com.github.dm.jrt.operator.OrElseInvocationFactory Maven / Gradle / Ivy

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/*
 * Copyright 2016 Davide Maestroni
 *
 * 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 com.github.dm.jrt.operator;

import com.github.dm.jrt.core.channel.Channel;
import com.github.dm.jrt.core.invocation.Invocation;
import com.github.dm.jrt.core.invocation.InvocationFactory;
import com.github.dm.jrt.core.invocation.TemplateInvocation;

import org.jetbrains.annotations.NotNull;

import static com.github.dm.jrt.core.util.Reflection.asArgs;

/**
 * Invocation factory generating outputs when no one has been received.
 * 
 * Created by davide-maestroni on 04/29/2016.
 *
 * @param  the data type.
 */
class OrElseInvocationFactory extends InvocationFactory {

  private final Channel mChannel;

  /**
   * Constructor.
   *
   * @param channel the output channel.
   */
  OrElseInvocationFactory(@NotNull final Channel channel) {
    super(asArgs(channel));
    mChannel = channel;
  }

  @NotNull
  @Override
  public Invocation newInvocation() {
    return new OrElseInvocation(mChannel);
  }

  /**
   * Invocation generating outputs when no one has been received.
   *
   * @param  the data type.
   */
  private static class OrElseInvocation extends TemplateInvocation {

    private final Channel mChannel;

    private boolean mHasOutputs;

    /**
     * Constructor.
     *
     * @param channel the output channel.
     */
    OrElseInvocation(@NotNull final Channel channel) {
      mChannel = channel;
    }

    @Override
    public void onComplete(@NotNull final Channel result) {
      if (!mHasOutputs) {
        result.pass(mChannel);
      }
    }

    @Override
    public void onInput(final DATA input, @NotNull final Channel result) {
      mHasOutputs = true;
      result.pass(input);
    }

    @Override
    public void onRestart() {
      mHasOutputs = false;
    }
  }
}