在集合之间移动 `unique_ptr`s [英] Move `unique_ptr`s between sets

问题描述

我有两个集合和一个 a 元素的迭代器:

I have two sets and an iterator to an element of a:

set<unique_ptr<X>> a, b;
set<unique_ptr<X>>::iterator iter = find something in a;

我想从a中移除iter所指向的元素，并插入到b中.是否可以?怎么样?

I would like to remove the element pointed by iter from a and insert it into b. Is it possible? How?

推荐答案

好吧，我怀疑没有正常的方法可以做到这一点.但总有一个不正常的:)您可以执行以下操作:

Well, I suspect there is no normal way to do it. But there is always a non-normal one :) You can do the following:

auto tmp = const_cast<std::unique_ptr<std::string>&&>(*iter);
a.erase(iter);
b.insert(std::move(tmp));

好的，第一行违反了 set 不变量，这很可怕，但据我了解，这应该不是问题，因为在下一行我们从集合中删除了这个邪恶节点.

Ok, the very first line violated set invariant and it is horrible but as far as I understand it should not be a problem since on the very next line we remove this evil node from the set.

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