jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/MappingTools.java - dali/webtools.dali - Git at Google

 /*******************************************************************************
  * Copyright (c) 2006, 2011 Oracle. All rights reserved.
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v1.0, which accompanies this distribution
  * and is available at http://www.eclipse.org/legal/epl-v10.html.
  *
  * Contributors:
  *     Oracle - initial API and implementation
  ******************************************************************************/
 package org.eclipse.jpt.jpa.core.internal.context;

 import java.util.Iterator;
 import org.eclipse.jpt.common.utility.internal.CollectionTools;
 import org.eclipse.jpt.common.utility.internal.StringTools;
 import org.eclipse.jpt.common.utility.internal.Transformer;
 import org.eclipse.jpt.jpa.core.context.AttributeMapping;
 import org.eclipse.jpt.jpa.core.context.Column;
 import org.eclipse.jpt.jpa.core.context.ColumnMapping;
 import org.eclipse.jpt.jpa.core.context.Entity;
 import org.eclipse.jpt.jpa.core.context.JoinColumn;
 import org.eclipse.jpt.jpa.core.context.JoinTable;
 import org.eclipse.jpt.jpa.core.context.JpaNamedContextNode;
 import org.eclipse.jpt.jpa.core.context.PersistentType;
 import org.eclipse.jpt.jpa.core.context.ReadOnlyAttributeOverride;
 import org.eclipse.jpt.jpa.core.context.ReadOnlyJoinColumn;
 import org.eclipse.jpt.jpa.core.context.ReadOnlyPersistentAttribute;
 import org.eclipse.jpt.jpa.core.context.ReadOnlyRelationship;
 import org.eclipse.jpt.jpa.core.context.ReferenceTable;
 import org.eclipse.jpt.jpa.core.context.Relationship;
 import org.eclipse.jpt.jpa.core.context.RelationshipMapping;
 import org.eclipse.jpt.jpa.core.context.TypeMapping;
 import org.eclipse.jpt.jpa.core.jpa2.context.AttributeMapping2_0;
 import org.eclipse.jpt.jpa.core.jpa2.context.CollectionMapping2_0;
 import org.eclipse.jpt.jpa.core.jpa2.context.ElementCollectionMapping2_0;
 import org.eclipse.jpt.jpa.core.jpa2.context.MetamodelField;
 import org.eclipse.jpt.jpa.db.Table;

 /**
  * Gather some of the behavior common to the Java and XML models. :-(
  */
 public final class MappingTools {

 	/**
 	 * Default join table name from the JPA spec:<br>
 	 * 	"The concatenated names of the two associated primary
 	 * 	entity tables, separated by a underscore."
 	 * <pre>
 	 * [owning table name]_[target table name]
 	 * </pre>
 	 * <strong>NB:</strong> The <em>names</em> are concatenated,
 	 * <em>not</em> the <em>identifiers</em>.
 	 * E.g. the join table for <code>"Foo"</code> and <code>"baR"</code>
 	 * (where the "delimited" identifier is required) is:
 	 * <pre>
 	 *     "Foo_baR"
 	 * </pre>
 	 * not
 	 * <pre>
 	 *     "Foo"_"baR"
 	 * </pre>
 	 * As a result, we cannot honestly calculate the default name without a
 	 * database connection. We need the database to convert the resulting name
 	 * to an identifier appropriate to the current database.
 	 */
 	public static String buildJoinTableDefaultName(ReadOnlyRelationship relationship) {
 		if (relationship.getJpaProject().getDataSource().connectionProfileIsActive()) {
 			return buildDbJoinTableDefaultName(relationship);
 		}
 		// continue with a "best effort":
 		String owningTableName = relationship.getTypeMapping().getPrimaryTableName();
 		if (owningTableName == null) {
 			return null;
 		}
 		RelationshipMapping relationshipMapping = relationship.getMapping();
 		if (relationshipMapping == null) {
 			return null;
 		}
 		Entity targetEntity = relationshipMapping.getResolvedTargetEntity();
 		if (targetEntity == null) {
 			return null;
 		}
 		String targetTableName = targetEntity.getPrimaryTableName();
 		if (targetTableName == null) {
 			return null;
 		}
 		return owningTableName + '_' + targetTableName;
 	}

