src/org/apache/xpath/XPath.java - xalan-j - Git at Google

 /*
  * The Apache Software License, Version 1.1
  *
  *
  * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. The end-user documentation included with the redistribution,
  *    if any, must include the following acknowledgment:
  *       "This product includes software developed by the
  *        Apache Software Foundation (http://www.apache.org/)."
  *    Alternately, this acknowledgment may appear in the software itself,
  *    if and wherever such third-party acknowledgments normally appear.
  *
  * 4. The names "Xalan" and "Apache Software Foundation" must
  *    not be used to endorse or promote products derived from this
  *    software without prior written permission. For written
  *    permission, please contact apache@apache.org.
  *
  * 5. Products derived from this software may not be called "Apache",
  *    nor may "Apache" appear in their name, without prior written
  *    permission of the Apache Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  * ====================================================================
  *
  * This software consists of voluntary contributions made by many
  * individuals on behalf of the Apache Software Foundation and was
  * originally based on software copyright (c) 1999, Lotus
  * Development Corporation., http://www.lotus.com.  For more
  * information on the Apache Software Foundation, please see
  * <http://www.apache.org/>.
  */
 package org.apache.xpath;

 import java.io.Serializable;

 import javax.xml.transform.ErrorListener;
 import javax.xml.transform.SourceLocator;
 import javax.xml.transform.TransformerException;

 import org.apache.xalan.res.XSLMessages;
 import org.apache.xml.dtm.DTM;
 import org.apache.xml.utils.PrefixResolver;
 import org.apache.xml.utils.SAXSourceLocator;
 import org.apache.xpath.compiler.Compiler;
 import org.apache.xpath.compiler.FunctionTable;
 import org.apache.xpath.compiler.XPathParser;
 import org.apache.xpath.functions.Function;
 import org.apache.xpath.objects.XObject;
 import org.apache.xpath.res.XPATHErrorResources;

 /**
  * The XPath class wraps an expression object and provides general services
  * for execution of that expression.
  * @xsl.usage advanced
  */
 public class XPath implements Serializable, ExpressionOwner
 {

   /** The top of the expression tree.
    *  @serial */
   private Expression m_mainExp;

   /**
    * Get the raw Expression object that this class wraps.
    *
    *
    * @return the raw Expression object, which should not normally be null.
    */
   public Expression getExpression()
   {
     return m_mainExp;
   }

   /**
    * This function is used to fixup variables from QNames to stack frame
    * indexes at stylesheet build time.
    * @param 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).
    */
   public void fixupVariables(java.util.Vector vars, int globalsSize)
   {
     m_mainExp.fixupVariables(vars, globalsSize);
   }

   /**
    * Set the raw expression object for this object.
    *
    *
    * @param exp the raw Expression object, which should not normally be null.
    */
   public void setExpression(Expression exp)
   {
   	if(null != m_mainExp)
     	exp.exprSetParent(m_mainExp.exprGetParent()); // a bit bogus
     m_mainExp = exp;
   }

   /**
    * Get the SourceLocator on the expression object.
    *
    *
    * @return the SourceLocator on the expression object, which may be null.
    */
   public SourceLocator getLocator()
   {
     return m_mainExp;
   }

 //  /**
 //   * Set the SourceLocator on the expression object.
 //   *
 //   *
 //   * @param l the SourceLocator on the expression object, which may be null.
 //   */
 //  public void setLocator(SourceLocator l)
 //  {
 //    // Note potential hazards -- l may not be serializable, or may be changed
 //      // after being assigned here.
 //    m_mainExp.setSourceLocator(l);
 //  }

   /** The pattern string, mainly kept around for diagnostic purposes.
    *  @serial  */
   String m_patternString;

   /**
    * Return the XPath string associated with this object.
    *
    *
    * @return the XPath string associated with this object.
    */
   public String getPatternString()
   {
     return m_patternString;
   }

   /** Represents a select type expression. */
   public static final int SELECT = 0;

   /** Represents a match type expression.  */
   public static final int MATCH = 1;

