net.sf.saxon.s9api

Class XPathCompiler


public class XPathCompiler
extends java.lang.Object

An XPathCompiler object allows XPath queries to be compiled. The compiler holds information that represents the static context for an XPath expression.

To construct an XPathCompiler, use the factory method Processor.newXPathCompiler().

An XPathCompiler may be used repeatedly to compile multiple queries. Any changes made to the XPathCompiler (that is, to the static context) do not affect queries that have already been compiled. An XPathCompiler may be used concurrently in multiple threads, but it should not then be modified once initialized.

Changes to an XPathCompiler are cumulative. There is no simple way to reset the XPathCompiler to its initial state; instead, simply create a new XPathCompiler.

Constructor Summary

XPathCompiler(Configuration config)
Protected constructor

Method Summary

XPathExecutable
compile(String source)
Compile an XPath expression, supplied as a character string.
void
declareNamespace(String prefix, String uri)
Declare a namespace binding as part of the static context for XPath expressions compiled using this XPathCompiler
void
declareVariable(QName qname)
Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler.
void
declareVariable(QName qname, ItemType itemType, OccurrenceIndicator occurrences)
Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler.
URI
getBaseURI()
Get the static base URI for XPath expressions compiled using this XPathCompiler.
boolean
isBackwardsCompatible()
Ask whether XPath 1.0 backwards compatibility mode is in force.
void
setBackwardsCompatible(boolean option)
Set whether XPath 1.0 backwards compatibility mode is to be used.
void
setBaseURI(URI uri)
Set the static base URI for XPath expressions compiled using this XPathCompiler.

Constructor Details

XPathCompiler

protected XPathCompiler(Configuration config)
Protected constructor
Parameters:
config - the Saxon configuration

Method Details

compile

public XPathExecutable compile(String source)
            throws SaxonApiException
Compile an XPath expression, supplied as a character string.
Parameters:
source - A string containing the source text of the XPath expression
Returns:
An XPathExecutable which represents the compiled xpath expression object. The XPathExecutable may be run as many times as required, in the same or a different thread. The XPathExecutable is not affected by any changes made to the XPathCompiler once it has been compiled.
Throws:
SaxonApiException - if any static error is detected while analyzing the expression

declareNamespace

public void declareNamespace(String prefix,
                             String uri)
Declare a namespace binding as part of the static context for XPath expressions compiled using this XPathCompiler
Parameters:
prefix - The namespace prefix. If the value is a zero-length string, this method sets the default namespace for elements and types.
uri - The namespace URI. It is possible to specify a zero-length string to "undeclare" a namespace; in this case the prefix will not be available for use, except in the case where the prefix is also a zero length string, in which case the absence of a prefix implies that the name is in no namespace.

declareVariable

public void declareVariable(QName qname)
Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler. It is an error for the XPath expression to refer to a variable unless it has been declared. This method declares the existence of the variable, but it does not bind any value to the variable; that is done later, when the XPath expression is evaluated. The variable is allowed to have any type (that is, the required type is item()*).
Parameters:
qname - The name of the variable, expressions as a QName

declareVariable

public void declareVariable(QName qname,
                            ItemType itemType,
                            OccurrenceIndicator occurrences)
            throws SaxonApiException
Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler. It is an error for the XPath expression to refer to a variable unless it has been declared. This method declares the existence of the variable, and defines the required type of the variable, but it does not bind any value to the variable; that is done later, when the XPath expression is evaluated.
Parameters:
qname - The name of the variable, expressed as a QName
itemType - The required item type of the value of the variable
occurrences - The allowed number of items in the sequence forming the value of the variable
Throws:
SaxonApiException - if the requiredType is syntactically invalid or if it refers to namespace prefixes or schema components that are not present in the static context

getBaseURI

public URI getBaseURI()
Get the static base URI for XPath expressions compiled using this XPathCompiler. The base URI is part of the static context, and is used to resolve any relative URIs appearing within an XPath expression, for example a relative URI passed as an argument to the doc() function. If no static base URI has been explicitly set, this method returns null.
Returns:
the base URI from the static context

isBackwardsCompatible

public boolean isBackwardsCompatible()
Ask whether XPath 1.0 backwards compatibility mode is in force.
Returns:
true if XPath 1.0 backwards compatibility is enabled, false if it is disabled.

setBackwardsCompatible

public void setBackwardsCompatible(boolean option)
Set whether XPath 1.0 backwards compatibility mode is to be used. In backwards compatibility mode, more implicit type conversions are allowed in XPath expressions, for example it is possible to compare a number with a string. The default is false (backwards compatibility mode is off).
Parameters:
option - true if XPath 1.0 backwards compatibility is to be enabled, false if it is to be disabled.

setBaseURI

public void setBaseURI(URI uri)
Set the static base URI for XPath expressions compiled using this XPathCompiler. The base URI is part of the static context, and is used to resolve any relative URIs appearing within an XPath expression, for example a relative URI passed as an argument to the doc() function. If no static base URI is supplied, then the current working directory is used.
Parameters:
uri - the base URI to be set in the static context. This must be an absolute URI.