net.sf.saxon.sxpath

Class XPathEvaluator

java.lang.Object

net.sf.saxon.sxpath.XPathEvaluator

Direct Known Subclasses:

XSDAssert.CustomizedXPath

public class XPathEvaluator
extends java.lang.Object

This class provides a native Saxon API for free-standing evaluation of XPath expressions. Unlike the JAXP API offered by XPathEvaluator it exposes Saxon classes and interfaces and thus provides a more strongly-typed interface with greater control over the detailed behaviour.

However, the preferred API for user applications calling XPath is the s9api XPathCompiler interface.

Since:

8.4

Author:

Michael H. Kay

Constructor Summary

Constructors

Constructor and Description
XPathEvaluator() Default constructor.
XPathEvaluator(Configuration config) Construct an XPathEvaluator with a specified configuration.

Method Summary

Modifier and Type	Method and Description
XPathExpression	createExpression(java.lang.String expression) Prepare (compile) an XPath expression for subsequent evaluation.
XPathExpression	createPattern(java.lang.String pattern) Prepare (compile) an XSLT pattern for subsequent evaluation.
Configuration	getConfiguration() Get the Configuration in use.
XPathStaticContext	getStaticContext() Get the current static context.
protected Expression	postProcess(Expression exp, ExpressionVisitor visitor, ContextItemStaticInfo cit) Customize the expression post-optimization.
void	setStaticContext(XPathStaticContext context) Set the static context for compiling XPath expressions.

Methods inherited from class java.lang.Object

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

Constructor Detail

XPathEvaluator

public XPathEvaluator()

Default constructor. Creates an XPathEvaluator with a default configuration and name pool. Note that any source documents used by an XPath expression under this XPathEvaluator must be built using the Configuration that is implicitly created by this constructor, which is accessible using the getConfiguration() method.

XPathEvaluator

public XPathEvaluator(Configuration config)

Construct an XPathEvaluator with a specified configuration.

Parameters:

config - the configuration to be used. If the XPathEvaluator is to be used to run schema-aware XPath expressions this must be an instance of EnterpriseConfiguration

Method Detail

getConfiguration

public Configuration getConfiguration()

Get the Configuration in use.

Returns:

the Saxon configuration

setStaticContext

public void setStaticContext(XPathStaticContext context)

Set the static context for compiling XPath expressions. This provides more detailed 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 IndependentContext 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 XPath static context

Setting a new static context clears any variables and namespaces that have previously been declared.

getStaticContext

public XPathStaticContext getStaticContext()

Get the current static context. This will always return a value; if no static context has been supplied by the user, the system will have created its own. A system-created static context will always be an instance of IndependentContext

Returns:

the static context object

createExpression

public XPathExpression createExpression(java.lang.String expression)
                                 throws XPathException

Prepare (compile) an XPath expression for subsequent evaluation.

Parameters:

expression - The XPath expression to be compiled, 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.

postProcess

protected Expression postProcess(Expression exp,
                                 ExpressionVisitor visitor,
                                 ContextItemStaticInfo cit)
                          throws XPathException

Customize the expression post-optimization. This method does nothing, but can be overridden in a subclass

Parameters:

exp - the expression after optimization

visitor - an expression visitor that includes static context information

cit - information about the context item type

Throws:

XPathException

createPattern

public XPathExpression createPattern(java.lang.String pattern)
                              throws XPathException

Prepare (compile) an XSLT pattern for subsequent evaluation. The result is an XPathExpression object representing a (pseudo-) expression that when evaluated returns a boolean result: true if the context node matches the pattern, false if it does not.

Parameters:

pattern - the XSLT pattern to be compiled, supplied as a string

Returns:

an XPathExpression object representing the pattern, wrapped as an expression

Throws:

XPathException - if the syntax of the expression is wrong, or if it references namespaces, variables, or functions that have not been declared.

Since:

9.1