   /**
    * Construct an XPath object.
    *
    * (Needs review -sc) This method initializes an XPathParser/
    * Compiler and compiles the expression.
    * @param exprString The XPath expression.
    * @param locator The location of the expression, may be null.
    * @param prefixResolver A prefix resolver to use to resolve prefixes to
    *                       namespace URIs.
    * @param type one of {@link #SELECT} or {@link #MATCH}.
    * @param errorListener The error listener, or null if default should be used.
    *
    * @throws javax.xml.transform.TransformerException if syntax or other error.
    */
   public XPath(
           String exprString, SourceLocator locator, PrefixResolver prefixResolver, int type,
           ErrorListener errorListener)
             throws javax.xml.transform.TransformerException
   {
     if(null == errorListener)
       errorListener = new org.apache.xml.utils.DefaultErrorHandler();

     m_patternString = exprString;

     XPathParser parser = new XPathParser(errorListener, locator);
     Compiler compiler = new Compiler(errorListener, locator);

     if (SELECT == type)
       parser.initXPath(compiler, exprString, prefixResolver);
     else if (MATCH == type)
       parser.initMatchPattern(compiler, exprString, prefixResolver);
     else
       throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_CANNOT_DEAL_XPATH_TYPE, new Object[]{Integer.toString(type)})); //"Can not deal with XPath type: " + type);

     // System.out.println("----------------");
     Expression expr = compiler.compile(0);

     // System.out.println("expr: "+expr);
     this.setExpression(expr);

     if((null != locator) && locator instanceof ExpressionNode)
     {
     	expr.exprSetParent((ExpressionNode)locator);
     }

   }

   /**
    * Construct an XPath object.
    *
    * (Needs review -sc) This method initializes an XPathParser/
    * Compiler and compiles the expression.
    * @param exprString The XPath expression.
    * @param locator The location of the expression, may be null.
    * @param prefixResolver A prefix resolver to use to resolve prefixes to
    *                       namespace URIs.
    * @param type one of {@link #SELECT} or {@link #MATCH}.
    *
    * @throws javax.xml.transform.TransformerException if syntax or other error.
    */
   public XPath(
           String exprString, SourceLocator locator, PrefixResolver prefixResolver, int type)
             throws javax.xml.transform.TransformerException
   {
     this(exprString, locator, prefixResolver, type, null);
   }

   /**
    * Construct an XPath object.
    *
    * @param expr The Expression object.
    *
    * @throws javax.xml.transform.TransformerException if syntax or other error.
    */
   public XPath(Expression expr)
   {
     this.setExpression(expr);
   }

   /**
    * Given an expression and a context, evaluate the XPath
    * and return the result.
    *
    * @param xctxt The execution context.
    * @param contextNode The node that "." expresses.
    * @param namespaceContext The context in which namespaces in the
    * XPath are supposed to be expanded.
    *
    * @return The result of the XPath or null if callbacks are used.
    * @throws TransformerException thrown if
    * the error condition is severe enough to halt processing.
    *
    * @throws javax.xml.transform.TransformerException
    * @xsl.usage experimental
    */
   public XObject execute(
           XPathContext xctxt, org.w3c.dom.Node contextNode,
           PrefixResolver namespaceContext)
             throws javax.xml.transform.TransformerException
   {
     return execute(
           xctxt, xctxt.getDTMHandleFromNode(contextNode),
           namespaceContext);
   }


   /**
    * Given an expression and a context, evaluate the XPath
    * and return the result.
    *
    * @param xctxt The execution context.
    * @param contextNode The node that "." expresses.
    * @param 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.
    *
    * @throws javax.xml.transform.TransformerException
    * @xsl.usage experimental
    */
   public XObject execute(
           XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)
             throws javax.xml.transform.TransformerException
   {

     xctxt.pushNamespaceContext(namespaceContext);

     xctxt.pushCurrentNodeAndExpression(contextNode, contextNode);

