lang: fix a bunch of memory leaks

lang/ast/ctx.c

@@ -39,8 +39,31 @@ enum ivy_status ivy_parser_create(struct ivy_parser **parser)
 	return IVY_OK;
 }
 
-void ivy_parser_destroy(struct ivy_parser *parser)
+void ivy_parser_destroy(struct ivy_parser *parser, struct ivy_ast_node **result)
 {
+	struct ivy_ast_node *root = NULL;
+
+	b_queue_iterator it;
+	b_queue_iterator_begin(&parser->p_state, &it);
+	while (b_queue_iterator_is_valid(&it)) {
+		struct parser_state *state
+			= b_unbox(struct parser_state, it.entry, s_entry);
+		b_queue_iterator_erase(&it);
+
+		if (root) {
+			ivy_ast_node_destroy(root);
+		}
+
+		root = state->s_node;
+		free(state);
+	}
+
+	if (result) {
+		*result = root;
+	} else if (root) {
+		ivy_ast_node_destroy(root);
+	}
+
 	free(parser);
 }