predicatednodetest.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: PredicatedNodeTest.java,v 1.2.4.2 2005/09/14 19:45:20 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.axes;

import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.dtm.DTMIterator;
import com.sun.org.apache.xml.internal.utils.PrefixResolver;
import com.sun.org.apache.xpath.internal.Expression;
import com.sun.org.apache.xpath.internal.ExpressionOwner;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.XPathVisitor;
import com.sun.org.apache.xpath.internal.compiler.Compiler;
import com.sun.org.apache.xpath.internal.objects.XObject;
import com.sun.org.apache.xpath.internal.patterns.NodeTest;

public abstract class PredicatedNodeTest extends NodeTest implements SubContextList
{
    static final long serialVersionUID = -6193530757296377351L;

  /**
   * Construct an AxesWalker using a LocPathIterator.
   *
   * @param locPathIterator non-null reference to the parent iterator.
   */
  PredicatedNodeTest(LocPathIterator locPathIterator)
  {
    m_lpi = locPathIterator;
  }
  
  /**
   * Construct an AxesWalker.  The location path iterator will have to be set
   * before use.
   */
  PredicatedNodeTest()
  {
  }
  
  /**
   * Read the object from a serialization stream.
   *
   * @param stream Input stream to read from
   *
   * @throws java.io.IOException
   * @throws javax.xml.transform.TransformerException
   */
  private void readObject(java.io.ObjectInputStream stream)
          throws java.io.IOException, javax.xml.transform.TransformerException
  {
    try
    {
      stream.defaultReadObject();
      m_predicateIndex = -1;
      resetProximityPositions();
    }
    catch (ClassNotFoundException cnfe)
    {
      throw new javax.xml.transform.TransformerException(cnfe);
    }
  }
  
  /**
   * Get a cloned PrdicatedNodeTest.
   *
   * @return A new PredicatedNodeTest that can be used without mutating this one.
   *
   * @throws CloneNotSupportedException
   */
  public Object clone() throws CloneNotSupportedException
  {
    // Do not access the location path itterator during this operation!
    
    PredicatedNodeTest clone = (PredicatedNodeTest) super.clone();

    if ((null != this.m_proximityPositions)
            && (this.m_proximityPositions == clone.m_proximityPositions))
    {
      clone.m_proximityPositions = new int[this.m_proximityPositions.length];

      System.arraycopy(this.m_proximityPositions, 0,
                       clone.m_proximityPositions, 0,
                       this.m_proximityPositions.length);
    }
    
    if(clone.m_lpi == this)
      clone.m_lpi = (LocPathIterator)clone;

    return clone;
  }
  
  // Only for clones for findLastPos.  See bug4638.
  protected int m_predCount = -1;

  /**
   * Get the number of predicates that this walker has.
   *
   * @return the number of predicates that this walker has.
   */
  public int getPredicateCount()
  {
    if(-1 == m_predCount)
      return (null == m_predicates) ? 0 : m_predicates.length;
    else
      return m_predCount;
  }

  /**
   * Set the number of predicates that this walker has.  This does more 
   * that one would think, as it creates a new predicate array of the 
   * size of the count argument, and copies count predicates into the new 
   * one from the old, and then reassigns the predicates value.  All this 
   * to keep from having to have a predicate count value.
   *
   * @param count The number of predicates, which must be equal or less 
   *               than the existing count.
   */
  public void setPredicateCount(int count)
  {
    if(count > 0)
    {
      Expression[] newPredicates = new Expression[count];
      for (int i = 0; i < count; i++) 
      {
        newPredicates[i] = m_predicates[i];
      }
      m_predicates = newPredicates;
    }
    else
      m_predicates = null;
    
  }

  /**
   * Init predicate info.
   *
   * @param compiler The Compiler object that has information about this 
   *                 walker in the op map.
   * @param opPos The op code position of this location step.
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected void initPredicateInfo(Compiler compiler, int opPos)
          throws javax.xml.transform.TransformerException
  {

    int pos = compiler.getFirstPredicateOpPos(opPos);

    if(pos > 0)
    {
      m_predicates = compiler.getCompiledPredicates(pos);
      if(null != m_predicates)
      {
      	for(int i = 0; i < m_predicates.length; i++)
      	{
      		m_predicates[i].exprSetParent(this);
      	}
      }
    }
  }

  /**
   * Get a predicate expression at the given index.
   *
   *
   * @param index Index of the predicate.
   *
   * @return A predicate expression.
   */
  public Expression getPredicate(int index)
  {
    return m_predicates[index];
  }
  
  /**
   * Get the current sub-context position.
   *
   * @return The node position of this walker in the sub-context node list.
   */
  public int getProximityPosition()
  {

    // System.out.println("getProximityPosition - m_predicateIndex: "+m_predicateIndex);
    return getProximityPosition(m_predicateIndex);
  }

  /**
   * Get the current sub-context position.
   *
   * @param xctxt The XPath runtime context.
   *
   * @return The node position of this walker in the sub-context node list.
   */
  public int getProximityPosition(XPathContext xctxt)
  {
    return getProximityPosition();
  }
  
  /**
   * Get the index of the last node that can be itterated to.
   *
   *
   * @param xctxt XPath runtime context.
   *
   * @return the index of the last node that can be itterated to.
   */
  public abstract int getLastPos(XPathContext xctxt);

  /**
   * Get the current sub-context position.
   *
   * @param predicateIndex The index of the predicate where the proximity 
   *                       should be taken from.
   *
   * @return The node position of this walker in the sub-context node list.
   */
  protected int getProximityPosition(int predicateIndex)
  {
    return (predicateIndex >= 0) ? m_proximityPositions[predicateIndex] : 0;
  }

  /**
   * Reset the proximity positions counts.
   */
  public void resetProximityPositions()
  {
    int nPredicates = getPredicateCount();
    if (nPredicates > 0)
    {
      if (null == m_proximityPositions)
        m_proximityPositions = new int[nPredicates];

      for (int i = 0; i < nPredicates; i++)
      {
        try
        {
          initProximityPosition(i);
        }
        catch(Exception e)
        {
          // TODO: Fix this...
          throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(e);
        }
      }
    }
  }

  /**
   * Init the proximity position to zero for a forward axes.
   *
   * @param i The index into the m_proximityPositions array.
   *
   * @throws javax.xml.transform.TransformerException
   */
  public void initProximityPosition(int i) throws javax.xml.transform.TransformerException
  {
    m_proximityPositions[i] = 0;
  }

  /**
   * Count forward one proximity position.
   *
   * @param i The index into the m_proximityPositions array, where the increment 
   *          will occur.
   */
  protected void countProximityPosition(int i)
  {
  	// Note that in the case of a UnionChildIterator, this may be a 
  	// static object and so m_proximityPositions may indeed be null!
  	int[] pp = m_proximityPositions;
    if ((null != pp) && (i < pp.length))
      pp[i]++;
  }

  /**
   * Tells if this is a reverse axes.
   *
   * @return false, unless a derived class overrides.
   */
  public boolean isReverseAxes()
  {
    return false;
  }

  /**
   * Get which predicate is executing.
   *
   * @return The current predicate index, or -1 if no predicate is executing.
   */
  public int getPredicateIndex()
  {
    return m_predicateIndex;
  }

  /**
   * Process the predicates.
   *
   * @param context The current context node.
   * @param xctxt The XPath runtime context.
   *
   * @return the result of executing the predicate expressions.
   *
   * @throws javax.xml.transform.TransformerException
   */
  boolean executePredicates(int context, XPathContext xctxt)
          throws javax.xml.transform.TransformerException
  {
    
    int nPredicates = getPredicateCount();