/Users/yzchen/ns/ns-allinone-2.33/ns-2.33/common/heap.h

/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */

/*
 * Copyright (C) 1997 by the University of Southern California
 * $Id: heap.h,v 1.9 2005/08/25 18:58:02 johnh Exp $
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 *
 *
 * The copyright of this module includes the following
 * linking-with-specific-other-licenses addition:
 *
 * In addition, as a special exception, the copyright holders of
 * this module give you permission to combine (via static or
 * dynamic linking) this module with free software programs or
 * libraries that are released under the GNU LGPL and with code
 * included in the standard release of ns-2 under the Apache 2.0
 * license or under otherwise-compatible licenses with advertising
 * requirements (or modified versions of such code, with unchanged
 * license).  You may copy and distribute such a system following the
 * terms of the GNU GPL for this module and the licenses of the
 * other code concerned, provided that you include the source code of
 * that other code when and as the GNU GPL requires distribution of
 * source code.
 *
 * Note that people who make modified versions of this module
 * are not obligated to grant this special exception for their
 * modified versions; it is their choice whether to do so.  The GNU
 * General Public License gives permission to release a modified
 * version without this exception; this exception also makes it
 * possible to release a modified version which carries forward this
 * exception.
 *
 */

/* 
 * @(#) $Header: /cvsroot/nsnam/ns-2/common/heap.h,v 1.9 2005/08/25 18:58:02 johnh Exp $ (USC/ISI)
 */

#ifndef ns_heap_h
#define ns_heap_h

#define HEAP_DEFAULT_SIZE       32

// This code has a long and rich history.  It was stolen from the MaRS-2.0
// distribution, that had in its turn acquired it from the NetSim
// distribution (or so I have been told).  It has been customised for
// event queue handling.  I, Kannan, added prolific comments to it in order
// to better understand the data structure for myself, and turned into
// a standalone C++ class that you see in this version now.

typedef double heap_key_t;
typedef unsigned long heap_secondary_key_t;

// This code has (atleast?) one flaw:  It does not check for memory allocated,
// especially in the constructor, and in heap_insert() when trying
// to resize the h_elems[] array.

class Heap 
{
        struct Heap_elem {
                heap_key_t he_key;
                heap_secondary_key_t he_s_key;
                void*           he_elem;
        } *h_elems;
        unsigned int    h_s_key;
        unsigned int    h_size;
        unsigned int    h_maxsize;
        unsigned int    h_iter;

        unsigned int    parent(unsigned int i)  { return ((i - 1) / 2); }
        unsigned int    left(unsigned int i)    { return ((i * 2) + 1); }
        unsigned int    right(unsigned int i)   { return ((i + 1) * 2); }
        void swap(unsigned int i, unsigned int j) {
                // swap elems[i] with elems[j] in this
                Heap_elem __he = h_elems[i];
                h_elems[i] = h_elems[j];
                h_elems[j] = __he;
                return;
        };
        unsigned int    KEY_LESS_THAN(heap_key_t k1, heap_secondary_key_t ks1,
                                      heap_key_t k2, heap_secondary_key_t ks2) {
                return (k1 < k2) || ((k1==k2)&&(ks1<ks2));
        };
        unsigned int    KEY_LESS_OR_EQUAL_THAN(heap_key_t k1, heap_key_t k2) {
                return (k1 <= k2);
        };

public:
        Heap(int size=HEAP_DEFAULT_SIZE);
        ~Heap();

        /*
         * int  heap_member(Heap *h, void *elem):               O(n) algorithm.
         */
        int     heap_member(void* elem);

        /*
         * int  heap_delete(Heap *h, void *elem):               O(n) algorithm
         *
         *      Returns 1 for success, 0 otherwise.
         */
        int heap_delete(void* elem);

        /*
         * Couple of functions to support iterating through all things on the
         * heap without having to know what a heap looks like.  To be used as
         * follows:
         *
         *      for (elem = heap_iter_init(h); elem; elem = heap_iter(h))
         *              Do whatever to the elem.
         *
         * You cannot use heap_iter to do anything but inspect the heap.  If
         * heap_insert(), heap_extract_min(), or heap_delete() are called
         * while iterating through the heap, all bets are off.
         *
         * Tue Nov 14 20:17:59 PST 1995 -- kva
         *      Actually now, heap_create() initialises h_iter correctly,
         *      and heap_iter() correctly resets h_iter
         *      when the heap is traversed, So, we do not really need
         *      heap_iter_init() anymore, except to break off a current
         *      iteration and restart.
         */
        void*   heap_iter_init() {
                h_iter = 1;
                return heap_min();
        };
        void*   heap_iter() {
                if (h_iter >= h_size) {
                        h_iter = 0;
                        return 0;
                } else {
                        return h_elems[h_iter++].he_elem;
                }
        };

        /*
         * void heap_insert(Heap *h, heap_key_t *key, void *elem)
         *
         * Insert <key, elem> into heap h.
         * Adjust heap_size if we hit the limit.
         */
        void heap_insert(heap_key_t key, void* elem);

        /*
         * void *heap_min(Heap *h)
         *
         *      Returns the smallest element in the heap, if it exists,
         *      NULL otherwise.   The element is still in the heap.
         */
        void* heap_min() {
                return (h_size > 0 ? h_elems[0].he_elem : 0);
        };
                        
        /*
         * void *heap_extract_min(Heap *h)
         *
         *      Returns the smallest element in the heap, if it exists.
         *      NULL otherwise.
         */
        void* heap_extract_min();
};

#endif /* ns_heap_h */