walkerfactory.java

java1.6众多例子参考

  {
    return (0 != (analysis & BIT_NODETEST_ANY));
  }

  public static boolean walksAncestors(int analysis)
  {
    return isSet(analysis, BIT_ANCESTOR | BIT_ANCESTOR_OR_SELF);
  }
  
  public static boolean walksAttributes(int analysis)
  {
    return (0 != (analysis & BIT_ATTRIBUTE));
  }

  public static boolean walksNamespaces(int analysis)
  {
    return (0 != (analysis & BIT_NAMESPACE));
  }  

  public static boolean walksChildren(int analysis)
  {
    return (0 != (analysis & BIT_CHILD));
  }

  public static boolean walksDescendants(int analysis)
  {
    return isSet(analysis, BIT_DESCENDANT | BIT_DESCENDANT_OR_SELF);
  }

  public static boolean walksSubtree(int analysis)
  {
    return isSet(analysis, BIT_DESCENDANT | BIT_DESCENDANT_OR_SELF | BIT_CHILD);
  }
  
  public static boolean walksSubtreeOnlyMaybeAbsolute(int analysis)
  {
    return walksSubtree(analysis)
           && !walksExtraNodes(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           ;
  }
  
  public static boolean walksSubtreeOnly(int analysis)
  {
    return walksSubtreeOnlyMaybeAbsolute(analysis) 
           && !isAbsolute(analysis) 
           ;
  }

  public static boolean walksFilteredList(int analysis)
  {
    return isSet(analysis, BIT_FILTER);
  }
  
  public static boolean walksSubtreeOnlyFromRootOrContext(int analysis)
  {
    return walksSubtree(analysis)
           && !walksExtraNodes(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && !isSet(analysis, BIT_FILTER) 
           ;
  }

  public static boolean walksInDocOrder(int analysis)
  {
    return (walksSubtreeOnlyMaybeAbsolute(analysis)
           || walksExtraNodesOnly(analysis)
           || walksFollowingOnlyMaybeAbsolute(analysis)) 
           && !isSet(analysis, BIT_FILTER) 
           ;
  }
  
  public static boolean walksFollowingOnlyMaybeAbsolute(int analysis)
  {
    return isSet(analysis, BIT_SELF | BIT_FOLLOWING_SIBLING | BIT_FOLLOWING)
           && !walksSubtree(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           ;
  }
  
  public static boolean walksUp(int analysis)
  {
    return isSet(analysis, BIT_PARENT | BIT_ANCESTOR | BIT_ANCESTOR_OR_SELF);
  }
  
  public static boolean walksSideways(int analysis)
  {
    return isSet(analysis, BIT_FOLLOWING | BIT_FOLLOWING_SIBLING | 
                           BIT_PRECEDING | BIT_PRECEDING_SIBLING);
  }
  
  public static boolean walksExtraNodes(int analysis)
  {
    return isSet(analysis, BIT_NAMESPACE | BIT_ATTRIBUTE);
  }

  public static boolean walksExtraNodesOnly(int analysis)
  {
    return walksExtraNodes(analysis)
           && !isSet(analysis, BIT_SELF) 
           && !walksSubtree(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && !isAbsolute(analysis) 
           ;
  }

  public static boolean isAbsolute(int analysis)
  {
    return isSet(analysis, BIT_ROOT | BIT_FILTER);
  }
  
  public static boolean walksChildrenOnly(int analysis)
  {
    return walksChildren(analysis)
           && !isSet(analysis, BIT_SELF)
           && !walksExtraNodes(analysis)
           && !walksDescendants(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && (!isAbsolute(analysis) || isSet(analysis, BIT_ROOT))
           ;
  }
  
  public static boolean walksChildrenAndExtraAndSelfOnly(int analysis)
  {
    return walksChildren(analysis)
           && !walksDescendants(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && (!isAbsolute(analysis) || isSet(analysis, BIT_ROOT))
           ;
  }
  
  public static boolean walksDescendantsAndExtraAndSelfOnly(int analysis)
  {
    return !walksChildren(analysis)
           && walksDescendants(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && (!isAbsolute(analysis) || isSet(analysis, BIT_ROOT))
           ;
  }
  
  public static boolean walksSelfOnly(int analysis)
  {
    return isSet(analysis, BIT_SELF) 
           && !walksSubtree(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && !isAbsolute(analysis) 
           ;
  }

  
  public static boolean walksUpOnly(int analysis)
  {
    return !walksSubtree(analysis) 
           && walksUp(analysis) 
           && !walksSideways(analysis) 
           && !isAbsolute(analysis) 
           ;
  }
  
  public static boolean walksDownOnly(int analysis)
  {
    return walksSubtree(analysis) 
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && !isAbsolute(analysis) 
           ;
  }

  public static boolean walksDownExtraOnly(int analysis)
  {
    return walksSubtree(analysis) &&  walksExtraNodes(analysis)
           && !walksUp(analysis) 
           && !walksSideways(analysis) 
           && !isAbsolute(analysis) 
           ;
  }
  
