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/*
 * $Header: /cvs/jaxen/jaxen/src/java/main/org/jaxen/JaxenHandler.java,v 1.15 2006/03/30 13:53:11 elharo Exp $
 * $Revision: 1.15 $
 * $Date: 2006/03/30 13:53:11 $
 *
 * ====================================================================
 *
 * Copyright 2000-2002 bob mcwhirter & James Strachan.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 
 *   * Neither the name of the Jaxen Project nor the names of its
 *     contributors may be used to endorse or promote products derived 
 *     from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * ====================================================================
 * This software consists of voluntary contributions made by many 
 * individuals on behalf of the Jaxen Project and was originally 
 * created by bob mcwhirter  and 
 * James Strachan .  For more information on the 
 * Jaxen Project, please see .
 * 
 * $Id: JaxenHandler.java,v 1.15 2006/03/30 13:53:11 elharo Exp $
 */



package org.navimatrix.jaxen;

import java.util.Iterator;
import java.util.LinkedList;

import org.navimatrix.jaxen.expr.DefaultXPathFactory;
import org.navimatrix.jaxen.expr.Expr;
import org.navimatrix.jaxen.expr.FilterExpr;
import org.navimatrix.jaxen.expr.FunctionCallExpr;
import org.navimatrix.jaxen.expr.LocationPath;
import org.navimatrix.jaxen.expr.Predicate;
import org.navimatrix.jaxen.expr.Predicated;
import org.navimatrix.jaxen.expr.Step;
import org.navimatrix.jaxen.expr.XPathExpr;
import org.navimatrix.jaxen.expr.XPathFactory;
import org.navimatrix.jaxen.saxpath.Operator;
import org.navimatrix.jaxen.saxpath.XPathHandler;

/** SAXPath XPathHandler implementation capable
 *  of building Jaxen expression trees which can walk various
 *  different object models.
 *
 *  @author bob mcwhirter ([email protected])
 */
public class JaxenHandler implements XPathHandler
{
    private XPathFactory xpathFactory;
    private XPathExpr    xpath;
    
    /**
     * ????
     */
    protected boolean simplified;

    /**
     * This may be changed to an ArrayList in the future (i.e. version >= 1.2). 
     * You really shouldn't be accessing this field directly, but
     * if you are please try to use it as a generic List. Don't use the 
     * methods that are only available in LinkedList.
     */
    protected LinkedList stack;

    /** Constructor
     */
    public JaxenHandler()
    {
        this.stack        = new LinkedList();
        this.xpathFactory = new DefaultXPathFactory();
    }
    
    /** Set the Jaxen XPathFactory that constructs
     *  the XPath expression tree during the parse.
     *
     *  @param xpathFactory the factory to use during the parse
     */
    public void setXPathFactory(XPathFactory xpathFactory)
    {
        this.xpathFactory = xpathFactory;
    }

    /** Retrieve the Jaxen XPathFactory used
     *  during the parse to construct the XPath expression tree.
     *
     *  @return the XPathFactory used during the parse.
     */
    public XPathFactory getXPathFactory()
    {
        return this.xpathFactory;
    }

    /** Retrieve the simplified Jaxen XPath expression tree.
     *
     *  

* This method is only valid once XPathReader.parse(...) * successfully returned. *

* * @return the XPath expression tree */ public XPathExpr getXPathExpr() { return getXPathExpr( true ); } /** Retrieve the Jaxen XPath expression tree, optionally * simplified. * *

* This method is only valid once XPathReader.parse(...) * successfully returned. *

