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Minor tweak #12

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Merged
YexuanXiao merged 1 commit into from
Feb 14, 2026
Merged

Minor tweak #12

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18 changes: 9 additions & 9 deletions deque.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3014,8 +3014,8 @@ class deque
return begin();
}
// 此时容器一定不为空
auto const back_diff = end_pre - pos + ::std::size_t(0);
auto const front_diff = pos - begin_pre + ::std::size_t(0);
auto const back_diff = end_pre - pos;
auto const front_diff = pos - begin_pre;
// NB:
// 如果args是当前容器的元素的引用，那么必须使得该元素先被emplace_back/front后再被移动到正确位置，否则该引用会失效，同时reserve不会导致引用失效
// 此处逻辑和无分配器版本稍微不一样
Expand All @@ -3024,7 +3024,7 @@ class deque
reserve_back_(::std::size_t(2));
emplace_back_noalloc_(::std::forward<Args>(args)...); // 满足标准要求经过A::construct
// back_emplace向后移动1个元素并插入，因此先reserve以获得一个不失效的pos
auto new_pos = begin() + static_cast<difference_type>(front_diff);
auto new_pos = begin() + front_diff;
back_emplace_(new_pos.block_elem_curr_, new_pos.elem_curr_);
*new_pos = ::std::move(back());
pop_back();
Expand All @@ -3034,7 +3034,7 @@ class deque
{
reserve_front_(::std::size_t(2));
emplace_front_noalloc_(::std::forward<Args>(args)...);
auto new_pos = end() - static_cast<difference_type>(back_diff);
auto new_pos = end() - back_diff;
front_emplace_(new_pos.block_elem_curr_, new_pos.elem_curr_);
*(--new_pos) = ::std::move(front());
pop_front();
Expand Down Expand Up @@ -3130,20 +3130,20 @@ class deque
}
auto const front_diff = pos - begin_pre;
auto const back_diff = end_pre - pos;
auto const old_size = front_diff + back_diff;
auto const old_size = static_cast<size_type>(front_diff + back_diff);
if (back_diff <= front_diff)
{
partial_guard_<true> guard(this, static_cast<size_type>(old_size));
partial_guard_<true> guard(this, old_size);
append_range_noguard_(first, last);
guard.release();
::std::rotate(begin() + front_diff, begin() + old_size, end());
::std::rotate(begin() + front_diff, begin() + static_cast<difference_type>(old_size), end());
}
else
{
partial_guard_<false> guard(this, static_cast<size_type>(old_size));
partial_guard_<false> guard(this, old_size);
prepend_range_noguard_(first, last);
guard.release();
::std::rotate(begin(), begin() + (static_cast<difference_type>(size()) - old_size), end() - back_diff);
::std::rotate(begin(), begin() + static_cast<difference_type>(size() - old_size), end() - back_diff);
}
return begin() + front_diff;
}
Expand Down