Package net.sf.saxon.om

Class MemoSequence.ProgressiveIterator

java.lang.Object
net.sf.saxon.om.MemoSequence.ProgressiveIterator
All Implemented Interfaces:
Closeable, AutoCloseable, LastPositionFinder, SequenceIterator, GroundedIterator
Enclosing class:
MemoSequence
public static final class MemoSequence.ProgressiveIterator extends Object implements SequenceIterator, LastPositionFinder, GroundedIterator
A ProgressiveIterator starts by reading any items already held in the reservoir; when the reservoir is exhausted, it reads further items from the inputIterator, copying them into the reservoir as they are read.

  • Constructor Details

    • ProgressiveIterator

      public ProgressiveIterator(MemoSequence container)
      Create a ProgressiveIterator
      Parameters:
      container - the containing MemoSequence

  • Method Details

    • getMemoSequence

      public MemoSequence getMemoSequence()
      Get the containing MemoSequence
      Returns:
      the containing MemoSequence

    • next

      public Item next()
      Description copied from interface: SequenceIterator
      Get the next item in the sequence. This method changes the state of the iterator.
      Specified by:
      next in interface SequenceIterator
      Returns:
      the next item, or null if there are no more items. Once a call on next() has returned null, no further calls should be made. The preferred action for an iterator if subsequent calls on next() are made is to return null again, and all implementations within Saxon follow this rule.

    • supportsGetLength

      public boolean supportsGetLength()
      Description copied from interface: LastPositionFinder
      Ask whether this iterator supports use of the LastPositionFinder.getLength() method. This method should always be called before calling LastPositionFinder.getLength(), because an iterator that implements this interface may support use of LastPositionFinder.getLength() in some situations and not in others
      Specified by:
      supportsGetLength in interface LastPositionFinder
      Returns:
      true if the LastPositionFinder.getLength() method can be called to determine the length of the underlying sequence.

    • getLength

      public int getLength()
      Get the last position (that is, the number of items in the sequence)
      Specified by:
      getLength in interface LastPositionFinder
      Returns:
      the number of items in the sequence

    • isActuallyGrounded

      public boolean isActuallyGrounded()
      Description copied from interface: GroundedIterator
      Ask if the iterator is actually grounded. This method must be called before calling GroundedIterator.materialize() or GroundedIterator.getResidue(), because the iterator might be grounded under some conditions and not others (usually when it delegates to another iterator)
      Specified by:
      isActuallyGrounded in interface GroundedIterator
      Returns:
      true if this iterator is grounded

    • materialize

      public GroundedValue materialize()
      Return a value containing all the items in the sequence returned by this SequenceIterator
      Specified by:
      materialize in interface GroundedIterator
      Returns:
      the corresponding value

    • getResidue

      public GroundedValue getResidue()
      Description copied from interface: GroundedIterator
      Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position. This should be an "in-memory" value, not a Closure. This method does not change the state of the iterator (in particular, it does not consume the iterator).
      Specified by:
      getResidue in interface GroundedIterator
      Returns:
      the corresponding Value

    • close

      public void close()
      Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.

      For example, the iterator returned by the unparsed-text-lines() function has a close() method that causes the underlying input stream to be closed, whether or not the file has been read to completion.

      Closing an iterator is important when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.

      Closing an iterator is not necessary if the iterator is read to completion: if a call on next() returns null, the iterator will be closed automatically. An explicit call on close() is needed only when iteration is abandoned prematurely.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Specified by:
      close in interface SequenceIterator
      Since:
      9.1. Default implementation added in 9.9.