Combining route name parser with router delegate.

router.dart

abstract class RoutingConfig {
  RouteParsingResult parseRouteName(String routeName);

  Widget build(BuildContext context);
}

class RouteParsingResult {
  RouteParsingResult({});

  /// The part of the route name that was matched/consumed by this routing node.
  final String matchedRouteName;

  /// The part of the route name that's remaining to be consumed by child
  /// routing nodes.
  final String remainingRouteName;


}

class DefaultRoutingConfig implements RoutingConfig {
  DefaultRoutingConfig({this.routes});

  final Map<String, RoutingConfig> routes;

  RouteParsingResult parseRouteName(String routeName) {
    for (final String key in routes) {
      if (routeName.startsWith(key)) {
        return RouteParsingResult(
          matched: key,
          remaining: routeName.substring(key.length),
          childConfig: routes[key],
        );
      }
    }
  }

  Widget build() { ... }  
}