Implement an initial version of reference counting.

src/refcount.c

@@ -0,0 +1,57 @@
+#include "refcount.h"
+#include <stdlib.h>
+#include <string.h>
+
+libab_result libab_ref_new(libab_ref* ref, void* data, void (*free_func)(void* data)) {
+    libab_result result = LIBAB_SUCCESS;
+    ref->strong = 1;
+    ref->data = data;
+    if((ref->count = malloc(sizeof(*(ref->count))))) {
+        ref->count->strong = ref->count->weak = 1;
+        ref->count->free_func = free_func;
+    } else {
+        result = LIBAB_MALLOC;
+    }
+    return result;
+}
+
+void _libab_ref_changed(libab_ref* ref) {
+    if(ref->count->strong == 0) {
+        ref->count->strong--;
+        if(ref->count->free_func) {
+            ref->count->free_func(ref->data);
+        }
+        free(ref->data);
+    }
+    if(ref->count->weak == 0) {
+        free(ref->count);
+    }
+}
+
+void libab_ref_weaken(libab_ref* ref) {
+    if(ref->strong) {
+        ref->count->strong--;
+        ref->strong = 0;
+        _libab_ref_changed(ref);
+    }
+}
+
+void libab_ref_free(libab_ref* ref) {
+    ref->count->strong -= ref->strong;
+    ref->count->weak--;
+    _libab_ref_changed(ref);
+}
+
+void libab_ref_copy(libab_ref* ref, libab_ref* into) {
+    ref->count->strong++;
+    ref->count->weak++;
+    memcpy(into, ref, sizeof(*ref));
+}
+
+void* libab_ref_get(libab_ref* ref) {
+    void* to_return = NULL;
+    if(ref->count->strong > 0) {
+        to_return = ref->data;
+    }
+    return to_return;
+}