 	/**
 	 * Use the database to build a more accurate default name.
 	 */
 	private static String buildDbJoinTableDefaultName(ReadOnlyRelationship relationship) {
 		Table owningTable = relationship.getTypeMapping().getPrimaryDbTable();
 		if (owningTable == null) {
 			return null;
 		}
 		RelationshipMapping relationshipMapping = relationship.getMapping();
 		if (relationshipMapping == null) {
 			return null;
 		}
 		Entity targetEntity = relationshipMapping.getResolvedTargetEntity();
 		if (targetEntity == null) {
 			return null;
 		}
 		Table targetTable = targetEntity.getPrimaryDbTable();
 		if (targetTable == null) {
 			return null;
 		}
 		String name = owningTable.getName() + '_' + targetTable.getName();
 		return owningTable.getDatabase().convertNameToIdentifier(name);
 	}

 	/**
 	 * Default collection table name from the JPA spec:<br>
 	 * 	"The concatenation of the name of the containing entity and
 	 *  the name of the collection attribute, separated by an underscore."
 	 * <pre>
 	 * [owning entity name]_[attribute name]
 	 * </pre>
 	 */
 	public static String buildCollectionTableDefaultName(ElementCollectionMapping2_0 mapping) {
 		Entity entity = mapping.getEntity();
 		if (entity == null) {
 			return null;
 		}
 		String owningEntityName = entity.getName();
 		String attributeName = mapping.getName();
 		return owningEntityName + '_' + attributeName;
 	}

 	/**
 	 * Return the join column's default name;
 	 * which is typically<pre>
 	 *     [attribute name]_[referenced column name]
 	 * </pre>
 	 * But, if we don't have an attribute name (e.g. in a unidirectional
 	 * one-to-many or many-to-many) is<pre>
 	 *     [target entity name]_[referenced column name]
 	 * </pre>
 	 * @see #buildJoinTableDefaultName(ReadOnlyRelationship)
 	 */
 	public static String buildJoinColumnDefaultName(ReadOnlyJoinColumn joinColumn, ReadOnlyJoinColumn.Owner owner) {
 		if (owner.joinColumnsSize() != 1) {
 			return null;
 		}
 		String prefix = owner.getAttributeName();
 		if (prefix == null) {
 			Entity targetEntity = owner.getRelationshipTarget();
 			if (targetEntity == null) {
 				return null;
 			}
 			prefix = targetEntity.getName();
 		}
 		// It's not clear which of these is correct....
 		// The spec implies that the referenced column is always the
 		// *primary key* column of the target entity; i.e. the primary key as
 		// defined on the *database* (or, possibly, the primary key as defined
 		// by the target entity's Id mapping?), not the name of the referenced
 		// column irrespective of whether it is the primary key on the target
 		// entity's table. But this seems like it would be wrong; since the
 		// referenced column need not be a primary key and we don't always have
 		// access to the database.
 		//
 		// Column targetColumn = joinColumn.getTargetPrimaryKeyDbColumn();
 		String targetColumnName = joinColumn.getReferencedColumnName();
 		if (targetColumnName == null) {
 			return null;
 		}
 		String name = prefix + '_' + targetColumnName;
 		// Again, it's not clear which of these is correct....
 		// Converting the name to an identifier will result in the identifier
 		// being delimited nearly every time (at least on non-Sybase/MS
 		// databases); but that probably is not the intent of the spec....
 		//
 		// return targetColumn.getDatabase().convertNameToIdentifier(name);
 		return name;
 	}

 	/**
 	 * Return the name of the attribute in the specified mapping's target entity
 	 * that is owned by the mapping.
 	 */
 	public static String getTargetAttributeName(RelationshipMapping relationshipMapping) {
 		if (relationshipMapping == null) {
 			return null;
 		}
 		Entity targetEntity = relationshipMapping.getResolvedTargetEntity();
 		if (targetEntity == null) {
 			return null;
 		}
 		for (ReadOnlyPersistentAttribute attribute : CollectionTools.iterable(targetEntity.getPersistentType().allAttributes())) {
 			if (attribute.getMapping().isOwnedBy(relationshipMapping)) {
 				return attribute.getName();
 			}
 		}
 		return null;
 	}

