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## net.sf.saxon.xpath
Class XPathEvaluator

    java.lang.Object
      net.sf.saxon.xpath.XPathEvaluator

All Implemented Interfaces:
  javax.xml.xpath.XPath

public class XPathEvaluator
extends java.lang.Object
implements javax.xml.xpath.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.

Constructor Summary
`XPathEvaluator()` Default constructor.
`XPathEvaluator(Configuration config)` Construct an XPathEvaluator with a specified configuration.
`XPathEvaluator(javax.xml.transform.Source source)` Construct an XPathEvaluator to process a particular source document.

Method Summary
`javax.xml.xpath.XPathExpression` | `compile(java.lang.String expr)` Compile an XPath 2.0 expression
`XPathExpressionImpl` | `createExpression(java.lang.String expression)` Prepare an XPath expression for subsequent evaluation.
`java.util.List` | `evaluate(java.lang.String expression)` Prepare and execute an XPath expression, supplied as a string, and returning the results as a List.
`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
`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 2.0 expression.
`java.lang.Object` | `evaluateSingle(java.lang.String expression)` Prepare and execute an XPath expression, supplied as a string, and returning the first item in the result.
`javax.xml.namespace.NamespaceContext` | `getNamespaceContext()` Get the namespace context, if one has been set using `setNamespaceContext(javax.xml.namespace.NamespaceContext)`
`StandaloneContext` | `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
`boolean` | `isBackwardsCompatible()` Get the value of XPath 1.0 compatibility mode
`static void` | `main(java.lang.String[] args)` 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(javax.xml.namespace.NamespaceContext namespaceContext)` Set the namespace context to be used.
`NodeInfo` | `setSource(javax.xml.transform.Source source)` 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(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`

Constructor Detail

### XPathEvaluator

    public XPathEvaluator()

  Default constructor. Creates an XPathEvaluator with a default configuration and name pool.

### XPathEvaluator

    public XPathEvaluator(Configuration config)

  Construct an XPathEvaluator with a specified configuration.

Parameters:
  `config` - the configuration to be used

### XPathEvaluator

    public XPathEvaluator(javax.xml.transform.Source source)
                   throws XPathException

  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).

Method Detail

### 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.

### setSource

    public NodeInfo setSource(javax.xml.transform.Source source)
                       throws XPathException

  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 Saxon `DocumentInfo` (indeed any `NodeInfo`) can be used as a Source. To use a third-party DOM Document as a source, create an instance of `DOMSource` 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`

### setStaticContext

    public void setStaticContext(StandaloneContext context)

  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

    public StandaloneContext getStaticContext()

  Get the current static context

### createExpression

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

  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.

### setContextNode

    public void setContextNode(NodeInfo node)

  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:
    `java.lang.NullPointerException` - if the argument is null
    `java.lang.IllegalArgumentException` - if the supplied node is not a node in the context document

### evaluate

    public java.util.List evaluate(java.lang.String expression)
                            throws XPathException

  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`

### reset

    public void reset()

  Specified by:
    `reset` in interface `javax.xml.xpath.XPath`

### 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.

### isBackwardsCompatible

    public boolean isBackwardsCompatible()

  Get the value of XPath 1.0 compatibility mode

  Returns:
    true if XPath 1.0 compatibility mode is set

### 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` -

### 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` -

### 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. This supplements any namespaces declared directly using declareNamespace on the staticContext object

  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

### compile

    public javax.xml.xpath.XPathExpression compile(java.lang.String expr)
                                            throws javax.xml.xpath.XPathExpressionException

  Compile an XPath 2.0 expression

  Specified by:
    `compile` in interface `javax.xml.xpath.XPath`
  Parameters:
    `expr` - the XPath 2.0 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 2.0 expression.

  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
    `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
  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.

### 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.

### evaluateSingle

    public java.lang.Object evaluateSingle(java.lang.String expression)
                                    throws XPathException

  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`

### main

    public static void main(java.lang.String[] args)
                     throws java.lang.Exception

  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:
    `java.lang.Exception`

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