any &Other)
Definition: Any.h:61
LLVM_EXTERNAL_VISIBILITY
#define LLVM_EXTERNAL_VISIBILITY
Definition: Compiler.h:132
move
compiles ldr LCPI1_0 ldr ldr mov lsr tst moveq r1 ldr LCPI1_1 and r0 bx lr It would be better to do something like to fold the shift into the conditional move
Definition: README.txt:546
llvm::Any::operator=
Any & operator=(Any Other)
Definition: Any.h:96
assert
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
llvm::move
OutputIt move(R &&Range, OutputIt Out)
Provide wrappers to std::move which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1592
std::swap
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:840
llvm::any_isa
bool any_isa(const Any &Value)
Definition: Any.h:119
remove_cvref_t
llvm::Any::reset
void reset()
Definition: Any.h:103
llvm::Any
Definition: Any.h:26
std
Definition: BitVector.h:838
llvm::any_cast
T any_cast(const Any &Value)
Definition: Any.h:125
llvm::TargetStackID::Value
Value
Definition: TargetFrameLowering.h:27
llvm::Any::swap
Any & swap(Any &Other)
Definition: Any.h:91
llvm::negation
Definition: STLForwardCompat.h:28
llvm::AMDGPU::VGPRIndexMode::Id
Id
Definition: SIDefines.h:221
llvm::Value
LLVM Value Representation.
Definition: Value.h:75
Other
Optional< std::vector< StOtherPiece > > Other
Definition: ELFYAML.cpp:1172