 	/**
 	 * If appropriate, return the name of the single primary key column of the
 	 * relationship target.
 	 * Spec states:<br>
 	 *     "The same name as the primary key column of the referenced table."<br>
 	 * We are assuming that the primary key column is defined by the mappings instead of the database.
 	 */
 	public static String buildJoinColumnDefaultReferencedColumnName(ReadOnlyJoinColumn.Owner joinColumnOwner) {
 		if (joinColumnOwner.joinColumnsSize() != 1) {
 			return null;
 		}
 		Entity targetEntity = joinColumnOwner.getRelationshipTarget();
 		if (targetEntity == null) {
 			return null;
 		}
 		return targetEntity.getPrimaryKeyColumnName();
 	}

 	public static ColumnMapping getColumnMapping(String attributeName, PersistentType persistentType) {
 		if ((attributeName == null) || (persistentType == null)) {
 			return null;
 		}
 		for (Iterator<ReadOnlyPersistentAttribute> stream = persistentType.allAttributes(); stream.hasNext(); ) {
 			ReadOnlyPersistentAttribute persAttribute = stream.next();
 			if (attributeName.equals(persAttribute.getName())) {
 				if (persAttribute.getMapping() instanceof ColumnMapping) {
 					return (ColumnMapping) persAttribute.getMapping();
 				}
 				// keep looking or return null???
 			}
 		}
 		return null;
 	}

 	public static RelationshipMapping getRelationshipMapping(String attributeName, TypeMapping typeMapping) {
 		if ((attributeName == null) || (typeMapping == null)) {
 			return null;
 		}
 		for (Iterator<AttributeMapping> stream = typeMapping.allAttributeMappings(); stream.hasNext(); ) {
 			AttributeMapping attributeMapping = stream.next();
 			if (attributeName.equals(attributeMapping.getName())) {
 				if (attributeMapping instanceof RelationshipMapping) {
 					return (RelationshipMapping) attributeMapping;
 				}
 				// keep looking or return null???
 			}
 		}
 		return null;
 	}

 	public static void convertReferenceTableDefaultToSpecifiedJoinColumn(ReferenceTable referenceTable) {
 		JoinColumn defaultJoinColumn = referenceTable.getDefaultJoinColumn();
 		if (defaultJoinColumn != null) {
 			String columnName = defaultJoinColumn.getDefaultName();
 			String referencedColumnName = defaultJoinColumn.getDefaultReferencedColumnName();
 			JoinColumn joinColumn = referenceTable.addSpecifiedJoinColumn();
 			joinColumn.setSpecifiedName(columnName);
 			joinColumn.setSpecifiedReferencedColumnName(referencedColumnName);
 		}
 	}

 	public static void convertJoinTableDefaultToSpecifiedInverseJoinColumn(JoinTable joinTable) {
 		JoinColumn defaultInverseJoinColumn = joinTable.getDefaultInverseJoinColumn();
 		if (defaultInverseJoinColumn != null) {
 			String columnName = defaultInverseJoinColumn.getDefaultName();
 			String referencedColumnName = defaultInverseJoinColumn.getDefaultReferencedColumnName();
 			JoinColumn joinColumn = joinTable.addSpecifiedInverseJoinColumn(0);
 			joinColumn.setSpecifiedName(columnName);
 			joinColumn.setSpecifiedReferencedColumnName(referencedColumnName);
 		}
 	}

 	public static String getMetamodelFieldMapKeyTypeName(CollectionMapping2_0 mapping) {
 		PersistentType targetType = mapping.getResolvedTargetType();
 		String mapKey = mapping.getMapKey();
 		if ((mapKey == null) || (targetType == null)) {
 			String mapKeyClass = mapping.getMapKeyClass();
 			return mapKeyClass != null ? mapKeyClass : MetamodelField.DEFAULT_TYPE_NAME;
 		}
 		ReadOnlyPersistentAttribute mapKeyAttribute = targetType.resolveAttribute(mapKey);
 		if (mapKeyAttribute == null) {
 			return MetamodelField.DEFAULT_TYPE_NAME;
 		}
 		AttributeMapping2_0 mapKeyMapping = (AttributeMapping2_0) mapKeyAttribute.getMapping();
 		if (mapKeyMapping == null) {
 			return MetamodelField.DEFAULT_TYPE_NAME;
 		}
 		return mapKeyMapping.getMetamodelTypeName();
 	}

 	// TODO move to TypeMapping? may need different name (or may need to rename existing #resolve...)
 	public static Column resolveOverriddenColumn(TypeMapping overridableTypeMapping, String attributeName) {
 		// convenience null check to simplify client code
 		if (overridableTypeMapping == null) {
 			return null;
 		}

 		for (TypeMapping typeMapping : CollectionTools.iterable(overridableTypeMapping.inheritanceHierarchy())) {
 			Column column = typeMapping.resolveOverriddenColumn(attributeName);
 			if (column != null) {
 				return column;
 			}
 		}
 		return null;
 	}