     XObject xobj = null;

     try
     {
       xobj = m_mainExp.execute(xctxt);
     }
     catch (TransformerException te)
     {
       te.setLocator(this.getLocator());
       ErrorListener el = xctxt.getErrorListener();
       if(null != el) // defensive, should never happen.
       {
         el.error(te);
       }
       else
         throw te;
     }
     catch (Exception e)
     {
       while (e instanceof org.apache.xml.utils.WrappedRuntimeException)
       {
         e = ((org.apache.xml.utils.WrappedRuntimeException) e).getException();
       }
       // e.printStackTrace();

       String msg = e.getMessage();

       if (msg == null || msg.length() == 0) {
            msg = XSLMessages.createXPATHMessage(
                XPATHErrorResources.ER_XPATH_ERROR, null);

       }
       TransformerException te = new TransformerException(msg,
               getLocator(), e);
       ErrorListener el = xctxt.getErrorListener();
       // te.printStackTrace();
       if(null != el) // defensive, should never happen.
       {
         el.fatalError(te);
       }
       else
         throw te;
     }
     finally
     {
       xctxt.popNamespaceContext();

       xctxt.popCurrentNodeAndExpression();
     }

     return xobj;
   }

   /**
    * Given an expression and a context, evaluate the XPath
    * and return the result.
    *
    * @param xctxt The execution context.
    * @param contextNode The node that "." expresses.
    * @param 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.
    *
    * @throws javax.xml.transform.TransformerException
    * @xsl.usage experimental
    */
   public boolean bool(
           XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)
             throws javax.xml.transform.TransformerException
   {

     xctxt.pushNamespaceContext(namespaceContext);

     xctxt.pushCurrentNodeAndExpression(contextNode, contextNode);

     try
     {
       return m_mainExp.bool(xctxt);
     }
     catch (TransformerException te)
     {
       te.setLocator(this.getLocator());
       ErrorListener el = xctxt.getErrorListener();
       if(null != el) // defensive, should never happen.
       {
         el.error(te);
       }
       else
         throw te;
     }
     catch (Exception e)
     {
       while (e instanceof org.apache.xml.utils.WrappedRuntimeException)
       {
         e = ((org.apache.xml.utils.WrappedRuntimeException) e).getException();
       }
       // e.printStackTrace();

       String msg = e.getMessage();

       if (msg == null || msg.length() == 0) {
            msg = XSLMessages.createXPATHMessage(
                XPATHErrorResources.ER_XPATH_ERROR, null);

       }

       TransformerException te = new TransformerException(msg,
               getLocator(), e);
       ErrorListener el = xctxt.getErrorListener();
       // te.printStackTrace();
       if(null != el) // defensive, should never happen.
       {
         el.fatalError(te);
       }
       else
         throw te;
     }
     finally
     {
       xctxt.popNamespaceContext();

       xctxt.popCurrentNodeAndExpression();
     }

     return false;
   }

   /** Set to true to get diagnostic messages about the result of
    *  match pattern testing.  */
   private static final boolean DEBUG_MATCHES = false;

   /**
    * Get the match score of the given node.
    *
    * @param xctxt XPath runtime context.
    * @param context The current source tree context node.
    *
    * @return score, one of {@link #MATCH_SCORE_NODETEST},
    * {@link #MATCH_SCORE_NONE}, {@link #MATCH_SCORE_OTHER},
    * or {@link #MATCH_SCORE_QNAME}.
    *
    * @throws javax.xml.transform.TransformerException
    */
   public double getMatchScore(XPathContext xctxt, int context)
           throws javax.xml.transform.TransformerException
   {

     xctxt.pushCurrentNode(context);
     xctxt.pushCurrentExpressionNode(context);

     try
     {
       XObject score = m_mainExp.execute(xctxt);

       if (DEBUG_MATCHES)
       {
         DTM dtm = xctxt.getDTM(context);
         System.out.println("score: " + score.num() + " for "
                            + dtm.getNodeName(context) + " for xpath "
                            + this.getPatternString());
       }

       return score.num();
     }
     finally
     {
       xctxt.popCurrentNode();
       xctxt.popCurrentExpressionNode();
     }

