On 25/03/25 13:30 +0100, Tomasz Kamiński wrote:
This is another piece of P1206R7, adding from_range constructor, append_range,
prepend_range, insert_range, and assign_range members to std::deque.
For append_front of input non-sized range, we are emplacing element at the
front and
then reverse inserted elements. This does not existing elements, and properly
handle
aliasing ranges.
For insert_range, the handling of insertion in the middle of input-only ranges
that are sized could be optimized, we still insert nodes one-by-one in such
case.
For forward and stronger ranges, we reduce them to common_range case, by
computing
the iterator when computing the distance. This is slightly suboptimal, as it
require
range to be iterated for non-common forward ranges that are sized, but reduces
number of instantiations.
This patch extract _M_range_prepend, _M_range_append helper functions that
accepts
(iterator, sentinel) pair. This all used in all standard modes.
PR libstdc++/111055
libstdc++-v3/ChangeLog:
* include/bits/deque.tcc (deque::prepend_range, deque::append_range)
(deque::insert_range, _advance_dist): Define.
There should be two underscores at the start of _advance_dist.
(deque::_M_range_prepend, deque::_M_range_append):
Extract from _M_range_insert_aux for _ForwardIterator(s).
* include/bits/stl_deque.h (deque::assing_range): Define.
Spelling "assign"
(deque::prepend_range, deque::append_range, deque::insert_range):
Declare.
deque(from_range_t, _Rg&&, const allocator_type&): Define constructor
Missing parentheses around the function name:
(deque(from_range_t, _Rg&&, const allocator_type&)): Define
constructor and deduction guide.
and deduction guide.
* include/debug/deque (deque::prepend_range, deque::append_range),
No comma at the end of the line here.
(assing_range): Define.
Spelling "assign" again.
deque(from_range_t, _Rg&&, const allocator_type&): Define constructor
Missing parens again.
and deduction guide.
* testsuite/23_containers/deque/cons/from_range.cc: New test.
* testsuite/23_containers/deque/modifiers/append_range.cc: New test.
* testsuite/23_containers/deque/modifiers/assign/assign_range.cc: New
test.
* testsuite/23_containers/deque/modifiers/prepend_range.cc: New test.
---
Expanded the documentetion comments. Tests for the stability of
pointers/references
to existing elements, when inserting at front/end.
libstdc++-v3/include/bits/deque.tcc | 229 +++++++++++++++---
libstdc++-v3/include/bits/stl_deque.h | 110 +++++++++
libstdc++-v3/include/debug/deque | 51 ++++
.../23_containers/deque/cons/from_range.cc | 117 +++++++++
.../deque/modifiers/append_range.cc | 128 ++++++++++
.../deque/modifiers/assign/assign_range.cc | 109 +++++++++
.../deque/modifiers/insert/insert_range.cc | 142 +++++++++++
.../deque/modifiers/prepend_range.cc | 140 +++++++++++
8 files changed, 995 insertions(+), 31 deletions(-)
create mode 100644 libstdc++-v3/testsuite/23_containers/deque/cons/from_range.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/deque/modifiers/append_range.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/deque/modifiers/assign/assign_range.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/deque/modifiers/insert/insert_range.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/deque/modifiers/prepend_range.cc
diff --git a/libstdc++-v3/include/bits/deque.tcc
b/libstdc++-v3/include/bits/deque.tcc
index fcbecca55b4..6de76ebc116 100644
--- a/libstdc++-v3/include/bits/deque.tcc
+++ b/libstdc++-v3/include/bits/deque.tcc
@@ -583,6 +583,51 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
this->_M_impl._M_start._M_cur = this->_M_impl._M_start._M_first;
}
+ template <typename _Tp, typename _Alloc>
+ template <typename _InputIterator, typename _Sentinel>
+ void
+ deque<_Tp, _Alloc>::
+ _M_range_prepend(_InputIterator __first, _Sentinel __last,
+ size_type __n)
+ {
+ iterator __new_start = _M_reserve_elements_at_front(__n);
+ __try
+ {
+ std::__uninitialized_copy_a(_GLIBCXX_MOVE(__first), __last,
+ __new_start, _M_get_Tp_allocator());
+ this->_M_impl._M_start = __new_start;
+ }
+ __catch(...)
+ {
+ _M_destroy_nodes(__new_start._M_node,
+ this->_M_impl._M_start._M_node);
+ __throw_exception_again;
+ }
+ }
+
+ template <typename _Tp, typename _Alloc>
+ template <typename _InputIterator, typename _Sentinel>
+ void
+ deque<_Tp, _Alloc>::
+ _M_range_append(_InputIterator __first, _Sentinel __last,
+ size_type __n)
+ {
+ iterator __new_finish = _M_reserve_elements_at_back(__n);
+ __try
+ {
+ std::__uninitialized_copy_a(_GLIBCXX_MOVE(__first), __last,
+ this->_M_impl._M_finish,
+ _M_get_Tp_allocator());
+ this->_M_impl._M_finish = __new_finish;
+ }
+ __catch(...)
