protected function parse_string_rules( $rules ) {
		$split_rules = explode( '|', $rules );
		$parse_rules = [];

		foreach ( $split_rules as $rule ) {
			$parameters = [];

			// Format rule and parameters follows {rule}:{parameters}.
			if ( strpos( $rule, ':' ) !== false ) {
				list( $rule, $parameter ) = explode( ':', $rule, 2 );

				$parameter = false !== strpos( $parameter, ',' )
					? str_getcsv( $parameter )
					: [ $parameter ];

				$parameters = $this->wrap_parameters( $rule, $parameter );
			}

			$parse_rules[] = [ $this->normalize( $rule ), $parameters ];
		}

		return $parse_rules;
	}