/*
* 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.apache.flink.api.common.functions;
import org.apache.flink.annotation.Public;
import java.io.Serializable;
/**
* Base interface for Map functions. Map functions take elements and transform them,
* element wise. A Map function always produces a single result element for each input element.
* Typical applications are parsing elements, converting data types, or projecting out fields.
* Operations that produce multiple result elements from a single input element can be implemented
* using the {@link FlatMapFunction}.
* <p>
* The basic syntax for using a MapFunction is as follows:
* <pre>{@code
* DataSet<X> input = ...;
*
* DataSet<Y> result = input.map(new MyMapFunction());
* }</pre>
*
* @param <T> Type of the input elements.
* @param <O> Type of the returned elements.
*/
@Public
public interface MapFunction<T, O> extends Function, Serializable {
/**
* The mapping method. Takes an element from the input data set and transforms
* it into exactly one element.
*
* @param value The input value.
* @return The transformed value
*
* @throws Exception This method may throw exceptions. Throwing an exception will cause the operation
* to fail and may trigger recovery.
*/
O map(T value) throws Exception;
}