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"
15 /** @addtogroup XBT_heap
16 * \brief This section describes the API to generic heap with O(log(n)) access.
19 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(heap, xbt, "Heap");
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);
78 H->size = 2 * size + 1;
80 (void *) realloc(H->items,
81 (H->size) * sizeof(struct xbt_heapItem));
83 item = &(H->items[count - 1]);
85 item->content = content;
86 xbt_heap_increaseKey(H, count - 1);
91 * @brief Extracts from the heap and returns the element with the smallest key.
92 * \param H the heap we're working on
93 * \return the element with the smallest key
95 * Extracts from the heap and returns the element with the smallest
96 * key. The element with the next smallest key is automatically moved
97 * at the top of the heap.
99 void *xbt_heap_pop(xbt_heap_t H)
108 H->items[0] = H->items[(H->count) - 1];
110 xbt_heap_maxHeapify(H);
111 if (H->count < H->size / 4 && H->size > 16) {
112 H->size = H->size / 2 + 1;
114 (void *) realloc(H->items,
115 (H->size) * sizeof(struct xbt_heapItem));
121 * @brief returns the smallest key in the heap (heap unchanged)
122 * \param H the heap we're working on
124 * \return the smallest key in the heap without modifying the heap.
126 double xbt_heap_maxkey(xbt_heap_t H)
128 xbt_assert0(H->count != 0,"Empty heap");
133 * @brief returns the value associated to the smallest key in the heap (heap unchanged)
134 * \param H the heap we're working on
136 * \return the value associated to the smallest key in the heap
137 * without modifying the heap.
139 void *xbt_heap_maxcontent(xbt_heap_t H)
141 xbt_assert0(H->count != 0,"Empty heap");
142 return CONTENT(H, 0);
146 * \param H the heap we're working on
148 * Restores the heap property once an element has been deleted.
150 static void xbt_heap_maxHeapify(xbt_heap_t H)
157 int count = H->count;
158 if (l < count && KEY(H, l) < KEY(H, i))
160 if (r < count && KEY(H, r) < KEY(H, greatest))
163 struct xbt_heapItem tmp = H->items[i];
164 H->items[i] = H->items[greatest];
165 H->items[greatest] = tmp;
173 * \param H the heap we're working on
174 * \param i an item position in the heap
176 * Moves up an item at position i to its correct position. Works only
177 * when called from xbt_heap_push. Do not use otherwise.
179 static void xbt_heap_increaseKey(xbt_heap_t H, int i)
181 while (i > 0 && KEY(H, PARENT(i)) > KEY(H, i)) {
182 struct xbt_heapItem tmp = H->items[i];
183 H->items[i] = H->items[PARENT(i)];
184 H->items[PARENT(i)] = tmp;