FIFOQueue

java.lang.Object
- ptolemy.actor.util.FIFOQueue

All Implemented Interfaces:

java.lang.Cloneable
```
public class FIFOQueue
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.

Since:

Ptolemy II 0.2

Version:

$Id: FIFOQueue.java 69607 2014-07-30 17:07:26Z cxh $

Author:

Edward A. Lee, Xiaojun Liu

Accepted Rating:
Green (liuj)

Proposed Rating:
Green (eal)

Field Summary

Fields
Modifier and Type Field and Description

static int INFINITE_CAPACITY
Used to indicate that the size of the queue or the history queue is infinite.

Fields
Modifier and Type	Field and Description
`static int`	`INFINITE_CAPACITY` Used to indicate that the size of the queue or the history queue is infinite.

Constructor Summary

Constructors
Constructor and Description
`FIFOQueue()` Construct an empty queue with no container.
`FIFOQueue(FIFOQueue model)` Copy constructor.
`FIFOQueue(Nameable container)` Construct an empty queue with the specified container.

Method Summary

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`void`	`clear()` Remove all items currently stored in the queue and clear the history queue.
`java.lang.Object`	`clone()` Clone this queue.
`java.util.List`	`elementList()` List the objects in the queue, beginning with the oldest.
`java.util.Enumeration`	`elements()` Deprecated. Used elementList() instead.
`java.lang.Object`	`get(int offset)` Return an object in the queue or history.
`int`	`getCapacity()` Return the queue capacity, or INFINITE_CAPACITY if it is unbounded.
`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.List`	`historyElementList()` List 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.
`java.util.Enumeration`	`historyElements()` Deprecated. Use historyElementList() instead.
`int`	`historySize()` Return the number of objects in the history.
`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.
`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.

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
- Constructor Detail
  - FIFOQueue
```
public FIFOQueue()
```
    Construct an empty queue with no container.
  - FIFOQueue
```
public FIFOQueue(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.
  - FIFOQueue
```
public FIFOQueue(FIFOQueue 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()
```
    Remove all items currently stored in the queue and clear the history queue. The queue capacity, history capacity and container remain unchanged.
  - clone
```
public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException
```
    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.
    
    Throws:
    
    java.lang.CloneNotSupportedException - If thrown by object.clone().F
  - elementList
```
public java.util.List elementList()
```
    List the objects in the queue, beginning with the oldest.
    
    Returns:
    
    A list of objects.
  - elements
```
@Deprecated
public java.util.Enumeration elements()
```
    Deprecated. Used elementList() instead.
    
    Enumerate the objects in the queue, beginning with the oldest. This method is deprecated and calls elementList()
    
    Returns:
    
    An enumeration 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, or INFINITE_CAPACITY if it is unbounded.
    
    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(ptolemy.kernel.util.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)
  - historyElementList
```
public java.util.List historyElementList()
```
    List 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 list includes all objects previously taken from the queue. If the history capacity is zero, then return an empty list.
    
    Returns:
    
    A list of objects in the history.
  - historyElements
```
@Deprecated
public java.util.Enumeration historyElements()
```
    Deprecated. Use historyElementList() instead.
    
    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. This method is deprecated and calls historyElementList().
    
    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.
  - 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.
  - 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()
                      throws java.util.NoSuchElementException
```
    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.

Class FIFOQueue

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

INFINITE_CAPACITY

Constructor Detail

FIFOQueue

FIFOQueue

FIFOQueue

Method Detail

clear

clone

elementList

elements

get

getCapacity

getContainer

getHistoryCapacity

historyElementList

historyElements

historySize

isFull

put

setCapacity

setContainer

setHistoryCapacity

size

take