     // return XPath.MATCH_SCORE_NONE;
   }

   /**
    * Install a built-in function.
    * @param name The unqualified name of the function; not currently used.
    * @param funcIndex The index of the function in the table.
    * @param func An Implementation of an XPath Function object.
    * @return the position of the function in the internal index.
    */
   public void installFunction(String name, int funcIndex, Function func)
   {
     FunctionTable.installFunction(func, funcIndex);
   }

   /**
    * Warn the user of an problem.
    *
    * @param xctxt The XPath runtime context.
    * @param sourceNode Not used.
    * @param msg An error msgkey that corresponds to one of the constants found
    *            in {@link org.apache.xpath.res.XPATHErrorResources}, which is
    *            a key for a format string.
    * @param 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.
    */
   public void warn(
           XPathContext xctxt, int sourceNode, String msg, Object[] args)
             throws javax.xml.transform.TransformerException
   {

     String fmsg = XSLMessages.createXPATHWarning(msg, args);
     ErrorListener ehandler = xctxt.getErrorListener();

     if (null != ehandler)
     {

       // TO DO: Need to get stylesheet Locator from here.
       ehandler.warning(new TransformerException(fmsg, (SAXSourceLocator)xctxt.getSAXLocator()));
     }
   }

   /**
    * Tell the user of an assertion error, and probably throw an
    * exception.
    *
    * @param b  If false, a runtime exception will be thrown.
    * @param msg The assertion message, which should be informative.
    *
    * @throws RuntimeException if the b argument is false.
    */
   public void assertion(boolean b, String msg)
   {

     if (!b)
     {
       String fMsg = XSLMessages.createXPATHMessage(
         XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
         new Object[]{ msg });

       throw new RuntimeException(fMsg);
     }
   }

   /**
    * Tell the user of an error, and probably throw an
    * exception.
    *
    * @param xctxt The XPath runtime context.
    * @param sourceNode Not used.
    * @param msg An error msgkey that corresponds to one of the constants found
    *            in {@link org.apache.xpath.res.XPATHErrorResources}, which is
    *            a key for a format string.
    * @param 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.
    */
   public void error(
           XPathContext xctxt, int sourceNode, String msg, Object[] args)
             throws javax.xml.transform.TransformerException
   {

     String fmsg = XSLMessages.createXPATHMessage(msg, args);
     ErrorListener ehandler = xctxt.getErrorListener();

     if (null != ehandler)
     {
       ehandler.fatalError(new TransformerException(fmsg,
                               (SAXSourceLocator)xctxt.getSAXLocator()));
     }
     else
     {
       SourceLocator slocator = xctxt.getSAXLocator();
       System.out.println(fmsg + "; file " + slocator.getSystemId()
                          + "; line " + slocator.getLineNumber() + "; column "
                          + slocator.getColumnNumber());
     }
   }

   /**
    * This will traverse the heararchy, calling the visitor for
    * each member.  If the called visitor method returns
    * false, the subtree should not be called.
    *
    * @param owner The owner of the visitor, where that path may be
    *              rewritten if needed.
    * @param visitor The visitor whose appropriate method will be called.
    */
   public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
   {
   	m_mainExp.callVisitors(this, visitor);
   }

   /**
    * The match score if no match is made.
    * @xsl.usage advanced
    */
   public static final double MATCH_SCORE_NONE = Double.NEGATIVE_INFINITY;

   /**
    * The match score if the pattern has the form
    * of a QName optionally preceded by an @ character.
    * @xsl.usage advanced
    */
   public static final double MATCH_SCORE_QNAME = 0.0;

   /**
    * The match score if the pattern pattern has the form NCName:*.
    * @xsl.usage advanced
    */
   public static final double MATCH_SCORE_NSWILD = -0.25;

   /**
    * The match score if the pattern consists of just a NodeTest.
    * @xsl.usage advanced
    */
   public static final double MATCH_SCORE_NODETEST = -0.5;

