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Implement views::take and views::drop #1253

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Merged
CaseyCarter merged 8 commits into from
Sep 5, 2020
Merged

Implement views::take and views::drop #1253

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55e77fd
Implement views::take and views::drop
CaseyCarter Sep 1, 2020
6aadabe
P/R => proposed resolution
CaseyCarter Sep 1, 2020
23f3ad7
Fix overlength lines - thanks, validator!
CaseyCarter Sep 1, 2020
8d7359c
Review comments
CaseyCarter Sep 2, 2020
27d0444
Update stl/inc/ranges
CaseyCarter Sep 2, 2020
6e2a75d
LWG-3482 now has a number
CaseyCarter Sep 2, 2020
327ab74
Merge branch 'master' into take_drop
CaseyCarter Sep 4, 2020
2cc6201
Merge branch 'master' into take_drop
CaseyCarter Sep 4, 2020
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37 changes: 22 additions & 15 deletions stl/inc/iterator
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Original file line number Diff line number Diff line change
Expand Up @@ -534,21 +534,20 @@ public:
requires convertible_to<const _Other&, _Iter>
constexpr counted_iterator(const counted_iterator<_Other>& _Right) noexcept(
is_nothrow_constructible_v<_Iter, const _Other&>) // strengthened
: _Current(_Right._Current), _Length(_Right._Length) {}
: _Current(_Right.base()), _Length(_Right.count()) {}

template <class _Other>
requires assignable_from<_Iter&, const _Other&>
constexpr counted_iterator& operator=(const counted_iterator<_Other>& _Right) noexcept(
is_nothrow_assignable_v<_Iter&, const _Other&>) /* strengthened */ {
// clang-format on
_Current = _Right._Current;
_Length = _Right._Length;
_Current = _Right.base();
_Length = _Right.count();
return *this;
}

// [counted.iter.access]
_NODISCARD constexpr _Iter base() const& noexcept(is_nothrow_copy_constructible_v<_Iter>) /* strengthened */
requires copy_constructible<_Iter> {
_NODISCARD constexpr const _Iter& base() const& noexcept /* strengthened */ { // Per LWG-3391
return _Current;
}

Expand Down Expand Up @@ -720,8 +719,8 @@ public:

template <indirectly_swappable<_Iter> _Other>
friend constexpr void iter_swap(const counted_iterator& _Left, const counted_iterator<_Other>& _Right) noexcept(
noexcept(_RANGES iter_swap(_Left._Current, _Right._Current))) {
_RANGES iter_swap(_Left._Current, _Right._Current);
noexcept(_RANGES iter_swap(_Left._Current, _Right.base()))) {
_RANGES iter_swap(_Left._Current, _Right.base());
}

template <common_with<_Iter> _Other>
Expand Down Expand Up @@ -750,7 +749,7 @@ public:
template <common_with<_Iter> _Other>
friend constexpr void _Verify_range(const counted_iterator& _Left, const counted_iterator<_Other>& _Right) {
if constexpr (_Range_verifiable_v<_Iter, _Other>) {
_Verify_range(_Left._Current, _Right._Current);
_Verify_range(_Left._Current, _Right.base());
}
#if _ITERATOR_DEBUG_LEVEL != 0
_Same_sequence(_Left, _Right);
Expand Down Expand Up @@ -784,23 +783,20 @@ public:
requires _Wrapped_seekable_v<_Iter, const _Other&>
constexpr void _Seek_to(const counted_iterator<_Other>& _It) {
// clang-format on
_Current._Seek_to(_It._Current);
_Length = _It._Length;
_Current._Seek_to(_It.base());
_Length = _It.count();
}

// clang-format off
template <class _Other>
requires _Wrapped_seekable_v<_Iter, _Other>
constexpr void _Seek_to(counted_iterator<_Other>&& _It) {
// clang-format on
_Current._Seek_to(_STD move(_It)._Current);
_Length = _It._Length;
_Current._Seek_to(_STD move(_It).base());
_Length = _It.count();
}

private:
template <input_or_output_iterator>
friend class counted_iterator;

_Iter _Current{};
iter_difference_t<_Iter> _Length = 0;
};
Expand All @@ -814,6 +810,17 @@ template <input_iterator _Iter>
struct iterator_traits<counted_iterator<_Iter>> : iterator_traits<_Iter> {
using pointer = void;
};

template <contiguous_iterator _Iter>
struct pointer_traits<counted_iterator<_Iter>> { // TRANSITION, address LWG-3408 and include this
using pointer = counted_iterator<_Iter>;
using element_type = remove_reference_t<iter_reference_t<_Iter>>;
using difference_type = iter_difference_t<_Iter>;

_NODISCARD static constexpr element_type* to_address(const pointer _It) noexcept {
return _STD to_address(_It.base());
}
};
#endif // __cpp_lib_concepts

_STD_END
Expand Down
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