I have a node graph with the following definition:
class Node {
public:
// Joint configuration associated with the node
Eigen::VectorXd q;
std::shared_ptr<Node> parent;
// Dictionary of neighboring nodes and their distances
std::unordered_map<std::shared_ptr<Node>, double> neighbors;
// Constructor
Node(const Eigen::VectorXd& q, std::shared_ptr<Node> parent = nullptr) {
this->q = q;
this->parent = parent;
}
struct Hash {
std::size_t operator()(const std::shared_ptr<Node>& node) const {
return std::hash<std::string>()(std::string(reinterpret_cast<const char*>(node->q.data()), node->q.size() * sizeof(double)));
}
};
struct Equal {
bool operator()(const std::shared_ptr<Node>& a, const std::shared_ptr<Node>& b) const {
return a->q == b->q;
}
};
struct Compare {
bool operator()(const std::shared_ptr<Node>& a, const std::shared_ptr<Node>& b) const {
return std::lexicographical_compare(a->q.begin(), a->q.end(), b->q.begin(), b->q.end());
}
};
};
And i am creating a edge graph that needs to access the Node::Hash operator
class Edge {
public:
std::shared_ptr<Node> node_a;
std::shared_ptr<Node> node_b;
double cost;
// Constructor
Edge(std::shared_ptr<Node> node_a, std::shared_ptr<Node> node_b, double cost = 0.0)
{
this->node_a = node_a;
this->node_b = node_b;
this->cost = cost;
}
// Return a string representation of the edge.
std::string to_string() const
{
return "Edge(node_a=(" + this->node_a->to_string() + "), node_b=(" + this->node_b->to_string()
+ "), cost=" + std::to_string(this->cost) + ")";
}
struct Hash {
std::size_t operator()(const std::shared_ptr<Edge>& edge) const {
return 0;
//return Node::Hash::operator(edge->node_a) ^ (Node::Hash::operator(edge->node_b) << 1);
}
};
struct Equal {
bool operator()(const std::shared_ptr<Edge>& a, const std::shared_ptr<Edge>& b) const {
return a->node_a == b->node_a && a->node_b == b->node_b;
}
};
};
However, the syntax return Node::Hash::operator(edge->node_a) ^ (Node::Hash::operator(edge->node_b) << 1); does not seem to work. How do i actually call the operator?
Answer
Here's my example of using a functor:
#include <iostream>
#include <string>
struct Functor
{
void operator()(const std::string text)
{ std::cout << text << "\n";}
};
// Usage:
int main()
{
Functor f;
f("Hello World!");
return EXIT_SUCCESS;
}