+ {
+ _M_destroy_nodes(this->_M_impl._M_finish._M_node + 1,
+ __new_finish._M_node + 1);
+ __throw_exception_again;
+ }
+ }
+
template <typename _Tp, typename _Alloc>
template <typename _InputIterator>
void
@@ -605,38 +650,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
return;
if (__pos._M_cur == this->_M_impl._M_start._M_cur)
- {
- iterator __new_start = _M_reserve_elements_at_front(__n);
- __try
- {
- std::__uninitialized_copy_a(__first, __last, __new_start,
- _M_get_Tp_allocator());
- this->_M_impl._M_start = __new_start;
- }
- __catch(...)
- {
- _M_destroy_nodes(__new_start._M_node,
- this->_M_impl._M_start._M_node);
- __throw_exception_again;
- }
- }
+ _M_range_prepend(__first, __last, __n);
else if (__pos._M_cur == this->_M_impl._M_finish._M_cur)
- {
- iterator __new_finish = _M_reserve_elements_at_back(__n);
- __try
- {
- std::__uninitialized_copy_a(__first, __last,
- this->_M_impl._M_finish,
- _M_get_Tp_allocator());
- this->_M_impl._M_finish = __new_finish;
- }
- __catch(...)
- {
- _M_destroy_nodes(this->_M_impl._M_finish._M_node + 1,
- __new_finish._M_node + 1);
- __throw_exception_again;
- }
- }
+ _M_range_append(__first, __last, __n);
else
_M_insert_aux(__pos, __first, __last, __n);
}
@@ -857,6 +873,157 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
}
}
+#if __glibcxx_ranges_to_container // C++ >= 23
+ template<ranges::forward_range _Rg>
+ auto __advance_dist(_Rg& __rg)
+ {
+ struct _Res
+ {
+ ranges::iterator_t<_Rg> __last;
+ ranges::range_difference_t<_Rg> __size;
+ };
+ if constexpr (ranges::common_range<_Rg>)
+ return _Res{ranges::end(__rg), ranges::distance(__rg)};
+ else if constexpr (ranges::sized_range<_Rg>)
+ {
+ auto const __n = ranges::distance(__rg);
+ auto __it = ranges::begin(__rg);
+ if constexpr (ranges::random_access_range<_Rg>)
+ __it += __n;
+ else
+ ranges::advance(__it, ranges::end(__rg));
+ return _Res{__it, __n};
+ }
+ else
+ {
+ auto __it = ranges::begin(__rg);
+ auto const __last = ranges::end(__rg);
+ ranges::range_difference_t<_Rg> __n(0);
+ for (; __it != __last; ++__it)
+ ++__n;
+ return _Res{__it, __n};
+ }
+ }
+
+ template<typename _Tp, typename _Alloc>
+ template<__detail::__container_compatible_range<_Tp> _Rg>
+ auto
+ deque<_Tp, _Alloc>::
+ insert_range(const_iterator __pos, _Rg&& __rg)
+ -> iterator
+ {
+ if (__pos == cend())
+ {
+ const auto __ins_idx = size();
+ append_range(std::forward<_Rg>(__rg));
+ return begin() + __ins_idx;
+ }
+
+ if (__pos == cbegin())
+ {
+ prepend_range(std::forward<_Rg>(__rg));
+ return begin();
+ }
+
+ const auto __ins_idx = __pos - begin();
Using cbegin() would be a tiny bit faster for unoptimized builds,
avoiding a conversion from iterator to const_iterator.
+ if constexpr (ranges::forward_range<_Rg>)
+ {
+ auto [__last, __n] = __advance_dist(__rg);
+ if (__builtin_expect(__n != 0, 1))
Since this is C++23 code, you can use the (IMHO more readable) likely
attribute:
if (__n != 0) [[likely]]
+ _M_insert_aux(__pos._M_const_cast(),
+ ranges::begin(__rg), __last,
+ __n);
+ }
+ else
+ {
+ auto __first = ranges::begin(__rg);
+ const auto __last = ranges::end(__rg);
+ for (auto __it = __pos._M_const_cast(); __first != __last;
+ (void)++__first, ++__it)
+ __it = _M_emplace_aux(__it, *__first);
+ }
+ return begin() + __ins_idx;
+ }
+
+ template<typename _Tp, typename _Alloc>
+ template<__detail::__container_compatible_range<_Tp> _Rg>
+ void
+ deque<_Tp, _Alloc>::
+ prepend_range(_Rg&& __rg)
+ {
+ if (empty())
+ append_range(std::forward<_Rg>(__rg));
Nice shortcut.
