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## org.apache.xpath
Class XPath

    java.lang.Object
      |
      +--org.apache.xpath.XPath

public class XPath
extends java.lang.Object
implements java.io.Serializable, ExpressionOwner

**For advanced use only** The XPath class wraps an expression object and provides general services for execution of that expression.

See Also:
  Serialized Form

Field Summary
`static int` | `MATCH` Represents a match type expression.
`static double` | `MATCH_SCORE_NODETEST` **For advanced use only** The match score if the pattern consists of just a NodeTest.
`static double` | `MATCH_SCORE_NONE` **For advanced use only** The match score if no match is made.
`static double` | `MATCH_SCORE_NSWILD` **For advanced use only** The match score if the pattern pattern has the form NCName:*.
`static double` | `MATCH_SCORE_OTHER` **For advanced use only** The match score if the pattern consists of something other than just a NodeTest or just a qname.
`static double` | `MATCH_SCORE_QNAME` **For advanced use only** The match score if the pattern has the form of a QName optionally preceded by an @ character.
`static int` | `SELECT` Represents a select type expression.

Constructor Summary
`XPath(Expression expr)` Construct an XPath object.
`XPath(java.lang.String exprString, SourceLocator locator, PrefixResolver prefixResolver, int type)` Construct an XPath object.
`XPath(java.lang.String exprString, SourceLocator locator, PrefixResolver prefixResolver, int type, ErrorListener errorListener)` Construct an XPath object.

Method Summary
`void` | `assertion(boolean b, java.lang.String msg)` Tell the user of an assertion error, and probably throw an exception.
`boolean` | `bool(XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)` **Experimental** Given an expression and a context, evaluate the XPath and return the result.
`void` | `callVisitors(ExpressionOwner owner, XPathVisitor visitor)` This will traverse the heararchy, calling the visitor for each member.
`void` | `error(XPathContext xctxt, int sourceNode, int msg, java.lang.Object[] args)` Tell the user of an error, and probably throw an exception.
`XObject` | `execute(XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)` **Experimental** Given an expression and a context, evaluate the XPath and return the result.
`XObject` | `execute(XPathContext xctxt, Node contextNode, PrefixResolver namespaceContext)` **Experimental** Given an expression and a context, evaluate the XPath and return the result.
`void` | `fixupVariables(java.util.Vector vars, int globalsSize)` This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
`Expression` | `getExpression()` Get the raw Expression object that this class wraps.
`SourceLocator` | `getLocator()` Get the SourceLocator on the expression object.
`double` | `getMatchScore(XPathContext xctxt, int context)` Get the match score of the given node.
`java.lang.String` | `getPatternString()` Return the XPath string associated with this object.
`void` | `installFunction(java.lang.String name, int funcIndex, Function func)` Install a built-in function.
`void` | `setExpression(Expression exp)` Set the raw expression object for this object.
`void` | `warn(XPathContext xctxt, int sourceNode, int msg, java.lang.Object[] args)` Warn the user of an problem.

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### SELECT

    public static final int SELECT

  Represents a select type expression.

### MATCH

    public static final int MATCH

  Represents a match type expression.

### MATCH_SCORE_NONE

    public static final double MATCH_SCORE_NONE

  **For advanced use only** The match score if no match is made.

### MATCH_SCORE_QNAME

    public static final double MATCH_SCORE_QNAME

  **For advanced use only** The match score if the pattern has the form of a QName optionally preceded by an @ character.

### MATCH_SCORE_NSWILD

    public static final double MATCH_SCORE_NSWILD

  **For advanced use only** The match score if the pattern pattern has the form NCName:*.

### MATCH_SCORE_NODETEST

    public static final double MATCH_SCORE_NODETEST

  **For advanced use only** The match score if the pattern consists of just a NodeTest.

### MATCH_SCORE_OTHER

    public static final double MATCH_SCORE_OTHER

  **For advanced use only** The match score if the pattern consists of something other than just a NodeTest or just a qname.

Constructor Detail

### XPath

    public XPath(java.lang.String exprString,
                 SourceLocator locator,
                 PrefixResolver prefixResolver,
                 int type,
                 ErrorListener errorListener)
          throws TransformerException

  Construct an XPath object. (Needs review -sc) This method initializes an XPathParser/ Compiler and compiles the expression.
  Parameters:
    `exprString` - The XPath expression.
    `locator` - The location of the expression, may be null.
    `prefixResolver` - A prefix resolver to use to resolve prefixes to namespace URIs.
    `type` - one of `SELECT` or `MATCH`.
    `errorListener` - The error listener, or null if default should be used.
  Throws:
    TransformerException - if syntax or other error.

### XPath

    public XPath(java.lang.String exprString,
                 SourceLocator locator,
                 PrefixResolver prefixResolver,
                 int type)
          throws TransformerException

  Construct an XPath object. (Needs review -sc) This method initializes an XPathParser/ Compiler and compiles the expression.
  Parameters:
    `exprString` - The XPath expression.
    `locator` - The location of the expression, may be null.
    `prefixResolver` - A prefix resolver to use to resolve prefixes to namespace URIs.
    `type` - one of `SELECT` or `MATCH`.
  Throws:
    TransformerException - if syntax or other error.

### XPath

    public XPath(Expression expr)

  Construct an XPath object.
  Parameters:
    `expr` - The Expression object.
  Throws:
    TransformerException - if syntax or other error.

