Package net.sf.saxon.expr
Class ContextMappingIterator
java.lang.Object
net.sf.saxon.expr.ContextMappingIterator
- All Implemented Interfaces:
AtomizableIterator
,SequenceIterator
public final class ContextMappingIterator
extends Object
implements SequenceIterator, AtomizableIterator
ContextMappingIterator merges a sequence of sequences into a single flat
sequence. It takes as inputs an iteration, and a mapping function to be
applied to each Item returned by that iteration. The mapping function itself
returns another iteration. The result is an iteration of the concatenation of all
the iterations returned by the mapping function.
This is a specialization of the MappingIterator class: it differs in that it sets each item being processed as the context item
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Field Summary
Fields inherited from interface net.sf.saxon.om.SequenceIterator
ATOMIZABLE, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD
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Constructor Summary
ConstructorsConstructorDescriptionContextMappingIterator
(ContextMappingFunction action, XPathContext context) Construct a ContextMappingIterator that will apply a specified ContextMappingFunction to each Item returned by the base iterator. -
Method Summary
Modifier and TypeMethodDescriptioncurrent()
Get the current value in the sequence (the one returned by the most recent call on next()).Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.int
Get properties of this iterator, as a bit-significant integer.next()
Get the next item in the sequence.int
position()
Get the current position.void
setIsAtomizing
(boolean atomizing) Indicate that any nodes returned in the sequence will be atomized.
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Constructor Details
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ContextMappingIterator
Construct a ContextMappingIterator that will apply a specified ContextMappingFunction to each Item returned by the base iterator.- Parameters:
action
- the mapping function to be appliedcontext
- the processing context. The mapping function is applied to each item returned by context.getCurrentIterator() in turn.
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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, in particular it affects the result of subsequent calls of position() and current().- 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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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
Description copied from interface:SequenceIterator
Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.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.
- 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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setIsAtomizing
public void setIsAtomizing(boolean atomizing) Indicate that any nodes returned in the sequence will be atomized. This means that if it wishes to do so, the implementation can return the typed values of the nodes rather than the nodes themselves. The implementation is free to ignore this hint.- Specified by:
setIsAtomizing
in interfaceAtomizableIterator
- Parameters:
atomizing
- true if the caller of this iterator will atomize any nodes that are returned, and is therefore willing to accept the typed value of the nodes instead of the nodes themselves.
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