+ else if constexpr (ranges::forward_range<_Rg> ||
ranges::sized_range<_Rg>)
+ {
+ const size_type __n(ranges::distance(__rg));
+ if (__builtin_expect(__n != 0, 1))
+ _M_range_prepend(ranges::begin(__rg), ranges::end(__rg), __n);
+ }
+ else
+ {
+ struct _Guard_elts_front
+ {
+ deque& __self;
+ size_type __n = 0;
+
+ ~_Guard_elts_front()
+ {
+ if (__n > 0)
+ __self._M_erase_at_begin(__self.begin() + __n);
+ }
+ };
+
+ _Guard_elts_front __guard{*this};
+ auto __first = ranges::begin(__rg);
+ const auto __last = ranges::end(__rg);
+ for (; __first != __last; (void)++__first, ++__guard.__n)
+ emplace_front(*__first);
+
+ for (auto __fins = begin(), __lins = begin() + __guard.__n;
+ __fins != __lins && __fins != --__lins; ++__fins)
+ std::iter_swap(__fins, __lins);
Aha, so that's how to do prepend_range for input iterators!
+
+ __guard.__n = 0;
+ }
+ }
+
+ template<typename _Tp, typename _Alloc>
+ template<__detail::__container_compatible_range<_Tp> _Rg>
+ void
+ deque<_Tp, _Alloc>::
+ append_range(_Rg&& __rg)
+ {
+ if constexpr (ranges::forward_range<_Rg> || ranges::sized_range<_Rg>)
+ {
+ const size_type __n(ranges::distance(__rg));
+ if (__builtin_expect(__n != 0, 1))
+ _M_range_append(ranges::begin(__rg), ranges::end(__rg), __n);
+ }
+ else
+ {
+ struct _Guard_elts_back
+ {
+ deque& __self;
+ size_type __n = __self.size();
+
+ ~_Guard_elts_back()
+ {
+ if (__n < __self.size())
+ __self._M_erase_at_end(__self.begin() + __n);
+ }
+ };
+
+ _Guard_elts_back __guard{*this};
+ auto __first = ranges::begin(__rg);
+ const auto __last = ranges::end(__rg);
+ for (; __first != __last; (void)++__first)
+ emplace_back(*__first);
+
+ __guard.__n = size();
+ }
+ }
+#endif // ranges_to_container
+
template<typename _Tp, typename _Alloc>
void
deque<_Tp, _Alloc>::
diff --git a/libstdc++-v3/include/bits/stl_deque.h
b/libstdc++-v3/include/bits/stl_deque.h
index 69367140c8e..51faf6e7f89 100644
--- a/libstdc++-v3/include/bits/stl_deque.h
+++ b/libstdc++-v3/include/bits/stl_deque.h
@@ -66,6 +66,9 @@
#if __cplusplus > 201703L
# include <compare>
#endif
+#if __cplusplus > 202002L
+# include <bits/ranges_algobase.h> // ranges::copy
+#endif
#include <debug/assertions.h>
@@ -1019,6 +1022,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
}
#endif
+#if __glibcxx_ranges_to_container // C++ >= 23
+ /**
+ * @brief Construct a deque from a range.
+ * @param __rg A range of values that are convertible to `value_type`.
+ * @since C++23
+ */
+ template<__detail::__container_compatible_range<_Tp> _Rg>
+ deque(from_range_t, _Rg&& __rg, const allocator_type& __a = _Alloc())
+ : deque(__a)
+ { append_range(std::forward<_Rg>(__rg)); }
+#endif
+
/**
* The dtor only erases the elements, and note that if the elements
* themselves are pointers, the pointed-to memory is not touched in any
@@ -1135,6 +1150,52 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
{ _M_assign_aux(__l.begin(), __l.end(), random_access_iterator_tag()); }
#endif
+#if __glibcxx_ranges_to_container // C++ >= 23
+ /**
+ * @brief Assign a range to the deque.
+ * @param __rg A range of values that are convertible to `value_type`.
We can add "@pre `__rg` and `*this` do not overlap." here.
+ * @since C++23
+ */
+ template<__detail::__container_compatible_range<_Tp> _Rg>
+ constexpr void
+ assign_range(_Rg&& __rg)
+ {
+ static_assert(assignable_from<_Tp&, ranges::range_reference_t<_Rg>>);
+
+ if constexpr (ranges::forward_range<_Rg> || ranges::sized_range<_Rg>)
+ {
+ const size_type __n(ranges::distance(__rg));
+ if (__n <= size())
+ {
+ auto __res = ranges::copy(__rg, begin());
+ return _M_erase_at_end(__res.out);
+ }
+
+ auto __rest = ranges::copy_n(ranges::begin(__rg), size(),
+ begin()).in;
+ _M_range_append(std::move(__rest), ranges::end(__rg),
+ __n - size());
+ }
+ else
+ {
+ auto __first = ranges::begin(__rg);
+ const auto __last = ranges::end(__rg);
+ for (iterator __it = begin(), __end = end();
+ __it != __end; (void)++__first, ++__it)
+ {
+ if (__first == __last)
+ return _M_erase_at_end(__it);
+
+ *__it = *__first;
+ }
+
+ for (; __first != __last; ++__first)
+ emplace_back(*__first);
+ }
+ }
+#endif // ranges_to_container
