wp-includes/class-wp-customize-widgets.php:651Converts a widget setting ID (option path) to its id_base and number components.
$setting_idstringarray|WP_Error public function parse_widget_setting_id( $setting_id ) { if ( ! preg_match( '/^(widget_(.+?))(?:\[(\d+)\])?$/', $setting_id, $matches ) ) { return new WP_Error( 'widget_setting_invalid_id' ); } $id_base = $matches[2]; $number = isset( $matches[3] ) ? (int) $matches[3] : null; return compact( 'id_base', 'number' ); }Introduced in 3.9.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-customize-widgets.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.