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_GRAPH_DETAIL_MUTABLE_HEAP_H

    12 #define BOOST_GRAPH_DETAIL_MUTABLE_HEAP_H

    13 

    14 /*

    15   There are a few things wrong with this set of functions.

    16 

    17   ExternalData should be removed, it is not part of the core

    18   algorithm. It can be handled inside the tree nodes.

    19 

    20   The swap() should be replaced by assignment since its use is causing

    21   the number of memory references to double.

    22 

    23   The min_element should be replaced by a fixed length loop

    24   (fixed at d for d-heaps).

    25 

    26   The member functions of TreeNode should be changed to global

    27   functions.

    28 

    29   These functions will be replaced by those in heap_tree.h

    30 

    31  */

    32 

    33 namespace boost {

    34 

    35   template <class TreeNode, class Compare, class ExternalData>

    36   inline TreeNode up_heap(TreeNode x, const Compare& comp, ExternalData& edata) {

    37     while (x.has_parent() && comp(x, x.parent()))

    38       x.swap(x.parent(), edata);

    39     return x;

    40   }

    41 

    42   template <class TreeNode, class Compare, class ExternalData>

    43   inline TreeNode down_heap(TreeNode x, const Compare& comp, ExternalData& edata) {

    44     while (x.children().size() > 0) {

    45       typename TreeNode::children_type::iterator 

    46         child_iter = std::min_element(x.children().begin(),

    47                                       x.children().end(), 

    48                                       comp);

    49       if (comp(*child_iter, x))

    50         x.swap(*child_iter, edata);

    51       else

    52         break;

    53     }

    54     return x;

    55   }

    56 

    57   template <class TreeNode, class Compare, class ExternalData>

    58   inline void update_heap(TreeNode x, const Compare& comp, ExternalData& edata) {

    59     x = down_heap(x, comp, edata);

    60     (void)up_heap(x, comp, edata);

    61   }

    62 

    63 }

    64 #endif