cgal/Packages/Spatial_searching/include/CGAL/Nearest_neighbour_PQ.h

// ======================================================================
//
// Copyright (c) 1997 The CGAL Consortium

// ======================================================================
//
// Copyright (c) 2001 The CGAL Consortium
//
// This software and related documentation is part of an INTERNAL release
// of the Computational Geometry Algorithms Library (CGAL). It is not
// intended for general use.
//
// ----------------------------------------------------------------------
//
// release       :
// release_date  :
//
// file          : include/CGAL/Nearest_neighbour_PQ.h
// package       : APSPAS
// revision      : 1.0 
// revision_date : 2001/06/15 
// maintainer    : Hans Tangelder (<hanst@cs.uu.nl>)
//
// ======================================================================

#ifndef  NEAREST_NEIGHBOUR_PQ_H
#define  NEAREST_NEIGHBOUR_PQ_H

#include <cstring>
#include <list>
#include <queue>
#include <memory>
#include <CGAL/Extended_internal_node.h>
#include <CGAL/Box.h>

// copy to example.cpp
// #include <CGAL/Kd_tree_traits_point.h>
// #include <CGAL/Weighted_Minkowski_distance.h>

using std::list; // to avoid compiler crash on MSVC++

namespace CGAL {

// copy to example.cpp
// typedef Search_traits_template<Tree_traits> Search_traits;

template <class Tree_traits, class Search_traits>
class Nearest_neighbour_PQ {

    private:

    typedef Tree_traits::Item Item;
    typedef Item::FT NT;
    typedef Item** Item_iterator;
    typedef Base_node<Tree_traits> Node;
    typedef Binary_search_tree<Tree_traits> Tree;

    typedef Tree_traits::Item_with_distance Item_with_distance;
    typedef std::pair<Node*,NT> Node_with_distance;

    public:

    class Iterator;

    private:
    
    class Priority_higher
    {
    public:
        //highest priority is smallest distance
        bool operator() (Node_with_distance* n1, Node_with_distance* n2) const {
                return (n1->second > n2->second);
        }
    };

    class Distance_smaller
    {
    public:
		//in contrast with k nearest neighbours
        //highest priority is smallest distance
        bool operator() (Item_with_distance* p1, Item_with_distance* p2) const {
                return (p1->second > p2->second);
        }
    };

    typedef std::vector<Node_with_distance*> Node_with_distance_vector;

    typedef std::vector<Item_with_distance*> Item_with_distance_vector;

    typedef std::vector<NT> Distance_vector;

    Iterator *start;
    Iterator *past_the_end;

    public:

    // constructor
    Nearest_neighbour_PQ(Tree& tree, Item& q, Search_traits& tr, NT Eps=0.0) {
        start = new Iterator(tree,q,tr,Eps);
        past_the_end = new Iterator();
    };

    // destructor
    ~Nearest_neighbour_PQ() {
		delete start;
                delete past_the_end;
    };

    Iterator begin() {
		return *start;
    }

    Iterator end() {
		return *past_the_end;
    }

    class Iterator {

    public:

    typedef typename std::input_iterator_tag iterator_category;
    typedef typename Item_with_distance value_type;
    typedef int distance_type;

    class Iterator_implementation;
    Iterator_implementation *Ptr_implementation;

    public:

    // default constructor
    class Iterator() {Ptr_implementation=0;}

    int The_number_of_items_visited() {
        return Ptr_implementation->number_of_items_visited;
    }

    // constructor
    class Iterator(Tree& tree, Item& q, Search_traits& tr, NT eps=0.0) {
        Ptr_implementation = new Iterator_implementation(tree, q, tr, eps);
    }

    // copy constructor
    class Iterator(Iterator& Iter) {
        Ptr_implementation = Iter.Ptr_implementation;
        if (Ptr_implementation != 0) Ptr_implementation->reference_count++;
    }

    Item_with_distance& operator* () {
                return *(*Ptr_implementation);
    }

    // prefix operator
    Iterator& operator++() {
        ++(*Ptr_implementation);
        return *this;
    }

    // postfix operator
    std::auto_ptr<Item_with_distance> operator++(int) {
        std::auto_ptr<Item_with_distance> result = (*Ptr_implementation)++;
        return result;
    }

    bool operator==(const Iterator& It) const {

        if (
                ((Ptr_implementation == 0) || Ptr_implementation->Item_PriorityQueue.empty()) &&
                ((It.Ptr_implementation == 0) ||  It.Ptr_implementation->Item_PriorityQueue.empty())
        )
        return true;
        // else
        return (Ptr_implementation == It.Ptr_implementation);
    }

    bool operator!=(const Iterator& It) const {
        return !(*this == It);
    }

    ~Iterator() {
        if (Ptr_implementation != 0) {
                Ptr_implementation->reference_count--;
                if (Ptr_implementation->reference_count==0) {
                        delete Ptr_implementation;
                        Ptr_implementation = 0;
                }
        }
    }


    class Iterator_implementation {

    public:

    int number_of_neighbours_computed;
    int number_of_internal_nodes_visited;
    int number_of_leaf_nodes_visited;
    int number_of_items_visited;

    private:

    NT multiplication_factor;

    Item* query_point;

    int total_item_number;

    NT distance_to_root;
    NT max_distance;

    NT nn_dist;
    NT rd;

    std::priority_queue<Node_with_distance*, Node_with_distance_vector,
    Priority_higher> PriorityQueue;

    Search_traits* Search_traits_instance;

    public:

    int reference_count;

    std::priority_queue<Item_with_distance*, Item_with_distance_vector,
    Distance_smaller> Item_PriorityQueue;

