Package net.sf.saxon.expr
Class FilterIterator
- java.lang.Object
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- net.sf.saxon.expr.FilterIterator
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- All Implemented Interfaces:
java.io.Closeable,java.lang.AutoCloseable,SequenceIterator
- Direct Known Subclasses:
FilterIterator.NonNumeric
public class FilterIterator extends java.lang.Object implements SequenceIterator
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 Classes Modifier and Type Class Description static classFilterIterator.NonNumericSubclass to handle the common special case where it is statically known that the filter cannot return a numeric value-
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 FocusIteratorbaseprotected Expressionfilterprotected XPathContextfilterContext
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Constructor Summary
Constructors Constructor Description FilterIterator(SequenceIterator base, Expression filter, XPathContext context)Constructor
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description voidclose()Close the iterator.protected ItemgetNextMatchingItem()Get the next item in the base sequence that matches the filter predicate if there is such an item, or null if not.protected booleanmatches()Determine whether the context item matches the filter predicateItemnext()Get the next item if there is onevoidsetSequence(SequenceIterator base, XPathContext context)Set the base iteratorstatic booleantestPredicateValue(SequenceIterator iterator, long position, Expression filter)-
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, getProperties, materialize
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Field Detail
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base
protected FocusIterator base
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filter
protected Expression filter
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filterContext
protected XPathContext filterContext
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Constructor Detail
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FilterIterator
public FilterIterator(SequenceIterator base, Expression filter, XPathContext context)
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 Detail
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setSequence
public void setSequence(SequenceIterator base, XPathContext context)
Set the base iterator- Parameters:
base- the iterator over the sequence to be filteredcontext- the context in which the (outer) filter expression is evaluated
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next
public Item next() throws XPathException
Get the next item if there is one- 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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getNextMatchingItem
protected Item getNextMatchingItem() throws XPathException
Get the next item in the base sequence that matches the filter predicate if there is such an item, or null if not.- Returns:
- the next item that matches the predicate
- Throws:
XPathException- if a dynamic error occurs
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matches
protected boolean matches() throws XPathExceptionDetermine whether the context item matches the filter predicate- Returns:
- true if the context item matches
- Throws:
XPathException- if an error occurs evaluating the match
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testPredicateValue
public static boolean testPredicateValue(SequenceIterator iterator, long position, Expression filter) throws XPathException
- Throws:
XPathException
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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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