1 files changed, 113 insertions, 0 deletions
diff --git a/analyzer/structures/heap.c b/analyzer/structures/heap.c
new file mode 100644
index 0000000..1267668
--- /dev/null
+++ b/analyzer/structures/heap.c
@@ -0,0 +1,113 @@
+#include "structures/heap.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "utils/memory.h"
+
+Heap *heap_new(size_t element_size, int (*compare)(void *element1, void *element2), void (*element_cleanup)(void *element)) {
+    Heap *heap = safe_malloc(sizeof(Heap));
+    heap->data = safe_malloc(INIT_HEAP_CAPACITY * sizeof(void *));
+    heap->n_elements = 0;
+    heap->element_size = element_size;
+    heap->capacity = INIT_HEAP_CAPACITY;
+    heap->compare = compare;
+    heap->element_cleanup = element_cleanup;
+    return heap;
+}
+
+// return index of parent in heap
+size_t parent(size_t i) {
+    return (i - 1) / 2;
+}
+
+// return index of left child in heap
+size_t left(size_t i) {
+    return 2 * i + 1;
+}
+
+// return index of right child in heap
+size_t right(size_t i) {
+    return 2 * i + 2;
+}
+
+// swap two elements
+void swap(void **p_el1, void **p_el2) {
+    void *tmp = *p_el1;
+    *p_el1 = *p_el2;
+    *p_el2 = tmp;
+}
+
+// expand heap exponentially to fit el_count elements
+void expand_heap(Heap *heap, size_t el_count) {
+    while (heap->capacity < el_count)
+        heap->capacity = (heap->capacity << 1) | 1;
+    heap->data = safe_realloc(heap->data, heap->capacity * sizeof(void *));
+}
+
+void heap_insert(Heap *heap, void *element) {
+    // expand heap if capacity is too small
+    if (heap->n_elements >= heap->capacity)
+        expand_heap(heap, heap->n_elements + 1);
+
+    // insert into the last position
+    size_t i = heap->n_elements;
+    heap->data[i] = safe_malloc(heap->element_size);
+    memcpy(heap->data[i], element, heap->element_size);
+    heap->n_elements++;
+
+    // heapify up
+    while (i > 0 && heap->compare(heap->data[i], heap->data[parent(i)])) {
+        swap(&heap->data[i], &heap->data[parent(i)]);
+        i = parent(i);
+    }
+}
+
+void *heap_top_get(Heap *heap) {
+    return heap->n_elements <= 0 ? NULL : heap->data[0];
+}
+
+void free_heap_element(Heap *heap, size_t index) {
+    if (heap->element_cleanup)
+        heap->element_cleanup(heap->data[index]);
+    free(heap->data[index]);
+}
+
+void heap_top_remove(Heap *heap) {
+    if (heap->n_elements <= 0)
+        return;
+
+    free_heap_element(heap, 0);
+
+    // move last element to root
+    heap->data[0] = heap->data[--heap->n_elements];
+
+    // heapify down
+    size_t i = 0;
+    int changed;
+    do {
+        size_t l = left(i);
+        size_t r = right(i);
+        size_t to_be_parent = i;
+
+        if (l < heap->n_elements && heap->compare(heap->data[l], heap->data[to_be_parent]))
+            to_be_parent = l;
+        if (r < heap->n_elements && heap->compare(heap->data[r], heap->data[to_be_parent]))
+            to_be_parent = r;
+
+        if ((changed = to_be_parent != i)) {
+            swap(&heap->data[to_be_parent], &heap->data[i]);
+            i = to_be_parent;
+        }
+    } while (changed);
+}
+
+void heap_free(Heap *heap) {
+    if (!heap)
+        return;
+    for (size_t i = 0; i < heap->n_elements; i++) {
+        free_heap_element(heap, i);
+    }
+    free(heap->data);
+    free(heap);
+}