defaultfilterexpr.java

XML的解析、编译、查询等技术的JAVA源代码。

/*
 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/DefaultFilterExpr.java,v 1.19 2006/11/30 18:49:26 elharo Exp $
 * $Revision: 1.19 $
 * $Date: 2006/11/30 18:49:26 $
 *
 * ====================================================================
 *
 * 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 <[e-mail]> and 
 * James Strachan <[e-mail]>.  For more information on the 
 * Jaxen Project, please see <http://www.jaxen.org/>.
 * 
 * $Id: DefaultFilterExpr.java,v 1.19 2006/11/30 18:49:26 elharo Exp $
 */



package org.jaxen.expr;

import java.util.ArrayList;
import java.util.List;
import org.jaxen.Context;
import org.jaxen.JaxenException;

/**
 * @deprecated this class will become non-public in the future;
 *     use the interface instead
 */
public class DefaultFilterExpr extends DefaultExpr implements FilterExpr, Predicated
{
    /**
     * 
     */
    private static final long serialVersionUID = -549640659288005735L;
    private Expr expr;
    private PredicateSet predicates;

    public DefaultFilterExpr(PredicateSet predicateSet)
    {
        this.predicates = predicateSet;
    }

    public DefaultFilterExpr(Expr expr, PredicateSet predicateSet)
    {
        this.expr       = expr;
        this.predicates = predicateSet;
    }

    public void addPredicate(Predicate predicate)
    {
        this.predicates.addPredicate( predicate );
    }

    public List getPredicates()
    {
        return this.predicates.getPredicates();
    }

    public PredicateSet getPredicateSet()
    {
        return this.predicates;
    }

    public Expr getExpr()
    {
        return this.expr;
    }

    public String toString()
    {
        return "[(DefaultFilterExpr): expr: " + expr + " predicates: " + predicates + " ]";
    }

    public String getText()
    {
        String text = "";
        if ( this.expr != null )
        {
            text = this.expr.getText();
        }
        text += predicates.getText();
        return text;
    }

    public Expr simplify()
    {
        this.predicates.simplify();

        if ( this.expr != null ) 
        {
            this.expr = this.expr.simplify();
        }

        if ( this.predicates.getPredicates().size() == 0 )
        {
            return getExpr();
        }

        return this;
    }

    /** Returns true if the current filter matches at least one of the context nodes
     */
    public boolean asBoolean(Context context) throws JaxenException 
    {
        Object results = null;
        if ( expr != null ) 
        {
            results = expr.evaluate( context );
        }
        else
        {
            List nodeSet = context.getNodeSet();
            ArrayList list = new ArrayList(nodeSet.size());
            list.addAll( nodeSet );
            results = list;
        }
        
        if ( results instanceof Boolean ) 
        {
            Boolean b = (Boolean) results;
            return b.booleanValue();
        }
        if ( results instanceof List )
        {
            return getPredicateSet().evaluateAsBoolean( 
                (List) results, context.getContextSupport() 
            );
        }
        
        return false;
    }
    
    public Object evaluate(Context context) throws JaxenException
    {
        Object results = getExpr().evaluate( context );
        
        if ( results instanceof List )
        {
            List newresults = getPredicateSet().evaluatePredicates( (List) results,
                                    context.getContextSupport() );
        results = newresults;
        }

        return results;
    }

}