如何在boost::multi_index_container中找到具有相同键值的所有元素

Question

构建boost multi_index_container后，我想访问具有相同键值的所有元素。下面的代码给出了预期结果的基本概念:

#include <iostream>
#include <boost/multi_index_container.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index/identity.hpp>
#include <boost/multi_index/member.hpp>

using namespace std;
using namespace :: boost;
using namespace ::boost::multi_index;

struct name{};
struct id{};
struct employee
{
int         id;
std::string name;
employee(int id,const std::string& name):id(id),name(name){}

};

// define a multiply indexed set with indices by id and name
typedef multi_index_container<
employee,
indexed_by<
ordered_unique<tag<id>,member<employee,int,&employee::id>>,

ordered_non_unique<tag<name>,member<employee,std::string,&employee::name> >
> 
> employee_set;

int main() {
employee_set employee_collection ;
employee_collection.insert(employee(1,"Tony"));
employee_collection.insert(employee(2,"Bob"));
employee_collection.insert(employee(4,"Thomas"));
employee_collection.insert(employee(5,"Richard"));
employee_collection.insert(employee(6,"Bill"));
employee_collection.insert(employee(7,"Robert"));
employee_collection.insert(employee(8,"Bob"));

typedef employee_set::index<name>::type employee_set_by_name;
employee_set_by_name::iterator it  =
employee_collection.get<name>().find("Bob"); // I want a collection of "Bob"s
cout << (*it).id<< endl;
/* This won't compile
for(it = employee_collection.get<name>().find("Bob").begin();
it != employee_collection.get<name>().find("Bob").end(); ++it){
cout << (*it).id << endl;
}*/
return 0 ;
}
// References:
// Boost documentation

上面的代码查找按字母顺序排列的第一个Bob，同时有两个Bob感兴趣。

Answer 1

使用equal_range:

typedef employee_set::index<name>::type employee_set_by_name;
std::pair<
employee_set_by_name::iterator, 
employee_set_by_name::iterator > p = employee_collection.get<name>().equal_range("Bob");
while(p.first != p.second) {
cout << (*p.first).id << endl;
++p.first;
}