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java.lang.Object net.sf.saxon.expr.ItemMappingIterator<F,T>
public final class ItemMappingIterator<F extends Item,T extends Item>
ItemMappingIterator applies a mapping function to each item in a sequence. The mapping function either returns a single item, or null (representing an empty sequence).
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.
Field Summary |
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Fields inherited from interface net.sf.saxon.om.SequenceIterator |
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GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD |
Constructor Summary | |
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ItemMappingIterator(SequenceIterator<F> base,
ItemMappingFunction<F,T> action)
Construct an ItemMappingIterator that will apply a specified DummyItemMappingFunction to each Item returned by the base iterator. |
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ItemMappingIterator(SequenceIterator<F> base,
ItemMappingFunction<F,T> action,
boolean oneToOne)
Construct an ItemMappingIterator that will apply a specified DummyItemMappingFunction to each Item returned by the base iterator. |
Method Summary | |
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void |
close()
Close the iterator. |
T |
current()
Get the current value in the sequence (the one returned by the most recent call on next()). |
SequenceIterator<T> |
getAnother()
Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence. |
int |
getLength()
Get the last position (that is, the number of items in the sequence). |
int |
getProperties()
Get properties of this iterator, as a bit-significant integer. |
boolean |
hasNext()
Determine whether there are more items to come. |
boolean |
isOneToOne()
Ask whether this ItemMappingIterator is one-to-one: that is, for every input item, there is always exactly one output item. |
T |
next()
Get the next item in the sequence. |
int |
position()
Get the current position. |
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 |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public ItemMappingIterator(SequenceIterator<F> base, ItemMappingFunction<F,T> action)
base
- the base iteratoraction
- the mapping function to be applied.public ItemMappingIterator(SequenceIterator<F> base, ItemMappingFunction<F,T> action, boolean oneToOne)
base
- the base iteratoraction
- the mapping function to be appliedoneToOne
- true if this iterator is one-to-oneMethod Detail |
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public void setOneToOne(boolean oneToOne)
oneToOne
- true if this iterator is one-to-onepublic boolean isOneToOne()
public boolean hasNext()
LookaheadIterator
SequenceIterator.LOOKAHEAD
hasNext
in interface LookaheadIterator<T extends Item>
public T next() throws XPathException
SequenceIterator
next
in interface SequenceIterator<T extends Item>
XPathException
- if an error occurs retrieving the next itempublic T current()
SequenceIterator
current
in interface SequenceIterator<T extends Item>
public int position()
SequenceIterator
This method does not change the state of the iterator.
position
in interface SequenceIterator<T extends Item>
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<T extends Item>
public SequenceIterator<T> getAnother() throws XPathException
SequenceIterator
This method allows access to all the items in the sequence without disturbing the current position of the iterator. Internally, its main use is in evaluating the last() function.
This method does not change the state of the iterator.
getAnother
in interface SequenceIterator<T extends Item>
XPathException
- if any error occurspublic int getLength() throws XPathException
LastPositionFinder
SequenceIterator.LAST_POSITION_FINDER
getLength
in interface LastPositionFinder<T extends Item>
XPathException
- if an error occurs evaluating the sequence in order to determine
the number of itemspublic int getProperties()
getProperties
in interface SequenceIterator<T extends Item>
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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