I have to develop a component which will have a more than 100,000 instances of a class. And i want to generate a report based on the different different criteria (members) of the particular class. for example, A employee class with data fields id, names, addr, phoneno. Report generation wiil be based on
- names_ascending
- names_descending
- addr_ascending
- phoneno_asceding
- unique_names
- unique_addr
- unique_phoneno
runtime iteration of instances for each call is very slow since it is a linear operation on large number of instances and requires sorting mechanism.
So i have stored a pointers of each instances in a container on different sorted manner. But requires more memory than required. Please suggest me a better way of doing this. I have posted sample code snippet that i followed to achieve above.
class Employee
{
int m_id;
string m_name;
string m_addr;
string m_phone;
public:
Employee(int id, string name, string addr, string phone) :
m_id(id), m_name(name), m_addr(addr), m_phone(phone) { }
int id() const { return m_id; }
string name() const { return m_name; }
string addr() const { return m_addr; }
string phoneno() const { return m_phone; }
};
//custom predicate for std containers
struct IDComparator
{
bool operator() (const Employee* e1, const Employee* e2 )
{
return e1->id() < e2->id();
}
};
struct NameComparator
{
bool operator() (const Employee* e1, const Employee* e2 )
{
return e1->name() < e2->name();
}
}
struct AddressComparator
{
bool operator() (const Employee* e1, const Employee* e2 )
{
return e1->addr() < e2->addr();
}
};
struct PhoneComparator
{
bool operator() (const Employee* e1, const Employee* e2 )
{
return e1->phoneno() < e2->phoneno();
}
};
//Class which holds huge number of employee instances
class Dept
{
private:
typedef set<Employee*, IDComparator> EMPID; //unnique id
typedef EMPID::iterator EMPID_ITER;
typedef multiset<const Employee*, NameComparator> EMPNAME; // for sorted names
typedef EMPNAME::iterator NAME_ITER;
typedef multiset<const Employee*, AddressComparator> EMPADDR; // for sorted addr
typedef EMPADDR::iterator ADDR_ITER;
typedef multiset<const Employee*, PhoneComparator> EMPPHONE; // for sorted phoneno
typedef EMPPHONE::iterator PHONE_ITER;
private:
EMPID m_empids;
EMPNAME m_names ;
EMPADDR m_addr;
EMPPHONE m_phoneno;
public:
Dept() { }
~Dept() { //delete the instances of employees }
void add(Employee* e)
{
EMP_ITER iter = m_empids.insert(e).first;
const Employee* empptr = &*iter;
m_names.insert(empptr); // adds employee pointer to name multimap
m_addr.insert(empptr); // adds employee pointer to addr multimap
m_phoneno.insert(empptr); // adds employee pointer to phone multimap
}
void print_emp_dtls() const; //prints all the emp dtls iterating though EMPID
void print_unique_names() const; //iterate EMPNAME & use upperbound & lowerbound, prints unique names
void print_asc_name() const; //iterate EMPNAME & prints all names in ascending order
void print_desc_name() const; //back iterate EMPNAME & prints all names in descending order
void print_unique_adrr() const; //iterate EMPADDR & use upperbound & lowerbound, prints unique address
void print_asc_addr() const; //iterate EMPADDR & prints all addr in ascending order
void print_desc_addr() const; //back iterate EMPADDR & prints all address in descending order
void print_unique_phoneno() const; //iterate EMPPHONE & use upperbound & lowerbound,prints unique phoneno
void print_asc_phoneno() const; //iterate EMPPHONE & prints all phoneno in ascending order
void print_desc_phoneno() const; //back iterate EMPPHONE & prints all phoneno in };
