boost/pending/mutable_queue.hpp

   1 //
   2 //=======================================================================
   3 // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
   4 // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
   5 //
   6 // Distributed under the Boost Software License, Version 1.0. (See
   7 // accompanying file LICENSE_1_0.txt or copy at
   8 // http://www.boost.org/LICENSE_1_0.txt)
   9 //=======================================================================
  10 //
  11 #ifndef BOOST_MUTABLE_QUEUE_HPP
  12 #define BOOST_MUTABLE_QUEUE_HPP
  13
  14 #include <vector>
  15 #include <algorithm>
  16 #include <functional>
  17 #include <boost/property_map/property_map.hpp>
  18 #include <boost/pending/mutable_heap.hpp>
  19 #include <boost/pending/is_heap.hpp>
  20 #include <boost/graph/detail/array_binary_tree.hpp>
  21 #include <iterator>
  22
  23 namespace boost {
  24
  25   // The mutable queue whose elements are indexed
  26   //
  27   // This adaptor provides a special kind of priority queue that has
  28   // and update operation. This allows the ordering of the items to
  29   // change. After the ordering criteria for item x changes, one must
  30   // call the Q.update(x)
  31   //
  32   // In order to efficiently find x in the queue, a functor must be
  33   // provided to map value_type to a unique ID, which the
  34   // mutable_queue will then use to map to the location of the
  35   // item. The ID's generated must be between 0 and N, where N is the
  36   // value passed to the constructor of mutable_queue
  37
  38   template <class IndexedType,
  39             class RandomAccessContainer = std::vector<IndexedType>,
  40             class Comp = std::less<typename RandomAccessContainer::value_type>,
  41             class ID = identity_property_map >
  42   class mutable_queue {
  43   public:
  44     typedef IndexedType value_type;
  45     typedef typename RandomAccessContainer::size_type size_type;
  46   protected:
  47     typedef typename RandomAccessContainer::iterator iterator;
  48 #if !defined BOOST_NO_STD_ITERATOR_TRAITS
  49     typedef  adstl::array_binary_tree_node<iterator, ID> Node;
  50 #else
  51     typedef  adstl::array_binary_tree_node<iterator, value_type, ID> Node;
  52 #endif
  53     typedef  adstl::compare_array_node<RandomAccessContainer,Comp> Compare;
  54     typedef std::vector<size_type> IndexArray;
  55   public:
  56     typedef Compare value_compare;
  57     typedef ID id_generator;
  58
  59     mutable_queue(size_type n, const Comp& x, const ID& _id)
  60       : index_array(n), comp(x), id(_id) {
  61       c.reserve(n);
  62     }
  63     template <class ForwardIterator>
  64     mutable_queue(ForwardIterator first, ForwardIterator last,
  65                   const Comp& x, const ID& _id)
  66       : index_array(std::distance(first, last)), comp(x), id(_id)
  67     {
  68       while( first != last ) {
  69         push(*first);
  70         ++first;
  71       }
  72     }
  73
  74     bool empty() const { return c.empty(); }
  75
  76     void pop() {
  77       value_type tmp = c.back();
  78       c.back() = c.front();
  79       c.front() = tmp;
  80
  81       size_type id_f = get(id, c.back());
  82       size_type id_b = get(id, tmp);
  83       size_type i = index_array[ id_b ];
  84       index_array[ id_b ] = index_array[ id_f ];
  85       index_array[ id_f ] = i;
  86
  87       c.pop_back();
  88       Node node(c.begin(), c.end(), c.begin(), id);
  89       down_heap(node, comp, index_array);
  90     }
  91     void push(const IndexedType& x) {
  92       c.push_back(x);
  93       /*set index-array*/
  94       index_array[ get(id, x) ] = c.size()-1;
  95       Node node(c.begin(), c.end(), c.end() - 1, id);
  96       up_heap(node, comp, index_array);
  97     }
  98
  99     void update(const IndexedType& x) {
 100       size_type current_pos = index_array[ get(id, x) ];
 101       c[current_pos] = x;
 102
 103       Node node(c.begin(), c.end(), c.begin()+current_pos, id);
 104       update_heap(node, comp, index_array);
 105     }
 106
 107     value_type& front() { return c.front(); }
 108     value_type& top() { return c.front(); }
 109
 110     const value_type& front() const { return c.front(); }
 111     const value_type& top() const { return c.front(); }
 112
 113     size_type size() const { return c.size(); }
 114
 115     void clear() { c.clear(); }
 116
 117 #if 0
 118         // dwa 2003/7/11 - I don't know what compiler is supposed to
 119         // be able to compile this, but is_heap is not standard!!
 120     bool test() {
 121       return std::is_heap(c.begin(), c.end(), Comp());
 122     }
 123 #endif
 124
 125    protected:
 126     IndexArray index_array;
 127     Compare comp;
 128     RandomAccessContainer c;
 129     ID id;
 130   };
 131
 132
 133 }
 134
 135 #endif // BOOST_MUTABLE_QUEUE_HPP