Package ptolemy.domains.sdf.kernel

Class ArrayFIFOQueue

  • All Implemented Interfaces:
    java.lang.Cloneable
    public final class ArrayFIFOQueue
extends java.lang.Object
implements java.lang.Cloneable
    A first-in, first-out (FIFO) queue with variable capacity and optional history. Objects are appended to the queue with the put() method, and removed from the queue with the take() method. The object removed is the oldest one in the queue. By default, the capacity is infinite, but it can be set to any nonnegative size. If the history capacity is greater than zero (or infinite, by setting the capacity to INFINITE_CAPACITY), then objects removed from the queue are transferred to a history queue rather than simply removed. By default, the history capacity is zero.

    This queue is implemented as a circular array. When the array becomes full, it is transparently doubled in size.

    Since:
    Ptolemy II 0.2
    Version:
    $Id$
    Author:
    Steve Neuendorffer, contributor: Brian Hudson
    Pt.AcceptedRating:
    Yellow (johnr)
    Pt.ProposedRating:
    Yellow (neuendor)

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int DEFAULT_CAPACITY
      The default capacity of the queue.
      static int DEFAULT_HISTORY_CAPACITY
      The default capacity of the history queue.
      static int INFINITE_CAPACITY
      Used to indicate that the size of the queue or the history queue is infinite.
      static int STARTING_ARRAYSIZE
      The starting size of the circular buffer, if the capacity is infinite.

    • Constructor Summary

      Constructors 
      Constructor Description
      ArrayFIFOQueue()
      Construct an empty queue with no container, and an infinite capacity.
      ArrayFIFOQueue​(int size)
      Construct an empty queue with no container and the given capacity.
      ArrayFIFOQueue​(ArrayFIFOQueue model)
      Copy constructor.
      ArrayFIFOQueue​(Nameable container)
      Construct an empty queue with the specified container.
      ArrayFIFOQueue​(Nameable container, int size)
      Construct an empty queue with the specified container and the given size.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clear this queue of any contained objects.
      java.lang.Object clone()
      Clone this queue.
      java.util.List elementList()
      Return a list containing all the elements in the queue, beginning with the oldest.
      java.util.Enumeration elements()
      Enumerate the objects in the queue, beginning with the oldest.
      java.lang.Object get​(int offset)
      Return an object in the queue or history.
      int getCapacity()
      Return the queue capacity.
      Nameable getContainer()
      Return the container of the queue, or null if there is none.
      int getHistoryCapacity()
      Return the capacity of the history queue.
      java.util.Enumeration historyElements()
      Enumerate the objects in the history, which are the N most recent objects taken from the queue, beginning with the oldest, where N is less than or equal to the history capacity.
      int historySize()
      Return the number of objects in the history.
      boolean isEmpty()
      Return true if the number of objects in the queue is zero.
      boolean isFull()
      Return true if the number of objects in the queue equals the queue capacity.
      boolean put​(java.lang.Object element)
      Put an object in the queue and return true if this will not cause the capacity to be exceeded.
      boolean putArray​(java.lang.Object[] element)
      Put an array of objects in the queue and return true if this will not cause the capacity to be exceeded.
      boolean putArray​(java.lang.Object[] element, int count)
      Put an array of objects in the queue and return true if this will not cause the capacity to be exceeded.
      void setCapacity​(int capacity)
      Set queue capacity.
      void setContainer​(Nameable container)
      Set the container of the queue.
      void setHistoryCapacity​(int capacity)
      Set the capacity of the history queue.
      int size()
      Return the number of objects in the queue.
      java.lang.Object take()
      Remove the oldest object from the queue and return it.
      void takeArray​(java.lang.Object[] objects)
      Remove the count oldest objects from the queue and return them.
      void takeArray​(java.lang.Object[] objects, int count)
      Remove the count oldest objects from the queue and return them.

