particle property iterators about espresso HOT 1 CLOSED

#include <boost/iterator/transform_iterator.hpp>

class Particle {
public:
  const Vector3d& pos() const {
    return position_;
  }

private:
  Vector3d position_;
};

// Define a function object to extract the pos() member from a Particle object
struct ExtractPos {
  const Vector3d& operator()(const Particle& particle) const {
    return particle.pos();
  }
};

int main() {
  std::vector<Particle> particles = /* ... */;

  // Create a transform iterator that extracts the pos() member from each Particle object
  auto pos_iterator = boost::make_transform_iterator(particles.begin(), ExtractPos{});

  // Iterate over the pos() members of the particles
  for (auto pos : pos_iterator) {
    // Do something with pos, which is a reference to a Vector3d object
  }

  return 0;
}