/**
* Copyright 2009 Google Inc.
*
* Licensed 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 under the License.
*/
package org.waveprotocol.wave.model.operation.core;
import org.waveprotocol.wave.model.operation.Operation;
import org.waveprotocol.wave.model.operation.OperationException;
import org.waveprotocol.wave.model.wave.data.core.CoreWaveletData;
public abstract class CoreWaveletOperation implements Operation<CoreWaveletData> {
// Package visibility so that the set of subtypes is fixed.
CoreWaveletOperation() {}
/**
* This method delegates the operation logic to {@link #doApply(CoreWaveletData)}.
*/
public final void apply(CoreWaveletData wavelet) throws OperationException {
// Execute subtype logic first, because if the subtype logic throws an exception, we must
// leave this wrapper untouched as though the operation never happened. The subtype is
// responsible for making sure if they throw an exception they must leave themselves in a
// state as if the op never happened.
doApply(wavelet);
}
/**
* Applies this operation's logic to a given wavelet. This method can be
* arbitrarily overridden by subclasses.
*
* @param wavelet wavelet on which this operation is to apply itself
* @throws OperationException
*/
protected abstract void doApply(CoreWaveletData wavelet) throws OperationException;
/**
* Get the inverse of the operation, such that any {@CoreWaveletData} object applying this
* operation followed by its inverse will remain unchanged.
*
* @return the inverse of this operation
*/
public abstract CoreWaveletOperation getInverse();
}