Class ItemMappingIterator
- All Implemented Interfaces:
Closeable
,AutoCloseable
,LastPositionFinder
,SequenceIterator
,LookaheadIterator
This is a specialization of the more general MappingIterator class, for use in cases where a single input item never maps to a sequence of more than one output item.
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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
ConstructorsConstructorDescriptionItemMappingIterator
(SequenceIterator base, ItemMappingFunction action) Construct an ItemMappingIterator that will apply a specified DummyItemMappingFunction to each Item returned by the base iterator.ItemMappingIterator
(SequenceIterator base, ItemMappingFunction action, boolean oneToOne) Construct an ItemMappingIterator that will apply a specified ItemMappingFunction to each Item returned by the base iterator. -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Close the iterator.protected SequenceIterator
Get the base (input) iteratorint
Get the last position (that is, the number of items in the sequence).protected ItemMappingFunction
Get the mapping function (the function applied to each item in the input sequenceGet properties of this iterator, as a bit-significant integer.boolean
hasNext()
Determine whether there are more items to come.boolean
Ask whether this ItemMappingIterator is one-to-one: that is, for every input item, there is always exactly one output item.next()
Get the next item in the sequence.void
setOneToOne
(boolean oneToOne) Say whether this ItemMappingIterator is one-to-one: that is, for every input item, there is always exactly one output item.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, materialize
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Constructor Details
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ItemMappingIterator
Construct an ItemMappingIterator that will apply a specified DummyItemMappingFunction to each Item returned by the base iterator.- Parameters:
base
- the base iteratoraction
- the mapping function to be applied.
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ItemMappingIterator
Construct an ItemMappingIterator that will apply a specified ItemMappingFunction to each Item returned by the base iterator.- Parameters:
base
- the base iteratoraction
- the mapping function to be appliedoneToOne
- true if this iterator is one-to-one
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Method Details
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setOneToOne
public void setOneToOne(boolean oneToOne) Say whether this ItemMappingIterator is one-to-one: that is, for every input item, there is always exactly one output item. The default is false.- Parameters:
oneToOne
- true if this iterator is one-to-one
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isOneToOne
public boolean isOneToOne()Ask whether this ItemMappingIterator is one-to-one: that is, for every input item, there is always exactly one output item. The default is false.- Returns:
- true if this iterator is one-to-one
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getBaseIterator
Get the base (input) iterator- Returns:
- the iterator over the input sequence
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getMappingFunction
Get the mapping function (the function applied to each item in the input sequence- Returns:
- the mapping function
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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 property
SequenceIterator.Property.LOOKAHEAD
- Specified by:
hasNext
in interfaceLookaheadIterator
- Returns:
- true if there are more items in the sequence
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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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getLength
Description copied from interface:LastPositionFinder
Get the last position (that is, the number of items in the sequence). This method is non-destructive: it does not change the state of the iterator. The result is undefined if the next() method of the iterator has already returned null. This method must not be called unless the result of getProperties() on the iterator includes the bit settingSequenceIterator.Property.LAST_POSITION_FINDER
- Specified by:
getLength
in interfaceLastPositionFinder
- Returns:
- the number of items in the sequence
- Throws:
XPathException
- if an error occurs evaluating the sequence in order to determine the number of items
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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.Property.GROUNDED
,SequenceIterator.Property.LAST_POSITION_FINDER
, andSequenceIterator.Property.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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