[graphl-cvs] graphl/src/org/jaxen/expr DefaultRelativeLocationPath.java

[Flo L. <fl...@us...>]

Update of /cvsroot/graphl/graphl/src/org/jaxen/expr
In directory sc8-pr-cvs2.sourceforge.net:/tmp/cvs-serv16361/src/org/jaxen/expr

Added Files:
	DefaultRelativeLocationPath.java 
Log Message:
backup commit - first implementation of xpath-based structural filters

--- NEW FILE: DefaultRelativeLocationPath.java ---
/*
 * Created on 10.07.2006
 */

package org.jaxen.expr;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.jaxen.Context;
import org.jaxen.ContextSupport;
import org.jaxen.JaxenException;
import org.jaxen.util.SingletonList;
import org.mediavirus.graphl.jaxen.DocumentNavigator;
import org.mediavirus.graphl.jaxen.GraphlContext;


public class DefaultRelativeLocationPath extends DefaultLocationPath {


    public String toString()
    {
        return "[(DefaultRelativeLocationPath): " + super.toString() + "]";
    }
    
    public void accept(Visitor visitor)
    {
        visitor.visit(this);
    }
    
    public Object evaluate(Context context) throws JaxenException
    {
        List nodeSet = context.getNodeSet();
        List contextNodeSet = new ArrayList(nodeSet);
        ContextSupport support = context.getContextSupport();
        Context stepContext = new Context(support);
        if (!(context instanceof GraphlContext)) {
            Iterator stepIter = getSteps().iterator();
            while ( stepIter.hasNext() )
            {
                Step eachStep = (Step) stepIter.next();
                
                List results = new ArrayList();
                for (Object o : contextNodeSet) {                
                    stepContext.setNodeSet(new SingletonList(o));
                    List result = eachStep.evaluate(stepContext);
                    results.addAll(result);
                    
                    if (support.getNavigator() instanceof org.mediavirus.graphl.jaxen.DocumentNavigator) {
                        ((DocumentNavigator)support.getNavigator()).visit(eachStep, o, result);
                    }
                }
                contextNodeSet = results;
                // now we need to reverse the list if this is a reverse axis
                if (isReverseAxis(eachStep)) {
                    Collections.reverse(contextNodeSet);
                }
                
            }
            
            if (getSteps().size() > 1) {
                Collections.sort(contextNodeSet, new NodeComparator(support.getNavigator()));
            }
            return contextNodeSet;
        }
        else {
            stepContext.setNodeSet(contextNodeSet);
            return doStep(getSteps(), 0, stepContext);
        }
        
    }
    
    /**
     * Recursively performs stepping through the path, returning all paths that were leading to an end node.
     * @param pathSoFar
     * @param stepIter
     * @param stepContext
     * @return A List of Lists, containing the successful paths (the result node is at the end)
     */
    protected List doStep(List steps, int stepnum, Context stepContext) throws JaxenException{
        if (stepnum < steps.size()) {
            Step currentStep = (Step) steps.get(stepnum++);
            List results = new ArrayList();
            List nextContext = currentStep.evaluate(stepContext); 
            for (Object o : nextContext) {
                // this selects the nodes for the next step
                stepContext.setNodeSet(new SingletonList(o));
                // this returns a list of lists, the paths to end nodes
                List result = doStep(steps, stepnum, stepContext);
                for (Object o2 : result) {
                    List path = (List)o2;
                    path.add(0,o);
                }
                results.addAll(result);                
            }
            return results;
        }
        else {
            // we are at the end of the path - just create the list for filling in the results from the callers
            List results = new ArrayList();
            results.add(new ArrayList());
            return results;
        }
    }
    
    private boolean isReverseAxis(Step step) {

        int axis = step.getAxis();
        return axis == org.jaxen.saxpath.Axis.PRECEDING
          || axis == org.jaxen.saxpath.Axis.PRECEDING_SIBLING
          || axis == org.jaxen.saxpath.Axis.ANCESTOR
          || axis == org.jaxen.saxpath.Axis.ANCESTOR_OR_SELF;
    }

}