 	// TODO move to TypeMapping? may need different name (or may need to rename existing #resolve...)
 	public static Relationship resolveOverriddenRelationship(TypeMapping overridableTypeMapping, String attributeName) {
 		// convenience null check to simplify client code
 		if (overridableTypeMapping == null) {
 			return null;
 		}

 		for (TypeMapping typeMapping : CollectionTools.iterable(overridableTypeMapping.inheritanceHierarchy())) {
 			Relationship relationship = typeMapping.resolveOverriddenRelationship(attributeName);
 			if (relationship != null) {
 				return relationship;
 			}
 		}
 		return null;
 	}

 	/**
 	 * Return whether the specified nodes are "duplicates".
 	 * @see JpaNamedContextNode#duplicates(Object)
 	 */
 	public static <T extends JpaNamedContextNode<? super T>> boolean nodesAreDuplicates(T node1, T node2) {
 		return (node1 != node2) &&
 				! StringTools.stringIsEmpty(node1.getName()) &&
 				node1.getName().equals(node2.getName()) &&
 				! node1.overrides(node2) &&
 				! node2.overrides(node1);
 	}

 	/**
 	 * Return whether the first specified node "overrides" the second,
 	 * based on the "precedence" of their classes.
 	 * @see JpaNamedContextNode#overrides(Object)
 	 */
 	public static <T extends JpaNamedContextNode<? super T>> boolean nodeOverrides(T node1, T node2, Iterable<Class<? extends T>> precedenceTypeList) {
 		// this isn't ideal, but use it until adopters protest...
 		return (node1.getName() != null) &&
 				(node2.getName() != null) &&
 				node1.getName().equals(node2.getName()) &&
 				(node1.getPersistenceUnit() == node2.getPersistenceUnit()) &&
 				(calculatePrecedence(node1, precedenceTypeList) < calculatePrecedence(node2, precedenceTypeList));
 	}

 	/**
 	 * Loop through the specified classes; return the index of the first class
 	 * the specified node is an instance of.
 	 */
 	private static <T extends JpaNamedContextNode<? super T>> int calculatePrecedence(T node, Iterable<Class<? extends T>> precedenceTypeList) {
 		int precedence = 0;
 		for (Class<?> nodeClass : precedenceTypeList) {
 			if (nodeClass.isInstance(node)) {
 				return precedence;
 			}
 			precedence++;
 		}
 		throw new IllegalArgumentException("unknown named node: " + node); //$NON-NLS-1$
 	}

 	public static String getPrimaryKeyColumnName(Entity entity) {
 		String pkColumnName = null;
 		for (Iterator<ReadOnlyPersistentAttribute> stream = entity.getPersistentType().allAttributes(); stream.hasNext(); ) {
 			ReadOnlyPersistentAttribute attribute = stream.next();
 			String current = attribute.getPrimaryKeyColumnName();
 			if (current != null) {
 				// 229423 - if the attribute is a primary key, but it has an attribute override,
 				// use the override column instead
 				ReadOnlyAttributeOverride attributeOverride = entity.getAttributeOverrideContainer().getOverrideNamed(attribute.getName());
 				if (attributeOverride != null) {
 					current = attributeOverride.getColumn().getName();
 				}
 			}
 			if (pkColumnName == null) {
 				pkColumnName = current;
 			} else {
 				if (current != null) {
 					// if we encounter a composite primary key, return null
 					return null;
 				}
 			}
 		}
 		// if we encounter only a single primary key column name, return it
 		return pkColumnName;
 	}

 	/**
 	 * "Unqualify" the specified attribute name, removing the mapping's name
 	 * from the front of the attribute name if it is present. For example, if
 	 * the mapping's name is <code>"foo"</code>, the attribute name
 	 * <code>"foo.bar"</code> would be converted to <code>"bar"</code>).
 	 * Return <code>null</code> if the attribute name cannot be "unqualified".
 	 */
 	public static String unqualify(String mappingName, String attributeName) {
 		if (mappingName == null) {
 			return null;
 		}
 		if ( ! attributeName.startsWith(mappingName)) {
 			return null;
 		}
 		int mappingNameLength = mappingName.length();
 		if (attributeName.length() <= mappingNameLength) {
 			return null;
 		}
 		return (attributeName.charAt(mappingNameLength) == '.') ? attributeName.substring(mappingNameLength + 1) : null;
 	}

 	/**
 	 * This transformer will prepend a specified qualifier, followed by a
 	 * dot ('.'), to a string. For example, if a mapping's name is
 	 * <code>"foo"</code> and one of its attribute's is named
 	 * <code>"bar"</code>, the attribute's name will be transformed
 	 * into <code>"foo.bar"</code>. If the specified qualifier is
 	 * <code>null</code> (or an empty string), only a dot will be prepended
 	 * to a string.
 	 */
 	public static class QualifierTransformer
 		implements Transformer<String, String>
 	{
 		private final String prefix;
 		public QualifierTransformer(String qualifier) {
 			super();
 			this.prefix = (qualifier == null) ? "." : qualifier + '.'; //$NON-NLS-1$
 		}
 		public String transform(String s) {
 			return this.prefix + s;
 		}
 	}


