public class XPathExpressionImpl
extends java.lang.Object
implements javax.xml.xpath.XPathExpression
The JAXP XPathExpression interface represents a compiled XPath expression that can be repeatedly evaluated. This class is Saxon's implementation of that interface.
The class also includes some methods retained from Saxon's original XPath API. When these methods are used, the object contains the context node and other state, so it is not thread-safe.
Modifier | Constructor and Description |
---|---|
protected |
XPathExpressionImpl(Expression exp,
Executable exec)
The constructor is protected, to ensure that instances can only be
created using the compile() method of XPathEvaluator
|
Modifier and Type | Method and Description |
---|---|
java.lang.String |
evaluate(org.xml.sax.InputSource inputSource)
Evaluate the XPath expression against an input source to obtain a string result.
|
java.lang.Object |
evaluate(org.xml.sax.InputSource inputSource,
javax.xml.namespace.QName qName)
Evaluate the XPath expression against an input source to obtain a result of a specified type
|
java.lang.String |
evaluate(java.lang.Object node)
Evaluate the expression to return a string value
|
java.lang.Object |
evaluate(java.lang.Object node,
javax.xml.namespace.QName qName)
JAXP 1.3 evaluate() method
|
Configuration |
getConfiguration()
Get the Configuration under which this XPath expression was compiled
|
Expression |
getInternalExpression()
Low-level method to get the internal Saxon expression object.
|
SlotManager |
getStackFrameMap()
Get the stack frame map.
|
protected void |
setStackFrameMap(SlotManager map)
Define the number of slots needed for local variables within the expression.
|
protected XPathExpressionImpl(Expression exp, Executable exec)
exp
- the compiled expressionexec
- the executableprotected void setStackFrameMap(SlotManager map)
map
- description of the stack framepublic SlotManager getStackFrameMap()
public Configuration getConfiguration()
public java.lang.Object evaluate(java.lang.Object node, javax.xml.namespace.QName qName) throws javax.xml.xpath.XPathExpressionException
evaluate
in interface javax.xml.xpath.XPathExpression
node
- The context node. This must use a representation of nodes that this implementation understands.
This may be a Saxon NodeInfo, or a node in one of the external object models supported, for example
DOM, DOM4J, JDOM, or XOM, provided the support module for that object model is loaded.
An instance of TreeInfo
is also accepted.
Contrary to the interface specification, Saxon does not supply an empty document when the value is null. This is because XPath 2.0 allows the context item to be "absent" (null). So Saxon executes the XPath expression with the context item undefined.
qName
- Indicates the type of result required. This must be one of the constants defined in
the JAXP XPathConstants
class.
Saxon will attempt to convert the actual result of the expression to the required type using the
XPath 1.0 conversion rules.QName | Return Value |
BOOLEAN | The effective boolean value of the actual result, as a Java Boolean object |
STRING | The result of applying the string() function to the actual result, as a Java String object |
NUMBER | The result of applying the number() function to the actual result, as a Java Double object |
NODE | A single node, in the native data model supplied as input. If the expression returns more than one node, the first is returned. If the expression returns an empty sequence, null is returned. If the expression returns an atomic value, or if the first item in the result sequence is an atomic value, an exception is thrown. |
NODESET | This is interpreted as allowing any sequence, of nodes or atomic values. If the first argument is a wrapper around a DOM Node, then the result is returned as a DOM NodeList, and an exception is then thrown if the result sequence contains a value that is not a DOM Node. In all other cases the result is returned as a Java List object, unless it is empty, in which case null is returned. The contents of the list may be node objects (in the native data model supplied as input), or Java objects representing the XPath atomic values in the actual result: String for an xs:string, Double for a xs:double, Long for an xs:integer, and so on. (For safety, cast the values to a type such as xs:string within the XPath expression). |
javax.xml.xpath.XPathExpressionException
- if evaluation of the expression fails or if the
result cannot be converted to the requested type.public java.lang.String evaluate(java.lang.Object node) throws javax.xml.xpath.XPathExpressionException
evaluate
in interface javax.xml.xpath.XPathExpression
node
- the initial context node. This must be either an instance of NodeInfo or a node
recognized by a known external object model.
Contrary to the interface specification, Saxon does not supply an empty document when the value is null. This is because XPath 2.0 allows the context item to be "absent" (null). So Saxon executes the XPath expression with the context item undefined.
javax.xml.xpath.XPathExpressionException
- if evaluation failspublic java.lang.Object evaluate(org.xml.sax.InputSource inputSource, javax.xml.namespace.QName qName) throws javax.xml.xpath.XPathExpressionException
evaluate
in interface javax.xml.xpath.XPathExpression
inputSource
- The input source document against which the expression is evaluated.
If any error occurs reading or parsing this document, the error is notified
to the ErrorListener
registered with the Configuration
,
and also causes an exception to be thrown.
(Note that there is no caching. This will be parsed, and the parsed result will be discarded.)
If the supplied value is null then (contrary to the JAXP specifications), the XPath expression is evaluated with the context item undefined.
qName
- The type required, identified by a constant in XPathConstants
evaluate(Object, javax.xml.namespace.QName)
javax.xml.xpath.XPathExpressionException
public java.lang.String evaluate(org.xml.sax.InputSource inputSource) throws javax.xml.xpath.XPathExpressionException
evaluate
in interface javax.xml.xpath.XPathExpression
inputSource
- The input source document against which the expression is evaluated.
If any error occurs reading or parsing this document, the error is notified
to the ErrorListener
registered with the Configuration
,
and also causes an exception to be thrown.
(Note that there is no caching. This will be parsed, and the parsed result will be discarded.)
If the supplied value is null then (contrary to the JAXP specifications), the XPath expression is evaluated with the context item undefined.
javax.xml.xpath.XPathExpressionException
- in the event of an XPath dynamic errorjava.lang.NullPointerException
- If inputSource
is null
.public Expression getInternalExpression()
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