使用multipository_key从multi_index_container擦除每个键的元素 [英] Erase element per key from multi_index_container with composite_key

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

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);

这篇关于使用multipository_key从multi_index_container擦除每个键的元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！