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Consistent iterator type checking for parallel algorithms #3899

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Aug 1, 2023
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Consistent iterator type checking for parallel algorithms #3899

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e39e286
Consistent iterator type checking for parallel algorithms
frederick-vs-ja Jul 22, 2023
dee9874
`min_element`, `max_element`, `minmax_element` are non-modifying.
StephanTLavavej Jul 22, 2023
34e9f6c
Define and use `_REQUIRE_BIDIRECTIONAL_ITERATOR`
CaseyCarter Jul 26, 2023
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26 changes: 21 additions & 5 deletions stl/inc/algorithm
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,10 @@ _STD pair<_Ty*, _Ty*> __std_minmax_element(_Ty* _First, _Ty* _Last) noexcept {
#endif // _USE_STD_VECTOR_ALGORITHMS

_STD_BEGIN
#define _REQUIRE_CPP17_MUTABLE_RANDOM_ACCESS_ITERATOR(_Iter) \
static_assert(_Is_cpp17_random_iter_v<_Iter>, \
"This algorithm requires that mutable iterators be Cpp17RandomAccessIterators or stronger.")

_INLINE_VAR constexpr int _ISORT_MAX = 32; // maximum size for insertion sort

template <class _It>
Expand Down Expand Up @@ -581,8 +585,6 @@ _EXPORT_STD template <class _ExPo, class _FwdIt1, class _FwdIt2, _Enable_if_exec
_NODISCARD pair<_FwdIt1, _FwdIt2> mismatch(
_ExPo&& _Exec, const _FwdIt1 _First1, const _FwdIt1 _Last1, const _FwdIt2 _First2) noexcept /* terminates */ {
// return [_First1, _Last1)/[_First2, ...) mismatch
_REQUIRE_PARALLEL_ITERATOR(_FwdIt1);
_REQUIRE_PARALLEL_ITERATOR(_FwdIt2);
return _STD mismatch(_STD forward<_ExPo>(_Exec), _First1, _Last1, _First2, equal_to{});
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -636,8 +638,6 @@ _EXPORT_STD template <class _ExPo, class _FwdIt1, class _FwdIt2, _Enable_if_exec
_NODISCARD pair<_FwdIt1, _FwdIt2> mismatch(
_ExPo&& _Exec, _FwdIt1 _First1, _FwdIt1 _Last1, _FwdIt2 _First2, _FwdIt2 _Last2) noexcept /* terminates */ {
// return [_First1, _Last1)/[_First2, _Last2) mismatch
_REQUIRE_PARALLEL_ITERATOR(_FwdIt1);
_REQUIRE_PARALLEL_ITERATOR(_FwdIt2);
return _STD mismatch(_STD forward<_ExPo>(_Exec), _First1, _Last1, _First2, _Last2, equal_to{});
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -3432,6 +3432,8 @@ _EXPORT_STD template <class _ExPo, class _FwdIt1, class _FwdIt2, _Enable_if_exec
_FwdIt2 swap_ranges(_ExPo&&, _FwdIt1 _First1, _FwdIt1 _Last1, _FwdIt2 _Dest) noexcept /* terminates */ {
// swap [_First1, _Last1) with [_Dest, ...)
// not parallelized as benchmarks show it isn't worth it
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt1);
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt2);
return _STD swap_ranges(_First1, _Last1, _Dest);
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -4055,6 +4057,7 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, class _Fn, _Enable_if_execution
void generate(_ExPo&&, _FwdIt _First, _FwdIt _Last, _Fn _Func) noexcept /* terminates */ {
// replace [_First, _Last) with _Func()
// not parallelized at present due to unclear parallelism requirements on _Func
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
return _STD generate(_First, _Last, _Pass_fn(_Func));
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -4418,13 +4421,15 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, class _Pr, _Enable_if_execution
_NODISCARD_UNIQUE_ALG _FwdIt unique(_ExPo&&, _FwdIt _First, _FwdIt _Last, _Pr _Pred) noexcept /* terminates */ {
// remove each satisfying _Pred with previous
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
return _STD unique(_First, _Last, _Pass_fn(_Pred));
}

