#include <errno.h>
#include <stdlib.h>
#include <string.h>
+#include <assert.h>
#ifndef max_t
#define max_t(type, a, b) \
((type) (a) > (type) (b) ? (type) (a) : (type) (b))
#endif
-static __attribute__((unused))
+#ifdef DEBUG_HEAP
+void check_heap(const struct ptr_heap *heap)
+{
+ size_t i;
+
+ if (!heap->len)
+ return;
+
+ for (i = 1; i < heap->len; i++)
+ assert(!heap->gt(heap->ptrs[i], heap->ptrs[0]));
+}
+#endif
+
+static
size_t parent(size_t i)
{
- return i >> 1;
+ return (i - 1) >> 1;
}
static
size_t left(size_t i)
{
- return i << 1;
+ return (i << 1) + 1;
}
static
size_t right(size_t i)
{
- return (i << 1) + 1;
+ return (i << 1) + 2;
}
+/*
+ * Copy of heap->ptrs pointer is invalid after heap_grow.
+ */
static
int heap_grow(struct ptr_heap *heap, size_t new_len)
{
size_t l, r, largest;
for (;;) {
+ void *tmp;
+
l = left(i);
r = right(i);
- if (l <= heap->len && ptrs[l] > ptrs[i])
+ if (l < heap->len && heap->gt(ptrs[l], ptrs[i]))
largest = l;
else
largest = i;
- if (r <= heap->len && ptrs[r] > ptrs[largest])
+ if (r < heap->len && heap->gt(ptrs[r], ptrs[largest]))
largest = r;
- if (largest != i) {
- void *tmp;
-
- tmp = ptrs[i];
- ptrs[i] = ptrs[largest];
- ptrs[largest] = tmp;
- i = largest;
- continue;
- } else {
+ if (largest == i)
break;
- }
+ tmp = ptrs[i];
+ ptrs[i] = ptrs[largest];
+ ptrs[largest] = tmp;
+ i = largest;
}
+ check_heap(heap);
}
void *heap_replace_max(struct ptr_heap *heap, void *p)
{
void *res;
- void **ptrs = heap->ptrs;
if (!heap->len) {
(void) heap_set_len(heap, 1);
- ptrs[0] = p;
+ heap->ptrs[0] = p;
+ check_heap(heap);
return NULL;
}
/* Replace the current max and heapify */
- res = ptrs[0];
- ptrs[0] = p;
+ res = heap->ptrs[0];
+ heap->ptrs[0] = p;
heapify(heap, 0);
return res;
}
int heap_insert(struct ptr_heap *heap, void *p)
{
- void **ptrs = heap->ptrs;
+ void **ptrs;
+ size_t pos;
int ret;
ret = heap_set_len(heap, heap->len + 1);
if (ret)
return ret;
- /* Add the element to the end */
- ptrs[heap->len - 1] = p;
- /* rebalance */
- heapify(heap, 0);
+ ptrs = heap->ptrs;
+ pos = heap->len - 1;
+ while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) {
+ /* Move parent down until we find the right spot */
+ ptrs[pos] = ptrs[parent(pos)];
+ pos = parent(pos);
+ }
+ ptrs[pos] = p;
+ check_heap(heap);
return 0;
}
void *heap_remove(struct ptr_heap *heap)
{
- void **ptrs = heap->ptrs;
-
switch (heap->len) {
case 0:
return NULL;
case 1:
(void) heap_set_len(heap, 0);
- return ptrs[0];
+ return heap->ptrs[0];
}
/* Shrink, replace the current max by previous last entry and heapify */
heap_set_len(heap, heap->len - 1);
- return heap_replace_max(heap, ptrs[heap->len - 1]);
+ /* len changed. previous last entry is at heap->len */
+ return heap_replace_max(heap, heap->ptrs[heap->len]);
}
void *heap_cherrypick(struct ptr_heap *heap, void *p)
{
- void **ptrs = heap->ptrs;
size_t pos, len = heap->len;
for (pos = 0; pos < len; pos++)
- if (ptrs[pos] == p)
+ if (heap->ptrs[pos] == p)
goto found;
return NULL;
found:
if (heap->len == 1) {
(void) heap_set_len(heap, 0);
- return ptrs[0];
+ check_heap(heap);
+ return heap->ptrs[0];
}
/* Replace p with previous last entry and heapify. */
heap_set_len(heap, heap->len - 1);
- ptrs[pos] = ptrs[heap->len - 1];
+ /* len changed. previous last entry is at heap->len */
+ heap->ptrs[pos] = heap->ptrs[heap->len];
heapify(heap, pos);
return p;
}