   /**
    * The match score if the pattern consists of something
    * other than just a NodeTest or just a qname.
    * @xsl.usage advanced
    */
   public static final double MATCH_SCORE_OTHER = 0.5;
 }
	/*
	* The Apache Software License, Version 1.1
	*
	*
	* Copyright (c) 1999-2003 The Apache Software Foundation. All rights
	* reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. The end-user documentation included with the redistribution,
	* if any, must include the following acknowledgment:
	* "This product includes software developed by the
	* Apache Software Foundation (http://www.apache.org/)."
	* Alternately, this acknowledgment may appear in the software itself,
	* if and wherever such third-party acknowledgments normally appear.
	*
	* 4. The names "Xalan" and "Apache Software Foundation" must
	* not be used to endorse or promote products derived from this
	* software without prior written permission. For written
	* permission, please contact apache@apache.org.
	*
	* 5. Products derived from this software may not be called "Apache",
	* nor may "Apache" appear in their name, without prior written
	* permission of the Apache Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	* SUCH DAMAGE.
	* ====================================================================
	*
	* This software consists of voluntary contributions made by many
	* individuals on behalf of the Apache Software Foundation and was
	* originally based on software copyright (c) 1999, Lotus
	* Development Corporation., http://www.lotus.com. For more
	* information on the Apache Software Foundation, please see
	* <http://www.apache.org/>.
	*/
	package org.apache.xpath;

	import java.io.Serializable;

	import javax.xml.transform.ErrorListener;
	import javax.xml.transform.SourceLocator;
	import javax.xml.transform.TransformerException;

	import org.apache.xalan.res.XSLMessages;
	import org.apache.xml.dtm.DTM;
	import org.apache.xml.utils.PrefixResolver;
	import org.apache.xml.utils.SAXSourceLocator;
	import org.apache.xpath.compiler.Compiler;
	import org.apache.xpath.compiler.FunctionTable;
	import org.apache.xpath.compiler.XPathParser;
	import org.apache.xpath.functions.Function;
	import org.apache.xpath.objects.XObject;
	import org.apache.xpath.res.XPATHErrorResources;

	/**
	* The XPath class wraps an expression object and provides general services
	* for execution of that expression.
	* @xsl.usage advanced
	*/
	public class XPath implements Serializable, ExpressionOwner
	{

	/** The top of the expression tree.
	* @serial */
	private Expression m_mainExp;

	/**
	* Get the raw Expression object that this class wraps.
	*
	*
	* @return the raw Expression object, which should not normally be null.
	*/
	public Expression getExpression()
	{
	return m_mainExp;
	}

	/**
	* This function is used to fixup variables from QNames to stack frame
	* indexes at stylesheet build time.
	* @param 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).
	*/
	public void fixupVariables(java.util.Vector vars, int globalsSize)
	{
	m_mainExp.fixupVariables(vars, globalsSize);
	}

	/**
	* Set the raw expression object for this object.
	*
	*
	* @param exp the raw Expression object, which should not normally be null.
	*/
	public void setExpression(Expression exp)
	{
	if(null != m_mainExp)
	exp.exprSetParent(m_mainExp.exprGetParent()); // a bit bogus
	m_mainExp = exp;
	}

	/**
	* Get the SourceLocator on the expression object.
	*
	*
	* @return the SourceLocator on the expression object, which may be null.
	*/
	public SourceLocator getLocator()
	{
	return m_mainExp;
	}

	// /**
	// * Set the SourceLocator on the expression object.
	// *
	// *
	// * @param l the SourceLocator on the expression object, which may be null.
	// */
	// public void setLocator(SourceLocator l)
	// {
	// // Note potential hazards -- l may not be serializable, or may be changed
	// // after being assigned here.
	// m_mainExp.setSourceLocator(l);
	// }

	/** The pattern string, mainly kept around for diagnostic purposes.
	* @serial */
	String m_patternString;

	/**
	* Return the XPath string associated with this object.
	*
	*
	* @return the XPath string associated with this object.
	*/
	public String getPatternString()
	{
	return m_patternString;
	}

	/** Represents a select type expression. */
	public static final int SELECT = 0;

	/** Represents a match type expression. */
	public static final int MATCH = 1;

