code: /*
   * 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.rxjava3.core;
  
  import io.reactivex.rxjava3.annotations.NonNull;
  
  /**
   * Base interface for emitting signals in a push-fashion in various generator-like source
   * operators (create, generate).
   * <p>
   * Note that the {@link Emitter#onNext}, {@link Emitter#onError} and
   * {@link Emitter#onComplete} methods provided to the function via the {@link Emitter} instance should be called synchronously,
   * never concurrently. Calling them from multiple threads is not supported and leads to an
   * undefined behavior.
   *
   * @param <T> the value type emitted
   */
  public interface Emitter<@NonNull T> {
  
      /**
       * Signal a normal value.
       * @param value the value to signal, not {@code null}
       */
      void onNext(@NonNull T value);
  
      /**
       * Signal a {@link Throwable} exception.
       * @param error the {@code Throwable} to signal, not {@code null}
       */
      void onError(@NonNull Throwable error);
  
      /**
       * Signal a completion.
       */
      void onComplete();
  }
  