public class SingletonClosure extends Closure
The expression may depend on local variables and on the context item; these values are held in the saved XPathContext object that is kept as part of the Closure, and they will always be read from that object. The expression may also depend on global variables; these are unchanging, so they can be read from the Bindery in the normal way. Expressions that depend on other contextual information, for example the values of position(), last(), current(), current-group(), should not be evaluated using this mechanism: they should always be evaluated eagerly. This means that the Closure does not need to keep a copy of these context variables.
depth, expression, inputIterator, savedXPathContext
Constructor and Description |
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SingletonClosure(Expression exp,
XPathContext context)
Constructor should not be called directly, instances should be made using the make() method.
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Modifier and Type | Method and Description |
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Item |
asItem()
Return the value in the form of an Item
|
int |
getLength()
Get the length of the sequence
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Item |
itemAt(int n)
Get the n'th item in the sequence (starting from 0).
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SequenceIterator |
iterate()
Evaluate the expression in a given context to return an iterator over a sequence
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GroundedValue |
materialize()
Return a value containing all the items in the sequence returned by this
SequenceIterator
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getExpression, getSavedXPathContext, head, make, reduce, saveContext, setExpression, setSavedXPathContext
public SingletonClosure(Expression exp, XPathContext context) throws XPathException
exp
- the expression to be lazily evaluatedcontext
- the context in which the expression should be evaluatedXPathException
- if an error occurs saving the dynamic contextpublic SequenceIterator iterate() throws XPathException
iterate
in interface Sequence
iterate
in class Closure
XPathException
- in the situation where the sequence is evaluated lazily, and
constructing an iterator over the items causes a dynamic error.public Item asItem() throws XPathException
XPathException
public Item itemAt(int n) throws XPathException
XPathException
public int getLength() throws XPathException
XPathException
public GroundedValue materialize() throws XPathException
XPathException
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