	/**
	* Construct an XPath object.
	*
	* (Needs review -sc) This method initializes an XPathParser/
	* Compiler and compiles the expression.
	* @param exprString The XPath expression.
	* @param locator The location of the expression, may be null.
	* @param prefixResolver A prefix resolver to use to resolve prefixes to
	* namespace URIs.
	* @param type one of {@link #SELECT} or {@link #MATCH}.
	* @param errorListener The error listener, or null if default should be used.
	*
	* @throws javax.xml.transform.TransformerException if syntax or other error.
	*/
	public XPath(
	String exprString, SourceLocator locator, PrefixResolver prefixResolver, int type,
	ErrorListener errorListener)
	throws javax.xml.transform.TransformerException
	{
	if(null == errorListener)
	errorListener = new org.apache.xml.utils.DefaultErrorHandler();

	m_patternString = exprString;

	XPathParser parser = new XPathParser(errorListener, locator);
	Compiler compiler = new Compiler(errorListener, locator);

	if (SELECT == type)
	parser.initXPath(compiler, exprString, prefixResolver);
	else if (MATCH == type)
	parser.initMatchPattern(compiler, exprString, prefixResolver);
	else
	throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_CANNOT_DEAL_XPATH_TYPE, new Object[]{Integer.toString(type)})); //"Can not deal with XPath type: " + type);

	// System.out.println("----------------");
	Expression expr = compiler.compile(0);

	// System.out.println("expr: "+expr);
	this.setExpression(expr);

	if((null != locator) && locator instanceof ExpressionNode)
	{
	expr.exprSetParent((ExpressionNode)locator);
	}

	}

	/**
	* Construct an XPath object.
	*
	* (Needs review -sc) This method initializes an XPathParser/
	* Compiler and compiles the expression.
	* @param exprString The XPath expression.
	* @param locator The location of the expression, may be null.
	* @param prefixResolver A prefix resolver to use to resolve prefixes to
	* namespace URIs.
	* @param type one of {@link #SELECT} or {@link #MATCH}.
	*
	* @throws javax.xml.transform.TransformerException if syntax or other error.
	*/
	public XPath(
	String exprString, SourceLocator locator, PrefixResolver prefixResolver, int type)
	throws javax.xml.transform.TransformerException
	{
	this(exprString, locator, prefixResolver, type, null);
	}

	/**
	* Construct an XPath object.
	*
	* @param expr The Expression object.
	*
	* @throws javax.xml.transform.TransformerException if syntax or other error.
	*/
	public XPath(Expression expr)
	{
	this.setExpression(expr);
	}

	/**
	* Given an expression and a context, evaluate the XPath
	* and return the result.
	*
	* @param xctxt The execution context.
	* @param contextNode The node that "." expresses.
	* @param namespaceContext The context in which namespaces in the
	* XPath are supposed to be expanded.
	*
	* @return The result of the XPath or null if callbacks are used.
	* @throws TransformerException thrown if
	* the error condition is severe enough to halt processing.
	*
	* @throws javax.xml.transform.TransformerException
	* @xsl.usage experimental
	*/
	public XObject execute(
	XPathContext xctxt, org.w3c.dom.Node contextNode,
	PrefixResolver namespaceContext)
	throws javax.xml.transform.TransformerException
	{
	return execute(
	xctxt, xctxt.getDTMHandleFromNode(contextNode),
	namespaceContext);
	}


	/**
	* Given an expression and a context, evaluate the XPath
	* and return the result.
	*
	* @param xctxt The execution context.
	* @param contextNode The node that "." expresses.
	* @param 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.
	*
	* @throws javax.xml.transform.TransformerException
	* @xsl.usage experimental
	*/
	public XObject execute(
	XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)
	throws javax.xml.transform.TransformerException
	{

	xctxt.pushNamespaceContext(namespaceContext);

	xctxt.pushCurrentNodeAndExpression(contextNode, contextNode);