_EXPORT_STD template <class _ExPo, class _FwdIt, _Enable_if_execution_policy_t<_ExPo> = 0>
_NODISCARD_UNIQUE_ALG _FwdIt unique(_ExPo&&, _FwdIt _First, _FwdIt _Last) noexcept /* terminates */ {
// remove each matching previous
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
return _STD unique(_First, _Last);
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -4805,7 +4810,7 @@ _EXPORT_STD template <class _ExPo, class _BidIt, class _FwdIt, _Enable_if_execut
_FwdIt reverse_copy(_ExPo&&, _BidIt _First, _BidIt _Last, _FwdIt _Dest) noexcept /* terminates */ {
// copy reversing elements in [_First, _Last)
// not parallelized as benchmarks show it isn't worth it
_REQUIRE_PARALLEL_ITERATOR(_BidIt);
static_assert(_Is_ranges_bidi_iter_v<_BidIt>, "This algorithm requires bidirectional iterators or stronger.");
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_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
return _STD reverse_copy(_First, _Last, _Dest);
}
Expand Down Expand Up @@ -5498,6 +5503,7 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, _Enable_if_execution_policy_t<_
_FwdIt shift_left(_ExPo&&, _FwdIt _First, _FwdIt _Last, _Iter_diff_t<_FwdIt> _Pos_to_shift) noexcept /* terminates */ {
// shift [_First, _Last) left by _Pos_to_shift positions
// not parallelized as benchmarks show it isn't worth it
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
return _STD shift_left(_First, _Last, _Pos_to_shift);
}

Expand Down Expand Up @@ -5579,6 +5585,7 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, _Enable_if_execution_policy_t<_
_FwdIt shift_right(_ExPo&&, _FwdIt _First, _FwdIt _Last, _Iter_diff_t<_FwdIt> _Pos_to_shift) noexcept /* terminates */ {
// shift [_First, _Last) right by _Pos_to_shift positions
// not parallelized as benchmarks show it isn't worth it
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
return _STD shift_right(_First, _Last, _Pos_to_shift);
}
#endif // _HAS_CXX20
Expand Down Expand Up @@ -6121,6 +6128,7 @@ _EXPORT_STD template <class _ExPo, class _BidIt, class _Pr, _Enable_if_execution
_BidIt stable_partition(_ExPo&&, _BidIt _First, _BidIt _Last, _Pr _Pred) noexcept /* terminates */ {
// partition preserving order of equivalents
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_CPP17_MUTABLE_BIDIRECTIONAL_ITERATOR(_BidIt);
return _STD stable_partition(_First, _Last, _Pass_fn(_Pred));
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -7572,13 +7580,15 @@ _EXPORT_STD template <class _ExPo, class _BidIt, class _Pr, _Enable_if_execution
void inplace_merge(_ExPo&&, _BidIt _First, _BidIt _Mid, _BidIt _Last, _Pr _Pred) noexcept /* terminates */ {
// merge [_First, _Mid) with [_Mid, _Last)
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_CPP17_MUTABLE_BIDIRECTIONAL_ITERATOR(_BidIt);
_STD inplace_merge(_First, _Mid, _Last, _Pass_fn(_Pred));
}

_EXPORT_STD template <class _ExPo, class _BidIt, _Enable_if_execution_policy_t<_ExPo> = 0>
void inplace_merge(_ExPo&&, _BidIt _First, _BidIt _Mid, _BidIt _Last) noexcept /* terminates */ {
// merge [_First, _Mid) with [_Mid, _Last)
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_CPP17_MUTABLE_BIDIRECTIONAL_ITERATOR(_BidIt);
_STD inplace_merge(_First, _Mid, _Last);
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -8784,13 +8794,15 @@ _EXPORT_STD template <class _ExPo, class _RanIt, class _Pr, _Enable_if_execution
void partial_sort(_ExPo&&, _RanIt _First, _RanIt _Mid, _RanIt _Last, _Pr _Pred) noexcept /* terminates */ {
// order [_First, _Last) up to _Mid
// parallelism suspected to be infeasible
_REQUIRE_CPP17_MUTABLE_RANDOM_ACCESS_ITERATOR(_RanIt);
return _STD partial_sort(_First, _Mid, _Last, _Pass_fn(_Pred));
}

