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.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