walkerfactory.java

来自「java jdk 1.4的源码」· Java 代码 · 共 1,871 行 · 第 1/5 页

      case OpCodes.FROM_NAMESPACE :
        analysisResult |= BIT_NAMESPACE;
        break;
      case OpCodes.FROM_CHILDREN :
        analysisResult |= BIT_CHILD;
        break;
      case OpCodes.FROM_DESCENDANTS :
        analysisResult |= BIT_DESCENDANT;
        break;
      case OpCodes.FROM_DESCENDANTS_OR_SELF :

        // Use a special bit to to make sure we get the right analysis of "//foo".
        if (2 == stepCount && BIT_ROOT == analysisResult)
        {
          analysisResult |= BIT_ANY_DESCENDANT_FROM_ROOT;
        }

        analysisResult |= BIT_DESCENDANT_OR_SELF;
        break;
      case OpCodes.FROM_FOLLOWING :
        analysisResult |= BIT_FOLLOWING;
        break;
      case OpCodes.FROM_FOLLOWING_SIBLINGS :
        analysisResult |= BIT_FOLLOWING_SIBLING;
        break;
      case OpCodes.FROM_PRECEDING :
        analysisResult |= BIT_PRECEDING;
        break;
      case OpCodes.FROM_PRECEDING_SIBLINGS :
        analysisResult |= BIT_PRECEDING_SIBLING;
        break;
      case OpCodes.FROM_PARENT :
        analysisResult |= BIT_PARENT;
        break;
      case OpCodes.FROM_SELF :
        analysisResult |= BIT_SELF;
        break;
      case OpCodes.MATCH_ATTRIBUTE :
        analysisResult |= (BIT_MATCH_PATTERN | BIT_ATTRIBUTE);
        break;
      case OpCodes.MATCH_ANY_ANCESTOR :
        analysisResult |= (BIT_MATCH_PATTERN | BIT_ANCESTOR);
        break;
      case OpCodes.MATCH_IMMEDIATE_ANCESTOR :
        analysisResult |= (BIT_MATCH_PATTERN | BIT_PARENT);
        break;
      default :
        throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NULL_ERROR_HANDLER, new Object[]{Integer.toString(stepType)})); //"Programmer's assertion: unknown opcode: "
                                   //+ stepType);
      }

      if (OpCodes.NODETYPE_NODE == compiler.getOp(stepOpCodePos + 3))  // child::node()
      {
        analysisResult |= BIT_NODETEST_ANY;
      }

      stepOpCodePos = compiler.getNextStepPos(stepOpCodePos);

      if (stepOpCodePos < 0)
        break;
    }

    analysisResult |= (stepCount & BITS_COUNT);

    return analysisResult;
  }
  
  /**
   * Tell if the given axis goes downword.  Bogus name, if you can think of 
   * a better one, please do tell.  This really has to do with inverting 
   * attribute axis.
   * @param axis One of Axis.XXX.
   * @return true if the axis is not a child axis and does not go up from 
   * the axis root.
   */
  public static boolean isDownwardAxisOfMany(int axis)
  {
    return ((Axis.DESCENDANTORSELF == axis) ||
          (Axis.DESCENDANT == axis) 
          || (Axis.FOLLOWING == axis) 
//          || (Axis.FOLLOWINGSIBLING == axis) 
          || (Axis.PRECEDING == axis) 
//          || (Axis.PRECEDINGSIBLING == axis)
          );
  }

  /**
   * Read a <a href="http://www.w3.org/TR/xpath#location-paths">LocationPath</a>
   * as a generalized match pattern.  What this means is that the LocationPath
   * is read backwards, as a test on a given node, to see if it matches the
   * criteria of the selection, and ends up at the context node.  Essentially,
   * this is a backwards query from a given node, to find the context node.
   * <p>So, the selection "foo/daz[2]" is, in non-abreviated expanded syntax,
   * "self::node()/following-sibling::foo/child::daz[position()=2]".
   * Taking this as a match pattern for a probable node, it works out to
   * "self::daz/parent::foo[child::daz[position()=2 and isPrevStepNode()]
   * precedingSibling::node()[isContextNodeOfLocationPath()]", adding magic
   * isPrevStepNode and isContextNodeOfLocationPath operations.  Predicates in
   * the location path have to be executed by the following step,
   * because they have to know the context of their execution.
   *
   * @param mpi The MatchPatternIterator to which the steps will be attached.
   * @param compiler The compiler that holds the syntax tree/op map to
   * construct from.
   * @param stepOpCodePos The current op code position within the opmap.
   * @param stepIndex The top-level step index withing the iterator.
   *
   * @return A StepPattern object, which may contain relative StepPatterns.
   *
   * @throws javax.xml.transform.TransformerException
   */
  static StepPattern loadSteps(
          MatchPatternIterator mpi, Compiler compiler, int stepOpCodePos, 
                                                       int stepIndex)
            throws javax.xml.transform.TransformerException
  {
    if (DEBUG_PATTERN_CREATION)
    {
      System.out.println("================");
      System.out.println("loadSteps for: "+compiler.getPatternString());
    }
    int stepType;
    StepPattern step = null;
    StepPattern firstStep = null, prevStep = null;
    int analysis = analyze(compiler, stepOpCodePos, stepIndex);

    while (OpCodes.ENDOP != (stepType = compiler.getOp(stepOpCodePos)))
    {
      step = createDefaultStepPattern(compiler, stepOpCodePos, mpi, analysis,
                                      firstStep, prevStep);

      if (null == firstStep)
      {
        firstStep = step;
      }
      else
      {