_EXPORT_STD template <class _ExPo, class _RanIt, _Enable_if_execution_policy_t<_ExPo> = 0>
void partial_sort(_ExPo&&, _RanIt _First, _RanIt _Mid, _RanIt _Last) noexcept /* terminates */ {
// order [_First, _Last) up to _Mid
// parallelism suspected to be infeasible
_REQUIRE_CPP17_MUTABLE_RANDOM_ACCESS_ITERATOR(_RanIt);
return _STD partial_sort(_First, _Mid, _Last);
}

Expand Down Expand Up @@ -9054,13 +9066,15 @@ _EXPORT_STD template <class _ExPo, class _RanIt, class _Pr, _Enable_if_execution
void nth_element(_ExPo&&, _RanIt _First, _RanIt _Nth, _RanIt _Last, _Pr _Pred) noexcept /* terminates */ {
// order Nth element
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_CPP17_MUTABLE_RANDOM_ACCESS_ITERATOR(_RanIt);
_STD nth_element(_First, _Nth, _Last, _Pass_fn(_Pred));
}

_EXPORT_STD template <class _ExPo, class _RanIt, _Enable_if_execution_policy_t<_ExPo> = 0>
void nth_element(_ExPo&&, _RanIt _First, _RanIt _Nth, _RanIt _Last) noexcept /* terminates */ {
// order Nth element
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_CPP17_MUTABLE_RANDOM_ACCESS_ITERATOR(_RanIt);
_STD nth_element(_First, _Nth, _Last);
}

Expand Down Expand Up @@ -9894,13 +9908,15 @@ _NODISCARD pair<_FwdIt, _FwdIt> minmax_element(_ExPo&&, _FwdIt _First, _FwdIt _L
/* terminates */ {
// find smallest and largest elements
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD minmax_element(_First, _Last, _Pass_fn(_Pred));
}

_EXPORT_STD template <class _ExPo, class _FwdIt, _Enable_if_execution_policy_t<_ExPo> = 0>
_NODISCARD pair<_FwdIt, _FwdIt> minmax_element(_ExPo&&, _FwdIt _First, _FwdIt _Last) noexcept /* terminates */ {
// find smallest and largest elements
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD minmax_element(_First, _Last);
}