    // constructor
    Iterator_implementation(Tree& tree, Item& q, Search_traits& tr, NT Eps=0.0) {

        reference_count=1;
        Search_traits_instance=&tr;
        multiplication_factor=Search_traits_instance->Transformed_distance(1.0+Eps);

        max_distance=
        Search_traits_instance->Upper_bound_distance_to_box(q,*(tree.bounding_box()));
        distance_to_root=
        Search_traits_instance->Lower_bound_distance_to_box(q,*(tree.bounding_box()));
        std::cout << "max_distance=" << max_distance << std::endl;
        std::cout << "distance_to_root=" << distance_to_root << std::endl;

        query_point = &q;

        total_item_number=tree.item_number();

        number_of_leaf_nodes_visited=0;
        number_of_internal_nodes_visited=0;
        number_of_items_visited=0;
        number_of_neighbours_computed=0;

        nn_dist=max_distance;

        Node_with_distance *The_Root = new Node_with_distance(tree.root(),distance_to_root);
        PriorityQueue.push(The_Root);

        // rd is the distance of the top of the priority queue to q
        rd=The_Root->second;
        Compute_the_next_nearest_neighbour();
    }

    // * operator
    Item_with_distance& operator* () {
			return *(Item_PriorityQueue.top());
    }

    // prefix operator
    Iterator_implementation& operator++() {
        // std::cout << "called ++" << std::endl;
        Delete_the_current_item_top();
        Compute_the_next_nearest_neighbour();
        return *this;
    }

    // postfix operator
    std::auto_ptr<Item_with_distance> operator++(int) {
        Item_with_distance Value = *(Item_PriorityQueue.top());
        std::auto_ptr<Item_with_distance>
        result(new Item_with_distance(Value));
        ++*this;
        return result;
    }


    //destructor
    ~Iterator_implementation() {

        // std::cout << "called destructor" << std::endl;
	while (PriorityQueue.size()>0) {
                Node_with_distance* The_top=PriorityQueue.top();
                PriorityQueue.pop();
                delete The_top;
	};
	while (Item_PriorityQueue.size()>0) {
                Item_with_distance* The_top=Item_PriorityQueue.top();
                Item_PriorityQueue.pop();
                delete The_top;
        };
    }

    private:

    void Delete_the_current_item_top() {
        Item_with_distance* The_item_top=Item_PriorityQueue.top();
        Item_PriorityQueue.pop();
        delete The_item_top;
    }

    void Compute_the_next_nearest_neighbour() {

        // compute the next item
        bool next_neighbour_found=false;
        if (!(Item_PriorityQueue.empty()))
        next_neighbour_found=(multiplication_factor*rd > Item_PriorityQueue.top()->second);

        // otherwise browse the tree further
        while ((!next_neighbour_found) && (!PriorityQueue.empty())) {
                Node_with_distance* The_node_top=PriorityQueue.top();
                Node* N= The_node_top->first;
                PriorityQueue.pop();
                delete The_node_top;

                while (!(N->is_leaf())) { // compute new distance
                        number_of_internal_nodes_visited++;
                        int new_cut_dim=N->separator()->cutting_dimension();
                        NT old_off, new_rd;
                        NT new_off =
                        (*query_point)[new_cut_dim] - N->separator()->cutting_value();
                        if (new_off < 0.0) {
								old_off= (*query_point)[new_cut_dim]-N->low_value();
                                if (old_off>0.0) old_off=0.0;
                                new_rd=Search_traits_instance->New_Distance(rd,old_off,new_off,new_cut_dim);
                                Node_with_distance *Upper_Child =
                                new Node_with_distance(N->upper(),new_rd);
                                PriorityQueue.push(Upper_Child);
                                N=N->lower();
                        }
                        else { // compute new distance
								old_off= N->high_value() - (*query_point)[new_cut_dim];
                                if (old_off>0.0) old_off=0.0;
                                new_rd=Search_traits_instance->New_Distance(rd,old_off,new_off,new_cut_dim);
                                Node_with_distance *Lower_Child =
                                new Node_with_distance(N->lower(),new_rd);
                                PriorityQueue.push(Lower_Child);
                                N=N->upper();
                        }
                }
                // n is a leaf
                number_of_leaf_nodes_visited++;
                for (Item_iterator it=N->begin(); it != N->end(); it++) {
                        number_of_items_visited++;
                        NT distance_to_query_point=
                        Search_traits_instance->Distance(*query_point,**it);
                        Item_with_distance *NN_Candidate=
                        new Item_with_distance(*it,distance_to_query_point);
                        Item_PriorityQueue.push(NN_Candidate);
                }
                // old top of PriorityQueue has been processed,
                // hence update rd
                if (!PriorityQueue.empty()) {
                        rd = PriorityQueue.top()->second;
                        next_neighbour_found =
                        (multiplication_factor*rd >
                        Item_PriorityQueue.top()->second);
                }
                else // priority queue empty => last neighbour found
                {
                        next_neighbour_found=true;
                };
                number_of_neighbours_computed++;
        }   // next_neighbour_found or priority queue is empty
        // in the latter case also the item priority quee is empty
    }
}; // class Iterator_implementaion
}; // class Iterator
}; // class Nearest neighbour_L2

template <class Tree_traits, class Search_traits>
void swap (Nearest_neighbour_PQ<Tree_traits, Search_traits>::Iterator& x,
        Nearest_neighbour_PQ<Tree_traits, Search_traits>::Iterator& y) {
        Nearest_neighbour_PQ<Tree_traits, Search_traits>::Iterator::Iterator_implementation
        *tmp = x.Ptr_implementation;
        x.Ptr_implementation  = y.Ptr_implementation;
        y.Ptr_implementation = tmp;
};

} // namespace CGAL


#endif  // NEAREST_NEIGHBOUR_PQ_H