        //prevStep.setNextWalker(step);
        step.setRelativePathPattern(prevStep);
      }

      prevStep = step;
      stepOpCodePos = compiler.getNextStepPos(stepOpCodePos);

      if (stepOpCodePos < 0)
        break;
    }
    
    int axis = Axis.SELF;
    int paxis = Axis.SELF;
    StepPattern tail = step;
    for (StepPattern pat = step; null != pat; 
         pat = pat.getRelativePathPattern()) 
    {
      int nextAxis = pat.getAxis();
      //int nextPaxis = pat.getPredicateAxis();
      pat.setAxis(axis);
      
      // The predicate axis can't be moved!!!  Test Axes103
      // pat.setPredicateAxis(paxis);
      
      // If we have an attribute or namespace axis that went up, then 
      // it won't find the attribute in the inverse, since the select-to-match
      // axes are not invertable (an element is a parent of an attribute, but 
      // and attribute is not a child of an element).
      // If we don't do the magic below, then "@*/ancestor-or-self::*" gets
      // inverted for match to "self::*/descendant-or-self::@*/parent::node()",
      // which obviously won't work.
      // So we will rewrite this as:
      // "self::*/descendant-or-self::*/attribute::*/parent::node()"
      // Child has to be rewritten a little differently:
      // select: "@*/parent::*"
      // inverted match: "self::*/child::@*/parent::node()"
      // rewrite: "self::*/attribute::*/parent::node()"
      // Axes that go down in the select, do not have to have special treatment 
      // in the rewrite. The following inverted match will still not select 
      // anything.
      // select: "@*/child::*"
      // inverted match: "self::*/parent::@*/parent::node()"
      // Lovely business, this.
      // -sb
      int whatToShow = pat.getWhatToShow();
      if(whatToShow == DTMFilter.SHOW_ATTRIBUTE || 
         whatToShow == DTMFilter.SHOW_NAMESPACE)
      {
        int newAxis = (whatToShow == DTMFilter.SHOW_ATTRIBUTE) ? 
                       Axis.ATTRIBUTE : Axis.NAMESPACE;
        if(isDownwardAxisOfMany(axis))
        {
          StepPattern attrPat = new StepPattern(whatToShow, 
                                    pat.getNamespace(),
                                    pat.getLocalName(),
                                //newAxis, pat.getPredicateAxis);
                                                newAxis, 0); // don't care about the predicate axis
          XNumber score = pat.getStaticScore();
          pat.setNamespace(null);
          pat.setLocalName(NodeTest.WILD);
          attrPat.setPredicates(pat.getPredicates());
          pat.setPredicates(null);
          pat.setWhatToShow(DTMFilter.SHOW_ELEMENT);
          StepPattern rel = pat.getRelativePathPattern();
          pat.setRelativePathPattern(attrPat);
          attrPat.setRelativePathPattern(rel);
          attrPat.setStaticScore(score);
          
          // This is needed to inverse a following pattern, because of the 
          // wacky Xalan rules for following from an attribute.  See axes108.
          // By these rules, following from an attribute is not strictly 
          // inverseable.
          if(Axis.PRECEDING == pat.getAxis())
            pat.setAxis(Axis.PRECEDINGANDANCESTOR);
            
          else if(Axis.DESCENDANT == pat.getAxis())
            pat.setAxis(Axis.DESCENDANTORSELF);
          
          pat = attrPat;
        }
        else if(Axis.CHILD == pat.getAxis())
        {
          // In this case just change the axis.
          // pat.setWhatToShow(whatToShow);
          pat.setAxis(Axis.ATTRIBUTE);
        }
      }
      axis = nextAxis;
      //paxis = nextPaxis;
      tail = pat;
    }
    
    if(axis < Axis.ALL)
    {
      StepPattern selfPattern = new ContextMatchStepPattern(axis, paxis);
      // We need to keep the new nodetest from affecting the score...
      XNumber score = tail.getStaticScore();
      tail.setRelativePathPattern(selfPattern);
      tail.setStaticScore(score);
      selfPattern.setStaticScore(score);
    }        

    if (DEBUG_PATTERN_CREATION)
    {
      System.out.println("Done loading steps: "+step.toString());
            
      System.out.println("");
    }
    return step;  // start from last pattern?? //firstStep;
  }