* * @param shouldSimplify ???? * * @return the XPath expression tree */ public XPathExpr getXPathExpr(boolean shouldSimplify) { if ( shouldSimplify && ! this.simplified ) { this.xpath.simplify(); this.simplified = true; } return this.xpath; } public void startXPath() { this.simplified = false; pushFrame(); } public void endXPath() throws JaxenException { this.xpath = getXPathFactory().createXPath( (Expr) pop() ); popFrame(); } public void startPathExpr() { pushFrame(); } public void endPathExpr() throws JaxenException { // PathExpr ::= LocationPath // | FilterExpr // | FilterExpr / RelativeLocationPath // | FilterExpr // RelativeLocationPath // // If the current stack-frame has two items, it's a // FilterExpr and a LocationPath (of some flavor). // // If the current stack-frame has one item, it's simply // a FilterExpr, and more than likely boils down to a // primary expr of some flavor. But that's for another // method... FilterExpr filterExpr; LocationPath locationPath; Object popped; if ( stackSize() == 2 ) { locationPath = (LocationPath) pop(); filterExpr = (FilterExpr) pop(); } else { popped = pop(); if ( popped instanceof LocationPath ) { locationPath = (LocationPath) popped; filterExpr = null; } else { locationPath = null; filterExpr = (FilterExpr) popped; } } popFrame(); push( getXPathFactory().createPathExpr( filterExpr, locationPath ) ); } public void startAbsoluteLocationPath() throws JaxenException { pushFrame(); push( getXPathFactory().createAbsoluteLocationPath() ); } public void endAbsoluteLocationPath() throws JaxenException { endLocationPath(); } public void startRelativeLocationPath() throws JaxenException { pushFrame(); push( getXPathFactory().createRelativeLocationPath() ); } public void endRelativeLocationPath() throws JaxenException { endLocationPath(); } protected void endLocationPath() throws JaxenException { LocationPath path = (LocationPath) peekFrame().removeFirst(); addSteps( path, popFrame().iterator() ); push( path ); } protected void addSteps(LocationPath locationPath, Iterator stepIter) { while ( stepIter.hasNext() ) { locationPath.addStep( (Step) stepIter.next() ); } } public void startNameStep(int axis, String prefix, String localName) throws JaxenException { pushFrame(); push( getXPathFactory().createNameStep( axis, prefix, localName ) ); } public void endNameStep() { endStep(); } public void startTextNodeStep(int axis) throws JaxenException { //System.err.println("startTextNodeStep()"); pushFrame(); push( getXPathFactory().createTextNodeStep( axis ) ); } public void endTextNodeStep() { endStep(); } public void startCommentNodeStep(int axis) throws JaxenException { pushFrame(); push( getXPathFactory().createCommentNodeStep( axis ) ); } public void endCommentNodeStep() { endStep(); } public void startAllNodeStep(int axis) throws JaxenException { pushFrame(); push( getXPathFactory().createAllNodeStep( axis ) ); } public void endAllNodeStep() { endStep(); } public void startProcessingInstructionNodeStep(int axis, String name) throws JaxenException { pushFrame(); push( getXPathFactory().createProcessingInstructionNodeStep( axis, name ) ); } public void endProcessingInstructionNodeStep() { endStep(); } protected void endStep() { Step step = (Step) peekFrame().removeFirst(); addPredicates( step, popFrame().iterator() ); push( step ); } public void startPredicate() { pushFrame(); } public void endPredicate() throws JaxenException { Predicate predicate = getXPathFactory().createPredicate( (Expr) pop() ); popFrame(); push( predicate ); } public void startFilterExpr() { pushFrame(); } public void endFilterExpr() throws JaxenException { Expr expr = (Expr) peekFrame().removeFirst(); FilterExpr filter = getXPathFactory().createFilterExpr( expr ); Iterator predIter = popFrame().iterator(); addPredicates( filter, predIter ); push( filter ); } protected void addPredicates(Predicated obj, Iterator predIter) { while ( predIter.hasNext() ) { obj.addPredicate( (Predicate) predIter.next() ); } } protected void returnExpr() { Expr expr = (Expr) pop(); popFrame(); push( expr ); } public void startOrExpr() { } public void endOrExpr(boolean create) throws JaxenException { if ( create ) { Expr rhs = (Expr) pop(); Expr lhs = (Expr) pop(); push( getXPathFactory().createOrExpr( lhs, rhs ) ); } } public void startAndExpr() { } public void endAndExpr(boolean create) throws JaxenException { if ( create ) { Expr rhs = (Expr) pop(); Expr lhs = (Expr) pop(); push( getXPathFactory().createAndExpr( lhs, rhs ) ); } } public void startEqualityExpr() { } public void endEqualityExpr(int operator) throws JaxenException { if ( operator != Operator.NO_OP ) { Expr rhs = (Expr) pop(); Expr lhs = (Expr) pop(); push( getXPathFactory().createEqualityExpr( lhs, rhs, operator ) ); } } public void startRelationalExpr() { } public void endRelationalExpr(int operator) throws JaxenException { if ( operator != Operator.NO_OP ) { Expr rhs = (Expr) pop(); Expr lhs = (Expr) pop(); push( getXPathFactory().createRelationalExpr( lhs, rhs, operator ) ); } } public void startAdditiveExpr() { } public void endAdditiveExpr(int operator) throws JaxenException { if ( operator != Operator.NO_OP ) { Expr rhs = (Expr) pop(); Expr lhs = (Expr) pop(); push( getXPathFactory().createAdditiveExpr( lhs, rhs, operator ) ); } } public void startMultiplicativeExpr() { } public void endMultiplicativeExpr(int operator) throws JaxenException { if ( operator != Operator.NO_OP ) { Expr rhs = (Expr) pop(); Expr lhs = (Expr) pop(); push( getXPathFactory().createMultiplicativeExpr( lhs, rhs, operator ) ); } } public void startUnaryExpr() { } public void endUnaryExpr(int operator) throws JaxenException { if ( operator != Operator.NO_OP ) { push( getXPathFactory().createUnaryExpr( (Expr) pop(), operator ) ); } } public void startUnionExpr() { } public void endUnionExpr(boolean create) throws JaxenException { if ( create ) { Expr rhs = (Expr) pop(); Expr lhs = (Expr) pop(); push( getXPathFactory().createUnionExpr( lhs, rhs ) ); } } public void number(int number) throws JaxenException { push( getXPathFactory().createNumberExpr( number ) ); } public void number(double number) throws JaxenException { push( getXPathFactory().createNumberExpr( number ) ); } public void literal(String literal) throws JaxenException { push( getXPathFactory().createLiteralExpr( literal ) ); } public void variableReference(String prefix, String variableName) throws JaxenException { push( getXPathFactory().createVariableReferenceExpr( prefix, variableName ) ); } public void startFunction(String prefix, String functionName) throws JaxenException { pushFrame(); push( getXPathFactory().createFunctionCallExpr( prefix, functionName ) ); } public void endFunction() { FunctionCallExpr function = (FunctionCallExpr) peekFrame().removeFirst(); addParameters( function, popFrame().iterator() ); push( function ); } protected void addParameters(FunctionCallExpr function, Iterator paramIter) { while ( paramIter.hasNext() ) { function.addParameter( (Expr) paramIter.next() ); } } protected int stackSize() { return peekFrame().size(); } protected void push(Object obj) { peekFrame().addLast( obj ); } protected Object pop() { return peekFrame().removeLast(); } protected boolean canPop() { return ( peekFrame().size() > 0 ); } protected void pushFrame() { this.stack.addLast( new LinkedList() ); } protected LinkedList popFrame() { return (LinkedList) this.stack.removeLast(); } protected LinkedList peekFrame() { return (LinkedList) this.stack.getLast(); } }




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