/**
* 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 storm.trident.operation;
import storm.trident.tuple.TridentTuple;
import java.util.Map;
/**
* Filters take in a tuple as input and decide whether or not to keep that tuple or not.
*
* If the `isKeep()` method of a Filter returns `false` for a tuple, that tuple will be filtered out of the Stream
*
*
* ### Configuration
* If your `Filter` implementation has configuration requirements, you will typically want to extend
* {@link org.apache.storm.trident.operation.BaseFilter} and override the
* {@link org.apache.storm.trident.operation.Operation#prepare(Map, TridentOperationContext)} method to perform your custom
* initialization.
*
* @see org.apache.storm.trident.Stream
*/
public interface Filter extends EachOperation {
/**
* Determines if a tuple should be filtered out of a stream
*
* @param tuple the tuple being evaluated
* @return `false` to drop the tuple, `true` to keep the tuple
*/
boolean isKeep(TridentTuple tuple);
}