tmp/tmpd8h8gaaq/{from.md → to.md}
RENAMED
|
@@ -0,0 +1,78 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
#### Class template `drop_view` <a id="range.drop.view">[[range.drop.view]]</a>
|
| 2 |
+
|
| 3 |
+
``` cpp
|
| 4 |
+
namespace std::ranges {
|
| 5 |
+
template<view V>
|
| 6 |
+
class drop_view : public view_interface<drop_view<V>> {
|
| 7 |
+
public:
|
| 8 |
+
drop_view() = default;
|
| 9 |
+
constexpr drop_view(V base, range_difference_t<V> count);
|
| 10 |
+
|
| 11 |
+
constexpr V base() const& requires copy_constructible<V> { return base_; }
|
| 12 |
+
constexpr V base() && { return std::move(base_); }
|
| 13 |
+
|
| 14 |
+
constexpr auto begin()
|
| 15 |
+
requires (!(simple-view<V> && random_access_range<V>));
|
| 16 |
+
constexpr auto begin() const
|
| 17 |
+
requires random_access_range<const V>;
|
| 18 |
+
|
| 19 |
+
constexpr auto end()
|
| 20 |
+
requires (!simple-view<V>)
|
| 21 |
+
{ return ranges::end(base_); }
|
| 22 |
+
|
| 23 |
+
constexpr auto end() const
|
| 24 |
+
requires range<const V>
|
| 25 |
+
{ return ranges::end(base_); }
|
| 26 |
+
|
| 27 |
+
constexpr auto size()
|
| 28 |
+
requires sized_range<V>
|
| 29 |
+
{
|
| 30 |
+
const auto s = ranges::size(base_);
|
| 31 |
+
const auto c = static_cast<decltype(s)>(count_);
|
| 32 |
+
return s < c ? 0 : s - c;
|
| 33 |
+
}
|
| 34 |
+
|
| 35 |
+
constexpr auto size() const
|
| 36 |
+
requires sized_range<const V>
|
| 37 |
+
{
|
| 38 |
+
const auto s = ranges::size(base_);
|
| 39 |
+
const auto c = static_cast<decltype(s)>(count_);
|
| 40 |
+
return s < c ? 0 : s - c;
|
| 41 |
+
}
|
| 42 |
+
private:
|
| 43 |
+
V base_ = V(); // exposition only
|
| 44 |
+
range_difference_t<V> count_ = 0; // exposition only
|
| 45 |
+
};
|
| 46 |
+
|
| 47 |
+
template<class R>
|
| 48 |
+
drop_view(R&&, range_difference_t<R>) -> drop_view<views::all_t<R>>;
|
| 49 |
+
}
|
| 50 |
+
```
|
| 51 |
+
|
| 52 |
+
``` cpp
|
| 53 |
+
constexpr drop_view(V base, range_difference_t<V> count);
|
| 54 |
+
```
|
| 55 |
+
|
| 56 |
+
*Preconditions:* `count >= 0` is `true`.
|
| 57 |
+
|
| 58 |
+
*Effects:* Initializes *base\_* with `std::move(base)` and *count\_*
|
| 59 |
+
with `count`.
|
| 60 |
+
|
| 61 |
+
``` cpp
|
| 62 |
+
constexpr auto begin()
|
| 63 |
+
requires (!(simple-view<V> && random_access_range<V>));
|
| 64 |
+
constexpr auto begin() const
|
| 65 |
+
requires random_access_range<const V>;
|
| 66 |
+
```
|
| 67 |
+
|
| 68 |
+
*Returns:*
|
| 69 |
+
`ranges::next(ranges::begin(base_), count_, ranges::end(base_))`.
|
| 70 |
+
|
| 71 |
+
*Remarks:* In order to provide the amortized constant-time complexity
|
| 72 |
+
required by the `range` concept when `drop_view` models `forward_range`,
|
| 73 |
+
the first overload caches the result within the `drop_view` for use on
|
| 74 |
+
subsequent calls.
|
| 75 |
+
|
| 76 |
+
[*Note 1*: Without this, applying a `reverse_view` over a `drop_view`
|
| 77 |
+
would have quadratic iteration complexity. — *end note*]
|
| 78 |
+
|