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Cayenne Object Persistence Framework
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 *   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
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package org.apache.cayenne.map;

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

import org.apache.cayenne.DataRow;
import org.apache.cayenne.exp.Expression;

/**
 * A tree structure representing inheritance hierarchy 
 * of an ObjEntity and its subentities.
 * 
 * @since 1.1
 * @author Andrus Adamchik
 */
public class EntityInheritanceTree {
    protected ObjEntity entity;
    protected Collection subentities;
    protected Expression normalizedQualifier;

    public EntityInheritanceTree(ObjEntity entity) {
        this.entity = entity;
    }

    /**
     * Returns a qualifier Expression that matches root entity
     * of this tree and all its subentities.
     */
    public Expression qualifierForEntityAndSubclasses() {
        Expression qualifier = entity.getDeclaredQualifier();

        if (qualifier == null) {
            // match all
            return null;
        }

        if (subentities != null) {
            Iterator it = subentities.iterator();
            while (it.hasNext()) {
                EntityInheritanceTree child = (EntityInheritanceTree) it.next();
                Expression childQualifier = child.qualifierForEntityAndSubclasses();

                // if any child qualifier is null, just return null, since no filtering is possible
                if (childQualifier == null) {
                    return null;
                }

                qualifier = qualifier.orExp(childQualifier);
            }
        }

        return qualifier;
    }

    /**
     * Returns the deepest possible entity in the inheritance hierarchy 
     * that can be used to create objects from a given DataRow.
     */
    public ObjEntity entityMatchingRow(DataRow row) {
        // match depth first
        if (subentities != null) {
            Iterator it = subentities.iterator();
            while (it.hasNext()) {
                EntityInheritanceTree child = (EntityInheritanceTree) it.next();
                ObjEntity matched = child.entityMatchingRow(row);

                if (matched != null) {
                    return matched;
                }
            }
        }

        Expression qualifier = entity.getDeclaredQualifier();
        if (qualifier != null) {
            if (normalizedQualifier == null) {
                normalizedQualifier = entity.translateToDbPath(qualifier);
            }

            return normalizedQualifier.match(row) ? entity : null;
        }

        // no qualifier ... matches all rows
        return entity;
    }

    public void addChildNode(EntityInheritanceTree node) {
        if (subentities == null) {
            subentities = new ArrayList(2);
        }

        subentities.add(node);
    }

    public int getChildrenCount() {
        return (subentities != null) ? subentities.size() : 0;
    }

    public Collection getChildren() {
        return (subentities != null) ? subentities : Collections.EMPTY_LIST;
    }

    public ObjEntity getEntity() {
        return entity;
    }

    public Collection allAttributes() {
        if (subentities == null) {
            return entity.getAttributes();
        }

        Collection c = new ArrayList();
        appendDeclaredAttributes(c);

        // add base attributes if any
        ObjEntity superEntity = entity.getSuperEntity();
        if (superEntity != null) {
            c.addAll(superEntity.getAttributes());
        }

        return c;
    }

    public Collection allRelationships() {
        if (subentities == null) {
            return entity.getRelationships();
        }

        Collection c = new ArrayList();
        appendDeclaredRelationships(c);

        // add base relationships if any
        ObjEntity superEntity = entity.getSuperEntity();
        if (superEntity != null) {
            c.addAll(superEntity.getRelationships());
        }

        return c;
    }

    protected void appendDeclaredAttributes(Collection c) {
        c.addAll(entity.getDeclaredAttributes());

        if (subentities != null) {
            Iterator it = subentities.iterator();
            while (it.hasNext()) {
                EntityInheritanceTree child = (EntityInheritanceTree) it.next();
                child.appendDeclaredAttributes(c);
            }
        }
    }

    protected void appendDeclaredRelationships(Collection c) {
        c.addAll(entity.getDeclaredRelationships());

        if (subentities != null) {
            Iterator it = subentities.iterator();
            while (it.hasNext()) {
                EntityInheritanceTree child = (EntityInheritanceTree) it.next();
                child.appendDeclaredRelationships(c);
            }
        }
    }
}