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_INLINE 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 Set the update callback function.
41 * @param H the heap we're working on
42 * \param update_callback function to call on each element to update its index when needed.
44 XBT_INLINE void xbt_heap_set_update_callback(xbt_heap_t H,
45 void (*update_callback) (void *, int))
47 H->update_callback = update_callback;
52 * @brief kilkil a heap and its content
53 * @param H poor victim
55 void xbt_heap_free(xbt_heap_t H)
59 for (i = 0; i < H->count; i++)
60 (*(H->free)) (H->items[i].content);
67 * @brief returns the number of elements in the heap
68 * @param H the heap we're working on
69 * @return the number of elements in the heap
71 XBT_INLINE int xbt_heap_size(xbt_heap_t H)
77 * @brief Add an element into the heap.
78 * \param H the heap we're working on
79 * \param content the object you want to add to the heap
80 * \param key the key associated to this object
82 * The element with the smallest key is automatically moved at the top of the heap.
84 void xbt_heap_push(xbt_heap_t H, void *content, double key)
86 int count = ++(H->count);
92 H->size = 2 * size + 1;
94 (void *) realloc(H->items, (H->size) * sizeof(struct xbt_heapItem));
97 item = &(H->items[count - 1]);
99 item->content = content;
100 xbt_heap_increaseKey(H, count - 1);
105 * @brief Extracts from the heap and returns the element with the smallest key.
106 * \param H the heap we're working on
107 * \return the element with the smallest key
109 * Extracts from the heap and returns the element with the smallest
110 * key. The element with the next smallest key is automatically moved
111 * at the top of the heap.
113 void *xbt_heap_pop(xbt_heap_t H)
122 H->items[0] = H->items[(H->count) - 1];
124 xbt_heap_maxHeapify(H);
125 if (H->count < H->size / 4 && H->size > 16) {
126 H->size = H->size / 2 + 1;
128 (void *) realloc(H->items, (H->size) * sizeof(struct xbt_heapItem));
131 H->update_callback ? H->update_callback(max, -1) : NULL;
136 * @brief Extracts from the heap and returns the element at position i.
137 * \param H the heap we're working on
138 * \param i element position
139 * \return the element at position i if ok, NULL otherwise
141 * Extracts from the heap and returns the element at position i. The head is automatically reorded.
143 void *xbt_heap_remove(xbt_heap_t H, int i)
145 if ((i < 0) || (i > H->count - 1))
147 /* put element i at head */
149 KEY(H, i) = MIN_KEY_VALUE;
150 xbt_heap_increaseKey(H, i);
153 return xbt_heap_pop(H);
157 * @brief returns the smallest key in the heap (heap unchanged)
158 * \param H the heap we're working on
160 * \return the smallest key in the heap without modifying the heap.
162 XBT_INLINE double xbt_heap_maxkey(xbt_heap_t H)
164 xbt_assert0(H->count != 0, "Empty heap");
169 * @brief returns the value associated to the smallest key in the heap (heap unchanged)
170 * \param H the heap we're working on
172 * \return the value associated to the smallest key in the heap
173 * without modifying the heap.
175 void *xbt_heap_maxcontent(xbt_heap_t H)
177 xbt_assert0(H->count != 0, "Empty heap");
178 return CONTENT(H, 0);
182 * \param H the heap we're working on
184 * Restores the heap property once an element has been deleted.
186 static void xbt_heap_maxHeapify(xbt_heap_t H)
193 int count = H->count;
194 if (l < count && KEY(H, l) < KEY(H, i))
196 if (r < count && KEY(H, r) < KEY(H, greatest))
199 struct xbt_heapItem tmp = H->items[i];
200 H->items[i] = H->items[greatest];
201 H->items[greatest] = tmp;
202 H->update_callback ? H->update_callback(CONTENT(H, i), i) : NULL;
205 H->update_callback ? H->update_callback(CONTENT(H, i), i) : NULL;
212 * \param H the heap we're working on
213 * \param i an item position in the heap
215 * Moves up an item at position i to its correct position. Works only
216 * when called from xbt_heap_push. Do not use otherwise.
218 static void xbt_heap_increaseKey(xbt_heap_t H, int i)
220 while (i > 0 && KEY(H, PARENT(i)) > KEY(H, i)) {
221 struct xbt_heapItem tmp = H->items[i];
222 H->items[i] = H->items[PARENT(i)];
223 H->items[PARENT(i)] = tmp;
224 H->update_callback ? H->update_callback(CONTENT(H, i), i) : NULL;
227 H->update_callback ? H->update_callback(CONTENT(H, i), i) : NULL;