xpath.java

java1.6众多例子参考

/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: XPath.java,v 1.2.4.1 2005/09/15 01:41:57 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal;

import java.io.Serializable;

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

import com.sun.org.apache.xalan.internal.res.XSLMessages;
import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.utils.PrefixResolver;
import com.sun.org.apache.xml.internal.utils.SAXSourceLocator;
import com.sun.org.apache.xpath.internal.compiler.Compiler;
import com.sun.org.apache.xpath.internal.compiler.FunctionTable;
import com.sun.org.apache.xpath.internal.compiler.XPathParser;
import com.sun.org.apache.xpath.internal.functions.Function;
import com.sun.org.apache.xpath.internal.objects.XObject;
import com.sun.org.apache.xpath.internal.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
{
    static final long serialVersionUID = 3976493477939110553L;

  /** The top of the expression tree. 
   *  @serial */
  private Expression m_mainExp;
  
  /**
   * The function table for xpath build-in functions
   */
  private transient FunctionTable m_funcTable = null;

  /**
   * initial the function table
   */
  private void initFunctionTable(){
  	      m_funcTable = new FunctionTable();
  }

  /**
   * 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
  { 
    initFunctionTable();     
    if(null == errorListener)
      errorListener = new com.sun.org.apache.xml.internal.utils.DefaultErrorHandler();
    
    m_patternString = exprString;

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

    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}.
   * @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, FunctionTable aTable)
            throws javax.xml.transform.TransformerException
  { 
    m_funcTable = aTable;     
    if(null == errorListener)
      errorListener = new com.sun.org.apache.xml.internal.utils.DefaultErrorHandler();
    
    m_patternString = exprString;

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

    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);
    initFunctionTable();   
  }
  
  /**
   * 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
   */