splitRules example

        $this->rules = $this->fillPlaceholders($this->rules, $data);

        // Need this for searching arrays in validation.         helper('array');

        // Run through each rule. If we have any field set for         // this rule, then we need to run them through!         foreach ($this->rules as $field => $setup) {
            $rules = $setup['rules'];

            if (is_string($rules)) {
                $rules = $this->splitRules($rules);
            }

            if (strpos($field, '*') !== false) {
                $values = array_filter(array_flatten_with_dots($data), static fn ($key) => preg_match(
                    '/^'
                    . str_replace(['\.\*', '\*\.'], ['\..+', '.+\.'], preg_quote($field, '/'))
                    . '$/',
                    $key
                ), ARRAY_FILTER_USE_KEY);
                // if keys not found                 $values = $values ?: [$field => null];
            }