tmp/tmp3sto5601/{from.md → to.md}
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| 1 |
+
### Specializations for integral types <a id="atomics.ref.int">[[atomics.ref.int]]</a>
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+
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| 3 |
+
There are specializations of the `atomic_ref` class template for the
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+
integral types `char`, `signed char`, `unsigned char`, `short`,
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| 5 |
+
`unsigned short`, `int`, `unsigned int`, `long`, `unsigned long`,
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+
`long long`, `unsigned long long`, `char8_t`, `char16_t`, `char32_t`,
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| 7 |
+
`wchar_t`, and any other types needed by the typedefs in the header
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| 8 |
+
`<cstdint>`. For each such type `integral`, the specialization
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| 9 |
+
`atomic_ref<integral>` provides additional atomic operations appropriate
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| 10 |
+
to integral types.
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+
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+
[*Note 1*: The specialization `atomic_ref<bool>` uses the primary
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+
template [[atomics.ref.generic]]. — *end note*]
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+
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+
``` cpp
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| 16 |
+
namespace std {
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+
template<> struct atomic_ref<integral> {
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+
private:
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| 19 |
+
integral* ptr; // exposition only
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+
public:
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+
using value_type = integral;
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| 22 |
+
using difference_type = value_type;
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+
static constexpr size_t required_alignment = implementation-defined // required alignment for atomic_ref type's operations;
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| 24 |
+
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+
static constexpr bool is_always_lock_free = implementation-defined // whether a given atomic_ref type's operations are always lock free;
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| 26 |
+
bool is_lock_free() const noexcept;
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| 27 |
+
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+
explicit atomic_ref(integral&);
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+
atomic_ref(const atomic_ref&) noexcept;
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+
atomic_ref& operator=(const atomic_ref&) = delete;
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+
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+
void store(integral, memory_order = memory_order::seq_cst) const noexcept;
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integral operator=(integral) const noexcept;
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| 34 |
+
integral load(memory_order = memory_order::seq_cst) const noexcept;
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| 35 |
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operator integral() const noexcept;
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| 36 |
+
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+
integral exchange(integral,
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| 38 |
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memory_order = memory_order::seq_cst) const noexcept;
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| 39 |
+
bool compare_exchange_weak(integral&, integral,
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| 40 |
+
memory_order, memory_order) const noexcept;
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| 41 |
+
bool compare_exchange_strong(integral&, integral,
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| 42 |
+
memory_order, memory_order) const noexcept;
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| 43 |
+
bool compare_exchange_weak(integral&, integral,
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| 44 |
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memory_order = memory_order::seq_cst) const noexcept;
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| 45 |
+
bool compare_exchange_strong(integral&, integral,
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| 46 |
+
memory_order = memory_order::seq_cst) const noexcept;
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| 47 |
+
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| 48 |
+
integral fetch_add(integral,
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| 49 |
+
memory_order = memory_order::seq_cst) const noexcept;
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| 50 |
+
integral fetch_sub(integral,
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| 51 |
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memory_order = memory_order::seq_cst) const noexcept;
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| 52 |
+
integral fetch_and(integral,
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| 53 |
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memory_order = memory_order::seq_cst) const noexcept;
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| 54 |
+
integral fetch_or(integral,
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| 55 |
+
memory_order = memory_order::seq_cst) const noexcept;
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| 56 |
+
integral fetch_xor(integral,
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| 57 |
+
memory_order = memory_order::seq_cst) const noexcept;
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| 58 |
+
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| 59 |
+
integral operator++(int) const noexcept;
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| 60 |
+
integral operator--(int) const noexcept;
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| 61 |
+
integral operator++() const noexcept;
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| 62 |
+
integral operator--() const noexcept;
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| 63 |
+
integral operator+=(integral) const noexcept;
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| 64 |
+
integral operator-=(integral) const noexcept;
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| 65 |
+
integral operator&=(integral) const noexcept;
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| 66 |
+
integral operator|=(integral) const noexcept;
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| 67 |
+
integral operator^=(integral) const noexcept;
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| 68 |
+
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| 69 |
+
void wait(integral, memory_order = memory_order::seq_cst) const noexcept;
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| 70 |
+
void notify_one() const noexcept;
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| 71 |
+
void notify_all() const noexcept;
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| 72 |
+
};
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| 73 |
+
}
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| 74 |
+
```
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| 75 |
+
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| 76 |
+
Descriptions are provided below only for members that differ from the
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| 77 |
+
primary template.
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| 78 |
+
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| 79 |
+
The following operations perform arithmetic computations. The key,
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| 80 |
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operator, and computation correspondence is identified in
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| 81 |
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[[atomic.types.int.comp]].
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| 82 |
+
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| 83 |
+
``` cpp
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| 84 |
+
integral fetch_key(integral operand, memory_order order = memory_order::seq_cst) const noexcept;
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| 85 |
+
```
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| 86 |
+
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| 87 |
+
*Effects:* Atomically replaces the value referenced by `*ptr` with the
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| 88 |
+
result of the computation applied to the value referenced by `*ptr` and
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| 89 |
+
the given operand. Memory is affected according to the value of `order`.
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| 90 |
+
These operations are atomic read-modify-write
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| 91 |
+
operations [[intro.races]].
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| 92 |
+
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| 93 |
+
*Returns:* Atomically, the value referenced by `*ptr` immediately before
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| 94 |
+
the effects.
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| 95 |
+
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| 96 |
+
*Remarks:* For signed integer types, the result is as if the object
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| 97 |
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value and parameters were converted to their corresponding unsigned
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| 98 |
+
types, the computation performed on those types, and the result
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| 99 |
+
converted back to the signed type.
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| 100 |
+
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| 101 |
+
[*Note 1*: There are no undefined results arising from the
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| 102 |
+
computation. — *end note*]
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| 103 |
+
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| 104 |
+
``` cpp
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| 105 |
+
integral operator op=(integral operand) const noexcept;
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| 106 |
+
```
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| 107 |
+
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| 108 |
+
*Effects:* Equivalent to:
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| 109 |
+
`return fetch_`*`key`*`(operand) `*`op`*` operand;`
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| 110 |
+
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