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:
GroupIterator
,SequenceIterator
,LookaheadIterator
- Direct Known Subclasses:
GroupEndingIterator
,GroupStartingIterator
public abstract class GroupMatchingIterator extends java.lang.Object implements LookaheadIterator, GroupIterator
A GroupMatchingIterator contains code shared between GroupStartingIterator and GroupEndingIterator
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Field Summary
Fields Modifier and Type Field Description protected XPathContext
baseContext
protected Item
current
protected java.util.List
currentMembers
protected Item
next
protected Pattern
pattern
protected SequenceIterator
population
protected int
position
protected XPathContext
runningContext
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Fields inherited from interface net.sf.saxon.om.SequenceIterator
GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD
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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 void
advance()
void
close()
Close the iterator.Item
current()
Get the current value in the sequence (the one returned by the most recent call on next()).AtomicValue
getCurrentGroupingKey()
Get the grouping key of the current groupint
getProperties()
Get properties of this iterator, as a bit-significant integer.boolean
hasNext()
Determine whether there are more items to come.SequenceIterator
iterateCurrentGroup()
Get an iterator over the members of the current group, in population order.Item
next()
Get the next item in the sequence.int
position()
Get the current position.-
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
getAnother
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Field Detail
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population
protected SequenceIterator 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 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 AtomicValue getCurrentGroupingKey()
Description copied from interface:GroupIterator
Get the grouping key of the current group- Specified by:
getCurrentGroupingKey
in 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:GroupIterator
Get 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:
iterateCurrentGroup
in 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:LookaheadIterator
Determine 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 bit settingSequenceIterator.LOOKAHEAD
- Specified by:
hasNext
in 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:SequenceIterator
Get the next item in the sequence. This method changes the state of the iterator, in particular it affects the result of subsequent calls of position() and current().- Specified by:
next
in 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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current
public Item current()
Description copied from interface:SequenceIterator
Get the current value in the sequence (the one returned by the most recent call on next()). This will be null before the first call of next(). This method does not change the state of the iterator.- Specified by:
current
in interfaceSequenceIterator
- Returns:
- the current item, the one most recently returned by a call on next(). Returns null if next() has not been called, or if the end of the sequence has been reached.
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position
public int position()
Description copied from interface:SequenceIterator
Get the current position. This will usually be zero before the first call on next(), otherwise it will be the number of times that next() has been called. Once next() has returned null, the preferred action is for subsequent calls on position() to return -1, but not all existing implementations follow this practice. (In particular, the EmptyIterator is stateless, and always returns 0 as the value of position(), whether or not next() has been called.)This method does not change the state of the iterator.
- Specified by:
position
in interfaceSequenceIterator
- Returns:
- the current position, the position of the item returned by the most recent call of next(). This is 1 after next() has been successfully called once, 2 after it has been called twice, and so on. If next() has never been called, the method returns zero. If the end of the sequence has been reached, the value returned will always be <= 0; the preferred value is -1.
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close
public void close()
Description copied from interface:SequenceIterator
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.(Currently, closing an iterator is important only 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:
close
in interfaceSequenceIterator
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getProperties
public int getProperties()
Description copied from interface:SequenceIterator
Get properties of this iterator, as a bit-significant integer.- Specified by:
getProperties
in interfaceSequenceIterator
- Returns:
- the properties of this iterator. This will be some combination of
properties such as
SequenceIterator.GROUNDED
,SequenceIterator.LAST_POSITION_FINDER
, andSequenceIterator.LOOKAHEAD
. It is always acceptable to return the value zero, indicating that there are no known special properties. It is acceptable for the properties of the iterator to change depending on its state.
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