3 /* a generic and efficient heap */
5 /* Copyright (c) 2004 Arnaud Legrand. All rights reserved. */
7 /* This program is free software; you can redistribute it and/or modify it
8 * under the terms of the license (GNU LGPL) which comes with this package. */
10 #include "xbt/sysdep.h"
12 #include "heap_private.h"
17 /** @addtogroup XBT_heap
18 * \brief This section describes the API to generic heap with O(log(n)) access.
22 * @brief Creates a new heap.
23 * \param init_size initial size of the heap
24 * \param free_func function to call on each element when you want to free
25 * the whole heap (or NULL if nothing to do).
29 xbt_heap_t xbt_heap_new(int init_size, void_f_pvoid_t * const free_func)
31 xbt_heap_t H = xbt_new0(struct xbt_heap, 1);
34 H->items = (xbt_heapItem_t) xbt_new0(struct xbt_heapItem, init_size);
40 * @brief kilkil a heap and its content
41 * @param H poor victim
43 void xbt_heap_free(xbt_heap_t H)
47 for (i = 0; i < H->count; i++)
48 H->free(H->items[i].content);
55 * @brief returns the number of elements in the heap
56 * @param H the heap we're working on
57 * @return the number of elements in the heap
59 int xbt_heap_size(xbt_heap_t H)
65 * @brief Add an element into the heap.
66 * \param H the heap we're working on
67 * \param content the object you want to add to the heap
68 * \param key the key associated to this object
70 * The element with the smallest key is automatically moved at the top of the heap.
72 void xbt_heap_push(xbt_heap_t H, void *content, double key)
74 int count = ++(H->count);
80 H->size = 2 * size + 1;
81 H->items =(void *) realloc(H->items,(H->size) * sizeof(struct xbt_heapItem));
84 item = &(H->items[count - 1]);
86 item->content = content;
87 xbt_heap_increaseKey(H, count - 1);
92 * @brief Extracts from the heap and returns the element with the smallest key.
93 * \param H the heap we're working on
94 * \return the element with the smallest key
96 * Extracts from the heap and returns the element with the smallest
97 * key. The element with the next smallest key is automatically moved
98 * at the top of the heap.
100 void *xbt_heap_pop(xbt_heap_t H)
109 H->items[0] = H->items[(H->count) - 1];
111 xbt_heap_maxHeapify(H);
112 if (H->count < H->size / 4 && H->size > 16) {
113 H->size = H->size / 2 + 1;
115 (void *) realloc(H->items,
116 (H->size) * sizeof(struct xbt_heapItem));
122 * @brief returns the smallest key in the heap (heap unchanged)
123 * \param H the heap we're working on
125 * \return the smallest key in the heap without modifying the heap.
127 double xbt_heap_maxkey(xbt_heap_t H)
129 xbt_assert0(H->count != 0,"Empty heap");
134 * @brief returns the value associated to the smallest key in the heap (heap unchanged)
135 * \param H the heap we're working on
137 * \return the value associated to the smallest key in the heap
138 * without modifying the heap.
140 void *xbt_heap_maxcontent(xbt_heap_t H)
142 xbt_assert0(H->count != 0,"Empty heap");
143 return CONTENT(H, 0);
147 * \param H the heap we're working on
149 * Restores the heap property once an element has been deleted.
151 static void xbt_heap_maxHeapify(xbt_heap_t H)
158 int count = H->count;
159 if (l < count && KEY(H, l) < KEY(H, i))
161 if (r < count && KEY(H, r) < KEY(H, greatest))
164 struct xbt_heapItem tmp = H->items[i];
165 H->items[i] = H->items[greatest];
166 H->items[greatest] = tmp;
174 * \param H the heap we're working on
175 * \param i an item position in the heap
177 * Moves up an item at position i to its correct position. Works only
178 * when called from xbt_heap_push. Do not use otherwise.
180 static void xbt_heap_increaseKey(xbt_heap_t H, int i)
182 while (i > 0 && KEY(H, PARENT(i)) > KEY(H, i)) {
183 struct xbt_heapItem tmp = H->items[i];
184 H->items[i] = H->items[PARENT(i)];
185 H->items[PARENT(i)] = tmp;