[utils] cartesian product iterator for grid search during model selection

src/cartesian_product.h

@@ -0,0 +1,23 @@
+#ifndef CARTESIAN_PRODUCT_H
+#define CARTESIAN_PRODUCT_H
+
+#include <stdlib.h>
+#include <stdarg.h>
+
+#include "collections.h"
+
+typedef struct cartesian_product_iterator {
+    size_t remaining;
+    uint32_array *lengths;
+    uint32_array *state;
+} cartesian_product_iterator_t;
+
+cartesian_product_iterator_t *cartesian_product_iterator_new(size_t n, ...);
+cartesian_product_iterator_t *cartesian_product_iterator_new_vargs(size_t n, va_list args);
+uint32_t *cartesian_product_iterator_start(cartesian_product_iterator_t *self);
+uint32_t *cartesian_product_iterator_next(cartesian_product_iterator_t *self);
+bool cartesian_product_iterator_done(cartesian_product_iterator_t *self);
+
+void cartesian_product_iterator_destroy(cartesian_product_iterator_t *self);
+
+#endif