io.etcd.jetcd.Observers Maven / Gradle / Ivy

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/*
 * Copyright 2016-2019 The jetcd authors
 *
 * 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.etcd.jetcd;

import io.grpc.stub.StreamObserver;
import java.util.function.Consumer;
import java.util.function.Function;

public final class Observers {
  private Observers() {
  }

  public static  StreamObserver observer(Consumer onNext) {
    return new StreamObserver() {
      @Override
      public void onNext(V value) {
        onNext.accept(value);
      }

      @Override
      public void onError(Throwable throwable) {
      }

      @Override
      public void onCompleted() {
      }
    };
  }

  public static  StreamObserver observer(Consumer onNext, Consumer onError) {
    return new StreamObserver() {
      @Override
      public void onNext(V value) {
        onNext.accept(value);
      }

      @Override
      public void onError(Throwable throwable) {
        onError.accept(throwable);
      }

      @Override
      public void onCompleted() {
      }
    };
  }

  public static  StreamObserver observe(
      Function, StreamObserver> consumer,
      Consumer onNext,
      Consumer onError) {

    return consumer.apply(
      observer(onNext, onError)
    );
  }

  public static  Builder builder() {
    return new Builder<>();
  }

  public static final class Builder {
    private Consumer onNext;
    private Consumer onError;
    private Runnable onCompleted;

    public Builder onNext(Consumer onNext) {
      this.onNext = onNext;
      return this;
    }

    public Builder onError(Consumer onError) {
      this.onError = onError;
      return this;
    }

    public Builder onCompleted(Runnable onCompleted) {
      this.onCompleted = onCompleted;
      return this;
    }

    public StreamObserver build() {
      final Consumer doOnNext = this.onNext;
      final Consumer doOnnError = this.onError;
      final Runnable doOnnCompleted = this.onCompleted;

      return new StreamObserver() {
        @Override
        public void onNext(V value) {
          if (onNext != null) {
            doOnNext.accept(value);
          }
        }

        @Override
        public void onError(Throwable throwable) {
          if (doOnnError != null) {
            doOnnError.accept(throwable);
          }
        }

        @Override
        public void onCompleted() {
          if (doOnnCompleted != null) {
            doOnnCompleted.run();
          }
        }
      };
    }

  }
}