      • Methods inherited from class java.lang.Object

        equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • INFINITE_CAPACITY

        public static final int INFINITE_CAPACITY
        Used to indicate that the size of the queue or the history queue is infinite.
        See Also:
        Constant Field Values

      • DEFAULT_CAPACITY

        public static final int DEFAULT_CAPACITY
        The default capacity of the queue.
        See Also:
        Constant Field Values

      • STARTING_ARRAYSIZE

        public static final int STARTING_ARRAYSIZE
        The starting size of the circular buffer, if the capacity is infinite.
        See Also:
        Constant Field Values

      • DEFAULT_HISTORY_CAPACITY

        public static final int DEFAULT_HISTORY_CAPACITY
        The default capacity of the history queue.
        See Also:
        Constant Field Values

    • Constructor Detail

      • ArrayFIFOQueue

        public ArrayFIFOQueue()
        Construct an empty queue with no container, and an infinite capacity.

      • ArrayFIFOQueue

        public ArrayFIFOQueue​(int size)
        Construct an empty queue with no container and the given capacity.
        Parameters:
        size - The size of the queue.

      • ArrayFIFOQueue

        public ArrayFIFOQueue​(Nameable container)
        Construct an empty queue with the specified container. The container is only used for error reporting.
        Parameters:
        container - The container of the queue.

      • ArrayFIFOQueue

        public ArrayFIFOQueue​(Nameable container,
                      int size)
        Construct an empty queue with the specified container and the given size. The container is only used for error reporting.
        Parameters:
        container - The container of the queue.
        size - The size of the queue.

      • ArrayFIFOQueue

        public ArrayFIFOQueue​(ArrayFIFOQueue model)
        Copy constructor. Create a copy of the specified queue, but with no container. This is useful to permit enumerations over a queue while the queue continues to be modified. The objects in the queue themselves are not cloned.
        Parameters:
        model - The queue to be copied.

    • Method Detail

      • clear

        public void clear()
        Clear this queue of any contained objects.

      • clone

        public java.lang.Object clone()
        Clone this queue. The cloned queue has no container. The objects in the queue themselves are not cloned.
        Overrides:
        clone in class java.lang.Object
        Returns:
        A clone of this queue

      • elements

        public java.util.Enumeration elements()
        Enumerate the objects in the queue, beginning with the oldest.
        Returns:
        An enumeration of objects.

      • elementList

        public java.util.List elementList()
        Return a list containing all the elements in the queue, beginning with the oldest.
        Returns:
        A list of objects

      • get

        public java.lang.Object get​(int offset)
                     throws java.util.NoSuchElementException
        Return an object in the queue or history. The object is not removed from the queue or history. If the offset argument is zero, return the oldest object in the queue. If the offset is 1, return the second oldest object, etc. If there is no such object in the queue (the offset is greater than or equal to the current queue size), throw an exception. If the argument is -1, return the most recent object that was put in the history. If the argument is -2, return the second most recent object in the history, etc. If there is no such object in the history (the history capacity is zero or the absolute value of the offset is greater than the current size of the history queue), throw an exception.
        Parameters:
        offset - The position of the desired object.
        Returns:
        The desired object in the queue or history.
        Throws:
        java.util.NoSuchElementException - If the offset is out of range.

      • getCapacity

        public int getCapacity()
        Return the queue capacity. This will be INFINITE_CAPACITY if the capacity is infinite.
        Returns:
        The capacity of the queue.
        See Also:
        setCapacity(int)

      • getContainer

        public Nameable getContainer()
        Return the container of the queue, or null if there is none.
        Returns:
        The container of the queue.
        See Also:
        setContainer(Nameable)

      • getHistoryCapacity

        public int getHistoryCapacity()
        Return the capacity of the history queue. This will be zero if the history mechanism is disabled and INFINITE_CAPACITY if the history capacity is infinite.
        Returns:
        The capacity of the history queue.
        See Also:
        setHistoryCapacity(int)

      • historyElements

        public java.util.Enumeration historyElements()
        Enumerate the objects in the history, which are the N most recent objects taken from the queue, beginning with the oldest, where N is less than or equal to the history capacity. If the history capacity is infinite, then the enumeration includes all objects previously taken from the queue. If the history capacity is zero, then return an empty enumeration.
        Returns:
        An enumeration of objects in the history.

      • historySize

        public int historySize()
        Return the number of objects in the history.
        Returns:
        The current number of objects in the history.

