使用multipository_key从multi_index_container擦除每个键的元素

问题描述

我有一个multi_index_container，其索引为composite_key.但是我找不到通过其键擦除元素的方法.请参见以下内容:

I have a multi_index_container with an index that is a composite_key.But I can not find a way to erase an element by its key.Please see below:

#include <boost/multi_index_container.hpp>
#include <boost/multi_index/member.hpp>
#include <boost/multi_index/hashed_index.hpp>
#include <boost/multi_index/composite_key.hpp>

using namespace boost::multi_index;

struct Point
{
    int x, y;
};

void func()
{
  multi_index_container<Point,indexed_by<
    hashed_unique<
      composite_key<Point,
                    member<Point,int,&Point::x>,
                    member<Point,int,&Point::y> >
      > > > points;

  points.find( boost::make_tuple( 3, 3 ) );    // <- works
  points.erase( boost::make_tuple( 3, 3 ) );   // <- failes to compile
}

erase(key)适用于非复合索引.但是我找不到复合键的正确语法.

erase(key) works for indices that are not composite. But I am unable to find the correct syntax for composite keys.

推荐答案

erase没有允许与元组互操作的重载类型(从技术上讲，这与 兼容的扩展名 .)但是您可以达到相同的效果还有更多代码:

erasedoesn't have the type of overloads that allow for interoperation with tuples (technically, this relates to the concept of compatible extensions.) But you can have the same effect with a little more code:

auto p=points.equal_range(boost::make_tuple(3,3));
points.erase(p.first,p.second);

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