[Boost-users] shared_ptr to object in stl set container?

Subject: [Boost-users] shared_ptr to object in stl set container?
From: Galen (gjwilkerson_at_[hidden])
Date: 2011-12-12 22:23:51

Hi,

-- I'm trying to use shared_ptr in a stl set, but am having trouble with find()
   Any help?  Documentation on this seems hard to find.

-- Also, are the overloaded < and == useful or correct here?

thanks!

Output is: ------------------

0 adding neighbor 1
0 adding neighbor 2
1 adding neighbor 0
2 adding neighbor 1
0's neighbors
1 has 1 neighbors
0
2 has 1 neighbors
1
NOT WORKING
is 1 a neighbor of 0? 0
is 0 a neighbor of 1? 0

Code below: -------------------

#include<set>
#include<iostream>
#include<boost/shared_ptr.hpp>

using namespace std;

//use typedef instead in actual code
#define NodePtr boost::shared_ptr<Node>

// TODO: should this extend shared_ptr?
class Node {

private:

  int id;

  set<NodePtr> neighbors;

public:

  Node() {
  }

  Node(int newID) {
    id = newID;
  }

  ~Node() {
  }

  int getID() {
    return id;
  }

  int addNeighbor(NodePtr newNode) {

    int newID;
    newID = newNode->id;

    // if not already a neighbor, add
    if (!isNeighbor(newID))
      neighbors.insert(newNode);
  }

  set<NodePtr> getNeighbors() {
    return neighbors;
  }

  bool isNeighbor(int searchID) {

    set<NodePtr>::iterator it;

    // check if this neighbor already in list
    NodePtr searchNode(new Node(searchID));

    it = neighbors.find(searchNode);

    // if not found, add to neighbors
    if (it == neighbors.end()) {
      return false;
    }

    //else
    return true;
  }

  //overload == for find()
  bool operator== (NodePtr otherNode) {
    cout << "==: " << otherNode->id << " " << id << endl;

    return (otherNode->id == id);
  }

  //overload < in case we want to sort
  bool operator< (NodePtr otherNode) {
    return (id < otherNode->id);
  }

};

int main() {

  // the nodes are pointers to Node objects
  NodePtr n0(new Node(0));
  NodePtr n1(new Node(1));
  NodePtr n2(new Node(2));
  cout << n0->getID() << " adding neighbor " << n1->getID() << endl;
  n0->addNeighbor(n1);

  cout << n0->getID() << " adding neighbor " << n2->getID() << endl;
  n0->addNeighbor(n2);

  cout << n1->getID() << " adding neighbor " << n0->getID() << endl;
  n1->addNeighbor(n0);

  //  cout << n2->getID() << " adding neighbor " << n0->getID() <<
endl;
  //  n2->addNeighbor(n0);

  cout << n2->getID() << " adding neighbor " << n1->getID() << endl;
  n2->addNeighbor(n1);

  set<NodePtr> neighbors = n0->getNeighbors();
  set<NodePtr>::iterator NB;

  int id = n0->getID();

  cout << id << "'s neighbors" << endl;

  for (NB = neighbors.begin(); NB != neighbors.end() ; NB++) {

    set<NodePtr> neighborsList = (*NB)->getNeighbors();

    cout << (*NB)->getID() << " has " << neighborsList.size() << "
neighbors" << endl;
    cout << (*neighborsList.begin())->getID() << endl;
  }

  // http://www.engr.sjsu.edu/wbarrett/SortFind.htm
  cout << "NOT WORKING" << endl;
  cout << "is 1 a neighbor of 0? " << n0->isNeighbor(1) << endl;
  cout << "is 0 a neighbor of 1? " << n1->isNeighbor(0) << endl;
}