Package net.sf.saxon.expr
Class FilterIterator
java.lang.Object
net.sf.saxon.expr.FilterIterator
- All Implemented Interfaces:
SequenceIterator
- Direct Known Subclasses:
FilterIterator.Leading
,FilterIterator.NonNumeric
A FilterIterator filters an input sequence using a filter expression. Note that a FilterIterator
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.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic final class
Subclass to support the extension function saxon:leading, which terminates the iteration at the first item whose predicate is falsestatic final class
Subclass to handle the common special case where it is statically known that the filter cannot return a numeric value -
Field Summary
FieldsModifier and TypeFieldDescriptionprotected SequenceIterator
protected Expression
protected XPathContext
Fields inherited from interface net.sf.saxon.om.SequenceIterator
ATOMIZABLE, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD
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Constructor Summary
ConstructorsConstructorDescriptionFilterIterator
(SequenceIterator base, Expression filter, XPathContext context) Constructor -
Method Summary
Modifier and TypeMethodDescriptioncurrent()
Get the current value in the sequence (the one returned by the most recent call on next()).Get another iterator to return the same nodesprotected Item
Get the next node that matches the filter predicate if there is one, or null if not.int
Get properties of this iterator, as a bit-significant integer.protected boolean
matches()
Determine whether the context item matches the filter predicatenext()
Get the next item if there is oneint
position()
Get the current position.void
setFilterIsSingletonBoolean
(boolean isBoolean)
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Field Details
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base
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filter
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filterContext
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Constructor Details
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FilterIterator
Constructor- Parameters:
base
- An iteration of the items to be filteredfilter
- The expression defining the filter predicatecontext
- The context in which the expression is being evaluated
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Method Details
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setFilterIsSingletonBoolean
public void setFilterIsSingletonBoolean(boolean isBoolean) -
next
Get the next item if there is one- 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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getNextMatchingItem
Get the next node that matches the filter predicate if there is one, or null if not.- Throws:
XPathException
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matches
Determine whether the context item matches the filter predicate- Throws:
XPathException
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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 invalid input: '<'= 0; the preferred value is -1.
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getAnother
Get another iterator to return the same nodes- Specified by:
getAnother
in interfaceSequenceIterator
- Returns:
- a SequenceIterator that iterates over the same items, positioned before the first item
- Throws:
XPathException
- if any error occurs
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getProperties
public int getProperties()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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