 	// ********** constructor **********

 	/**
 	 * Suppress default constructor, ensuring non-instantiability.
 	 */
 	private MappingTools() {
 		super();
 		throw new UnsupportedOperationException();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2006, 2011 Oracle. All rights reserved.
	* This program and the accompanying materials are made available under the
	* terms of the Eclipse Public License v1.0, which accompanies this distribution
	* and is available at http://www.eclipse.org/legal/epl-v10.html.
	*
	* Contributors:
	* Oracle - initial API and implementation
	******************************************************************************/
	package org.eclipse.jpt.jpa.core.internal.context;

	import java.util.Iterator;
	import org.eclipse.jpt.common.utility.internal.CollectionTools;
	import org.eclipse.jpt.common.utility.internal.StringTools;
	import org.eclipse.jpt.common.utility.internal.Transformer;
	import org.eclipse.jpt.jpa.core.context.AttributeMapping;
	import org.eclipse.jpt.jpa.core.context.Column;
	import org.eclipse.jpt.jpa.core.context.ColumnMapping;
	import org.eclipse.jpt.jpa.core.context.Entity;
	import org.eclipse.jpt.jpa.core.context.JoinColumn;
	import org.eclipse.jpt.jpa.core.context.JoinTable;
	import org.eclipse.jpt.jpa.core.context.JpaNamedContextNode;
	import org.eclipse.jpt.jpa.core.context.PersistentType;
	import org.eclipse.jpt.jpa.core.context.ReadOnlyAttributeOverride;
	import org.eclipse.jpt.jpa.core.context.ReadOnlyJoinColumn;
	import org.eclipse.jpt.jpa.core.context.ReadOnlyPersistentAttribute;
	import org.eclipse.jpt.jpa.core.context.ReadOnlyRelationship;
	import org.eclipse.jpt.jpa.core.context.ReferenceTable;
	import org.eclipse.jpt.jpa.core.context.Relationship;
	import org.eclipse.jpt.jpa.core.context.RelationshipMapping;
	import org.eclipse.jpt.jpa.core.context.TypeMapping;
	import org.eclipse.jpt.jpa.core.jpa2.context.AttributeMapping2_0;
	import org.eclipse.jpt.jpa.core.jpa2.context.CollectionMapping2_0;
	import org.eclipse.jpt.jpa.core.jpa2.context.ElementCollectionMapping2_0;
	import org.eclipse.jpt.jpa.core.jpa2.context.MetamodelField;
	import org.eclipse.jpt.jpa.db.Table;

	/**
	* Gather some of the behavior common to the Java and XML models. :-(
	*/
	public final class MappingTools {

	/**
	* Default join table name from the JPA spec:<br>
	* "The concatenated names of the two associated primary
	* entity tables, separated by a underscore."
	* <pre>
	* [owning table name]_[target table name]
	* </pre>
	* <strong>NB:</strong> The <em>names</em> are concatenated,
	* <em>not</em> the <em>identifiers</em>.
	* E.g. the join table for <code>"Foo"</code> and <code>"baR"</code>
	* (where the "delimited" identifier is required) is:
	* <pre>
	* "Foo_baR"
	* </pre>
	* not
	* <pre>
	* "Foo"_"baR"
	* </pre>
	* As a result, we cannot honestly calculate the default name without a
	* database connection. We need the database to convert the resulting name
	* to an identifier appropriate to the current database.
	*/
	public static String buildJoinTableDefaultName(ReadOnlyRelationship relationship) {
	if (relationship.getJpaProject().getDataSource().connectionProfileIsActive()) {
	return buildDbJoinTableDefaultName(relationship);
	}
	// continue with a "best effort":
	String owningTableName = relationship.getTypeMapping().getPrimaryTableName();
	if (owningTableName == null) {
	return null;
	}
	RelationshipMapping relationshipMapping = relationship.getMapping();
	if (relationshipMapping == null) {
	return null;
	}
	Entity targetEntity = relationshipMapping.getResolvedTargetEntity();
	if (targetEntity == null) {
	return null;
	}
	String targetTableName = targetEntity.getPrimaryTableName();
	if (targetTableName == null) {
	return null;
	}
	return owningTableName + '_' + targetTableName;
	}