Expand Down
6 changes: 6 additions & 0 deletions stl/inc/execution
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Expand Up @@ -1653,6 +1653,7 @@ struct _Static_partitioned_adjacent_find3 {
_EXPORT_STD template <class _ExPo, class _FwdIt, class _Pr, _Enable_if_execution_policy_t<_ExPo> /* = 0 */>
_NODISCARD _FwdIt adjacent_find(_ExPo&&, _FwdIt _First, _FwdIt _Last, _Pr _Pred) noexcept /* terminates */ {
// find first satisfying _Pred with successor
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
_Adl_verify_range(_First, _Last);
auto _UFirst = _Get_unwrapped(_First);
const auto _ULast = _Get_unwrapped(_Last);
Expand Down Expand Up @@ -2247,6 +2248,7 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, class _Diff, class _Ty, class _
_NODISCARD _FwdIt search_n(_ExPo&&, const _FwdIt _First, _FwdIt _Last, const _Diff _Count_raw, const _Ty& _Val,
_Pr _Pred) noexcept /* terminates */ {
// find first _Count * _Val satisfying _Pred
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
const _Algorithm_int_t<_Diff> _Count = _Count_raw;
if (_Count <= 0) {
_Last = _First;
Expand Down Expand Up @@ -2584,6 +2586,7 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, class _Pr, _Enable_if_execution
_NODISCARD_REMOVE_ALG _FwdIt remove_if(_ExPo&&, _FwdIt _First, const _FwdIt _Last, _Pr _Pred) noexcept
/* terminates */ {
// remove each satisfying _Pred
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
_Adl_verify_range(_First, _Last);
auto _UFirst = _Get_unwrapped(_First);
const auto _ULast = _Get_unwrapped(_Last);
Expand Down Expand Up @@ -2722,6 +2725,7 @@ struct _Sort_operation { // context for background threads
_EXPORT_STD template <class _ExPo, class _RanIt, class _Pr, _Enable_if_execution_policy_t<_ExPo> /* = 0 */>
void sort(_ExPo&&, const _RanIt _First, const _RanIt _Last, _Pr _Pred) noexcept /* terminates */ {
// order [_First, _Last)
_REQUIRE_CPP17_MUTABLE_RANDOM_ACCESS_ITERATOR(_RanIt);
_Adl_verify_range(_First, _Last);
const auto _UFirst = _Get_unwrapped(_First);
const auto _ULast = _Get_unwrapped(_Last);
Expand Down Expand Up @@ -2979,6 +2983,7 @@ struct _Static_partitioned_stable_sort3 {
_EXPORT_STD template <class _ExPo, class _BidIt, class _Pr, _Enable_if_execution_policy_t<_ExPo> /* = 0 */>
void stable_sort(_ExPo&&, const _BidIt _First, const _BidIt _Last, _Pr _Pred) noexcept /* terminates */ {
// sort preserving order of equivalents
_REQUIRE_CPP17_MUTABLE_BIDIRECTIONAL_ITERATOR(_BidIt);
_Adl_verify_range(_First, _Last);
const auto _UFirst = _Get_unwrapped(_First);
const auto _ULast = _Get_unwrapped(_Last);
Expand Down Expand Up @@ -3541,6 +3546,7 @@ struct _Static_partitioned_partition2 {
_EXPORT_STD template <class _ExPo, class _FwdIt, class _Pr, _Enable_if_execution_policy_t<_ExPo> /* = 0 */>
_FwdIt partition(_ExPo&&, _FwdIt _First, const _FwdIt _Last, _Pr _Pred) noexcept /* terminates */ {
// move elements satisfying _Pred to beginning of sequence
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
_Adl_verify_range(_First, _Last);
const auto _UFirst = _Get_unwrapped(_First);
const auto _ULast = _Get_unwrapped(_Last);
Expand Down
4 changes: 0 additions & 4 deletions stl/inc/numeric
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Expand Up @@ -112,7 +112,6 @@ _NODISCARD _Ty reduce(_ExPo&& _Exec, _FwdIt _First, _FwdIt _Last, _Ty _Val, _Bin
_EXPORT_STD template <class _ExPo, class _FwdIt, class _Ty, _Enable_if_execution_policy_t<_ExPo> = 0>
_NODISCARD _Ty reduce(_ExPo&& _Exec, const _FwdIt _First, const _FwdIt _Last, _Ty _Val) noexcept /* terminates */ {
// return commutative and associative reduction of _Val and [_First, _Last)
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD reduce(_STD forward<_ExPo>(_Exec), _First, _Last, _STD move(_Val), plus{});
}

