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libstdc++: Simplify copy-pasted algorithms in <ranges>

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The <ranges> header currently copies some simple algorithms from
<bits/ranges_algo.h>, which was originally done in order to avoid a
circular dependency with the header.  This is no longer an issue since
the latter header now includes <bits/ranges_util.h> instead of all of
<ranges>.

This means we could now just include <bits/ranges_algo.h> and remove the
copied algorithms, but that'd increase the size of <ranges> by ~10%.
And we can't use the corresponding STL-style algorithms here because
they assume input iterators are copyable.  So this patch instead
simplifies these copied algorithms, removing their constraints and
unused parameters, and keeps them around.  In a subsequent patch we're
going to copy (a simplified version of) ranges::find into <ranges> as
well.

libstdc++-v3/ChangeLog:

	* include/std/ranges (__detail::find_if): Simplify.
	(__detail::find_if_not): Likewise.
	(__detail::min): Remove.
	(__detail::mismatch): Simplify.
	(take_view::size): Use std::min instead of __detail::min.
This commit is contained in:
Patrick Palka 2021-04-08 16:45:25 -04:00
parent c7fe68f365
commit c1ce418af2
1 changed files with 17 additions and 42 deletions
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59
libstdc++-v3/include/std/ranges
View File

@ -978,65 +978,40 @@ namespace views::__adaptor
using all_t = decltype(all(std::declval<_Range>()));
} // namespace views
// XXX: the following algos are copied from ranges_algo.h to avoid a circular
// dependency with that header.
// The following simple algos are transcribed from ranges_algo.h to avoid
// having to include that entire header.
namespace __detail
{
template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
typename _Proj = identity,
indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
template<typename _Iter, typename _Sent, typename _Pred>
constexpr _Iter
find_if(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {})
find_if(_Iter __first, _Sent __last, _Pred __pred)
{
while (__first != __last
&& !(bool)std::__invoke(__pred, std::__invoke(__proj, *__first)))
&& !(bool)std::__invoke(__pred, *__first))
++__first;
return __first;
}
template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
typename _Proj = identity,
indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
template<typename _Iter, typename _Sent, typename _Pred>
constexpr _Iter
find_if_not(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {})
find_if_not(_Iter __first, _Sent __last, _Pred __pred)
{
while (__first != __last
&& (bool)std::__invoke(__pred, std::__invoke(__proj, *__first)))
&& (bool)std::__invoke(__pred, *__first))
++__first;
return __first;
}
template<typename _Tp, typename _Proj = identity,
indirect_strict_weak_order<projected<const _Tp*, _Proj>>
_Comp = ranges::less>
constexpr const _Tp&
min(const _Tp& __a, const _Tp& __b, _Comp __comp = {}, _Proj __proj = {})
{
if (std::__invoke(std::move(__comp),
std::__invoke(__proj, __b),
std::__invoke(__proj, __a)))
return __b;
else
return __a;
}
template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
typename _Pred = ranges::equal_to,
typename _Proj1 = identity, typename _Proj2 = identity>
requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
template<typename _Iter1, typename _Sent1, typename _Iter2, typename _Sent2>
constexpr pair<_Iter1, _Iter2>
mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
_Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {})
mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2)
{
while (__first1 != __last1 && __first2 != __last2
&& (bool)std::__invoke(__pred,
std::__invoke(__proj1, *__first1),
std::__invoke(__proj2, *__first2)))
{
++__first1;
++__first2;
}
&& (bool)ranges::equal_to{}(*__first1, *__first2))
{
++__first1;
++__first2;
}
return { std::move(__first1), std::move(__first2) };
}
} // namespace __detail
@ -1847,14 +1822,14 @@ namespace views::__adaptor
size() requires sized_range<_Vp>
{
auto __n = ranges::size(_M_base);
return __detail::min(__n, static_cast<decltype(__n)>(_M_count));
return std::min(__n, static_cast<decltype(__n)>(_M_count));
}
constexpr auto
size() const requires sized_range<const _Vp>
{
auto __n = ranges::size(_M_base);
return __detail::min(__n, static_cast<decltype(__n)>(_M_count));
return std::min(__n, static_cast<decltype(__n)>(_M_count));
}
};