FieldGroupElement.java

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/*
 * FieldGroupElement.java
 *
 * Created on February 29, 2000, 4:57 PM
 */

package com.sun.jdo.api.persistence.model.jdo;

import com.sun.jdo.api.persistence.model.ModelException;

/** 
 *
 * @author raccah
 * @version %I%
 */
public abstract class FieldGroupElement extends PersistenceMemberElement
	implements FieldElementHolder
{
	/** Create new FieldGroupElement with no implementation. 
	 * This constructor should only be used for cloning and archiving.
	 */
	public FieldGroupElement ()
	{
		this(null, null);
	}

	/** Create new FieldGroupElement with the provided implementation. The 
	 * implementation is responsible for storing all properties of the object.
	 * @param impl the implementation to use
	 * @param declaringClass the class to attach to
	 */
	public FieldGroupElement (FieldGroupElement.Impl impl,
		PersistenceClassElement declaringClass)
	{
		super(impl, declaringClass);
	}

	/** @return implemetation factory for this field group
	 */
	final Impl getFieldGroupImpl () { return (Impl)getImpl(); }

	//================== Fields ===============================
	// PersistenceFieldElement handling, implementation of FieldElementHolder

	/** Add the supplied field to the collection of fields maintained by this
	 * holder.
	 * @param field the field to be added
	 * @exception ModelException if impossible
	 */
	public void addField (PersistenceFieldElement field) 
		throws ModelException 
	{
		addFields(new PersistenceFieldElement[]{field});
	}

	/** Add the supplied fields to the collection of fields maintained by this
	 * holder.
	 * @param fields the array of fields to be added
	 * @exception ModelException if impossible
	 */
	public void addFields(PersistenceFieldElement[] fields)
		throws ModelException 
	{
		getFieldGroupImpl().changeFields(fields, Impl.ADD);
	}

	/** Remove the supplied field from the collection of fields maintained by
	 * this holder.
	 * @param field the field to be removed
	 * @exception ModelException if impossible
	 */
	public void removeField (PersistenceFieldElement field)
		throws ModelException 
	{
		removeFields(new PersistenceFieldElement[]{field});
	}

	/** Removed the supplied fields from the collection of fields maintained
	 * by this holder.
	 * @param fields the array of fields to be removed
	 * @exception ModelException if impossible
	 */
	public void removeFields (PersistenceFieldElement[] fields)
		throws ModelException 
	{
		getFieldGroupImpl().changeFields(fields, Impl.REMOVE);
	}

	/** Returns the collection of fields maintained by this holder in the form
	 * of an array.
	 * @return the fields maintained by this holder
	 */
	public PersistenceFieldElement[] getFields ()
	{
		return getFieldGroupImpl().getFields();
	}

	/** Sets the collection of fields maintained by this holder to the contents
	 * of the supplied array.
	 * @param fields the fields maintained by this holder
	 * @exception ModelException if impossible
	 */
	public void setFields (PersistenceFieldElement[] fields)
		throws ModelException 
	{
		getFieldGroupImpl().changeFields(fields, Impl.SET);
	}

	/** Returns the field with the supplied name from the collection of fields
	 * maintained by this holder.
	 * @param name the name of the field to be found
	 * @return the field with the supplied name, <code>null</code> if none exists
	 */
	public PersistenceFieldElement getField (String name)
	{
		return getFieldGroupImpl().getField(name);
	}

	/** Tests whether the supplied field is in the collection of fields 
	 * maintained by this holder.
	 * @param field the field to be tested
	 */
	public boolean containsField (PersistenceFieldElement field)
	{
		return (getFieldGroupImpl().getField(field.getName()) != null);
	}

	/** Pluggable implementation of the storage of field element properties.
	 * @see PersistenceFieldElement#PersistenceFieldElement
	 */
	public interface Impl extends PersistenceMemberElement.Impl
	{
		/** Change the set of fields.
		 * @param fields the new fields
		 * @param action {@link #ADD}, {@link #REMOVE}, or {@link #SET}
		 * @exception ModelException if impossible
		 */
		public void changeFields (PersistenceFieldElement[] fields, int action)
			throws ModelException;

		/** Get all fields.
		 * @return the fields
		 */
		public PersistenceFieldElement[] getFields ();

		/** Find a field by name.
		 * @param name the name to match
		 * @return the field, or <code>null</code> if it does not exist
		 */
		public PersistenceFieldElement getField (String name);
	}
}