Expand All @@ -121,7 +120,6 @@ _NODISCARD _Iter_value_t<_FwdIt> reduce(_ExPo&& _Exec, const _FwdIt _First, cons
/* terminates */ {
// return commutative and associative reduction of
// iterator_traits<_FwdIt>::value_type{} and [_First, _Last)
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD reduce(_STD forward<_ExPo>(_Exec), _First, _Last, _Iter_value_t<_FwdIt>{}, plus{});
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -232,8 +230,6 @@ _EXPORT_STD template <class _ExPo, class _FwdIt1, class _FwdIt2, class _Ty, _Ena
_NODISCARD _Ty transform_reduce(_ExPo&& _Exec, _FwdIt1 _First1, _FwdIt1 _Last1, _FwdIt2 _First2, _Ty _Val) noexcept
/* terminates */ {
// return commutative and associative transform-reduction of sequences
_REQUIRE_PARALLEL_ITERATOR(_FwdIt1);
_REQUIRE_PARALLEL_ITERATOR(_FwdIt2);
return _STD transform_reduce(
_STD forward<_ExPo>(_Exec), _First1, _Last1, _First2, _STD move(_Val), plus{}, multiplies{});
}
Expand Down
10 changes: 10 additions & 0 deletions stl/inc/xutility
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Expand Up @@ -1120,6 +1120,10 @@ _INLINE_VAR constexpr bool _Is_ranges_random_iter_v =
static_assert(_Is_cpp17_fwd_iter_v<_Iter>, \
"Non-ranges algorithms require that mutable iterators be Cpp17ForwardIterators or stronger.")

#define _REQUIRE_CPP17_MUTABLE_BIDIRECTIONAL_ITERATOR(_Iter) \
static_assert(_Is_cpp17_bidi_iter_v<_Iter>, \
"This algorithm requires that mutable iterators be Cpp17BidirectionalIterators or stronger.")

template <class, class = void>
struct _Is_checked_helper {}; // default definition, no longer used, retained due to pseudo-documentation

Expand Down Expand Up @@ -6211,6 +6215,7 @@ _EXPORT_STD template <class _ExPo, class _BidIt, _Enable_if_execution_policy_t<_
void reverse(_ExPo&&, _BidIt _First, _BidIt _Last) noexcept /* terminates */ {
// reverse elements in [_First, _Last)
// not parallelized as benchmarks show it isn't worth it
_REQUIRE_CPP17_MUTABLE_BIDIRECTIONAL_ITERATOR(_BidIt);
return _STD reverse(_First, _Last);
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -6287,6 +6292,7 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, _Enable_if_execution_policy_t<_
_FwdIt rotate(_ExPo&&, _FwdIt _First, _FwdIt _Mid, _FwdIt _Last) noexcept /* terminates */ {
// rotate [_First, _Last) left by distance(_First, _Mid) positions
// not parallelized as benchmarks show it isn't worth it
_REQUIRE_CPP17_MUTABLE_ITERATOR(_FwdIt);
return _STD rotate(_First, _Mid, _Last);
}
#endif // _HAS_CXX17
Expand Down Expand Up @@ -6674,13 +6680,15 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, class _Pr, _Enable_if_execution
_NODISCARD _FwdIt max_element(_ExPo&&, _FwdIt _First, _FwdIt _Last, _Pr _Pred) noexcept /* terminates */ {
// find largest element
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD max_element(_First, _Last, _Pass_fn(_Pred));
}

_EXPORT_STD template <class _ExPo, class _FwdIt, _Enable_if_execution_policy_t<_ExPo> = 0>
_NODISCARD _FwdIt max_element(_ExPo&&, _FwdIt _First, _FwdIt _Last) noexcept /* terminates */ {
// find largest element
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD max_element(_First, _Last);
}

Expand Down Expand Up @@ -6868,13 +6876,15 @@ _EXPORT_STD template <class _ExPo, class _FwdIt, class _Pr, _Enable_if_execution
_NODISCARD _FwdIt min_element(_ExPo&&, _FwdIt _First, _FwdIt _Last, _Pr _Pred) noexcept /* terminates */ {
// find smallest element
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD min_element(_First, _Last, _Pass_fn(_Pred));
}

_EXPORT_STD template <class _ExPo, class _FwdIt, _Enable_if_execution_policy_t<_ExPo> = 0>
_NODISCARD _FwdIt min_element(_ExPo&&, _FwdIt _First, _FwdIt _Last) noexcept /* terminates */ {
// find smallest element
// not parallelized at present, parallelism expected to be feasible in a future release
_REQUIRE_PARALLEL_ITERATOR(_FwdIt);
return _STD min_element(_First, _Last);
}

Expand Down