	XObject xobj = null;

	try
	{
	xobj = m_mainExp.execute(xctxt);
	}
	catch (TransformerException te)
	{
	te.setLocator(this.getLocator());
	ErrorListener el = xctxt.getErrorListener();
	if(null != el) // defensive, should never happen.
	{
	el.error(te);
	}
	else
	throw te;
	}
	catch (Exception e)
	{
	while (e instanceof org.apache.xml.utils.WrappedRuntimeException)
	{
	e = ((org.apache.xml.utils.WrappedRuntimeException) e).getException();
	}
	// e.printStackTrace();

	String msg = e.getMessage();

	if (msg == null \|\| msg.length() == 0) {
	msg = XSLMessages.createXPATHMessage(
	XPATHErrorResources.ER_XPATH_ERROR, null);

	}
	TransformerException te = new TransformerException(msg,
	getLocator(), e);
	ErrorListener el = xctxt.getErrorListener();
	// te.printStackTrace();
	if(null != el) // defensive, should never happen.
	{
	el.fatalError(te);
	}
	else
	throw te;
	}
	finally
	{
	xctxt.popNamespaceContext();

	xctxt.popCurrentNodeAndExpression();
	}

	return xobj;
	}

	/**
	* Given an expression and a context, evaluate the XPath
	* and return the result.
	*
	* @param xctxt The execution context.
	* @param contextNode The node that "." expresses.
	* @param 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.
	*
	* @throws javax.xml.transform.TransformerException
	* @xsl.usage experimental
	*/
	public boolean bool(
	XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)
	throws javax.xml.transform.TransformerException
	{

	xctxt.pushNamespaceContext(namespaceContext);

	xctxt.pushCurrentNodeAndExpression(contextNode, contextNode);

	try
	{
	return m_mainExp.bool(xctxt);
	}
	catch (TransformerException te)
	{
	te.setLocator(this.getLocator());
	ErrorListener el = xctxt.getErrorListener();
	if(null != el) // defensive, should never happen.
	{
	el.error(te);
	}
	else
	throw te;
	}
	catch (Exception e)
	{
	while (e instanceof org.apache.xml.utils.WrappedRuntimeException)
	{
	e = ((org.apache.xml.utils.WrappedRuntimeException) e).getException();
	}
	// e.printStackTrace();

	String msg = e.getMessage();

	if (msg == null \|\| msg.length() == 0) {
	msg = XSLMessages.createXPATHMessage(
	XPATHErrorResources.ER_XPATH_ERROR, null);

	}

	TransformerException te = new TransformerException(msg,
	getLocator(), e);
	ErrorListener el = xctxt.getErrorListener();
	// te.printStackTrace();
	if(null != el) // defensive, should never happen.
	{
	el.fatalError(te);
	}
	else
	throw te;
	}
	finally
	{
	xctxt.popNamespaceContext();

	xctxt.popCurrentNodeAndExpression();
	}

	return false;
	}

	/** Set to true to get diagnostic messages about the result of
	* match pattern testing. */
	private static final boolean DEBUG_MATCHES = false;

	/**
	* Get the match score of the given node.
	*
	* @param xctxt XPath runtime context.
	* @param context The current source tree context node.
	*
	* @return score, one of {@link #MATCH_SCORE_NODETEST},
	* {@link #MATCH_SCORE_NONE}, {@link #MATCH_SCORE_OTHER},
	* or {@link #MATCH_SCORE_QNAME}.
	*
	* @throws javax.xml.transform.TransformerException
	*/
	public double getMatchScore(XPathContext xctxt, int context)
	throws javax.xml.transform.TransformerException
	{

	xctxt.pushCurrentNode(context);
	xctxt.pushCurrentExpressionNode(context);

	try
	{
	XObject score = m_mainExp.execute(xctxt);

	if (DEBUG_MATCHES)
	{
	DTM dtm = xctxt.getDTM(context);
	System.out.println("score: " + score.num() + " for "
	+ dtm.getNodeName(context) + " for xpath "
	+ this.getPatternString());
	}

	return score.num();
	}
	finally
	{
	xctxt.popCurrentNode();
	xctxt.popCurrentExpressionNode();
	}

