williamr@2: //
williamr@2: //=======================================================================
williamr@2: // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
williamr@2: // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //=======================================================================
williamr@2: //
williamr@2: #ifndef BOOST_MUTABLE_QUEUE_HPP
williamr@2: #define BOOST_MUTABLE_QUEUE_HPP
williamr@2: 
williamr@2: #include <vector>
williamr@2: #include <algorithm>
williamr@2: #include <functional>
williamr@2: #include <boost/property_map.hpp>
williamr@2: #include <boost/pending/mutable_heap.hpp>
williamr@2: #include <boost/pending/is_heap.hpp>
williamr@2: #include <boost/graph/detail/array_binary_tree.hpp>
williamr@2: #include <iterator>
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2:   // The mutable queue whose elements are indexed
williamr@2:   // 
williamr@2:   // This adaptor provides a special kind of priority queue that has
williamr@2:   // and update operation. This allows the ordering of the items to
williamr@2:   // change. After the ordering criteria for item x changes, one must
williamr@2:   // call the Q.update(x)
williamr@2:   // 
williamr@2:   // In order to efficiently find x in the queue, a functor must be
williamr@2:   // provided to map value_type to a unique ID, which the
williamr@2:   // mutable_queue will then use to map to the location of the
williamr@2:   // item. The ID's generated must be between 0 and N, where N is the
williamr@2:   // value passed to the constructor of mutable_queue
williamr@2: 
williamr@2:   template <class IndexedType, 
williamr@2:             class RandomAccessContainer = std::vector<IndexedType>, 
williamr@2:             class Comp = std::less<typename RandomAccessContainer::value_type>,
williamr@2:             class ID = identity_property_map >
williamr@2:   class mutable_queue {
williamr@2:   public:
williamr@2:     typedef IndexedType value_type;
williamr@2:     typedef typename RandomAccessContainer::size_type size_type;
williamr@2:   protected:
williamr@2:     typedef typename RandomAccessContainer::iterator iterator;
williamr@2: #if !defined BOOST_NO_STD_ITERATOR_TRAITS
williamr@2:     typedef  adstl::array_binary_tree_node<iterator, ID> Node;
williamr@2: #else
williamr@2:     typedef  adstl::array_binary_tree_node<iterator, value_type, ID> Node;
williamr@2: #endif
williamr@2:     typedef  adstl::compare_array_node<RandomAccessContainer,Comp> Compare;
williamr@2:     typedef std::vector<size_type> IndexArray;
williamr@2:   public:
williamr@2:     typedef Compare value_compare;
williamr@2:     typedef ID id_generator;
williamr@2: 
williamr@2:     mutable_queue(size_type n, const Comp& x, const ID& _id) 
williamr@2:       : index_array(n), comp(x), id(_id) {
williamr@2:       c.reserve(n); 
williamr@2:     }
williamr@2:     template <class ForwardIterator>
williamr@2:     mutable_queue(ForwardIterator first, ForwardIterator last, 
williamr@2:                   const Comp& x, const ID& _id) 
williamr@2:       : index_array(std::distance(first, last)), comp(x), id(_id)
williamr@2:     {
williamr@2:       while( first != last ) {
williamr@2:         push(*first);
williamr@2:         ++first;
williamr@2:       }
williamr@2:     }
williamr@2: 
williamr@2:     bool empty() const { return c.empty(); }
williamr@2:     
williamr@2:     void pop() {
williamr@2:       value_type tmp = c.back();
williamr@2:       c.back() = c.front();
williamr@2:       c.front() = tmp;
williamr@2: 
williamr@2:       size_type id_f = get(id, c.back());
williamr@2:       size_type id_b = get(id, tmp);
williamr@2:       size_type i = index_array[ id_b ];
williamr@2:       index_array[ id_b ] = index_array[ id_f ];
williamr@2:       index_array[ id_f ] = i;
williamr@2: 
williamr@2:       c.pop_back();
williamr@2:       Node node(c.begin(), c.end(), c.begin(), id);
williamr@2:       down_heap(node, comp, index_array);       
williamr@2:     }
williamr@2:     void push(const IndexedType& x) {
williamr@2:       c.push_back(x);
williamr@2:       /*set index-array*/
williamr@2:       index_array[ get(id, x) ] = c.size()-1;
williamr@2:       Node node(c.begin(), c.end(), c.end() - 1, id);
williamr@2:       up_heap(node, comp, index_array);
williamr@2:     }
williamr@2: 
williamr@2:     void update(const IndexedType& x) {
williamr@2:       size_type current_pos = index_array[ get(id, x) ];
williamr@2:       c[current_pos] = x;
williamr@2: 
williamr@2:       Node node(c.begin(), c.end(), c.begin()+current_pos, id);
williamr@2:       update_heap(node, comp, index_array);
williamr@2:     }
williamr@2: 
williamr@2:     value_type& front() { return c.front(); }
williamr@2:     value_type& top() { return c.front(); }
williamr@2: 
williamr@2:     const value_type& front() const { return c.front(); }
williamr@2:     const value_type& top() const { return c.front(); }
williamr@2: 
williamr@2:     size_type size() const { return c.size(); }
williamr@2: 
williamr@2:     void clear() { c.clear(); }
williamr@2: 
williamr@2: #if 0
williamr@2:         // dwa 2003/7/11 - I don't know what compiler is supposed to
williamr@2:         // be able to compile this, but is_heap is not standard!!
williamr@2:     bool test() {
williamr@2:       return std::is_heap(c.begin(), c.end(), Comp());
williamr@2:     }
williamr@2: #endif 
williamr@2: 
williamr@2:    protected:
williamr@2:     IndexArray index_array;
williamr@2:     Compare comp;
williamr@2:     RandomAccessContainer c;
williamr@2:     ID id;
williamr@2:   };
williamr@2: 
williamr@2: 
williamr@2: }
williamr@2: 
williamr@2: #endif // BOOST_MUTABLE_QUEUE_HPP