Package net.sf.saxon.xpath

Class XPathEvaluator

java.lang.Object
net.sf.saxon.xpath.XPathEvaluator
All Implemented Interfaces:
XPath
public class XPathEvaluator extends Object implements 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 later XPath versions (2.0, 3.0, 3.1).

The JAXP API is designed at one level to be object-model independent, but in other respects (especially in Java SE 9) it is designed specifically with DOM in mind. The Saxon implementation makes its own decisions about how to handle non-DOM nodes. Specifically, when an expression with return type XPathConstants.NODE is evaluated, Saxon returns the underlying node from the native object model; when the return type is given as XPathConstants.NODESET, the nodes are delivered as a DOM NodeList if they are DOM nodes, or as a List otherwise.

For an alternative XPath API, offering more complete access to Saxon capabilities, see XPathCompiler.

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 Details

    • XPathEvaluator

      public XPathEvaluator()
      Default constructor. Creates an XPathEvaluator with Configuration appropriate to the version of the Saxon software being run.

    • XPathEvaluator

      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 an EnterpriseConfiguration.

  • Method Details

    • getConfiguration

      public Configuration getConfiguration()
      Get the Configuration used by this XPathEvaluator
      Returns:
      the Configuration used by this XPathEvaluator

    • getStaticContext

      public JAXPXPathStaticContext getStaticContext()
      Get the current static context. The caller can set properties of the returned static context to influence the way in which XPath expressions are compiled and evaluated; for example it is possible to set whether XPath 1.0 backwards compatibility is enabled or not.
      Returns:
      the static context

    • reset

      public void reset()
      Specified by:
      reset in interface XPath

    • setXPathVariableResolver

      public void setXPathVariableResolver(XPathVariableResolver xPathVariableResolver)
      Set the resolver for XPath variables
      Specified by:
      setXPathVariableResolver in interface XPath
      Parameters:
      xPathVariableResolver - a resolver for variables

    • getXPathVariableResolver

      public XPathVariableResolver getXPathVariableResolver()
      Get the resolver for XPath variables
      Specified by:
      getXPathVariableResolver in interface XPath
      Returns:
      the resolver, if one has been set

    • setXPathFunctionResolver

      public void setXPathFunctionResolver(XPathFunctionResolver xPathFunctionResolver)
      Set the resolver for XPath functions
      Specified by:
      setXPathFunctionResolver in interface XPath
      Parameters:
      xPathFunctionResolver - a resolver for XPath function calls

    • getXPathFunctionResolver

      public XPathFunctionResolver getXPathFunctionResolver()
      Get the resolver for XPath functions
      Specified by:
      getXPathFunctionResolver in interface XPath
      Returns:
      the resolver, if one has been set

    • setNamespaceContext

      public void setNamespaceContext(NamespaceContext namespaceContext)
      Set the namespace context to be used.
      Specified by:
      setNamespaceContext in interface XPath
      Parameters:
      namespaceContext - The namespace context

    • getNamespaceContext

      public NamespaceContext getNamespaceContext()
      Get the namespace context, if one has been set using setNamespaceContext(javax.xml.namespace.NamespaceContext)
      Specified by:
      getNamespaceContext in interface XPath
      Returns:
      the namespace context if set, or null otherwise

    • importSchema

      public void importSchema(Source source) throws SchemaException
      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 invalid
      UnsupportedOperationException - if the configuration is not schema-aware

    • compile

      public XPathExpression compile(String expr) throws XPathExpressionException
      Compile an XPath 3.1 expression
      Specified by:
      compile in interface XPath
      Parameters:
      expr - the XPath 3.1 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.

    • evaluate

      public Object evaluate(String expr, Object node, QName qName) throws XPathExpressionException
      Single-shot method to compile and execute an XPath 3.1 expression.
      Specified by:
      evaluate in interface XPath
      Parameters:
      expr - The XPath 3.1 expression to be compiled and executed
      node - 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 XPath 2.0 allows the context item to be "absent" (null). So Saxon executes the XPath expression with the context item undefined.

      qName - The type of result required. For details, see XPathExpressionImpl.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

      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.
      Specified by:
      evaluate in interface XPath
      Parameters:
      expr - The XPath 2.0 expression to be compiled and executed
      node - 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 XPath 2.0 allows the context item to be "absent" (null). So Saxon 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.

    • 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 interface XPath
      Parameters:
      expr - The XPath 2.0 expression to be compiled and executed
      inputSource - 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, see XPathExpressionImpl.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

    • evaluate

      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
      Specified by:
      evaluate in interface XPath
      Parameters:
      expr - The XPath 2.0 expression to be compiled and executed
      inputSource - 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