  /**
   * Create a StepPattern that is contained within a LocationPath.
   *
   *
   * @param compiler The compiler that holds the syntax tree/op map to
   * construct from.
   * @param stepOpCodePos The current op code position within the opmap.
   * @param mpi The MatchPatternIterator to which the steps will be attached.
   * @param analysis 32 bits of analysis, from which the type of AxesWalker
   *                 may be influenced.
   * @param tail The step that is the first step analyzed, but the last 
   *                  step in the relative match linked list, i.e. the tail.
   *                  May be null.
   * @param head The step that is the current head of the relative 
   *                 match step linked list.
   *                 May be null.
   *
   * @return the head of the list.
   *
   * @throws javax.xml.transform.TransformerException
   */
  private static StepPattern createDefaultStepPattern(
          Compiler compiler, int opPos, MatchPatternIterator mpi, 
          int analysis, StepPattern tail, StepPattern head)
            throws javax.xml.transform.TransformerException
  {

    int stepType = compiler.getOp(opPos);
    boolean simpleInit = false;
    int totalNumberWalkers = (analysis & BITS_COUNT);
    boolean prevIsOneStepDown = true;
    int firstStepPos = compiler.getFirstChildPos(opPos);
    
    int whatToShow = compiler.getWhatToShow(opPos);
    StepPattern ai = null;
    int axis, predicateAxis;
    
    switch (stepType)
    {
    case OpCodes.OP_VARIABLE :
    case OpCodes.OP_EXTFUNCTION :
    case OpCodes.OP_FUNCTION :
    case OpCodes.OP_GROUP :
      prevIsOneStepDown = false;

      Expression expr;

      switch (stepType)
      {
      case OpCodes.OP_VARIABLE :
      case OpCodes.OP_EXTFUNCTION :
      case OpCodes.OP_FUNCTION :
      case OpCodes.OP_GROUP :
        expr = compiler.compile(opPos);
        break;
      default :
        expr = compiler.compile(opPos + 2);
      }

      axis = Axis.FILTEREDLIST;
      predicateAxis = Axis.FILTEREDLIST;
      ai = new FunctionPattern(expr, axis, predicateAxis);
      simpleInit = true;
      break;
    case OpCodes.FROM_ROOT :
      whatToShow = DTMFilter.SHOW_DOCUMENT
                   | DTMFilter.SHOW_DOCUMENT_FRAGMENT;

      axis = Axis.ROOT;
      predicateAxis = Axis.ROOT;
      ai = new StepPattern(DTMFilter.SHOW_DOCUMENT | 
                                DTMFilter.SHOW_DOCUMENT_FRAGMENT,
                                axis, predicateAxis);
      break;
    case OpCodes.FROM_ATTRIBUTES :
      whatToShow = DTMFilter.SHOW_ATTRIBUTE;
      axis = Axis.PARENT;
      predicateAxis = Axis.ATTRIBUTE;
      // ai = new StepPattern(whatToShow, Axis.SELF, Axis.SELF);
      break;
    case OpCodes.FROM_NAMESPACE :
      whatToShow = DTMFilter.SHOW_NAMESPACE;
      axis = Axis.PARENT;
      predicateAxis = Axis.NAMESPACE;
      // ai = new StepPattern(whatToShow, axis, predicateAxis);
      break;
    case OpCodes.FROM_ANCESTORS :
      axis = Axis.DESCENDANT;
      predicateAxis = Axis.ANCESTOR;
      break;
    case OpCodes.FROM_CHILDREN :
      axis = Axis.PARENT;
      predicateAxis = Axis.CHILD;
      break;
    case OpCodes.FROM_ANCESTORS_OR_SELF :
      axis = Axis.DESCENDANTORSELF;
      predicateAxis = Axis.ANCESTORORSELF;
      break;
    case OpCodes.FROM_SELF :
      axis = Axis.SELF;
      predicateAxis = Axis.SELF;
      break;
    case OpCodes.FROM_PARENT :
      axis = Axis.CHILD;
      predicateAxis = Axis.PARENT;
      break;
    case OpCodes.FROM_PRECEDING_SIBLINGS :
      axis = Axis.FOLLOWINGSIBLING;
      predicateAxis = Axis.PRECEDINGSIBLING;
      break;
    case OpCodes.FROM_PRECEDING :
      axis = Axis.FOLLOWING;
      predicateAxis = Axis.PRECEDING;
      break;
    case OpCodes.FROM_FOLLOWING_SIBLINGS :
      axis = Axis.PRECEDINGSIBLING;
      predicateAxis = Axis.FOLLOWINGSIBLING;
      break;
    case OpCodes.FROM_FOLLOWING :
      axis = Axis.PRECEDING;
      predicateAxis = Axis.FOLLOWING;
      break;
    case OpCodes.FROM_DESCENDANTS_OR_SELF :
      axis = Axis.ANCESTORORSELF;
      predicateAxis = Axis.DESCENDANTORSELF;
      break;