//

//=======================================================================

// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.

// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek

//

// Distributed under the Boost Software License, Version 1.0. (See

// accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)

//=======================================================================

//

#ifndef BOOST_MUTABLE_QUEUE_HPP

#define BOOST_MUTABLE_QUEUE_HPP

#include <vector>

#include <algorithm>

#include <functional>

#include <boost/property_map.hpp>

#include <boost/pending/mutable_heap.hpp>

#include <boost/pending/is_heap.hpp>

#include <boost/graph/detail/array_binary_tree.hpp>

#include <iterator>

namespace boost {

  // The mutable queue whose elements are indexed

  // 

  // This adaptor provides a special kind of priority queue that has

  // and update operation. This allows the ordering of the items to

  // change. After the ordering criteria for item x changes, one must

  // call the Q.update(x)

  // 

  // In order to efficiently find x in the queue, a functor must be

  // provided to map value_type to a unique ID, which the

  // mutable_queue will then use to map to the location of the

  // item. The ID's generated must be between 0 and N, where N is the

  // value passed to the constructor of mutable_queue

  template <class IndexedType, 

            class RandomAccessContainer = std::vector<IndexedType>, 

            class Comp = std::less<typename RandomAccessContainer::value_type>,

            class ID = identity_property_map >

  class mutable_queue {

  public:

    typedef IndexedType value_type;

    typedef typename RandomAccessContainer::size_type size_type;

  protected:

    typedef typename RandomAccessContainer::iterator iterator;

#if !defined BOOST_NO_STD_ITERATOR_TRAITS

    typedef  adstl::array_binary_tree_node<iterator, ID> Node;

#else

    typedef  adstl::array_binary_tree_node<iterator, value_type, ID> Node;

#endif

    typedef  adstl::compare_array_node<RandomAccessContainer,Comp> Compare;

    typedef std::vector<size_type> IndexArray;

  public:

    typedef Compare value_compare;

    typedef ID id_generator;

    mutable_queue(size_type n, const Comp& x, const ID& _id) 

      : index_array(n), comp(x), id(_id) {

      c.reserve(n); 

    }

    template <class ForwardIterator>

    mutable_queue(ForwardIterator first, ForwardIterator last, 

                  const Comp& x, const ID& _id) 

      : index_array(std::distance(first, last)), comp(x), id(_id)

    {

      while( first != last ) {

        push(*first);

        ++first;

      }

    }

    bool empty() const { return c.empty(); }

    void pop() {

      value_type tmp = c.back();

      c.back() = c.front();

      c.front() = tmp;

      size_type id_f = get(id, c.back());

      size_type id_b = get(id, tmp);

      size_type i = index_array[ id_b ];

      index_array[ id_b ] = index_array[ id_f ];

      index_array[ id_f ] = i;

      c.pop_back();

      Node node(c.begin(), c.end(), c.begin(), id);

      down_heap(node, comp, index_array);       

    }

    void push(const IndexedType& x) {

      c.push_back(x);

      /*set index-array*/

      index_array[ get(id, x) ] = c.size()-1;

      Node node(c.begin(), c.end(), c.end() - 1, id);

      up_heap(node, comp, index_array);

    }

    void update(const IndexedType& x) {

      size_type current_pos = index_array[ get(id, x) ];

      c[current_pos] = x;

      Node node(c.begin(), c.end(), c.begin()+current_pos, id);

      update_heap(node, comp, index_array);

    }

    value_type& front() { return c.front(); }

    value_type& top() { return c.front(); }

    const value_type& front() const { return c.front(); }

    const value_type& top() const { return c.front(); }

    size_type size() const { return c.size(); }

    void clear() { c.clear(); }

#if 0

        // dwa 2003/7/11 - I don't know what compiler is supposed to

        // be able to compile this, but is_heap is not standard!!

    bool test() {

      return std::is_heap(c.begin(), c.end(), Comp());

    }

#endif 

   protected:

    IndexArray index_array;

    Compare comp;

    RandomAccessContainer c;

    ID id;

  };

}

#endif // BOOST_MUTABLE_QUEUE_HPP