/**
* Copyright (c) 2016-present, RxJava Contributors.
*
* 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 io.reactivex;
import io.reactivex.annotations.*;
/**
* Interface to compose Singles.
*
* @param <Upstream> the upstream value type
* @param <Downstream> the downstream value type
*/
public interface SingleTransformer<Upstream, Downstream> {
/**
* Applies a function to the upstream Single and returns a SingleSource with
* optionally different element type.
* @param upstream the upstream Single instance
* @return the transformed SingleSource instance
*/
@NonNull
SingleSource<Downstream> apply(@NonNull Single<Upstream> upstream);
}