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/* ====================================================================
 * 
 * The ObjectStyle Group Software License, version 1.1
 * ObjectStyle Group - http://objectstyle.org/
 * 
 * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
 * of the software. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 
 * 2. 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.
 * 
 * 3. The end-user documentation included with the redistribution, if any,
 *    must include the following acknowlegement:
 *    "This product includes software developed by independent contributors
 *    and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 * 
 * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
 *    or promote products derived from this software without prior written
 *    permission. For written permission, email
 *    "andrus at objectstyle dot org".
 * 
 * 5. Products derived from this software may not be called "ObjectStyle"
 *    or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
 *    names without prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 OBJECTSTYLE GROUP OR
 * ITS 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 and hosted on ObjectStyle Group web site.  For more
 * information on the ObjectStyle Group, please see
 * .
 */
package org.objectstyle.cayenne.exp.parser;

import java.io.PrintWriter;
import java.util.Map;

import org.objectstyle.cayenne.DataObject;
import org.objectstyle.cayenne.ObjectId;
import org.objectstyle.cayenne.exp.Expression;
import org.objectstyle.cayenne.map.Entity;

/**
 * Path expression traversing DB relationships and attributes.
 * 
 * @since 1.1
 * @author Andrei Adamchik
 */
public class ASTDbPath extends ASTPath {
    ASTDbPath(int id) {
        super(id);
    }

    public ASTDbPath() {
        super(ExpressionParserTreeConstants.JJTDBPATH);
    }

    public ASTDbPath(Object value) {
        super(ExpressionParserTreeConstants.JJTDBPATH);
        setPath(value);
    }

    protected Object evaluateNode(Object o) throws Exception {
        // TODO: implement resolving DB_PATH for DataObjects

        if (o instanceof Entity) {
            return evaluateEntityNode((Entity) o);
        }

        Map map = toMap(o);
        return (map != null) ? map.get(path) : null;
    }

    protected Map toMap(Object o) {
        if (o instanceof Map) {
            return (Map) o;
        }
        else if (o instanceof ObjectId) {
            return ((ObjectId) o).getIdSnapshot();
        }
        else if (o instanceof DataObject) {
            DataObject dataObject = (DataObject) o;

            // TODO: returns ObjectId snapshot for now.. should probably
            // retrieve full snapshot...
            ObjectId oid = dataObject.getObjectId();
            return (oid != null) ? oid.getIdSnapshot() : null;
        }
        else {
            return null;
        }
    }

    /**
     * Creates a copy of this expression node, without copying children.
     */
    public Expression shallowCopy() {
        ASTDbPath copy = new ASTDbPath(id);
        copy.path = path;
        return copy;
    }

    public void encodeAsString(PrintWriter pw) {
        pw.print("db:");
        pw.print(path);
    }

    public int getType() {
        return Expression.DB_PATH;
    }
}