Method Detail

### getExpression

    public Expression getExpression()

  Get the raw Expression object that this class wraps.
  Specified by:
    getExpression in interface ExpressionOwner
  Returns:
    the raw Expression object, which should not normally be null.

### fixupVariables

    public void fixupVariables(java.util.Vector vars,
                               int globalsSize)

  This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
  Parameters:
    `vars` - List of QNames that correspond to variables. This list should be searched backwards for the first qualified name that corresponds to the variable reference qname. The position of the QName in the vector from the start of the vector will be its position in the stack frame (but variables above the globalsTop value will need to be offset to the current stack frame).

### setExpression

    public void setExpression(Expression exp)

  Set the raw expression object for this object.
  Specified by:
    setExpression in interface ExpressionOwner
  Parameters:
    `exp` - the raw Expression object, which should not normally be null.

### getLocator

    public SourceLocator getLocator()

  Get the SourceLocator on the expression object.
  Returns:
    the SourceLocator on the expression object, which may be null.

### getPatternString

    public java.lang.String getPatternString()

  Return the XPath string associated with this object.
  Returns:
    the XPath string associated with this object.

### execute

    public XObject execute(XPathContext xctxt,
                           Node contextNode,
                           PrefixResolver namespaceContext)
                    throws TransformerException

  **Experimental** Given an expression and a context, evaluate the XPath and return the result.
  Parameters:
    `xctxt` - The execution context.
    `contextNode` - The node that "." expresses.
    `namespaceContext` - The context in which namespaces in the XPath are supposed to be expanded.
  Returns:
    The result of the XPath or null if callbacks are used.
  Throws:
    TransformerException - thrown if the error condition is severe enough to halt processing.
    TransformerException -

### execute

    public XObject execute(XPathContext xctxt,
                           int contextNode,
                           PrefixResolver namespaceContext)
                    throws TransformerException

  **Experimental** Given an expression and a context, evaluate the XPath and return the result.
  Parameters:
    `xctxt` - The execution context.
    `contextNode` - The node that "." expresses.
    `namespaceContext` - The context in which namespaces in the XPath are supposed to be expanded.
  Throws:
    TransformerException - thrown if the active ProblemListener decides the error condition is severe enough to halt processing.
    TransformerException -

### bool

    public boolean bool(XPathContext xctxt,
                        int contextNode,
                        PrefixResolver namespaceContext)
                 throws TransformerException

  **Experimental** Given an expression and a context, evaluate the XPath and return the result.
  Parameters:
    `xctxt` - The execution context.
    `contextNode` - The node that "." expresses.
    `namespaceContext` - The context in which namespaces in the XPath are supposed to be expanded.
  Throws:
    TransformerException - thrown if the active ProblemListener decides the error condition is severe enough to halt processing.
    TransformerException -

### getMatchScore

    public double getMatchScore(XPathContext xctxt,
                                int context)
                         throws TransformerException

  Get the match score of the given node.
  Parameters:
    `xctxt` - XPath runtime context.
    `context` - The current source tree context node.
  Returns:
    score, one of `MATCH_SCORE_NODETEST`, `MATCH_SCORE_NONE`, `MATCH_SCORE_OTHER`, or `MATCH_SCORE_QNAME`.
  Throws:
    TransformerException -

### installFunction

    public void installFunction(java.lang.String name,
                                int funcIndex,
                                Function func)

  Install a built-in function.
  Parameters:
    `name` - The unqualified name of the function; not currently used.
    `funcIndex` - The index of the function in the table.
    `func` - An Implementation of an XPath Function object.
  Returns:
    the position of the function in the internal index.

### warn

    public void warn(XPathContext xctxt,
                     int sourceNode,
                     int msg,
                     java.lang.Object[] args)
              throws TransformerException

  Warn the user of an problem.
  Parameters:
    `xctxt` - The XPath runtime context.
    `sourceNode` - Not used.
    `msg` - An error number that corresponds to one of the numbers found in `XPATHErrorResources`, which is a key for a format string.
    `args` - An array of arguments represented in the format string, which may be null.
  Throws:
    TransformerException - if the current ErrorListoner determines to throw an exception.

### assertion

    public void assertion(boolean b,
                          java.lang.String msg)

  Tell the user of an assertion error, and probably throw an exception.
  Parameters:
    `b` - If false, a runtime exception will be thrown.
    `msg` - The assertion message, which should be informative.
  Throws:
    java.lang.RuntimeException - if the b argument is false.

### error

    public void error(XPathContext xctxt,
                      int sourceNode,
                      int msg,
                      java.lang.Object[] args)
               throws TransformerException

  Tell the user of an error, and probably throw an exception.
  Parameters:
    `xctxt` - The XPath runtime context.
    `sourceNode` - Not used.
    `msg` - An error number that corresponds to one of the numbers found in `XPATHErrorResources`, which is a key for a format string.
    `args` - An array of arguments represented in the format string, which may be null.
  Throws:
    TransformerException - if the current ErrorListoner determines to throw an exception.

### callVisitors

    public void callVisitors(ExpressionOwner owner,
                             XPathVisitor visitor)

  This will traverse the heararchy, calling the visitor for each member. If the called visitor method returns false, the subtree should not be called.
  Parameters:
    `owner` - The owner of the visitor, where that path may be rewritten if needed.
    `visitor` - The visitor whose appropriate method will be called.

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