	/**
	* Use the database to build a more accurate default name.
	*/
	private static String buildDbJoinTableDefaultName(ReadOnlyRelationship relationship) {
	Table owningTable = relationship.getTypeMapping().getPrimaryDbTable();
	if (owningTable == null) {
	return null;
	}
	RelationshipMapping relationshipMapping = relationship.getMapping();
	if (relationshipMapping == null) {
	return null;
	}
	Entity targetEntity = relationshipMapping.getResolvedTargetEntity();
	if (targetEntity == null) {
	return null;
	}
	Table targetTable = targetEntity.getPrimaryDbTable();
	if (targetTable == null) {
	return null;
	}
	String name = owningTable.getName() + '_' + targetTable.getName();
	return owningTable.getDatabase().convertNameToIdentifier(name);
	}

	/**
	* Default collection table name from the JPA spec:<br>
	* "The concatenation of the name of the containing entity and
	* the name of the collection attribute, separated by an underscore."
	* <pre>
	* [owning entity name]_[attribute name]
	* </pre>
	*/
	public static String buildCollectionTableDefaultName(ElementCollectionMapping2_0 mapping) {
	Entity entity = mapping.getEntity();
	if (entity == null) {
	return null;
	}
	String owningEntityName = entity.getName();
	String attributeName = mapping.getName();
	return owningEntityName + '_' + attributeName;
	}

	/**
	* Return the join column's default name;
	* which is typically<pre>
	* [attribute name]_[referenced column name]
	* </pre>
	* But, if we don't have an attribute name (e.g. in a unidirectional
	* one-to-many or many-to-many) is<pre>
	* [target entity name]_[referenced column name]
	* </pre>
	* @see #buildJoinTableDefaultName(ReadOnlyRelationship)
	*/
	public static String buildJoinColumnDefaultName(ReadOnlyJoinColumn joinColumn, ReadOnlyJoinColumn.Owner owner) {
	if (owner.joinColumnsSize() != 1) {
	return null;
	}
	String prefix = owner.getAttributeName();
	if (prefix == null) {
	Entity targetEntity = owner.getRelationshipTarget();
	if (targetEntity == null) {
	return null;
	}
	prefix = targetEntity.getName();
	}
	// It's not clear which of these is correct....
	// The spec implies that the referenced column is always the
	// primary key column of the target entity; i.e. the primary key as
	// defined on the database (or, possibly, the primary key as defined
	// by the target entity's Id mapping?), not the name of the referenced
	// column irrespective of whether it is the primary key on the target
	// entity's table. But this seems like it would be wrong; since the
	// referenced column need not be a primary key and we don't always have
	// access to the database.
	//
	// Column targetColumn = joinColumn.getTargetPrimaryKeyDbColumn();
	String targetColumnName = joinColumn.getReferencedColumnName();
	if (targetColumnName == null) {
	return null;
	}
	String name = prefix + '_' + targetColumnName;
	// Again, it's not clear which of these is correct....
	// Converting the name to an identifier will result in the identifier
	// being delimited nearly every time (at least on non-Sybase/MS
	// databases); but that probably is not the intent of the spec....
	//
	// return targetColumn.getDatabase().convertNameToIdentifier(name);
	return name;
	}

	/**
	* Return the name of the attribute in the specified mapping's target entity
	* that is owned by the mapping.
	*/
	public static String getTargetAttributeName(RelationshipMapping relationshipMapping) {
	if (relationshipMapping == null) {
	return null;
	}
	Entity targetEntity = relationshipMapping.getResolvedTargetEntity();
	if (targetEntity == null) {
	return null;
	}
	for (ReadOnlyPersistentAttribute attribute : CollectionTools.iterable(targetEntity.getPersistentType().allAttributes())) {
	if (attribute.getMapping().isOwnedBy(relationshipMapping)) {
	return attribute.getName();
	}
	}
	return null;
	}

