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java.lang.Object net.sf.saxon.expr.FilterIterator
public class FilterIterator
A CompiledFilterIterator filters an input sequence using a filter expression. Note that a CompiledFilterIterator is not used where the filter is a constant number (PositionFilter is used for this purpose instead), so this class does no optimizations for numeric predicates.
Nested Class Summary | |
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static class |
FilterIterator.NonNumeric
Subclass to handle the common special case where it is statically known that the filter cannot return a numeric value |
Field Summary | |
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protected SequenceIterator |
base
|
protected Expression |
filter
|
protected XPathContext |
filterContext
|
Fields inherited from interface net.sf.saxon.om.SequenceIterator |
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GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD |
Constructor Summary | |
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FilterIterator(SequenceIterator base,
Expression filter,
XPathContext context)
Constructor |
Method Summary | |
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void |
close()
Close the iterator. |
Item |
current()
Get the current value in the sequence (the one returned by the most recent call on next()). |
SequenceIterator |
getAnother()
Get another iterator to return the same nodes |
protected Item |
getNextMatchingItem()
Get the next item in the base sequence that matches the filter predicate if there is such an item, or null if not. |
int |
getProperties()
Get properties of this iterator, as a bit-significant integer. |
protected boolean |
matches()
Determine whether the context item matches the filter predicate |
Item |
next()
Get the next item if there is one |
int |
position()
Get the current position. |
void |
setSequence(SequenceIterator base,
XPathContext context)
Set the base iterator |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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protected SequenceIterator base
protected Expression filter
protected XPathContext filterContext
Constructor Detail |
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public FilterIterator(SequenceIterator base, Expression filter, XPathContext context)
base
- An iteration of the items to be filteredfilter
- The expression defining the filter predicatecontext
- The context in which the expression is being evaluatedMethod Detail |
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public void setSequence(SequenceIterator base, XPathContext context)
base
- the iterator over the sequence to be filteredcontext
- the context in which the (outer) filter expression is evaluatedpublic Item next() throws XPathException
next
in interface SequenceIterator
XPathException
- if an error occurs retrieving the next itemprotected Item getNextMatchingItem() throws XPathException
XPathException
protected boolean matches() throws XPathException
XPathException
public Item current()
SequenceIterator
current
in interface SequenceIterator
public int position()
SequenceIterator
This method does not change the state of the iterator.
position
in interface SequenceIterator
public void close()
SequenceIterator
(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.)
close
in interface SequenceIterator
public SequenceIterator getAnother() throws XPathException
getAnother
in interface SequenceIterator
XPathException
- if any error occurspublic int getProperties()
getProperties
in interface SequenceIterator
SequenceIterator.GROUNDED
, SequenceIterator.LAST_POSITION_FINDER
,
and SequenceIterator.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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