      • isEmpty

        public boolean isEmpty()
        Return true if the number of objects in the queue is zero.
        Returns:
        A boolean indicating whether the queue is empty.

      • isFull

        public boolean isFull()
        Return true if the number of objects in the queue equals the queue capacity.
        Returns:
        A boolean indicating whether the queue is full.

      • put

        public boolean put​(java.lang.Object element)
        Put an object in the queue and return true if this will not cause the capacity to be exceeded. Otherwise, do not put the object in the queue and return false.
        Parameters:
        element - An object to be put in the queue.
        Returns:
        A boolean indicating success.

      • putArray

        public boolean putArray​(java.lang.Object[] element)
        Put an array of objects in the queue and return true if this will not cause the capacity to be exceeded. Otherwise, do not put any of the object in the queue and return false.
        Parameters:
        element - An array of objects to be put in the queue.
        Returns:
        A boolean indicating success.

      • putArray

        public boolean putArray​(java.lang.Object[] element,
                        int count)
        Put an array of objects in the queue and return true if this will not cause the capacity to be exceeded. Otherwise, do not put any of the object in the queue and return false. The specified number of objects from the array will be put in the queue.
        Parameters:
        element - An array of objects to be put in the queue.
        count - The number of objects to be put in the queue.
        Returns:
        A boolean indicating success.

      • setCapacity

        public void setCapacity​(int capacity)
                 throws IllegalActionException
        Set queue capacity. Use INFINITE_CAPACITY to indicate unbounded capacity (which is the default). If the current size of the queue exceeds the desired capacity, throw an exception.
        Parameters:
        capacity - The desired capacity.
        Throws:
        IllegalActionException - If the queue contains more objects than the proposed capacity or the proposed capacity is illegal.
        See Also:
        getCapacity()

      • setContainer

        public void setContainer​(Nameable container)
        Set the container of the queue. The container is only used for error reporting.
        Parameters:
        container - The container of this queue.
        See Also:
        getContainer()

      • setHistoryCapacity

        public void setHistoryCapacity​(int capacity)
                        throws IllegalActionException
        Set the capacity of the history queue. Use 0 to disable the history mechanism and INFINITE_CAPACITY to make the history capacity unbounded. If the size of the history queue exceeds the desired capacity, remove the oldest objects from the history queue until its size equals the proposed capacity. Note that this can be used to clear the history queue by supplying 0 as the argument.
        Parameters:
        capacity - The desired capacity of the history queue.
        Throws:
        IllegalActionException - If the desired capacity is illegal.
        See Also:
        getHistoryCapacity()

      • size

        public int size()
        Return the number of objects in the queue.
        Returns:
        The number of objects in the queue.

      • take

        public java.lang.Object take()
        Remove the oldest object from the queue and return it. If there is no such object in the queue (the queue is empty), throw an exception. If the history mechanism is enabled, then put the taken object in the history queue. If the capacity of the history queue would be exceeded by this, then first remove the oldest object in the history queue.
        Returns:
        An object from the queue.
        Throws:
        java.util.NoSuchElementException - If the queue is empty.

      • takeArray

        public void takeArray​(java.lang.Object[] objects)
               throws java.util.NoSuchElementException
        Remove the count oldest objects from the queue and return them. If there is no such object in the queue (the queue is empty), throw an exception. If the history mechanism is enabled, then put the taken object in the history queue. If the capacity of the history queue would be exceeded by this, then first remove the oldest object in the history queue.
        Parameters:
        objects - An array of objects from the queue.
        Throws:
        java.util.NoSuchElementException - If the queue is empty.

      • takeArray

        public void takeArray​(java.lang.Object[] objects,
                      int count)
               throws java.util.NoSuchElementException
        Remove the count oldest objects from the queue and return them. If there is no such object in the queue (the queue is empty), throw an exception. If the history mechanism is enabled, then put the taken object in the history queue. If the capacity of the history queue would be exceeded by this, then first remove the oldest object in the history queue.
        Parameters:
        objects - An array of objects from the queue.
        count - The number of objects to return.
        Throws:
        java.util.NoSuchElementException - If the queue is empty.