/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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;
/**
* An operation sink is an opaque operation applier. It has a single method through which
* operations are passed, and must obey the contract that the intent of that operation gets
* executed. Note this is a weaker contract than actually executing the {@link
* Operation#apply(Object)} method on that operation (for example, the operation may be transformed
* into another operation instance, so that the new operation's {@code apply} method would be called
* instead).
*
* A sink also abstracts away the locating of the appropriate object to which the operation is
* applied. Usually, a sink will either pass the operation to another sink, or be a manager for
* instances of the target type to which the operation applies, and will identify the appropriate
* instance and then execute the operation's {@code apply} method on that instance.
*
*
* @param <T>
*/
public interface OperationSink<T extends Operation<?>> {
/**
* An operation sink which does nothing with consumed operations.
*/
static final OperationSink<Operation<?>> VOID =
new OperationSink<Operation<?>>() {
@Override
public void consume(Operation<?> op) {
}
};
/**
* Consumes an operation. Usually, this will involve finding an appropriate target for the
* operation, then calling {@link Operation#apply(Object)} on that target. However, this is not
* a strong guarantee. The only contract for a sink is to ensure that the intent of the given
* operation is effected.
*
* @param op operation to apply
*/
public void consume(T op) throws OperationException;
}