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[util.smartptr.shared.obs]

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@@ -1,15 +1,15 @@
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  ##### Observers <a id="util.smartptr.shared.obs">[[util.smartptr.shared.obs]]</a>
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  ``` cpp
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- element_type* get() const noexcept;
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  ```
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  *Returns:* The stored pointer.
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  ``` cpp
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- T& operator*() const noexcept;
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  ```
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  *Preconditions:* `get() != nullptr`.
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  *Returns:* `*get()`.
@@ -19,11 +19,11 @@ whether this member function is declared. If it is declared, it is
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  unspecified what its return type is, except that the declaration
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  (although not necessarily the definition) of the function shall be
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  well-formed.
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  ``` cpp
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- T* operator->() const noexcept;
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  ```
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  *Preconditions:* `get() != nullptr`.
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  *Returns:* `get()`.
@@ -32,15 +32,16 @@ T* operator->() const noexcept;
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  member function is declared. If it is declared, it is unspecified what
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  its return type is, except that the declaration (although not
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  necessarily the definition) of the function shall be well-formed.
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  ``` cpp
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- element_type& operator[](ptrdiff_t i) const;
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  ```
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- *Preconditions:* `get() != nullptr && i >= 0`. If `T` is `U[N]`,
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- `i < N`.
 
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  *Returns:* `get()[i]`.
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  *Throws:* Nothing.
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@@ -48,11 +49,11 @@ element_type& operator[](ptrdiff_t i) const;
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  member function is declared. If it is declared, it is unspecified what
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  its return type is, except that the declaration (although not
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  necessarily the definition) of the function shall be well-formed.
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  ``` cpp
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- long use_count() const noexcept;
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  ```
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  *Synchronization:* None.
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  *Returns:* The number of `shared_ptr` objects, `*this` included, that
@@ -68,24 +69,41 @@ share ownership with `*this`, or `0` when `*this` is empty.
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  `use_count()`, the result is approximate. In particular,
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  `use_count() == 1` does not imply that accesses through a previously
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  destroyed `shared_ptr` have in any sense completed. — *end note*]
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  ``` cpp
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- explicit operator bool() const noexcept;
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  ```
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  *Returns:* `get() != nullptr`.
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  ``` cpp
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- template<class U> bool owner_before(const shared_ptr<U>& b) const noexcept;
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- template<class U> bool owner_before(const weak_ptr<U>& b) const noexcept;
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  ```
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  *Returns:* An unspecified value such that
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- - `x.owner_before(y)` defines a strict weak ordering as defined
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  in  [[alg.sorting]];
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- - under the equivalence relation defined by `owner_before`,
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- `!a.owner_before(b) && !b.owner_before(a)`, two `shared_ptr` or
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- `weak_ptr` instances are equivalent if and only if they share
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- ownership or are both empty.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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  ##### Observers <a id="util.smartptr.shared.obs">[[util.smartptr.shared.obs]]</a>
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  ``` cpp
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+ constexpr element_type* get() const noexcept;
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  ```
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  *Returns:* The stored pointer.
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  ``` cpp
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+ constexpr T& operator*() const noexcept;
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  ```
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  *Preconditions:* `get() != nullptr`.
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  *Returns:* `*get()`.
 
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  unspecified what its return type is, except that the declaration
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  (although not necessarily the definition) of the function shall be
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  well-formed.
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  ``` cpp
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+ constexpr T* operator->() const noexcept;
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  ```
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  *Preconditions:* `get() != nullptr`.
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  *Returns:* `get()`.
 
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  member function is declared. If it is declared, it is unspecified what
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  its return type is, except that the declaration (although not
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  necessarily the definition) of the function shall be well-formed.
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  ``` cpp
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+ constexpr element_type& operator[](ptrdiff_t i) const;
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  ```
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+ *Preconditions:* `get() != nullptr` is `true`.
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+
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+ `i` ≥ 0. If `T` is `U[N]`, `i` < `N`.
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  *Returns:* `get()[i]`.
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  *Throws:* Nothing.
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  member function is declared. If it is declared, it is unspecified what
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  its return type is, except that the declaration (although not
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  necessarily the definition) of the function shall be well-formed.
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  ``` cpp
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+ constexpr long use_count() const noexcept;
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  ```
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  *Synchronization:* None.
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  *Returns:* The number of `shared_ptr` objects, `*this` included, that
 
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  `use_count()`, the result is approximate. In particular,
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  `use_count() == 1` does not imply that accesses through a previously
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  destroyed `shared_ptr` have in any sense completed. — *end note*]
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  ``` cpp
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+ constexpr explicit operator bool() const noexcept;
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  ```
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  *Returns:* `get() != nullptr`.
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  ``` cpp
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+ template<class U> constexpr bool owner_before(const shared_ptr<U>& b) const noexcept;
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+ template<class U> constexpr bool owner_before(const weak_ptr<U>& b) const noexcept;
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  ```
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  *Returns:* An unspecified value such that
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+ - `owner_before(b)` defines a strict weak ordering as defined
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  in  [[alg.sorting]];
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+ - `!owner_before(b) && !b.owner_before(*this)` is `true` if and only if
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+ `owner_equal(b)` is `true`.
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+
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+ ``` cpp
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+ size_t owner_hash() const noexcept;
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+ ```
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+
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+ *Returns:* An unspecified value such that, for any object `x` where
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+ `owner_equal(x)` is `true`, `owner_hash() == x.owner_hash()` is `true`.
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+
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+ ``` cpp
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+ template<class U>
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+ constexpr bool owner_equal(const shared_ptr<U>& b) const noexcept;
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+ template<class U>
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+ constexpr bool owner_equal(const weak_ptr<U>& b) const noexcept;
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+ ```
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+
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+ *Returns:* `true` if and only if `*this` and `b` share ownership or are
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+ both empty. Otherwise returns `false`.
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+
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+ *Remarks:* `owner_equal` is an equivalence relation.
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