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Implement resolution of LWG-3449 for take_view #1457

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Merged
StephanTLavavej merged 4 commits into from
Dec 17, 2020
Merged

Implement resolution of LWG-3449 for take_view #1457

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e948179
Implement resolution of LWG-3449 for take_view
miscco Nov 12, 2020
8ee062b
Hyphenate "non-const"
StephanTLavavej Nov 20, 2020
ec66fdf
Cleanup:
CaseyCarter Dec 3, 2020
019776e
Merge branch 'master' into lwg3449
StephanTLavavej Dec 11, 2020
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38 changes: 25 additions & 13 deletions stl/inc/ranges
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Original file line number Diff line number Diff line change
Expand Up @@ -1515,9 +1515,12 @@ namespace ranges {
template <bool, bool>
friend class _Sentinel;

using _Base_Ty = _Maybe_const<_Const, _Vw>;
using _Base_sentinel = _Maybe_wrapped<_Wrapped, sentinel_t<_Base_Ty>>;
using _Counted_Iter = counted_iterator<_Maybe_wrapped<_Wrapped, iterator_t<_Base_Ty>>>;
using _Base_t = _Maybe_const<_Const, _Vw>;
using _Base_sentinel = _Maybe_wrapped<_Wrapped, sentinel_t<_Base_t>>;
template <bool _OtherConst>
using _Base_iterator = _Maybe_wrapped<_Wrapped, iterator_t<_Maybe_const<_OtherConst, _Vw>>>;
template <bool _OtherConst>
using _Counted_iter = counted_iterator<_Base_iterator<_OtherConst>>;

_Base_sentinel _Last{};

Expand All @@ -1540,25 +1543,34 @@ namespace ranges {
return _Last;
}

_NODISCARD friend constexpr bool operator==(const _Counted_Iter& _Left, const _Sentinel& _Right) {
_NODISCARD friend constexpr bool operator==(const _Counted_iter<_Const>& _Left, const _Sentinel& _Right) {
return _Left.count() == 0 || _Left.base() == _Right._Last;
}

// clang-format off
template <bool _OtherConst = _Const>
requires sentinel_for<_Base_sentinel, _Base_iterator<_OtherConst>>
_NODISCARD friend constexpr bool operator==(
const _Counted_iter<_OtherConst>& _Left, const _Sentinel& _Right) {
// clang-format on
return _Left.count() == 0 || _Left.base() == _Right._Last;
}

using _Prevent_inheriting_unwrap = _Sentinel;

// clang-format off
_NODISCARD constexpr auto _Unwrapped() const&
requires _Wrapped && _Unwrappable_v<const iterator_t<_Base_Ty>&> {
requires _Wrapped && _Unwrappable_v<const iterator_t<_Base_t>&> {
// clang-format on
return _Sentinel<_Const, false>{_Get_unwrapped(_Last)};
}
// clang-format off
_NODISCARD constexpr auto _Unwrapped() && requires _Wrapped && _Unwrappable_v<iterator_t<_Base_Ty>> {
_NODISCARD constexpr auto _Unwrapped() && requires _Wrapped && _Unwrappable_v<iterator_t<_Base_t>> {
// clang-format on
return _Sentinel<_Const, false>{_Get_unwrapped(_STD move(_Last))};
}

static constexpr bool _Unwrap_when_unverified = _Do_unwrap_when_unverified_v<iterator_t<_Base_Ty>>;
static constexpr bool _Unwrap_when_unverified = _Do_unwrap_when_unverified_v<iterator_t<_Base_t>>;

constexpr void _Seek_to(const _Sentinel<_Const, false>& _That) requires _Wrapped {
_Seek_wrapped(_Last, _That._Last);
Expand Down Expand Up @@ -1753,9 +1765,9 @@ namespace ranges {
template <bool, bool>
friend class _Sentinel;

using _Base_Ty = _Maybe_const<_Const, _Vw>;
using _Base_iterator = _Maybe_wrapped<_Wrapped, iterator_t<_Base_Ty>>;
using _Base_sentinel = _Maybe_wrapped<_Wrapped, sentinel_t<_Base_Ty>>;
using _Base_t = _Maybe_const<_Const, _Vw>;
using _Base_iterator = _Maybe_wrapped<_Wrapped, iterator_t<_Base_t>>;
using _Base_sentinel = _Maybe_wrapped<_Wrapped, sentinel_t<_Base_t>>;

template <bool _OtherConst>
using _Maybe_const_iter = _Maybe_wrapped<_Wrapped, iterator_t<_Maybe_const<_OtherConst, _Vw>>>;
Expand Down Expand Up @@ -1799,17 +1811,17 @@ namespace ranges {

// clang-format off
_NODISCARD constexpr auto _Unwrapped() const&
requires _Wrapped && _Unwrappable_v<const iterator_t<_Base_Ty>&> {
requires _Wrapped && _Unwrappable_v<const iterator_t<_Base_t>&> {
// clang-format on
return _Sentinel<_Const, false>{_Get_unwrapped(_Last), _Pred};
}
// clang-format off
_NODISCARD constexpr auto _Unwrapped() && requires _Wrapped && _Unwrappable_v<iterator_t<_Base_Ty>> {
_NODISCARD constexpr auto _Unwrapped() && requires _Wrapped && _Unwrappable_v<iterator_t<_Base_t>> {
// clang-format on
return _Sentinel<_Const, false>{_Get_unwrapped(_STD move(_Last)), _Pred};
}

static constexpr bool _Unwrap_when_unverified = _Do_unwrap_when_unverified_v<iterator_t<_Base_Ty>>;
static constexpr bool _Unwrap_when_unverified = _Do_unwrap_when_unverified_v<iterator_t<_Base_t>>;

constexpr void _Seek_to(const _Sentinel<_Const, false>& _That) requires _Wrapped {
_Seek_wrapped(_Last, _That._Last);
Expand Down
18 changes: 14 additions & 4 deletions tests/std/tests/P0896R4_views_take/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -282,15 +282,25 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
}
STATIC_ASSERT(CanEnd<const R&> == range<const V>);
if (!is_empty) {
same_as<sentinel_t<R>> auto i = r.end();
same_as<sentinel_t<R>> auto s = r.end();
if constexpr (bidirectional_range<R> && common_range<R>) {
assert(*prev(i) == *prev(end(expected)));
assert(*prev(s) == *prev(end(expected)));
}

if constexpr (range<const V>) {
same_as<sentinel_t<const R>> auto i2 = as_const(r).end();
same_as<sentinel_t<const R>> auto sc = as_const(r).end();
if constexpr (bidirectional_range<const R> && common_range<const R>) {
assert(*prev(i2) == *prev(end(expected)));
assert(*prev(sc) == *prev(end(expected)));
}

if (forward_range<V>) { // intentionally not if constexpr
// Compare with const / non-const iterators
const same_as<iterator_t<R>> auto i = r.begin();
const same_as<iterator_t<const R>> auto ic = as_const(r).begin();
assert(s != i);
assert(s != ic);
assert(sc != i);
assert(sc != ic);
}
}
}
Expand Down