	// return XPath.MATCH_SCORE_NONE;
	}

	/**
	* Install a built-in function.
	* @param name The unqualified name of the function; not currently used.
	* @param funcIndex The index of the function in the table.
	* @param func An Implementation of an XPath Function object.
	* @return the position of the function in the internal index.
	*/
	public void installFunction(String name, int funcIndex, Function func)
	{
	FunctionTable.installFunction(func, funcIndex);
	}

	/**
	* Warn the user of an problem.
	*
	* @param xctxt The XPath runtime context.
	* @param sourceNode Not used.
	* @param msg An error msgkey that corresponds to one of the constants found
	* in {@link org.apache.xpath.res.XPATHErrorResources}, which is
	* a key for a format string.
	* @param 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.
	*/
	public void warn(
	XPathContext xctxt, int sourceNode, String msg, Object[] args)
	throws javax.xml.transform.TransformerException
	{

	String fmsg = XSLMessages.createXPATHWarning(msg, args);
	ErrorListener ehandler = xctxt.getErrorListener();

	if (null != ehandler)
	{

	// TO DO: Need to get stylesheet Locator from here.
	ehandler.warning(new TransformerException(fmsg, (SAXSourceLocator)xctxt.getSAXLocator()));
	}
	}

	/**
	* Tell the user of an assertion error, and probably throw an
	* exception.
	*
	* @param b If false, a runtime exception will be thrown.
	* @param msg The assertion message, which should be informative.
	*
	* @throws RuntimeException if the b argument is false.
	*/
	public void assertion(boolean b, String msg)
	{

	if (!b)
	{
	String fMsg = XSLMessages.createXPATHMessage(
	XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
	new Object[]{ msg });

	throw new RuntimeException(fMsg);
	}
	}

	/**
	* Tell the user of an error, and probably throw an
	* exception.
	*
	* @param xctxt The XPath runtime context.
	* @param sourceNode Not used.
	* @param msg An error msgkey that corresponds to one of the constants found
	* in {@link org.apache.xpath.res.XPATHErrorResources}, which is
	* a key for a format string.
	* @param 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.
	*/
	public void error(
	XPathContext xctxt, int sourceNode, String msg, Object[] args)
	throws javax.xml.transform.TransformerException
	{

	String fmsg = XSLMessages.createXPATHMessage(msg, args);
	ErrorListener ehandler = xctxt.getErrorListener();

	if (null != ehandler)
	{
	ehandler.fatalError(new TransformerException(fmsg,
	(SAXSourceLocator)xctxt.getSAXLocator()));
	}
	else
	{
	SourceLocator slocator = xctxt.getSAXLocator();
	System.out.println(fmsg + "; file " + slocator.getSystemId()
	+ "; line " + slocator.getLineNumber() + "; column "
	+ slocator.getColumnNumber());
	}
	}

	/**
	* This will traverse the heararchy, calling the visitor for
	* each member. If the called visitor method returns
	* false, the subtree should not be called.
	*
	* @param owner The owner of the visitor, where that path may be
	* rewritten if needed.
	* @param visitor The visitor whose appropriate method will be called.
	*/
	public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
	{
	m_mainExp.callVisitors(this, visitor);
	}

	/**
	* The match score if no match is made.
	* @xsl.usage advanced
	*/
	public static final double MATCH_SCORE_NONE = Double.NEGATIVE_INFINITY;

	/**
	* The match score if the pattern has the form
	* of a QName optionally preceded by an @ character.
	* @xsl.usage advanced
	*/
	public static final double MATCH_SCORE_QNAME = 0.0;

	/**
	* The match score if the pattern pattern has the form NCName:*.
	* @xsl.usage advanced
	*/
	public static final double MATCH_SCORE_NSWILD = -0.25;

	/**
	* The match score if the pattern consists of just a NodeTest.
	* @xsl.usage advanced
	*/
	public static final double MATCH_SCORE_NODETEST = -0.5;

	/**
	* The match score if the pattern consists of something
	* other than just a NodeTest or just a qname.
	* @xsl.usage advanced
	*/
	public static final double MATCH_SCORE_OTHER = 0.5;
	}