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## org.apache.cocoon.stax
Class AbstractStAXTransformer

    java.lang.Object
      org.apache.cocoon.pipeline.component.AbstractPipelineComponent
          org.apache.cocoon.stax.AbstractStAXPipelineComponent
              org.apache.cocoon.stax.AbstractStAXProducer
                  org.apache.cocoon.stax.AbstractStAXTransformer

All Implemented Interfaces:
  Consumer, PipelineComponent, Producer, StAXConsumer, StAXPipelineComponent, StAXProducer

Direct Known Subclasses:
  CleaningTransformer, IncludeTransformer, SAXForStAXPipelineWrapper

    public abstract class AbstractStAXTransformer

extends AbstractStAXProducer
implements StAXConsumer

Abstract transformer could/should be used for each StAXTransformer. This class implements the default behavior of the `StAXConsumer` and the `StAXConsumer` interfaces. Further more the `AbstractStAXTransformer` contains the queuing for StAX-events. This transformer abstracts the entire handling of `nextEvent()` and `peek()` behind a template method `produceEvents()` which saves all produced events in a buffer and handles `peek()`, `nextEvent()` and `hasNext()`.

Constructor Summary
`AbstractStAXTransformer()`

Method Summary
`protected void` | `addAllEventsToQueue(Collection<? extends XMLEvent> events)` Adds a `Collection` of `XMLEvent`s to an internal `Queue`.
`protected void` | `addEventToQueue(XMLEvent event)` Add a specific `XMLEvent` to an internal `Queue`.
`protected StAXProducer` | `getParent()` This `StAXProducer` is the parent of the module overwriting this `AbstractStAXTransformer`.
`boolean` | `hasNext()` Check if there are more events.
`void` | `initiatePullProcessing()` Since the workflow in a pull pipeline is completely inverted compared to for example a SAX pipeline, this method is required to push the `Starter.execute()` to the `Finisher` which should start processing.
`protected boolean` | `isQueueEmpty()` Checks and returns if the internal `Queue` of `XMLEvent`s is empty.
`XMLEvent` | `nextEvent()` Get the next XMLEvent
`XMLEvent` | `peek()` Check the next XMLEvent without reading it from the stream.
`protected abstract void` | `produceEvents()` Template method which has to produce at least one `XMLEvent` and should add this to the internal `Queue` with the `#add(XMLEvent)` and `#addAll(Collection)` methods.
`void` | `setParent(StAXProducer parent)` Used to connect a consumer to it's producer.

Methods inherited from class org.apache.cocoon.stax.AbstractStAXProducer
`getConsumer, setConsumer`

Methods inherited from class org.apache.cocoon.pipeline.component.AbstractPipelineComponent
`finish, setConfiguration, setup`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface org.apache.cocoon.pipeline.component.PipelineComponent
`finish, setConfiguration, setup`

Constructor Detail

### AbstractStAXTransformer

    public AbstractStAXTransformer()

Method Detail

### initiatePullProcessing

    public final void initiatePullProcessing()

  Since the workflow in a pull pipeline is completely inverted compared to for example a SAX pipeline, this method is required to push the `Starter.execute()` to the `Finisher` which should start processing.

  Specified by:
    `initiatePullProcessing` in interface `StAXConsumer`
  See Also:
    `StAXConsumer.initiatePullProcessing()`

### setParent

    public final void setParent(StAXProducer parent)

  Used to connect a consumer to it's producer. As to the nature of the control inversion and pulling it is required to specify a parent, which provides the consumer with events to consume. This function is called when the pipeline sets it's consumers.

  Specified by:
    `setParent` in interface `StAXConsumer`
  See Also:
    `StAXConsumer.setParent(StAXProducer)`

### hasNext

    public final boolean hasNext()
                          throws XMLStreamException

  Check if there are more events. Returns true if there are more events and false otherwise.

  Specified by:
    `hasNext` in interface `StAXProducer`
  Returns:
    true if the event reader has more events, false otherwise
  Throws:
    `XMLStreamException` - Error which could occure during producing events.
  See Also:
    `StAXProducer.hasNext()`

### nextEvent

    public final XMLEvent nextEvent()

  Get the next XMLEvent

  Specified by:
    `nextEvent` in interface `StAXProducer`
  See Also:
    `StAXProducer.nextEvent()`

### peek

    public final XMLEvent peek()

  Check the next XMLEvent without reading it from the stream. Returns null if the stream is at EOF or has no more XMLEvents. A call to peek() will be equal to the next return of next().

  Specified by:
    `peek` in interface `StAXProducer`
  See Also:
    `StAXProducer.peek()`

### addEventToQueue

    protected final void addEventToQueue(XMLEvent event)

  Add a specific `XMLEvent` to an internal `Queue`.

  Parameters:
    `event` - which should be added to the queue.

### getParent

    protected final StAXProducer getParent()

  This `StAXProducer` is the parent of the module overwriting this `AbstractStAXTransformer`. It could be used in the `produceEvents()` method to pull events from the parent or ask if it still has some.

### addAllEventsToQueue

    protected final void addAllEventsToQueue(Collection<? extends XMLEvent> events)

  Adds a `Collection` of `XMLEvent`s to an internal `Queue`.

  Parameters:
    `events` - are a `Collection` of `XMLEvent`s which should be added to an internal `Queue`.

### isQueueEmpty

    protected final boolean isQueueEmpty()

  Checks and returns if the internal `Queue` of `XMLEvent`s is empty.

  Returns:
    checks and returns if the internal `Queue` of `XMLEvent`s is empty.

### produceEvents

    protected abstract void produceEvents()
                                   throws XMLStreamException

  Template method which has to produce at least one `XMLEvent` and should add this to the internal `Queue` with the `#add(XMLEvent)` and `#addAll(Collection)` methods. If no `XMLEvent` is added by this method to the internal `Queue` an exception is thrown.

  Throws:
    `XMLStreamException` - thrown if the `StAXProducer.nextEvent()` or the `StAXProducer.peek()` method, called in the `produceEvents()` method throw any exceptions they have to be forwarded to the end of the pipeline.

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