net.sf.saxon.s9api
class XPathSelector extends Object implements Iterable<XdmItem>
Constructor Summary | |
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protected | XPathSelector(XPathExpression exp, ArrayList<XPathVariable> declaredVariables) |
Method Summary | |
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boolean | effectiveBooleanValue()
Evaluate the XPath expression, returning the effective boolean value of the result.
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XdmValue | evaluate()
Evaluate the expression, returning the result as an XdmValue (that is,
a sequence of nodes and/or atomic values).
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XdmItem | evaluateSingle()
Evaluate the XPath expression, returning the result as an XdmItem (that is,
a single node or atomic value).
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XdmItem | getContextItem()
Get the context item used for evaluating the XPath expression.
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Iterator<XdmItem> | iterator()
Evaluate the expression, returning the result as an Iterator (that is,
an iterator over a sequence of nodes and/or atomic values).
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void | setContextItem(XdmItem item)
Set the context item for evaluating the XPath expression.
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void | setVariable(QName name, XdmValue value)
Set the value of a variable
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Returns: a boolean
representing the effective boolean value of the result of evaluating
the expression, as defined by the rules for the fn:boolean() function.
Throws: SaxonApiException if a dynamic error occurs during the expression evaluation, or if the result of the expression is a value whose effective boolean value is not defined (for example, a date or a sequence of three integers)
Since: 9.1
XdmValue
(that is,
a sequence of nodes and/or atomic values).
Note: Although a singleton result may be represented as an XdmItem
, there is
no guarantee that this will always be the case. If you know that the expression will return at
most one node or atomic value, it is best to use the evaluateSingle
method, which
does guarantee that an XdmItem
(or null) will be returned.
Returns: An XdmValue
representing the results of the expression.
Throws: SaxonApiException if a dynamic error occurs during the expression evaluation.
XdmItem
(that is,
a single node or atomic value).
Returns: an XdmItem
representing the result of the expression, or null if the expression
returns an empty sequence. If the expression returns a sequence of more than one item,
any items after the first are ignored.
Throws: SaxonApiException if a dynamic error occurs during the expression evaluation.
Returns: The context item for evaluating the expression, or null if no context item has been set.
Iterator
(that is,
an iterator over a sequence of nodes and/or atomic values).
Because an XPathSelector
is an Iterable, it is possible to
iterate over the result using a Java 5 "for each" expression, for example:
XPathCompiler compiler = processor.newXPathCompiler(); XPathSelector seq = compiler.compile("1 to 20").load(); for (XdmItem item : seq) { System.err.println(item); }
Returns: An iterator over the sequence that represents the results of the expression.
Each object in this sequence will be an instance of XdmItem
. Note
that the expression may be evaluated lazily, which means that a successful response
from this method does not imply that the expression has executed successfully: failures
may be reported later while retrieving items from the iterator.
Throws: SaxonApiUncheckedException
if a dynamic error occurs during XPath evaluation that
can be detected at this point. It is also possible that an SaxonApiUncheckedException will
be thrown by the hasNext()
method of the returned iterator.
Parameters: item The context item for evaluating the expression. Must not be null.
Parameters: name The name of the variable. This must match the name of a variable that was declared to the XPathCompiler. No error occurs if the expression does not actually reference a variable with this name. value The value to be given to the variable.
Throws: SaxonApiException if the variable has not been declared or if the type of the value supplied does not conform to the required type that was specified when the variable was declared