From Jason Turner

[pointer.traits]

C++17 → C++20 3.8 KB 55 lines
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  1. tmp/tmpdsahzaqm/{from.md → to.md} +35 -17
tmp/tmpdsahzaqm/{from.md → to.md} RENAMED
@@ -20,57 +20,75 @@ namespace std {
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  using element_type = T;
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  using difference_type = ptrdiff_t;
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  template<class U> using rebind = U*;
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- static pointer pointer_to(see below r) noexcept;
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  };
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  }
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  ```
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- #### Pointer traits member types <a id="pointer.traits.types">[[pointer.traits.types]]</a>
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  ``` cpp
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  using element_type = see below;
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  ```
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  *Type:* `Ptr::element_type` if the *qualified-id* `Ptr::element_type` is
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- valid and denotes a type ([[temp.deduct]]); otherwise, `T` if `Ptr` is
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- a class template instantiation of the form `SomePointer<T, Args>`, where
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  `Args` is zero or more type arguments; otherwise, the specialization is
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  ill-formed.
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  ``` cpp
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  using difference_type = see below;
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  ```
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  *Type:* `Ptr::difference_type` if the *qualified-id*
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- `Ptr::difference_type` is valid and denotes a type ([[temp.deduct]]);
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  otherwise, `ptrdiff_t`.
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  ``` cpp
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  template<class U> using rebind = see below;
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  ```
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  *Alias template:* `Ptr::rebind<U>` if the *qualified-id*
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- `Ptr::rebind<U>` is valid and denotes a type ([[temp.deduct]]);
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- otherwise, `SomePointer<U, Args>` if `Ptr` is a class template
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- instantiation of the form `SomePointer<T, Args>`, where `Args` is zero
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- or more type arguments; otherwise, the instantiation of `rebind` is
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- ill-formed.
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- #### Pointer traits member functions <a id="pointer.traits.functions">[[pointer.traits.functions]]</a>
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  ``` cpp
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  static pointer pointer_traits::pointer_to(see below r);
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- static pointer pointer_traits<T*>::pointer_to(see below r) noexcept;
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  ```
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  *Remarks:* If `element_type` is cv `void`, the type of `r` is
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  unspecified; otherwise, it is `element_type&`.
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- *Returns:* The first member function returns a pointer to `r` obtained
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- by calling `Ptr::pointer_to(r)` through which indirection is valid; an
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- instantiation of this function is ill-formed if `Ptr` does not have a
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- matching `pointer_to` static member function. The second member function
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- returns `addressof(r)`.
 
 
 
 
 
 
 
 
 
 
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  using element_type = T;
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  using difference_type = ptrdiff_t;
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  template<class U> using rebind = U*;
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+ static constexpr pointer pointer_to(see below r) noexcept;
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  };
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  }
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  ```
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+ #### Member types <a id="pointer.traits.types">[[pointer.traits.types]]</a>
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  ``` cpp
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  using element_type = see below;
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  ```
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  *Type:* `Ptr::element_type` if the *qualified-id* `Ptr::element_type` is
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+ valid and denotes a type [[temp.deduct]]; otherwise, `T` if `Ptr` is a
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+ class template instantiation of the form `SomePointer<T, Args>`, where
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  `Args` is zero or more type arguments; otherwise, the specialization is
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  ill-formed.
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  ``` cpp
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  using difference_type = see below;
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  ```
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  *Type:* `Ptr::difference_type` if the *qualified-id*
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+ `Ptr::difference_type` is valid and denotes a type [[temp.deduct]];
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  otherwise, `ptrdiff_t`.
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  ``` cpp
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  template<class U> using rebind = see below;
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  ```
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  *Alias template:* `Ptr::rebind<U>` if the *qualified-id*
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+ `Ptr::rebind<U>` is valid and denotes a type [[temp.deduct]]; otherwise,
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+ `SomePointer<U, Args>` if `Ptr` is a class template instantiation of the
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+ form `SomePointer<T, Args>`, where `Args` is zero or more type
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+ arguments; otherwise, the instantiation of `rebind` is ill-formed.
 
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+ #### Member functions <a id="pointer.traits.functions">[[pointer.traits.functions]]</a>
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  ``` cpp
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  static pointer pointer_traits::pointer_to(see below r);
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+ static constexpr pointer pointer_traits<T*>::pointer_to(see below r) noexcept;
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  ```
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+ *Mandates:* For the first member function, `Ptr::pointer_to(r)` is
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+ well-formed.
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+
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+ *Preconditions:* For the first member function, `Ptr::pointer_to(r)`
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+ returns a pointer to `r` through which indirection is valid.
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+
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+ *Returns:* The first member function returns `Ptr::pointer_to(r)`. The
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+ second member function returns `addressof(r)`.
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+
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  *Remarks:* If `element_type` is cv `void`, the type of `r` is
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  unspecified; otherwise, it is `element_type&`.
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+ #### Optional members <a id="pointer.traits.optmem">[[pointer.traits.optmem]]</a>
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+
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+ Specializations of `pointer_traits` may define the member declared in
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+ this subclause to customize the behavior of the standard library.
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+
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+ ``` cpp
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+ static element_type* to_address(pointer p) noexcept;
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+ ```
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+
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+ *Returns:* A pointer of type `element_type*` that references the same
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+ location as the argument `p`.
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+
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+ [*Note 1*: This function should be the inverse of `pointer_to`. If
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+ defined, it customizes the behavior of the non-member function
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+ `to_address` [[pointer.conversion]]. — *end note*]
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