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WalkingIterator.javaAPI DocJava SE 6 API9577Tue Jun 10 00:23:14 BST 2008com.sun.org.apache.xpath.internal.axes

WalkingIterator

public class WalkingIterator extends LocPathIterator implements ExpressionOwner
Location path iterator that uses Walkers.

Fields Summary
static final long
serialVersionUID
protected AxesWalker
m_lastUsedWalker
The last used step walker in the walker list.
protected AxesWalker
m_firstWalker
The head of the step walker list.
Constructors Summary
WalkingIterator(Compiler compiler, int opPos, int analysis, boolean shouldLoadWalkers)
Create a WalkingIterator iterator, including creation of step walkers from the opcode list, and call back into the Compiler to create predicate expressions.

param
compiler The Compiler which is creating this expression.
param
opPos The position of this iterator in the opcode list from the compiler.
param
shouldLoadWalkers True if walkers should be loaded, or false if this is a derived iterator and it doesn't wish to load child walkers.
throws
javax.xml.transform.TransformerException

                                                                             
  
                 
             
  
    super(compiler, opPos, analysis, shouldLoadWalkers);
    
    int firstStepPos = compiler.getFirstChildPos(opPos);

    if (shouldLoadWalkers)
    {
      m_firstWalker = WalkerFactory.loadWalkers(this, compiler, firstStepPos, 0);
      m_lastUsedWalker = m_firstWalker;
    }
public WalkingIterator(PrefixResolver nscontext)
Create a WalkingIterator object.

param
nscontext The namespace context for this iterator, should be OK if null.


    super(nscontext);
Methods Summary
public voidcallVisitors(com.sun.org.apache.xpath.internal.ExpressionOwner owner, com.sun.org.apache.xpath.internal.XPathVisitor visitor)

see
com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)

  	 	if(visitor.visitLocationPath(owner, this))
  	 	{
  	 		if(null != m_firstWalker)
  	 		{
  	 			m_firstWalker.callVisitors(this, visitor);
  	 		}
  	 	}
public java.lang.Objectclone()
Get a cloned WalkingIterator that holds the same position as this iterator.

return
A clone of this iterator that holds the same node position.
throws
CloneNotSupportedException


    WalkingIterator clone = (WalkingIterator) super.clone();

    //    clone.m_varStackPos = this.m_varStackPos;
    //    clone.m_varStackContext = this.m_varStackContext;
    if (null != m_firstWalker)
    {
      clone.m_firstWalker = m_firstWalker.cloneDeep(clone, null);
    }

    return clone;
public booleandeepEquals(com.sun.org.apache.xpath.internal.Expression expr)

see
Expression#deepEquals(Expression)

      if (!super.deepEquals(expr))
                return false;

      AxesWalker walker1 = m_firstWalker;
      AxesWalker walker2 = ((WalkingIterator)expr).m_firstWalker;
      while ((null != walker1) && (null != walker2))
      {
        if(!walker1.deepEquals(walker2))
        	return false;
        walker1 = walker1.getNextWalker();
        walker2 = walker2.getNextWalker();
      }
      
      if((null != walker1) || (null != walker2))
      	return false;

      return true;
public voiddetach()
Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. Afterdetach has been invoked, calls to nextNode orpreviousNode will raise the exception INVALID_STATE_ERR.

   
    if(m_allowDetach)
    {
	  	AxesWalker walker = m_firstWalker; 
	    while (null != walker)
	    {
	      walker.detach();
	      walker = walker.getNextWalker();
	    }
	
	    m_lastUsedWalker = null;
	    
	    // Always call the superclass detach last!
	    super.detach();
    }
public voidfixupVariables(java.util.Vector vars, int globalsSize)
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).

    m_predicateIndex = -1;

    AxesWalker walker = m_firstWalker;

    while (null != walker)
    {
      walker.fixupVariables(vars, globalsSize);
      walker = walker.getNextWalker();
    }
public intgetAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.

return
One of WalkerFactory#BIT_DESCENDANT, etc.

    int bits = 0;
    if (null != m_firstWalker)
    {    	
      AxesWalker walker = m_firstWalker;

      while (null != walker)
      {
        int bit = walker.getAnalysisBits();
        bits |= bit;
        walker = walker.getNextWalker();
      }       
    }
    return bits;
public com.sun.org.apache.xpath.internal.ExpressiongetExpression()

see
ExpressionOwner#getExpression()

    return m_firstWalker;
public final com.sun.org.apache.xpath.internal.axes.AxesWalkergetFirstWalker()
Get the head of the walker list.

return
The head of the walker list, or null if this iterator does not implement walkers.
xsl.usage
advanced

    return m_firstWalker;
public final com.sun.org.apache.xpath.internal.axes.AxesWalkergetLastUsedWalker()
Get the last used walker.

return
The last used walker, or null.
xsl.usage
advanced

    return m_lastUsedWalker;
public intnextNode()
Returns the next node in the set and advances the position of the iterator in the set. After a NodeIterator is created, the first call to nextNode() returns the first node in the set.

return
The next Node in the set being iterated over, or null if there are no more members in that set.

  	if(m_foundLast)
  		return DTM.NULL;

    // If the variable stack position is not -1, we'll have to 
    // set our position in the variable stack, so our variable access 
    // will be correct.  Iterators that are at the top level of the 
    // expression need to reset the variable stack, while iterators 
    // in predicates do not need to, and should not, since their execution
    // may be much later than top-level iterators.  
    // m_varStackPos is set in setRoot, which is called 
    // from the execute method.
    if (-1 == m_stackFrame)
    {
      return returnNextNode(m_firstWalker.nextNode());
    }
    else
    {
      VariableStack vars = m_execContext.getVarStack();

      // These three statements need to be combined into one operation.
      int savedStart = vars.getStackFrame();

      vars.setStackFrame(m_stackFrame);

      int n = returnNextNode(m_firstWalker.nextNode());

      // These two statements need to be combined into one operation.
      vars.setStackFrame(savedStart);

      return n;
    }
public voidreset()
Reset the iterator.


    super.reset();

    if (null != m_firstWalker)
    {
      m_lastUsedWalker = m_firstWalker;

      m_firstWalker.setRoot(m_context);
    }
public voidsetExpression(com.sun.org.apache.xpath.internal.Expression exp)

see
ExpressionOwner#setExpression(Expression)

  	exp.exprSetParent(this);
  	m_firstWalker = (AxesWalker)exp;
public final voidsetFirstWalker(com.sun.org.apache.xpath.internal.axes.AxesWalker walker)
Set the head of the walker list.

param
walker Should be a valid AxesWalker.
xsl.usage
advanced

    m_firstWalker = walker;
public final voidsetLastUsedWalker(com.sun.org.apache.xpath.internal.axes.AxesWalker walker)
Set the last used walker.

param
walker The last used walker, or null.
xsl.usage
advanced

    m_lastUsedWalker = walker;
public voidsetRoot(int context, java.lang.Object environment)
Initialize the context values for this expression after it is cloned.

param
context The XPath runtime context for this transformation.


    super.setRoot(context, environment);
    
    if(null != m_firstWalker)
    {
      m_firstWalker.setRoot(context);
      m_lastUsedWalker = m_firstWalker;
    }