Module de.learnlib.filter.reuse
Package de.learnlib.filter.reuse.tree

Class BoundedDeque<E>

  • Type Parameters:
    E - element type
    All Implemented Interfaces:
    Iterable<E>, Collection<E>
    public class BoundedDeque<E>
extends AbstractCollection<E>
    A generic deque-derived container which transparently acts either as a stack or a queue, and optionally a capacity restriction with a configurable policy which element is evicted (or reject) if the maximum capacity is reached.

    Note: Like ArrayDeque, this deque implementation is not thread-safe. Concurrent access by multiple threads requires explicit synchronization.

    • Constructor Detail

      • BoundedDeque

        public BoundedDeque​(BoundedDeque.AccessPolicy accessPolicy)
        Constructor. Creates an unbounded deque with the given access policy.
        Parameters:
        accessPolicy - whether this deque acts as a stack or a queue

      • BoundedDeque

        public BoundedDeque​(int capacity,
                    BoundedDeque.AccessPolicy accessPolicy,
                    BoundedDeque.EvictPolicy evictPolicy)
        Constructor. Creates a possibly capacity-restricted deque with the given access policy.
        Parameters:
        capacity - the maximum capacity of this deque. A value less than or equal to 0 means unbounded
        accessPolicy - whether this deque acts as a stack or a queue
        evictPolicy - which elements to remove if the maximum capacity is reached. If the capacity is unbounded, this parameter has no effect

    • Method Detail

      • insert

        public @Nullable E insert​(E element)
        Inserts an element into the deque, and returns the one that had to be evicted in case of a capacity violation.
        Parameters:
        element - the element to insert
        Returns:
        the evicted element, null if the maximum capacity has not been reached

      • retrieve

        public @Nullable E retrieve()
        Retrieves and remove the top-most element, i.e., the element that is either the top of the stack or the head of the queue, depending on the configured BoundedDeque.AccessPolicy.
        Returns:
        the evicted element, may be null if the queue was empty

      • peek

        public @Nullable E peek()
        Retrieves, but does not remove the top-most element, i.e., the element that is either the top of the stack or the head of the queue, depending on the configured BoundedDeque.AccessPolicy. May be null if the stack is empty.
        Returns:
        the top-most element of the container

      • isBounded

        public boolean isBounded()
        Retrieves whether capacity restriction is in effect.
        Returns:
        true if the capacity is restricted, false otherwise