	/**
	* If appropriate, return the name of the single primary key column of the
	* relationship target.
	* Spec states:<br>
	* "The same name as the primary key column of the referenced table."<br>
	* We are assuming that the primary key column is defined by the mappings instead of the database.
	*/
	public static String buildJoinColumnDefaultReferencedColumnName(ReadOnlyJoinColumn.Owner joinColumnOwner) {
	if (joinColumnOwner.joinColumnsSize() != 1) {
	return null;
	}
	Entity targetEntity = joinColumnOwner.getRelationshipTarget();
	if (targetEntity == null) {
	return null;
	}
	return targetEntity.getPrimaryKeyColumnName();
	}

	public static ColumnMapping getColumnMapping(String attributeName, PersistentType persistentType) {
	if ((attributeName == null) \|\| (persistentType == null)) {
	return null;
	}
	for (Iterator<ReadOnlyPersistentAttribute> stream = persistentType.allAttributes(); stream.hasNext(); ) {
	ReadOnlyPersistentAttribute persAttribute = stream.next();
	if (attributeName.equals(persAttribute.getName())) {
	if (persAttribute.getMapping() instanceof ColumnMapping) {
	return (ColumnMapping) persAttribute.getMapping();
	}
	// keep looking or return null???
	}
	}
	return null;
	}

	public static RelationshipMapping getRelationshipMapping(String attributeName, TypeMapping typeMapping) {
	if ((attributeName == null) \|\| (typeMapping == null)) {
	return null;
	}
	for (Iterator<AttributeMapping> stream = typeMapping.allAttributeMappings(); stream.hasNext(); ) {
	AttributeMapping attributeMapping = stream.next();
	if (attributeName.equals(attributeMapping.getName())) {
	if (attributeMapping instanceof RelationshipMapping) {
	return (RelationshipMapping) attributeMapping;
	}
	// keep looking or return null???
	}
	}
	return null;
	}

	public static void convertReferenceTableDefaultToSpecifiedJoinColumn(ReferenceTable referenceTable) {
	JoinColumn defaultJoinColumn = referenceTable.getDefaultJoinColumn();
	if (defaultJoinColumn != null) {
	String columnName = defaultJoinColumn.getDefaultName();
	String referencedColumnName = defaultJoinColumn.getDefaultReferencedColumnName();
	JoinColumn joinColumn = referenceTable.addSpecifiedJoinColumn();
	joinColumn.setSpecifiedName(columnName);
	joinColumn.setSpecifiedReferencedColumnName(referencedColumnName);
	}
	}

	public static void convertJoinTableDefaultToSpecifiedInverseJoinColumn(JoinTable joinTable) {
	JoinColumn defaultInverseJoinColumn = joinTable.getDefaultInverseJoinColumn();
	if (defaultInverseJoinColumn != null) {
	String columnName = defaultInverseJoinColumn.getDefaultName();
	String referencedColumnName = defaultInverseJoinColumn.getDefaultReferencedColumnName();
	JoinColumn joinColumn = joinTable.addSpecifiedInverseJoinColumn(0);
	joinColumn.setSpecifiedName(columnName);
	joinColumn.setSpecifiedReferencedColumnName(referencedColumnName);
	}
	}

	public static String getMetamodelFieldMapKeyTypeName(CollectionMapping2_0 mapping) {
	PersistentType targetType = mapping.getResolvedTargetType();
	String mapKey = mapping.getMapKey();
	if ((mapKey == null) \|\| (targetType == null)) {
	String mapKeyClass = mapping.getMapKeyClass();
	return mapKeyClass != null ? mapKeyClass : MetamodelField.DEFAULT_TYPE_NAME;
	}
	ReadOnlyPersistentAttribute mapKeyAttribute = targetType.resolveAttribute(mapKey);
	if (mapKeyAttribute == null) {
	return MetamodelField.DEFAULT_TYPE_NAME;
	}
	AttributeMapping2_0 mapKeyMapping = (AttributeMapping2_0) mapKeyAttribute.getMapping();
	if (mapKeyMapping == null) {
	return MetamodelField.DEFAULT_TYPE_NAME;
	}
	return mapKeyMapping.getMetamodelTypeName();
	}

	// TODO move to TypeMapping? may need different name (or may need to rename existing #resolve...)
	public static Column resolveOverriddenColumn(TypeMapping overridableTypeMapping, String attributeName) {
	// convenience null check to simplify client code
	if (overridableTypeMapping == null) {
	return null;
	}

	for (TypeMapping typeMapping : CollectionTools.iterable(overridableTypeMapping.inheritanceHierarchy())) {
	Column column = typeMapping.resolveOverriddenColumn(attributeName);
	if (column != null) {
	return column;
	}
	}
	return null;
	}

	// TODO move to TypeMapping? may need different name (or may need to rename existing #resolve...)
	public static Relationship resolveOverriddenRelationship(TypeMapping overridableTypeMapping, String attributeName) {
	// convenience null check to simplify client code
	if (overridableTypeMapping == null) {
	return null;
	}

	for (TypeMapping typeMapping : CollectionTools.iterable(overridableTypeMapping.inheritanceHierarchy())) {
	Relationship relationship = typeMapping.resolveOverriddenRelationship(attributeName);
	if (relationship != null) {
	return relationship;
	}
	}
	return null;
	}

