Package net.sf.saxon.xpath
Class XPathEvaluator
java.lang.Object
net.sf.saxon.xpath.XPathEvaluator
- All Implemented Interfaces:
XPath
XPathEvaluator provides a simple 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.
- Author:
- Michael H. Kay
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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) Prepare an XPath expression for subsequent evaluation.Prepare and execute an XPath expression, supplied as a string, and returning the results as a List.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 documentevaluateSingle
(String expression) Prepare and execute an XPath expression, supplied as a string, and returning the first item in the result.Get 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) Set the context node.void
setNamespaceContext
(NamespaceContext namespaceContext) Set the namespace context to be used.Supply the document against which XPath expressions are to be executed.void
setStaticContext
(StandaloneContext context) Set the static context for compiling XPath expressions.void
setStripSpace
(boolean strip) Indicate whether all whitespace text nodes in the source document are to be removed.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 a default configuration and name pool. The default Configuration is not schema-aware. -
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 a SchemaAwareConfiguration.
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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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setStripSpace
public void setStripSpace(boolean strip) 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 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.
- Throws:
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 StandaloneContext 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. -
getStaticContext
Get the current static context -
createExpression
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.
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setContextNode
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. This must be a node within the context document (the document supplied using the setSource() method).- Throws:
NullPointerException
- if the argument is nullIllegalArgumentException
- if the supplied node is not a node in the context document
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evaluate
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)
- Throws:
XPathException
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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)- 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
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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
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getXPathFunctionResolver
Get the resolver for XPath functions- Specified by:
getXPathFunctionResolver
in interfaceXPath
- Returns:
- the resolver, if one has been set
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setNamespaceContext
Set the namespace context to be used. This supplements any namespaces declared directly using declareNamespace on the staticContext object- Specified by:
setNamespaceContext
in interfaceXPath
- Parameters:
namespaceContext
- The namespace context
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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
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importSchema
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 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 expressionqName
- 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.
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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 expression- 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 nodeqName
- 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.
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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.
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evaluateSingle
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
- Throws:
XPathException
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main
A simple command-line interface for the XPathEvaluator (not documented). First parameter is the filename containing the source document, second parameter is the XPath expression.- Throws:
Exception
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