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Relational Persistence for Java
There is a newer version: 3.6.0.Beta2
//$Id: JoinHelper.java 7586 2005-07-21 01:11:52Z oneovthafew $
package org.hibernate.engine;

import org.hibernate.persister.entity.Joinable;
import org.hibernate.persister.entity.OuterJoinLoadable;
import org.hibernate.persister.entity.PropertyMapping;
import org.hibernate.type.AssociationType;
import org.hibernate.util.ArrayHelper;
import org.hibernate.util.StringHelper;

/**
 * @author Gavin King
 */
public final class JoinHelper {
	
	private JoinHelper() {}
	
	/**
	 * Get the aliased columns of the owning entity which are to 
	 * be used in the join
	 */
	public static String[] getAliasedLHSColumnNames(
			AssociationType type, 
			String alias, 
			int property, 
			OuterJoinLoadable lhsPersister,
			Mapping mapping
	) {
		return getAliasedLHSColumnNames(type, alias, property, 0, lhsPersister, mapping);
	}
	
	/**
	 * Get the columns of the owning entity which are to 
	 * be used in the join
	 */
	public static String[] getLHSColumnNames(
			AssociationType type, 
			int property, 
			OuterJoinLoadable lhsPersister,
			Mapping mapping
	) {
		return getLHSColumnNames(type, property, 0, lhsPersister, mapping);
	}
	
	/**
	 * Get the aliased columns of the owning entity which are to 
	 * be used in the join
	 */
	public static String[] getAliasedLHSColumnNames(
			AssociationType type, 
			String alias, 
			int property, 
			int begin, 
			OuterJoinLoadable lhsPersister,
			Mapping mapping
	) {
		if ( type.useLHSPrimaryKey() ) {
			return StringHelper.qualify( alias, lhsPersister.getIdentifierColumnNames() );
		}
		else {
			String propertyName = type.getLHSPropertyName();
			if (propertyName==null) {
				return ArrayHelper.slice( 
						lhsPersister.toColumns(alias, property), 
						begin, 
						type.getColumnSpan(mapping) 
					);
			}
			else {
				return ( (PropertyMapping) lhsPersister ).toColumns(alias, propertyName); //bad cast
			}
		}
	}
	
	/**
	 * Get the columns of the owning entity which are to 
	 * be used in the join
	 */
	public static String[] getLHSColumnNames(
			AssociationType type, 
			int property, 
			int begin, 
			OuterJoinLoadable lhsPersister,
			Mapping mapping
	) {
		if ( type.useLHSPrimaryKey() ) {
			//return lhsPersister.getSubclassPropertyColumnNames(property);
			return lhsPersister.getIdentifierColumnNames();
		}
		else {
			String propertyName = type.getLHSPropertyName();
			if (propertyName==null) {
				//slice, to get the columns for this component
				//property
				return ArrayHelper.slice( 
						lhsPersister.getSubclassPropertyColumnNames(property),
						begin, 
						type.getColumnSpan(mapping) 
					);
			}
			else {
				//property-refs for associations defined on a
				//component are not supported, so no need to slice
				return lhsPersister.getPropertyColumnNames(propertyName);
			}
		}
	}
	
	public static String getLHSTableName(
		AssociationType type, 
		int property, 
		OuterJoinLoadable lhsPersister
	) {
		if ( type.useLHSPrimaryKey() ) {
			return lhsPersister.getTableName();
		}
		else {
			String propertyName = type.getLHSPropertyName();
			if (propertyName==null) {
				//if there is no property-ref, assume the join
				//is to the subclass table (ie. the table of the
				//subclass that the association belongs to)
				return lhsPersister.getSubclassPropertyTableName(property);
			}
			else {
				//handle a property-ref
				String propertyRefTable = lhsPersister.getPropertyTableName(propertyName);
				if (propertyRefTable==null) {
					//it is possible that the tree-walking in OuterJoinLoader can get to
					//an association defined by a subclass, in which case the property-ref
					//might refer to a property defined on a subclass of the current class
					//in this case, the table name is not known - this temporary solution 
					//assumes that the property-ref refers to a property of the subclass
					//table that the association belongs to (a reasonable guess)
					//TODO: fix this, add: OuterJoinLoadable.getSubclassPropertyTableName(String propertyName)
					propertyRefTable = lhsPersister.getSubclassPropertyTableName(property);
				}
				return propertyRefTable;
			}
		}
	}
	
	/**
	 * Get the columns of the associated table which are to 
	 * be used in the join
	 */
	public static String[] getRHSColumnNames(AssociationType type, SessionFactoryImplementor factory) {
		String uniqueKeyPropertyName = type.getRHSUniqueKeyPropertyName();
		Joinable joinable = type.getAssociatedJoinable(factory);
		if (uniqueKeyPropertyName==null) {
			return joinable.getKeyColumnNames();
		}
		else {
			return ( (OuterJoinLoadable) joinable ).getPropertyColumnNames(uniqueKeyPropertyName);
		}
	}
}