  public static boolean canSkipSubtrees(int analysis)
  {
    return isSet(analysis, BIT_CHILD) | walksSideways(analysis);
  }
  
  public static boolean canCrissCross(int analysis)
  {
    // This could be done faster.  Coded for clarity.
    if(walksSelfOnly(analysis))
      return false;
    else if(walksDownOnly(analysis) && !canSkipSubtrees(analysis))
      return false;
    else if(walksChildrenAndExtraAndSelfOnly(analysis))
      return false;
    else if(walksDescendantsAndExtraAndSelfOnly(analysis))
      return false;
    else if(walksUpOnly(analysis))
      return false;
    else if(walksExtraNodesOnly(analysis))
      return false;
    else if(walksSubtree(analysis) 
           && (walksSideways(analysis) 
            || walksUp(analysis) 
            || canSkipSubtrees(analysis)))
      return true;
    else
      return false;
  }
  
  /**
   * Tell if the pattern can be 'walked' with the iteration steps in natural 
   * document order, without duplicates.
   *
   * @param analysis The general analysis of the pattern.
   *
   * @return true if the walk can be done in natural order.
   *
   * @throws javax.xml.transform.TransformerException
   */
  static public boolean isNaturalDocOrder(int analysis)
  {
    if(canCrissCross(analysis) || isSet(analysis, BIT_NAMESPACE) ||
       walksFilteredList(analysis))
      return false;
      
    if(walksInDocOrder(analysis))
      return true;
      
    return false;
  }
  
  /**
   * Tell if the pattern can be 'walked' with the iteration steps in natural 
   * document order, without duplicates.
   *
   * @param compiler non-null reference to compiler object that has processed
   *                 the XPath operations into an opcode map.
   * @param stepOpCodePos The opcode position for the step.
   * @param stepIndex The top-level step index withing the iterator.
   * @param analysis The general analysis of the pattern.
   *
   * @return true if the walk can be done in natural order.
   *
   * @throws javax.xml.transform.TransformerException
   */
  private static boolean isNaturalDocOrder(
          Compiler compiler, int stepOpCodePos, int stepIndex, int analysis)
            throws javax.xml.transform.TransformerException
  {
    if(canCrissCross(analysis))
      return false;
      
    // Namespaces can present some problems, so just punt if we're looking for 
    // these.
    if(isSet(analysis, BIT_NAMESPACE))
      return false;
      
    // The following, preceding, following-sibling, and preceding sibling can 
    // be found in doc order if we get to this point, but if they occur 
    // together, they produce 
    // duplicates, so it's better for us to eliminate this case so we don't 
    // have to check for duplicates during runtime if we're using a 
    // WalkingIterator.
    if(isSet(analysis, BIT_FOLLOWING | BIT_FOLLOWING_SIBLING) && 
       isSet(analysis, BIT_PRECEDING | BIT_PRECEDING_SIBLING))
      return  false;
      
    // OK, now we have to check for select="@*/axis::*" patterns, which 
    // can also cause duplicates to happen.  But select="axis*/@::*" patterns 
    // are OK, as are select="@foo/axis::*" patterns.
    // Unfortunately, we can't do this just via the analysis bits.
    
    int stepType;
    int stepCount = 0;
    boolean foundWildAttribute = false;
    
    // Steps that can traverse anything other than down a 
    // subtree or that can produce duplicates when used in 
    // combonation are counted with this variable.
    int potentialDuplicateMakingStepCount = 0;
    
    while (OpCodes.ENDOP != (stepType = compiler.getOp(stepOpCodePos)))
    {        
      stepCount++;
        
      switch (stepType)
      {
      case OpCodes.FROM_ATTRIBUTES :
      case OpCodes.MATCH_ATTRIBUTE :
        if(foundWildAttribute) // Maybe not needed, but be safe.
          return false;
        
        // This doesn't seem to work as a test for wild card.  Hmph.
        // int nodeTestType = compiler.getStepTestType(stepOpCodePos);  
        
        String localName = compiler.getStepLocalName(stepOpCodePos);
        // System.err.println("localName: "+localName);
        if(localName.equals("*"))
        {
          foundWildAttribute = true;
        }
        break;
      case OpCodes.FROM_FOLLOWING :
      case OpCodes.FROM_FOLLOWING_SIBLINGS :
      case OpCodes.FROM_PRECEDING :
      case OpCodes.FROM_PRECEDING_SIBLINGS :
      case OpCodes.FROM_PARENT :
      case OpCodes.OP_VARIABLE :
      case OpCodes.OP_EXTFUNCTION :
      case OpCodes.OP_FUNCTION :
      case OpCodes.OP_GROUP :
      case OpCodes.FROM_NAMESPACE :
      case OpCodes.FROM_ANCESTORS :
      case OpCodes.FROM_ANCESTORS_OR_SELF :      
      case OpCodes.MATCH_ANY_ANCESTOR :
      case OpCodes.MATCH_IMMEDIATE_ANCESTOR :
      case OpCodes.FROM_DESCENDANTS_OR_SELF :
      case OpCodes.FROM_DESCENDANTS :
        if(potentialDuplicateMakingStepCount > 0)
            return false;
        potentialDuplicateMakingStepCount++;
      case OpCodes.FROM_ROOT :
      case OpCodes.FROM_CHILDREN :
      case OpCodes.FROM_SELF :
        if(foundWildAttribute)
          return false;
        break;
      default :
        throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NULL_ERROR_HANDLER, new Object[]{Integer.toString(stepType)})); //"Programmer's assertion: unknown opcode: "
                                  // + stepType);
      }

