Package org.spongepowered.configurate

Interface ConfigurationVisitor<S,​T,​E extends java.lang.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 java.lang.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
      (mappingNode
       | listNode
       | enterScalarNode)

 visit: newState?
        beginVisit
        node*
        endVisit

    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.

    Since:
    4.0.0
    See Also:
    to execute this configuration visitation

    • Method Detail

      • newState

        S newState()
    throws E extends java.lang.Exception
        Called to provide a state object if a visit is initiated without one already existing.
        Returns:
        a new state object to be passed through the rest of this visit
        Throws:
        E - when thrown by implementation
        E extends java.lang.Exception
        Since:
        4.0.0

      • beginVisit

        void beginVisit​(ConfigurationNode node,
                S state)
         throws E extends java.lang.Exception
        Called at the beginning of the visit with a state object created.
        Parameters:
        node - the root node
        state - the state
        Throws:
        E - when thrown by implementation
        E extends java.lang.Exception
        Since:
        4.0.0

      • enterNode

        void enterNode​(ConfigurationNode node,
               S state)
        throws E extends java.lang.Exception
        Called once per node, for every node.
        Parameters:
        node - the current node
        state - provided state
        Throws:
        E - when thrown by implementation
        E extends java.lang.Exception
        Since:
        4.0.0

      • exitMappingNode

        void exitMappingNode​(ConfigurationNode node,
                     S state)
              throws E extends java.lang.Exception
        Called for a list node after the node and any of its children have been visited.
        Parameters:
        node - the node that has been visited
        state - provided state
        Throws:
        E - when thrown by implementation
        E extends java.lang.Exception
        Since:
        4.0.0

      • exitListNode

        void exitListNode​(ConfigurationNode node,
                  S state)
           throws E extends java.lang.Exception
        Called for a list node after the node and any of its children have been visited.
        Parameters:
        node - the node that has been visited
        state - provided state
        Throws:
        E - when thrown by implementation
        E extends java.lang.Exception
        Since:
        4.0.0

      • endVisit

        T endVisit​(S state)
    throws E extends java.lang.Exception
        Called after every node has been visited, to allow for cleanup and validation.
        Parameters:
        state - provided state
        Returns:
        a terminal value
        Throws:
        E - when thrown by implementation
        E extends java.lang.Exception
        Since:
        4.0.0