Package net.sf.saxon.expr.sort
Class GroupMatchingIterator
- java.lang.Object
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- net.sf.saxon.expr.sort.GroupMatchingIterator
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- All Implemented Interfaces:
java.io.Closeable,java.lang.AutoCloseable,LastPositionFinder,GroupIterator,SequenceIterator,LookaheadIterator
- Direct Known Subclasses:
GroupEndingIterator,GroupStartingIterator
public abstract class GroupMatchingIterator extends java.lang.Object implements LookaheadIterator, LastPositionFinder, GroupIterator
A GroupMatchingIterator contains code shared between GroupStartingIterator and GroupEndingIterator
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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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Field Summary
Fields Modifier and Type Field Description protected XPathContextbaseContextprotected Itemcurrentprotected java.util.List<Item>currentMembersprotected Itemnextprotected Patternpatternprotected FocusIteratorpopulationprotected intpositionprotected XPathContextrunningContextprotected Expressionselect
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Constructor Summary
Constructors Constructor Description GroupMatchingIterator()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected abstract voidadvance()voidclose()Close the iterator.AtomicSequencegetCurrentGroupingKey()Get the grouping key of the current groupjava.util.EnumSet<SequenceIterator.Property>getProperties()Get properties of this iterator.ManualGroupIteratorgetSnapShot(XPathContext context)Get a sequence which is a snapshot of this sequence at the current positionbooleanhasNext()Determine whether there are more items to come.SequenceIteratoriterateCurrentGroup()Get an iterator over the members of the current group, in population order.Itemnext()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.expr.LastPositionFinder
getLength
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Methods inherited from interface net.sf.saxon.om.SequenceIterator
forEachOrFail, materialize
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Field Detail
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select
protected Expression select
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population
protected FocusIterator population
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pattern
protected Pattern pattern
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baseContext
protected XPathContext baseContext
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runningContext
protected XPathContext runningContext
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currentMembers
protected java.util.List<Item> currentMembers
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next
protected Item next
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current
protected Item current
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position
protected int position
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Method Detail
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advance
protected abstract void advance() throws XPathException- Throws:
XPathException
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getCurrentGroupingKey
public AtomicSequence getCurrentGroupingKey()
Description copied from interface:GroupIteratorGet the grouping key of the current group- Specified by:
getCurrentGroupingKeyin interfaceGroupIterator- Returns:
- the current grouping key in the case of group-by or group-adjacent, or null in the case of group-starting-with and group-ending-with
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iterateCurrentGroup
public SequenceIterator iterateCurrentGroup()
Description copied from interface:GroupIteratorGet an iterator over the members of the current group, in population order. This must always be a clean iterator, that is, an iterator that starts at the first item of the group.- Specified by:
iterateCurrentGroupin interfaceGroupIterator- Returns:
- an iterator over all the members of the current group, in population order.
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hasNext
public boolean hasNext()
Description copied from interface:LookaheadIteratorDetermine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.This method must not be called unless the result of getProperties() on the iterator includes the property
SequenceIterator.Property.LOOKAHEAD- Specified by:
hasNextin interfaceLookaheadIterator- Returns:
- true if there are more items in the sequence
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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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getProperties
public java.util.EnumSet<SequenceIterator.Property> getProperties()
Description copied from interface:SequenceIteratorGet properties of this iterator.- Specified by:
getPropertiesin interfaceSequenceIterator- Returns:
- the properties of this iterator. This will be some combination of
properties such as
SequenceIterator.Property.GROUNDED,SequenceIterator.Property.LAST_POSITION_FINDER, andSequenceIterator.Property.LOOKAHEAD. It is always acceptable to return the default valueEnumSet.noneOf(Property.class), indicating that there are no known special properties. It is acceptable (though unusual) for the properties of the iterator to change depending on its state.
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getSnapShot
public ManualGroupIterator getSnapShot(XPathContext context)
Description copied from interface:GroupIteratorGet a sequence which is a snapshot of this sequence at the current position- Specified by:
getSnapShotin interfaceGroupIterator
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