Package net.sf.saxon.om
Class MemoSequence.ProgressiveIterator
- java.lang.Object
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- net.sf.saxon.om.MemoSequence.ProgressiveIterator
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- All Implemented Interfaces:
java.io.Closeable,java.lang.AutoCloseable,LastPositionFinder,SequenceIterator,GroundedIterator
- Enclosing class:
- MemoSequence
public final class MemoSequence.ProgressiveIterator extends java.lang.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.
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Nested Class Summary
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Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator
SequenceIterator.Property
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Constructor Summary
Constructors Constructor Description ProgressiveIterator()Create a ProgressiveIterator
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voidclose()Close the iterator.intgetLength()Get the last position (that is, the number of items in the sequence)MemoSequencegetMemoSequence()Get the containing MemoSequencejava.util.EnumSet<SequenceIterator.Property>getProperties()Get properties of this iterator, as a bit-significant integer.GroundedValuegetResidue()Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.GroundedValuematerialize()Return a value containing all the items in the sequence returned by this SequenceIteratorItemnext()Get the next item in the sequence.-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface net.sf.saxon.om.SequenceIterator
forEachOrFail
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Method Detail
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getMemoSequence
public MemoSequence getMemoSequence()
Get the containing MemoSequence
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next
public Item next() throws XPathException
Description copied from interface:SequenceIteratorGet the next item in the sequence. This method changes the state of the iterator.- Specified by:
nextin interfaceSequenceIterator- 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.
- Throws:
XPathException- if an error occurs retrieving the next item
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close
public void close()
Description copied from interface:SequenceIteratorClose 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.
- Specified by:
closein interfacejava.lang.AutoCloseable- Specified by:
closein interfacejava.io.Closeable- Specified by:
closein interfaceSequenceIterator
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getLength
public int getLength() throws XPathExceptionGet the last position (that is, the number of items in the sequence)- Specified by:
getLengthin interfaceLastPositionFinder- Returns:
- the number of items in the sequence
- Throws:
XPathException- if an error occurs evaluating the sequence in order to determine the number of items
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materialize
public GroundedValue materialize() throws XPathException
Return a value containing all the items in the sequence returned by this SequenceIterator- Specified by:
materializein interfaceGroundedIterator- Specified by:
materializein interfaceSequenceIterator- Returns:
- the corresponding value
- Throws:
XPathException- if reading the SequenceIterator throws an error
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getResidue
public GroundedValue getResidue() throws XPathException
Description copied from interface:GroundedIteratorReturn 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:
getResiduein interfaceGroundedIterator- Returns:
- the corresponding Value
- Throws:
XPathException- in the cases of subclasses (such as the iterator over a MemoClosure) which cause evaluation of expressions while materializing the value.
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getProperties
public java.util.EnumSet<SequenceIterator.Property> getProperties()
Get properties of this iterator, as a bit-significant integer.- Specified by:
getPropertiesin interfaceSequenceIterator- Returns:
- the properties of this iterator. This will be some combination of
properties such as
SequenceIterator.Property.GROUNDEDandSequenceIterator.Property.LAST_POSITION_FINDER. It is always acceptable to return the value zero, indicating that there are no known special properties.
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