Operation.java

/*
 * Chrysalix
 * See the COPYRIGHT.txt file distributed with this work for information
 * regarding copyright ownership.  Some portions may be licensed
 * to Red Hat, Inc. under one or more contributor license agreements.
 * See the AUTHORS.txt file in the distribution for a full listing of 
 * individual contributors.
 *
 * Chrysalix is free software. Unless otherwise indicated, all code in Chrysalix
 * is licensed to you under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * Chrysalix is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.chrysalix.transformation;

import org.chrysalix.ChrysalixException;

/**
 * A class that produces a result by using zero or more {@link Value values}.
 * 
 * @param <T>
 *        the operation result type
 */
public interface Operation< T > extends Value< T >, Iterable< Value< ? > > {

    /**
     * An empty array of operations.
     */
    final Operation< ? >[] NO_OPERATIONS = new Operation< ? >[ 0 ];

    /**
     * @param descriptorId
     *        the identifier of the {@link ValueDescriptor descriptor} to use when adding the values (cannot be <code>null</code> or
     *        empty)
     * @param valuesBeingAdded
     *        the inputs being added (cannot be <code>null</code> or empty)
     * @throws IllegalArgumentException
     *         if the inputs being added is <code>null</code>, empty, or any value in the array is <code>null</code>
     * @throws ChrysalixException
     *         if the descriptor ID is not valid or if there is a problem adding any of the values
     */
    void addInput( final String descriptorId,
                   final Object... valuesBeingAdded ) throws ChrysalixException;

    /**
     * @return all inputs whose value is non-<code>null</code> (never <code>null</code> but can be empty)
     * @throws ChrysalixException
     *         if an error occurs
     */
    Value< ? >[] inputs() throws ChrysalixException;

    /**
     * @return the validation problems (never <code>null</code> but can be empty)
     * @throws ChrysalixException
     *         if an error occurs
     */
    ValidationProblems problems() throws ChrysalixException;

    /**
     * @param descriptorId
     *        the identifier of the {@link ValueDescriptor descriptor} to use when removing the values (cannot be <code>null</code>
     *        or empty)
     * @param valuesBeingRemoved
     *        the inputs being removed (cannot be <code>null</code> or empty)
     * @throws IllegalArgumentException
     *         if the inputs being removed is <code>null</code>, empty, or any value in the array is <code>null</code>; or if the
     *         descriptor ID is not valid
     * @throws ChrysalixException
     *         if there is a problem adding any of the values
     */
    void removeInput( final String descriptorId,
                      final Object... valuesBeingRemoved ) throws ChrysalixException;

    /**
     * @param descriptorId
     *        the identifier of the {@link ValueDescriptor descriptor} used when setting input values (cannot be <code>null</code>
     *        or empty)
     * @param valuesBeingSet
     *        the new input values (can be <code>null</code> or empty)
     * @throws ChrysalixException
     *         if there is a problem setting the input values
     */
    void setInput( final String descriptorId,
                   final Object... valuesBeingSet ) throws ChrysalixException;

    /**
     * @return the owning {@link Transformation transformation} (never <code>null</code>)
     */
    Transformation transformation();

}