Class XPathEvaluator
- All Implemented Interfaces:
XPath
XPathEvaluator implements the JAXP API for standalone XPath processing (that is, executing XPath expressions in the absence of an XSLT stylesheet). It is an implementation of the JAXP 1.3 XPath interface, with additional methods provided (a) for backwards compatibility (b) to give extra control over the XPath evaluation, and (c) to support XPath 2.0.
It is intended to evolve this so that it only supports the JAXP style of operation. Some of the methods are therefore marked as deprecated in this release, and will be dropped in a future release.
For an alternative XPath API, offering more direct access to Saxon capabilities,
see XPathEvaluator
.
Note that the XPathEvaluator
links to a Saxon Configuration
object. By default a new Configuration
is created automatically. In many
applications, however, it is desirable to share a configuration. The default configuration
is not schema aware. All source documents used by XPath expressions under this evaluator
must themselves be built using the Configuration
used by this evaluator.
- Author:
- Michael H. Kay
-
Constructor Summary
ConstructorsConstructorDescriptionDefault constructor.XPathEvaluator
(Source source) Construct an XPathEvaluator to process a particular source document.XPathEvaluator
(Configuration config) Construct an XPathEvaluator with a specified configuration. -
Method Summary
Modifier and TypeMethodDescriptionCompile an XPath 2.0 expressioncreateExpression
(String expression) Deprecated.Single-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.Single-shot method to compile and execute an XPath 2.0 expression.evaluate
(String expr, InputSource inputSource) Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document, returning the result as a stringevaluate
(String expr, InputSource inputSource, QName qName) Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that documentGet the Configuration used by this XPathEvaluatorGet the namespace context, if one has been set usingsetNamespaceContext(javax.xml.namespace.NamespaceContext)
Get the current static contextGet the resolver for XPath functionsGet the resolver for XPath variablesvoid
importSchema
(Source source) Import a schema.boolean
Get the value of XPath 1.0 compatibility modestatic void
A simple command-line interface for the XPathEvaluator (not documented).void
reset()
void
setBackwardsCompatible
(boolean compatible) Set XPath 1.0 compatibility mode on or off (by default, it is false).void
setContextNode
(NodeInfo node) Deprecated.since Saxon 8.9 - use the various method defined in the JAXP interface definition, which allow a NodeInfo object to be supplied as the value of the Source argumentvoid
setNamespaceContext
(NamespaceContext namespaceContext) Set the namespace context to be used.Supply a document against which XPath expressions are to be executed, converting it to a Saxon NodeInfo object.void
setStaticContext
(JAXPXPathStaticContext context) Set the static context for compiling XPath expressions.void
setStripSpace
(boolean strip) Deprecated.since 8.9.void
setXPathFunctionResolver
(XPathFunctionResolver xPathFunctionResolver) Set the resolver for XPath functionsvoid
setXPathVariableResolver
(XPathVariableResolver xPathVariableResolver) Set the resolver for XPath variablesMethods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface javax.xml.xpath.XPath
evaluateExpression, evaluateExpression, evaluateExpression, evaluateExpression
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Constructor Details
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XPathEvaluator
public XPathEvaluator()Default constructor. Creates an XPathEvaluator with Configuration appropriate to the version of the Saxon software being run. -
XPathEvaluator
Construct an XPathEvaluator with a specified configuration.- Parameters:
config
- the configuration to be used. If schema-aware XPath expressions are to be used, this must be an EnterpriseConfiguration.
-
XPathEvaluator
Construct an XPathEvaluator to process a particular source document. This is equivalent to using the default constructor and immediately calling setSource().- Parameters:
source
- The source document (or a specific node within it).- Throws:
XPathException
-
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Method Details
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getConfiguration
Get the Configuration used by this XPathEvaluator- Returns:
- the Configuration used by this XPathEvaluator
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setStripSpace
public void setStripSpace(boolean strip) Deprecated.since 8.9. The preferred way to define options for the way in which source documents are built is to use the classAugmentedSource
for any of the methods expecting aSource
object.Indicate whether all whitespace text nodes in the source document are to be removed. This option has no effect unless it is called before the call on setSource(), and unless the Source supplied to setSource() is a SAXSource or StreamSource.- Parameters:
strip
- True if all whitespace text nodes are to be stripped from the source document, false otherwise. The default if the method is not called is false.
