/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */
package org.apache.openjpa.kernel.exps;

import org.apache.openjpa.meta.FieldMetaData;
import org.apache.openjpa.meta.XMLMetaData;

/**
 * A path represents a traversal into fields of a candidate object.
 * Equivalent paths should compare equal.
 *
 * @author Abe White
 */
public interface Path
    extends Value {

    /**
     * Traverse into the given field of the current object, and update
     * the current object to that field value.
     *
     * @param nullTraversal if true, allow traversal through a null field
     */
    public void get(FieldMetaData field, boolean nullTraversal);

    /**
     * Return the last field in the path, or null if the path does not
     * not contain a final field.
     */
    public FieldMetaData last();

    /**
     * Traverse into the given field that maps to xml column, and update
     * the current object to that field value.
     * 
     * @param fmd field maps to xml column
     * @param meta associated xml mapping
     */
    public void get(FieldMetaData fmd, XMLMetaData meta);
    
    /**
     * Traverse into the gevin xpath name of the current object, and update
     * the current object to that xpath field.
     * 
     */
    public void get(XMLMetaData meta, String name);
    
    /**
     * Return the current XPath's xmlmapping metadata.
     * @return Return xmlmapping
     */
    public XMLMetaData getXmlMapping();

    /**
     * Set the schema alias (the identification variable)
     * this path is begin with.
     */
    public void setSchemaAlias(String schemaAlias);
        
    public String getSchemaAlias();
    
    public void setSubqueryContext(Context context, String correlationVar);

    public String getCorrelationVar();
}