	/**
	* Return whether the specified nodes are "duplicates".
	* @see JpaNamedContextNode#duplicates(Object)
	*/
	public static <T extends JpaNamedContextNode<? super T>> boolean nodesAreDuplicates(T node1, T node2) {
	return (node1 != node2) &&
	! StringTools.stringIsEmpty(node1.getName()) &&
	node1.getName().equals(node2.getName()) &&
	! node1.overrides(node2) &&
	! node2.overrides(node1);
	}

	/**
	* Return whether the first specified node "overrides" the second,
	* based on the "precedence" of their classes.
	* @see JpaNamedContextNode#overrides(Object)
	*/
	public static <T extends JpaNamedContextNode<? super T>> boolean nodeOverrides(T node1, T node2, Iterable<Class<? extends T>> precedenceTypeList) {
	// this isn't ideal, but use it until adopters protest...
	return (node1.getName() != null) &&
	(node2.getName() != null) &&
	node1.getName().equals(node2.getName()) &&
	(node1.getPersistenceUnit() == node2.getPersistenceUnit()) &&
	(calculatePrecedence(node1, precedenceTypeList) < calculatePrecedence(node2, precedenceTypeList));
	}

	/**
	* Loop through the specified classes; return the index of the first class
	* the specified node is an instance of.
	*/
	private static <T extends JpaNamedContextNode<? super T>> int calculatePrecedence(T node, Iterable<Class<? extends T>> precedenceTypeList) {
	int precedence = 0;
	for (Class<?> nodeClass : precedenceTypeList) {
	if (nodeClass.isInstance(node)) {
	return precedence;
	}
	precedence++;
	}
	throw new IllegalArgumentException("unknown named node: " + node); //$NON-NLS-1$
	}

	public static String getPrimaryKeyColumnName(Entity entity) {
	String pkColumnName = null;
	for (Iterator<ReadOnlyPersistentAttribute> stream = entity.getPersistentType().allAttributes(); stream.hasNext(); ) {
	ReadOnlyPersistentAttribute attribute = stream.next();
	String current = attribute.getPrimaryKeyColumnName();
	if (current != null) {
	// 229423 - if the attribute is a primary key, but it has an attribute override,
	// use the override column instead
	ReadOnlyAttributeOverride attributeOverride = entity.getAttributeOverrideContainer().getOverrideNamed(attribute.getName());
	if (attributeOverride != null) {
	current = attributeOverride.getColumn().getName();
	}
	}
	if (pkColumnName == null) {
	pkColumnName = current;
	} else {
	if (current != null) {
	// if we encounter a composite primary key, return null
	return null;
	}
	}
	}
	// if we encounter only a single primary key column name, return it
	return pkColumnName;
	}

	/**
	* "Unqualify" the specified attribute name, removing the mapping's name
	* from the front of the attribute name if it is present. For example, if
	* the mapping's name is <code>"foo"</code>, the attribute name
	* <code>"foo.bar"</code> would be converted to <code>"bar"</code>).
	* Return <code>null</code> if the attribute name cannot be "unqualified".
	*/
	public static String unqualify(String mappingName, String attributeName) {
	if (mappingName == null) {
	return null;
	}
	if ( ! attributeName.startsWith(mappingName)) {
	return null;
	}
	int mappingNameLength = mappingName.length();
	if (attributeName.length() <= mappingNameLength) {
	return null;
	}
	return (attributeName.charAt(mappingNameLength) == '.') ? attributeName.substring(mappingNameLength + 1) : null;
	}

	/**
	* This transformer will prepend a specified qualifier, followed by a
	* dot ('.'), to a string. For example, if a mapping's name is
	* <code>"foo"</code> and one of its attribute's is named
	* <code>"bar"</code>, the attribute's name will be transformed
	* into <code>"foo.bar"</code>. If the specified qualifier is
	* <code>null</code> (or an empty string), only a dot will be prepended
	* to a string.
	*/
	public static class QualifierTransformer
	implements Transformer<String, String>
	{
	private final String prefix;
	public QualifierTransformer(String qualifier) {
	super();
	this.prefix = (qualifier == null) ? "." : qualifier + '.'; //$NON-NLS-1$
	}
	public String transform(String s) {
	return this.prefix + s;
	}
	}


	// ******** constructor ********

	/**
	* Suppress default constructor, ensuring non-instantiability.
	*/
	private MappingTools() {
	super();
	throw new UnsupportedOperationException();
	}
	}