net.sf.saxon.sxpath
Class XPathExpression

java.lang.Object
  net.sf.saxon.sxpath.XPathExpression

public class XPathExpression

extends java.lang.Object

This class is a representation of an XPath Expression for use with the XPathEvaluator class. It is modelled on the XPath API defined in JAXP 1.3, but is cut down to remove any dependencies on JAXP 1.3, making it suitable for use on vanilla JDK 1.4 installations.

Constructor Summary

protected

XPathExpression(XPathEvaluator evaluator, Expression exp) The constructor is protected, to ensure that instances can only be created using the createExpression() method of XPathEvaluator

Method Summary

java.util.List	evaluate(javax.xml.transform.Source source) Execute a prepared XPath expression, returning the results as a List.
java.lang.Object	evaluateSingle(javax.xml.transform.Source source) Execute a prepared XPath expression, returning the first item in the result.
Expression	getInternalExpression() Low-level method to get the internal Saxon expression object.
SequenceIterator	rawIterator(javax.xml.transform.Source source) Get a raw iterator over the results of the expression.
protected void	setStackFrameMap(SlotManager map) Define the number of slots needed for local variables within the expression

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

XPathExpression

protected XPathExpression(XPathEvaluator evaluator,
                          Expression exp)

The constructor is protected, to ensure that instances can only be created using the createExpression() method of XPathEvaluator

Method Detail

setStackFrameMap

protected void setStackFrameMap(SlotManager map)

Define the number of slots needed for local variables within the expression

evaluate

public java.util.List evaluate(javax.xml.transform.Source source)
                        throws XPathException

Execute a prepared XPath expression, returning the results as a List.

Parameters:

source - the document or other node against which the XPath expression will be evaluated. This may be a Saxon NodeInfo object, representing a node in an existing tree, or it may be any kind of JAXP Source object such as a StreamSource SAXSource or DOMSource.

Returns:

The results of the expression, as a List. The List represents the sequence of items returned by the expression. Each item in the list will either be an instance of net.sf.saxon.om.NodeInfo, representing a node, or a Java object representing an atomic value.

Throws:

XPathException

evaluateSingle

public java.lang.Object evaluateSingle(javax.xml.transform.Source source)
                                throws XPathException

Execute a prepared XPath expression, returning the first item in the result. This is useful where it is known that the expression will only return a singleton value (for example, a single node, or a boolean).

Parameters:

source - the document or other node against which the XPath expression will be evaluated. This may be a Saxon NodeInfo object, representing a node in an existing tree, or it may be any kind of JAXP Source object such as a StreamSource SAXSource or DOMSource.

Returns:

The first item in the sequence returned by the expression. If the expression returns an empty sequence, this method returns null. Otherwise, it returns the first item in the result sequence, represented as a Java object using the same mapping as for the evaluate() method

Throws:

XPathException

rawIterator

public SequenceIterator rawIterator(javax.xml.transform.Source source)
                             throws XPathException

Get a raw iterator over the results of the expression. This returns results without any conversion of the returned items to "native" Java classes. This method is intended for use by applications that need to process the results of the expression using internal Saxon interfaces.

Parameters:

source - the document or other node against which the XPath expression will be evaluated. This may be a Saxon NodeInfo object, representing a node in an existing tree, or it may be any kind of JAXP Source object such as a StreamSource SAXSource or DOMSource.

Throws:

XPathException

getInternalExpression

public Expression getInternalExpression()

Low-level method to get the internal Saxon expression object. This exposes a wide range of internal methods that may be needed by specialized applications, and allows greater control over the dynamic context for evaluating the expression.

Returns:

the underlying Saxon expression object.