Package net.sf.saxon.expr
Class CardinalityCheckingIterator
java.lang.Object
net.sf.saxon.expr.CardinalityCheckingIterator
- All Implemented Interfaces:
Closeable
,AutoCloseable
,SequenceIterator
CardinalityCheckingIterator returns the items in an underlying sequence
unchanged, but checks that the number of items conforms to the required
cardinality. Because cardinality checks are required to take place even
if the consumer of the sequence does not require all the items, we read
the first two items at initialization time. This is sufficient to perform
the checks; after that we can simply return the items from the base sequence.
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Nested Class Summary
Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator
SequenceIterator.Property
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Constructor Summary
ConstructorsConstructorDescriptionCardinalityCheckingIterator
(SequenceIterator base, int requiredCardinality, RoleDiagnostic role, Location locator) Construct an CardinalityCheckingIterator that will return the same items as the base sequence, checking how many there are -
Method Summary
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface net.sf.saxon.om.SequenceIterator
forEachOrFail, getProperties, materialize
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Constructor Details
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CardinalityCheckingIterator
public CardinalityCheckingIterator(SequenceIterator base, int requiredCardinality, RoleDiagnostic role, Location locator) throws XPathException Construct an CardinalityCheckingIterator that will return the same items as the base sequence, checking how many there are- Parameters:
base
- the base iteratorrequiredCardinality
- the required Cardinalityrole
- information for use if a failure occurslocator
- the location in the source stylesheet or query- Throws:
XPathException
- if a failure is detected
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Method Details
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next
Description copied from interface:SequenceIterator
Get the next item in the sequence. This method changes the state of the iterator.- 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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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.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:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceSequenceIterator
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