      int nextStepOpCodePos = compiler.getNextStepPos(stepOpCodePos);

      if (nextStepOpCodePos < 0)
        break;
              
      stepOpCodePos = nextStepOpCodePos;
    }

    return true;
  }
  
  public static boolean isOneStep(int analysis)
  {
    return (analysis & BITS_COUNT) == 0x00000001;
  }

  public static int getStepCount(int analysis)
  {
    return (analysis & BITS_COUNT);
  }

  /**
   * First 8 bits are the number of top-level location steps.  Hopefully
   *  there will never be more that 255 location steps!!!
   */
  public static final int BITS_COUNT = 0x000000FF;

  /** 4 bits are reserved for future use. */
  public static final int BITS_RESERVED = 0x00000F00;

  /** Bit is on if the expression contains a top-level predicate. */
  public static final int BIT_PREDICATE = (0x00001000);

  /** Bit is on if any of the walkers contain an ancestor step. */
  public static final int BIT_ANCESTOR = (0x00001000 << 1);

  /** Bit is on if any of the walkers contain an ancestor-or-self step. */
  public static final int BIT_ANCESTOR_OR_SELF = (0x00001000 << 2);

  /** Bit is on if any of the walkers contain an attribute step. */
  public static final int BIT_ATTRIBUTE = (0x00001000 << 3);

  /** Bit is on if any of the walkers contain a child step. */
  public static final int BIT_CHILD = (0x00001000 << 4);

  /** Bit is on if any of the walkers contain a descendant step. */
  public static final int BIT_DESCENDANT = (0x00001000 << 5);

  /** Bit is on if any of the walkers contain a descendant-or-self step. */
  public static final int BIT_DESCENDANT_OR_SELF = (0x00001000 << 6);

  /** Bit is on if any of the walkers contain a following step. */
  public static final int BIT_FOLLOWING = (0x00001000 << 7);

  /** Bit is on if any of the walkers contain a following-sibiling step. */
  public static final int BIT_FOLLOWING_SIBLING = (0x00001000 << 8);

  /** Bit is on if any of the walkers contain a namespace step. */
  public static final int BIT_NAMESPACE = (0x00001000 << 9);

  /** Bit is on if any of the walkers contain a parent step. */
  public static final int BIT_PARENT = (0x00001000 << 10);

  /** Bit is on if any of the walkers contain a preceding step. */
  public static final int BIT_PRECEDING = (0x00001000 << 11);

  /** Bit is on if any of the walkers contain a preceding-sibling step. */
  public static final int BIT_PRECEDING_SIBLING = (0x00001000 << 12);

  /** Bit is on if any of the walkers contain a self step. */
  public static final int BIT_SELF = (0x00001000 << 13);

  /**
   * Bit is on if any of the walkers contain a filter (i.e. id(), extension
   *  function, etc.) step.
   */
  public static final int BIT_FILTER = (0x00001000 << 14);

  /** Bit is on if any of the walkers contain a root step. */
  public static final int BIT_ROOT = (0x00001000 << 15);

  /**
   * If any of these bits are on, the expression may likely traverse outside
   *  the given subtree.
   */
  public static final int BITMASK_TRAVERSES_OUTSIDE_SUBTREE = (BIT_NAMESPACE  // ??
                                                                | BIT_PRECEDING_SIBLING
                                                                | BIT_PRECEDING
                                                                | BIT_FOLLOWING_SIBLING
                                                                | BIT_FOLLOWING
                                                                | BIT_PARENT  // except parent of attrs.
                                                                | BIT_ANCESTOR_OR_SELF
                                                                | BIT_ANCESTOR
                                                                | BIT_FILTER
                                                                | BIT_ROOT);

  /**
   * Bit is on if any of the walkers can go backwards in document
   *  order from the context node.
   */
  public static final int BIT_BACKWARDS_SELF = (0x00001000 << 16);

  /** Found "//foo" pattern */
  public static final int BIT_ANY_DESCENDANT_FROM_ROOT = (0x00001000 << 17);

  /**
   * Bit is on if any of the walkers contain an node() test.  This is
   *  really only useful if the count is 1.
   */
  public static final int BIT_NODETEST_ANY = (0x00001000 << 18);

  // can't go higher than 18!

  /** Bit is on if the expression is a match pattern. */
  public static final int BIT_MATCH_PATTERN = (0x00001000 << 19);
}