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java.lang.Object
net.sf.saxon.xpath.XPathEvaluator
public class XPathEvaluator
extends java.lang.Object
implements XPath
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.
Constructor Summary | |
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Method Summary | |
XPathExpression |
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XPathExpressionImpl |
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List |
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String |
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Object |
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String |
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Object |
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Object |
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Configuration |
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Executable |
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NamespaceContext |
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JAXPXPathStaticContext |
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XPathFunctionResolver |
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XPathVariableResolver |
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void |
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boolean |
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static void |
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void |
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void |
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void |
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void |
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NodeInfo |
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void |
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void |
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void |
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void |
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public XPathEvaluator()
Default constructor. Creates an XPathEvaluator with a default configuration and name pool. The default Configuration is not schema-aware.
public XPathEvaluator(Source source) throws XPathException
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).
public XPathEvaluator(Configuration config)
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 a SchemaAwareConfiguration.
public XPathExpression compile(String expr) throws XPathExpressionException
Compile an XPath 2.0 expression
- Parameters:
expr
- the XPath 2.0 expression to be compiled, as a string
- Returns:
- the compiled form of the expression
public XPathExpressionImpl createExpression(String expression) throws XPathException
Deprecated. since Saxon 8.9 - use
compile(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.
public List evaluate(String expression) throws XPathException
Deprecated. since Saxon 8.9 - use the various method defined in the JAXP interface definition
Prepare and execute an XPath expression, supplied as a string, and returning the results as a List.
- Parameters:
expression
- The XPath expression to be evaluated, supplied as a string.
- 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 object representing a node, or a Java object representing an atomic value. The types of Java object that may be included in the list, and the XML Schema data types that they correspond to, are as follows:
- Boolean (xs:boolean)
- String (xs:string)
- BigDecimal (xs:decimal)
- Long (xs:integer and its derived types)
- Double (xs:double)
- Float (xs:float)
- Date (xs:date, xs:dateTime)
public String evaluate(String expr, InputSource inputSource) throws XPathExpressionException
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
- 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
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
- 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)
public String evaluate(String expr, Object node) throws XPathExpressionException
Single-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.
- 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 thesetContextNode(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
public Object evaluate(String expr, Object node, QName qName) throws XPathExpressionException
Single-shot method to compile and execute an XPath 2.0 expression.
- 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 thesetContextNode(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)
public Object evaluateSingle(String expression) throws XPathException
Deprecated. since Saxon 8.9 - use the methods defined in the JAXP interface
Prepare and execute an XPath expression, supplied as a string, and 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:
expression
- The XPath expression to be evaluated, supplied as a string.
- 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
public Configuration getConfiguration()
Get the Configuration used by this XPathEvaluator
- Returns:
- the Configuration used by this XPathEvaluator
public NamespaceContext getNamespaceContext()
Get the namespace context, if one has been set usingsetNamespaceContext(NamespaceContext)
- Returns:
- the namespace context if set, or null otherwise
public JAXPXPathStaticContext getStaticContext()
Get the current static context
- Returns:
- the static context
public XPathFunctionResolver getXPathFunctionResolver()
Get the resolver for XPath functions
- Returns:
- the resolver, if one has been set
public XPathVariableResolver getXPathVariableResolver()
Get the resolver for XPath variables
- Returns:
- the resolver, if one has been set
public void importSchema(Source source) throws SchemaException
Import a schema. This is possible only if the schema-aware version of Saxon is being used, and if the Configuration is a SchemaAwareConfiguration. 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 invalid
public boolean isBackwardsCompatible()
Get the value of XPath 1.0 compatibility mode
- Returns:
- true if XPath 1.0 compatibility mode is set
public static void main(String[] args) throws Exception
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.
public void reset()
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.
public 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 argument
Set 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.
public void setNamespaceContext(NamespaceContext namespaceContext)
Set the namespace context to be used.
- Parameters:
namespaceContext
- The namespace context
public NodeInfo setSource(Source source) throws XPathException
Supply the document against which XPath expressions are to be executed. This method must be called before preparing or executing an XPath expression. Setting a new source document clears all the namespaces that have been declared.
- 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.
public void setStaticContext(JAXPXPathStaticContext context)
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
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 class
AugmentedSource
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.
public void setXPathFunctionResolver(XPathFunctionResolver xPathFunctionResolver)
Set the resolver for XPath functions
- Parameters:
xPathFunctionResolver
- a resolver for XPath function calls
public void setXPathVariableResolver(XPathVariableResolver xPathVariableResolver)
Set the resolver for XPath variables
- Parameters:
xPathVariableResolver
- a resolver for variables