From Jason Turner

[range.drop.view]

C++20 → C++23 3.1 KB 37 lines
Current Draft | LaTeX Source
Archived: C++20 | C++23
Markdown: C++20 | C++23
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  1. tmp/tmpux2vl6uu/{from.md → to.md} +15 -18
tmp/tmpux2vl6uu/{from.md → to.md} RENAMED
@@ -3,44 +3,40 @@
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  ``` cpp
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  namespace std::ranges {
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  template<view V>
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  class drop_view : public view_interface<drop_view<V>> {
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  public:
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- drop_view() = default;
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- constexpr drop_view(V base, range_difference_t<V> count);
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  constexpr V base() const & requires copy_constructible<V> { return base_; }
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  constexpr V base() && { return std::move(base_); }
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  constexpr auto begin()
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- requires (!(simple-view<V> && random_access_range<V>));
 
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  constexpr auto begin() const
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- requires random_access_range<const V>;
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- constexpr auto end()
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- requires (!simple-view<V>)
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  { return ranges::end(base_); }
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- constexpr auto end() const
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- requires range<const V>
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  { return ranges::end(base_); }
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- constexpr auto size()
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- requires sized_range<V>
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- {
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  const auto s = ranges::size(base_);
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  const auto c = static_cast<decltype(s)>(count_);
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  return s < c ? 0 : s - c;
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  }
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- constexpr auto size() const
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- requires sized_range<const V>
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- {
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  const auto s = ranges::size(base_);
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  const auto c = static_cast<decltype(s)>(count_);
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  return s < c ? 0 : s - c;
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  }
 
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  private:
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  V base_ = V(); // exposition only
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  range_difference_t<V> count_ = 0; // exposition only
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  };
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@@ -48,27 +44,28 @@ namespace std::ranges {
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  drop_view(R&&, range_difference_t<R>) -> drop_view<views::all_t<R>>;
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  }
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  ```
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  ``` cpp
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- constexpr drop_view(V base, range_difference_t<V> count);
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  ```
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  *Preconditions:* `count >= 0` is `true`.
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  *Effects:* Initializes *base\_* with `std::move(base)` and *count\_*
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  with `count`.
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  ``` cpp
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  constexpr auto begin()
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- requires (!(simple-view<V> && random_access_range<V>));
 
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  constexpr auto begin() const
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- requires random_access_range<const V>;
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  ```
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  *Returns:*
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- `ranges::next(ranges::begin(base_), count_, ranges::end(base_))`.
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  *Remarks:* In order to provide the amortized constant-time complexity
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  required by the `range` concept when `drop_view` models `forward_range`,
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  the first overload caches the result within the `drop_view` for use on
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  subsequent calls.
 
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  ``` cpp
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  namespace std::ranges {
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  template<view V>
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  class drop_view : public view_interface<drop_view<V>> {
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  public:
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+ drop_view() requires default_initializable<V> = default;
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+ constexpr explicit drop_view(V base, range_difference_t<V> count);
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  constexpr V base() const & requires copy_constructible<V> { return base_; }
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  constexpr V base() && { return std::move(base_); }
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  constexpr auto begin()
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+ requires (!(simple-view<V> &&
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+ random_access_range<const V> && sized_range<const V>));
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  constexpr auto begin() const
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+ requires random_access_range<const V> && sized_range<const V>;
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+ constexpr auto end() requires (!simple-view<V>)
 
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  { return ranges::end(base_); }
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+ constexpr auto end() const requires range<const V>
 
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  { return ranges::end(base_); }
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+ constexpr auto size() requires sized_range<V> {
 
 
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  const auto s = ranges::size(base_);
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  const auto c = static_cast<decltype(s)>(count_);
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  return s < c ? 0 : s - c;
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  }
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+ constexpr auto size() const requires sized_range<const V> {
 
 
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  const auto s = ranges::size(base_);
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  const auto c = static_cast<decltype(s)>(count_);
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  return s < c ? 0 : s - c;
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  }
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+
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  private:
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  V base_ = V(); // exposition only
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  range_difference_t<V> count_ = 0; // exposition only
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  };
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  drop_view(R&&, range_difference_t<R>) -> drop_view<views::all_t<R>>;
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  }
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  ```
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  ``` cpp
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+ constexpr explicit drop_view(V base, range_difference_t<V> count);
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  ```
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  *Preconditions:* `count >= 0` is `true`.
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  *Effects:* Initializes *base\_* with `std::move(base)` and *count\_*
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  with `count`.
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  ``` cpp
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  constexpr auto begin()
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+ requires (!(simple-view<V> &&
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+ random_access_range<const V> && sized_range<const V>));
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  constexpr auto begin() const
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+ requires random_access_range<const V> && sized_range<const V>;
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  ```
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  *Returns:*
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+ `ranges::next(ranges::begin(`*`base_`*`), `*`count_`*`, ranges::end(`*`base_`*`))`.
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  *Remarks:* In order to provide the amortized constant-time complexity
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  required by the `range` concept when `drop_view` models `forward_range`,
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  the first overload caches the result within the `drop_view` for use on
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  subsequent calls.