From Jason Turner

[iterator.assoc.types]

C++23 → Trunk 2.7 KB 25 lines
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Archived: C++23
Markdown: C++23 | Trunk
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  1. tmp/tmp02zln8si/{from.md → to.md} +9 -11
tmp/tmp02zln8si/{from.md → to.md} RENAMED
@@ -29,11 +29,11 @@ namespace std {
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  : incrementable_traits<I> { };
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  template<class T>
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  requires requires { typename T::difference_type; }
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  struct incrementable_traits<T> {
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- using difference_type = typename T::difference_type;
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  };
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  template<class T>
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  requires (!requires { typename T::difference_type; } &&
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  requires(const T& a, const T& b) { { a - b } -> integral; })
@@ -234,27 +234,27 @@ The members of a specialization `iterator_traits<I>` generated from the
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  - If `I` has valid [[temp.deduct]] member types `difference_type`,
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  `value_type`, `reference`, and `iterator_category`, then
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  `iterator_traits<I>` has the following publicly accessible members:
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  ``` cpp
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- using iterator_category = typename I::iterator_category;
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- using value_type = typename I::value_type;
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- using difference_type = typename I::difference_type;
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  using pointer = see below;
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- using reference = typename I::reference;
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  ```
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  If the *qualified-id* `I::pointer` is valid and denotes a type, then
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  `iterator_traits<I>::pointer` names that type; otherwise, it names
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  `void`.
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  - Otherwise, if `I` satisfies the exposition-only concept
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  `cpp17-input-iterator`, `iterator_traits<I>` has the following
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  publicly accessible members:
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  ``` cpp
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  using iterator_category = see below;
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- using value_type = typename indirectly_readable_traits<I>::value_type;
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- using difference_type = typename incrementable_traits<I>::difference_type;
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  using pointer = see below;
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  using reference = see below;
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  ```
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  - If the *qualified-id* `I::pointer` is valid and denotes a type,
@@ -324,16 +324,14 @@ To implement a generic `reverse` function, a C++ program can do the
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  following:
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  ``` cpp
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  template<class BI>
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  void reverse(BI first, BI last) {
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- typename iterator_traits<BI>::difference_type n =
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- distance(first, last);
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  --n;
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  while (n > 0) {
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- typename iterator_traits<BI>::value_type
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- tmp = *first;
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  *first++ = *--last;
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  *last = tmp;
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  n -= 2;
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  }
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  }
 
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  : incrementable_traits<I> { };
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  template<class T>
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  requires requires { typename T::difference_type; }
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  struct incrementable_traits<T> {
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+ using difference_type = T::difference_type;
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  };
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  template<class T>
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  requires (!requires { typename T::difference_type; } &&
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  requires(const T& a, const T& b) { { a - b } -> integral; })
 
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  - If `I` has valid [[temp.deduct]] member types `difference_type`,
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  `value_type`, `reference`, and `iterator_category`, then
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  `iterator_traits<I>` has the following publicly accessible members:
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  ``` cpp
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+ using iterator_category = I::iterator_category;
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+ using value_type = I::value_type;
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+ using difference_type = I::difference_type;
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  using pointer = see below;
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+ using reference = I::reference;
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  ```
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  If the *qualified-id* `I::pointer` is valid and denotes a type, then
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  `iterator_traits<I>::pointer` names that type; otherwise, it names
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  `void`.
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  - Otherwise, if `I` satisfies the exposition-only concept
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  `cpp17-input-iterator`, `iterator_traits<I>` has the following
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  publicly accessible members:
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  ``` cpp
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  using iterator_category = see below;
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+ using value_type = indirectly_readable_traits<I>::value_type;
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+ using difference_type = incrementable_traits<I>::difference_type;
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  using pointer = see below;
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  using reference = see below;
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  ```
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  - If the *qualified-id* `I::pointer` is valid and denotes a type,
 
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  following:
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  ``` cpp
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  template<class BI>
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  void reverse(BI first, BI last) {
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+ typename iterator_traits<BI>::difference_type n = distance(first, last);
 
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  --n;
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  while (n > 0) {
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+ typename iterator_traits<BI>::value_type tmp = *first;
 
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  *first++ = *--last;
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  *last = tmp;
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  n -= 2;
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  }
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  }