Package net.sf.saxon.xpath

Class XPathEvaluator

  • All Implemented Interfaces:
    javax.xml.xpath.XPath
    public class XPathEvaluator
extends java.lang.Object
implements javax.xml.xpath.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.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      javax.xml.xpath.XPathExpression compile​(java.lang.String expr)
      Compile an XPath 3.1 expression
      java.lang.String evaluate​(java.lang.String expr, java.lang.Object node)
      Single-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.
      java.lang.Object evaluate​(java.lang.String expr, java.lang.Object node, javax.xml.namespace.QName qName)
      Single-shot method to compile and execute an XPath 3.1 expression.
      java.lang.String evaluate​(java.lang.String expr, org.xml.sax.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 string
      java.lang.Object evaluate​(java.lang.String expr, org.xml.sax.InputSource inputSource, javax.xml.namespace.QName qName)
      Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document
      Configuration getConfiguration()
      Get the Configuration used by this XPathEvaluator
      javax.xml.namespace.NamespaceContext getNamespaceContext()
      Get the namespace context, if one has been set using setNamespaceContext(javax.xml.namespace.NamespaceContext)
      JAXPXPathStaticContext getStaticContext()
      Get the current static context.
      javax.xml.xpath.XPathFunctionResolver getXPathFunctionResolver()
      Get the resolver for XPath functions
      javax.xml.xpath.XPathVariableResolver getXPathVariableResolver()
      Get the resolver for XPath variables
      void importSchema​(javax.xml.transform.Source source)
      Import a schema.
      void reset()  
      void setNamespaceContext​(javax.xml.namespace.NamespaceContext namespaceContext)
      Set the namespace context to be used.
      void setXPathFunctionResolver​(javax.xml.xpath.XPathFunctionResolver xPathFunctionResolver)
      Set the resolver for XPath functions
      void setXPathVariableResolver​(javax.xml.xpath.XPathVariableResolver xPathVariableResolver)
      Set the resolver for XPath variables

      • Methods 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

    • Constructor Detail

      • 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 Detail

      • 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 javax.xml.xpath.XPath

      • setXPathVariableResolver

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

      • getXPathVariableResolver

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

      • setXPathFunctionResolver

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

      • getXPathFunctionResolver

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

      • setNamespaceContext

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

      • getNamespaceContext

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

      • importSchema

        public void importSchema​(javax.xml.transform.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
        java.lang.UnsupportedOperationException - if the configuration is not schema-aware

      • compile

        public javax.xml.xpath.XPathExpression compile​(java.lang.String expr)
                                        throws javax.xml.xpath.XPathExpressionException
        Compile an XPath 3.1 expression
        Specified by:
        compile in interface javax.xml.xpath.XPath
        Parameters:
        expr - the XPath 3.1 expression to be compiled, as a string
        Returns:
        the compiled form of the expression
        Throws:
        javax.xml.xpath.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 java.lang.Object evaluate​(java.lang.String expr,
                                 java.lang.Object node,
                                 javax.xml.namespace.QName qName)
                          throws javax.xml.xpath.XPathExpressionException
        Single-shot method to compile and execute an XPath 3.1 expression.
        Specified by:
        evaluate in interface javax.xml.xpath.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:
        javax.xml.xpath.XPathExpressionException - if any static or dynamic error occurs in evaluating the expression.

      • evaluate

        public java.lang.String evaluate​(java.lang.String expr,
                                 java.lang.Object node)
                          throws javax.xml.xpath.XPathExpressionException
        Single-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.
        Specified by:
        evaluate in interface javax.xml.xpath.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:
        javax.xml.xpath.XPathExpressionException - if any static or dynamic error occurs in evaluating the expression.

      • evaluate

        public java.lang.Object evaluate​(java.lang.String expr,
                                 org.xml.sax.InputSource inputSource,
                                 javax.xml.namespace.QName qName)
                          throws javax.xml.xpath.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 javax.xml.xpath.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:
        javax.xml.xpath.XPathExpressionException - if any static or dynamic error occurs in evaluating the expression.
        java.lang.NullPointerException - if any of the three arguments is null

      • evaluate

        public java.lang.String evaluate​(java.lang.String expr,
                                 org.xml.sax.InputSource inputSource)
                          throws javax.xml.xpath.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 javax.xml.xpath.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:
        javax.xml.xpath.XPathExpressionException - if any static or dynamic error occurs in evaluating the expression.
        java.lang.NullPointerException - if either of the two arguments is null