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setSource
Supply a document against which XPath expressions are to be executed, converting it to a Saxon NodeInfo object.If the supplied source is a
NodeInfo
, it is returned unchanged.If the supplied source is a
DOMSource
, the result is a SaxonNodeInfo
wrapper around the DOM Node contained by the DOMSource.In all other cases, the result is a document node, and is the same as the result of calling
Configuration.buildDocument(javax.xml.transform.Source)
with the same argument; except that when whitespace stripping has been requested usingsetStripSpace(boolean)
, this request is passed on.Despite the name of this method, it does not change the state of the
XPathEvaluator
in any way.- Parameters:
source
- Any javax.xml.transform.Source object representing the document against which XPath expressions will be executed. Note that a SaxonDocumentInfo
(indeed anyNodeInfo
) can be used as a Source. To use a third-party DOM Document as a source, create an instance ofDOMSource
to wrap it.The Source object supplied also determines the initial setting of the context item. In most cases the context node will be the root of the supplied document; however, if a NodeInfo or DOMSource is supplied it can be any node in the document.
- Returns:
- the NodeInfo of the start node in the resulting document object.
- Throws:
XPathException
- if the supplied Source is a NodeInfo object that was built using an incompatible Configuration (that is, a Configuration using a different NamePool). Also, if any error occurs parsing the document supplied as the Source.XPathException
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setStaticContext
Set the static context for compiling XPath expressions. This provides control over the environment in which the expression is compiled, for example it allows namespace prefixes to be declared, variables to be bound and functions to be defined. For most purposes, the static context can be defined by providing and tailoring an instance of the JAXPXPathStaticContext class. Until this method is called, a default static context is used, in which no namespaces are defined other than the standard ones (xml, xslt, and saxon), and no variables or functions (other than the core XPath functions) are available.- Parameters:
context
- the static context- Throws:
IllegalArgumentException
- if the supplied static context uses a different and incompatible Configuration from the one used in this XPathEvaluator
-
getStaticContext
Get the current static context- Returns:
- the static context
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createExpression
Deprecated.since Saxon 8.9 - usecompile(String)
Prepare an XPath expression for subsequent evaluation.- Parameters:
expression
- The XPath expression to be evaluated, supplied as a string.- Returns:
- an XPathExpression object representing the prepared expression
- Throws:
XPathException
- if the syntax of the expression is wrong, or if it references namespaces, variables, or functions that have not been declared.
-
setContextNode
Deprecated.since Saxon 8.9 - use the various method defined in the JAXP interface definition, which allow a NodeInfo object to be supplied as the value of the Source argumentSet the context node. This provides the context node for any expressions executed after this method is called, including expressions that were prepared before it was called.- Parameters:
node
- The node to be used as the context node. The node must be within a tree built using the same SaxonConfiguration
as used by this XPathEvaluator.- Throws:
IllegalArgumentException
- if the supplied node was built using the wrong Configuration
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reset
public void reset() -
setBackwardsCompatible
public void setBackwardsCompatible(boolean compatible) Set XPath 1.0 compatibility mode on or off (by default, it is false). This applies to any XPath expression compiled while this option is in force.- Parameters:
compatible
- true if XPath 1.0 compatibility mode is to be set to true, false if it is to be set to false.
