Iterator for increasing multi-index on increasing KEY :: optional parameter
#include <iostream>
using namespace std;
#include <typeinfo>
#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>
#include <boost/optional.hpp>
using boost::multi_index_container;
namespace mi = boost::multi_index;
class employee
{
public :
std::string name;
boost::optional<unsigned int> id;
unsigned int presence;
};
struct ByName{};
struct ById{};
int main()
{
typedef boost::multi_index_container<
employee,
mi::indexed_by<
// sort by less<string> on name
mi::ordered_unique<mi::tag<ByName>,mi::member<employee,std::string,&employee::name>>,
mi::ordered_unique<mi::tag<ById>,mi::member<employee,boost::optional<unsigned int>,&employee::id>>
>
>employee_set;
employee_set empDataBase;
class employee emp1, emp2, emp3;
std::string name("Mahesh");
emp1.name = name;
emp1.presence = true;
emp1.id = 1000;
std::string name1("Rajesh");
emp2.name = name1;
emp2.presence = true;
std::string name3("Piku");
emp3.name = name3;
emp3.presence = true;
emp3.id = 2000;
bool result = empDataBase.insert(emp1).second;
printf("result 1 is %d\n", result);
result = empDataBase.insert(emp2).second;
printf("result 2 is %d\n", result);
result = empDataBase.insert(emp3).second;
printf("result 3 is %d\n", result);
/* Get the value from the multi-index using first and second ordered index */
employee_set::iterator i = empDataBase.get<ByName>().find(name1);
printf ("name - %s, presence - %d, Id intialized ? %d\n", (*i).name.c_str(), (*i).presence, (*i).id.is_initialized());
employee_set::iterator ii = empDataBase.get<ById>().find(2000);
printf ("name - %s, presence - %d, id Value %d\n", (*ii).name.c_str(), (*ii).presence, (*ii).id.get());
empDataBase.erase(i);
empDataBase.erase(ii);
/* Get the value from the multi-index using first and second ordered index */
i = empDataBase.get<ByName>().find(name1);
printf ("name - %s, presence - %d, Id intialized ? %d\n", (*i).name.c_str(), (*i).presence, (*i).id.is_initialized());
return 0;
}
employee_set::iterator ii
gives me the following error. How do I define an iterator?
prog.cpp: In function 'int main ()': prog.cpp: 76: 63: error: conversion from 'boost :: multi_index :: detail :: ordered_index, & employee :: id>, std :: less>, boost :: multi_index :: detail :: nth_layer <2, employee, boost :: multi_index :: indexed_by, boost :: multi_index :: member, & employee :: name ->, boost :: multi_index :: ordered_unique, boost :: multi_index :: member, & employee :: id →>, std :: allocator>, boost :: mpl :: v_item, 0>, boost :: multi_index :: detail :: ordered_unique_tag> :: iterator {aka boost :: multi_index: : detail :: bidir_node_iterator →>} 'for non-scalar type "Boost :: multi_index :: multi_index_container, boost :: multi_index :: member, & employee :: name →, boost :: multi_index :: ordered_unique, boost :: multi_index :: member, & employee ::id → → :: iterator {aka boost :: multi_index :: detail :: bidir_node_iterator → →} employee_set :: iterator ii = empDataBase.get (). find (2000);
source to share
Each index a multi_index_container
has its own type iterator
, which cannot be freely changed compared to other indexes. So, you need to write something like
employee_set::index<ById>::type::iterator ii = empDataBase.get<ById>().find(2000);
or, if using C ++ 11, just
auto ii = empDataBase.get<ById>().find(2000);
in the understanding that the type is ii
not the same as the type i
. Similarly, the line
empDataBase.erase(ii);
won't work because it ii
is an index iterator ById
, whereas empDataBase
, without additional qualifications, refers to index # 0 ( ByName
). Therefore you need to write
empDataBase.get<ById>().erase(ii);
or refer to the projection of the iterator .
source to share