Interface ConfigurationVisitor<S,​T,​E extends Exception>

  • Type Parameters:
    S - a state object that will be used for one visit
    T - the terminal value, that can be returned at the end of the visit
    E - exception type that may be thrown
    All Known Subinterfaces:
    ConfigurationVisitor.Safe<S,​T>, ConfigurationVisitor.Stateless<E>

    public interface ConfigurationVisitor<S,​T,​E extends Exception>
    A visitor to traverse node hierarchies in a depth-first order.

    Instances of stateful implementations may be reusable by taking advantage of the state object. During each visitation, a visitor will experience the node tree as a sequence of events, described by the following pseudo-grammar:

     mappingNode: enterMappingNode node* exitMappingNode
     listNode: enterListNode node* exitListNode
     node: enterNode
           | listNode
           | enterScalarNode)
     visit: newState?

    If the starting node has no value, no node events will be received. Otherwise, the first event received will be for the starting node itself, and will continue from there.

    The children to visit for list and mapping nodes will only be collected after both the enterNode and enter(List|Mapping)Node methods have been executed for the node, and changes to the node values may be made to control which nodes will be visited.

    Any exceptions thrown within the visitor will result in the visitation ending immediately and the exception being rethrown within the visit method.

    There are a few specializations of the visitor interface available: ConfigurationVisitor.Stateless carries no state and can act as a functional interface type, and ConfigurationVisitor.Safe which throws no checked exceptions and therefore can be visited without having to handle any exceptions.

    See Also:
    to execute this configuration visitation