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Interface FrontierStructure<Node>

Type Parameters:
Node - The type of tree nodes stored in the frontier.
All Known Subinterfaces:
FrontierCheckingStructure<Node>
All Known Implementing Classes:
Frontiers.DebuggablePriorityQueue, Frontiers.DebuggingFrontier, Frontiers.PriorityQueue, Frontiers.Queue, Frontiers.StateKeyedPriorityQueue
public interface FrontierStructure<Node>
Methods required of a representation of a search tree frontier. The Frontiers class contains some standard implementations and utilities of this interface.
See Also:
GraphSearcher.search(State), Frontiers

  • Method Summary

    Modifier and Type Method Description
    void add​(Node n)
    Adds a (usually newly-generated) tree node to the frontier.
    int countOpen()
    Returns the number of open nodes sitting unexpanded in the frontier.
    default void debugDisplayFrontier()
    Print debugging information about the frontier.
    boolean isEmpty()
    Checks whether any tree nodes remain in the frontier
    Node pop()
    Removes one tree node from the frontier, and returns it.

  • Method Details

    • add

      void add​(Node n)
      Adds a (usually newly-generated) tree node to the frontier.
      Parameters:
      n - The new node

    • isEmpty

      boolean isEmpty()
      Checks whether any tree nodes remain in the frontier
      Returns:
      false when the frontier is empty, which generally indicates that the search has failed.

    • pop

      Node pop()
      Removes one tree node from the frontier, and returns it.
      Returns:
      The dequeued tree node
      Throws:
      IllegalStateException - when this method is called but the frontier is empty; the exception may contain a cause if the exception was generated by some other data structure.

    • countOpen

      int countOpen()
      Returns the number of open nodes sitting unexpanded in the frontier.
      Returns:
      The number of open nodes

    • debugDisplayFrontier

      default void debugDisplayFrontier()
      Print debugging information about the frontier. By default, does nothing.