Import of the watch repository from Pebble

src/libutil/iterator.c

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "util/iterator.h"
+
+#include "util/assert.h"
+
+#include <stdbool.h>
+
+void iter_init(Iterator* iter, IteratorCallback next, IteratorCallback prev, IteratorState state) {
+  *iter = (Iterator) {
+    .next = next,
+    .prev = prev,
+    .state = state
+  };
+}
+
+bool iter_next(Iterator* iter) {
+  UTIL_ASSERT(iter->next);
+  return iter->next(iter->state);
+}
+
+bool iter_prev(Iterator* iter) {
+  UTIL_ASSERT(iter->prev);
+  return iter->prev(iter->state);
+}
+