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isBackwardsCompatible
public boolean isBackwardsCompatible()Get the value of XPath 1.0 compatibility mode- Returns:
- true if XPath 1.0 compatibility mode is set
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setXPathVariableResolver
Set the resolver for XPath variables- Specified by:
setXPathVariableResolver
in interfaceXPath
- Parameters:
xPathVariableResolver
- a resolver for variables
-
getXPathVariableResolver
Get the resolver for XPath variables- Specified by:
getXPathVariableResolver
in interfaceXPath
- Returns:
- the resolver, if one has been set
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setXPathFunctionResolver
Set the resolver for XPath functions- Specified by:
setXPathFunctionResolver
in interfaceXPath
- Parameters:
xPathFunctionResolver
- a resolver for XPath function calls
-
getXPathFunctionResolver
Get the resolver for XPath functions- Specified by:
getXPathFunctionResolver
in interfaceXPath
- Returns:
- the resolver, if one has been set
-
setNamespaceContext
Set the namespace context to be used.- Specified by:
setNamespaceContext
in interfaceXPath
- Parameters:
namespaceContext
- The namespace context
-
getNamespaceContext
Get the namespace context, if one has been set usingsetNamespaceContext(javax.xml.namespace.NamespaceContext)
- Specified by:
getNamespaceContext
in interfaceXPath
- Returns:
- the namespace context if set, or null otherwise
-
importSchema
Import a schema. This is possible only if Saxon-EE is being used, and if the Configuration is an EnterpriseConfiguration. Having imported a schema, the types defined in that schema become part of the static context.- Parameters:
source
- A Source object identifying the schema document to be loaded- Throws:
SchemaException
- if the schema contained in this document is invalidUnsupportedOperationException
- if the configuration is not schema-aware
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compile
Compile an XPath 2.0 expression- Specified by:
compile
in interfaceXPath
- Parameters:
expr
- the XPath 2.0 expression to be compiled, as a string- Returns:
- the compiled form of the expression
- Throws:
XPathExpressionException
- if there are any static errors in the expression. Note that references to undeclared variables are not treated as static errors, because variables are not pre-declared using this API.
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evaluate
Single-shot method to compile and execute an XPath 2.0 expression.- Specified by:
evaluate
in interfaceXPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executednode
- The context node for evaluation of the expression.This may be a NodeInfo object, representing a node in Saxon's native implementation of the data model, or it may be a node in any supported external object model: DOM, JDOM, DOM4J, or XOM, or any other model for which support has been configured in the Configuration. Note that the supporting libraries for the chosen model must be on the class path.
Contrary to the interface specification, Saxon does not supply an empty document when the value is null. This is because Saxon supports multiple object models, and it's unclear what kind of document node would be appropriate. Instead, Saxon uses the node supplied to the
setContextNode(net.sf.saxon.om.NodeInfo)
method if available, and if none is available, executes the XPath expression with the context item undefined.qName
- The type of result required. For details, seeXPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Returns:
- the result of evaluating the expression, returned as described in
XPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Throws:
XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.
-
evaluate
Single-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.- Specified by:
evaluate
in interfaceXPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executednode
- The context node for evaluation of the expressionThis may be a NodeInfo object, representing a node in Saxon's native implementation of the data model, or it may be a node in any supported external object model: DOM, JDOM, DOM4J, or XOM, or any other model for which support has been configured in the Configuration. Note that the supporting libraries for the chosen model must be on the class path.
Contrary to the interface specification, Saxon does not supply an empty document when the value is null. This is because Saxon supports multiple object models, and it's unclear what kind of document node would be appropriate. Instead, Saxon uses the node supplied to the
setContextNode(net.sf.saxon.om.NodeInfo)
method if available, and if none is available, executes the XPath expression with the context item undefined.- Returns:
- the result of evaluating the expression, converted to a string as if by calling the XPath string() function
- Throws:
XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.
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evaluate
public Object evaluate(String expr, InputSource inputSource, QName qName) throws XPathExpressionException Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document- Specified by:
evaluate
in interfaceXPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executedinputSource
- The source document: this will be parsed and built into a tree, and the XPath expression will be executed with the root node of the tree as the context node.qName
- The type of result required. For details, seeXPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Returns:
- the result of evaluating the expression, returned as described in
XPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Throws:
XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.NullPointerException
- if any of the three arguments is null
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evaluate
Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document, returning the result as a string- Specified by:
evaluate
in interfaceXPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executedinputSource
- The source document: this will be parsed and built into a tree, and the XPath expression will be executed with the root node of the tree as the context node- Returns:
- the result of evaluating the expression, converted to a string as if by calling the XPath string() function
- Throws:
XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.NullPointerException
- if either of the two arguments is null
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main
A simple command-line interface for the XPathEvaluator (not documented).- Parameters:
args
- command line arguments. First parameter is the filename containing the source document, second parameter is the XPath expression.- Throws:
Exception
- if any error occurs
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compile(String)