com.github.dm.jrt.operator.BinaryOperatorInvocation 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 com.github.dm.jrt.function.BiFunction;
import com.github.dm.jrt.function.BiFunctionDecorator;
import com.github.dm.jrt.function.Functions;

import org.jetbrains.annotations.NotNull;

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

/**
 * Invocation implementation computing the result by applying a bi-function instance to the inputs.
 * 
 * Created by davide-maestroni on 06/15/2016.
 *
 * @param  the data type.
 */
class BinaryOperatorInvocation extends TemplateInvocation {

  private final BiFunction mBinaryFunction;

  private boolean mIsFirst;

  private DATA mResult;

  /**
   * Constructor.
   *
   * @param binaryFunction the operator bi-function instance.
   */
  private BinaryOperatorInvocation(@NotNull final BiFunction binaryFunction) {
    mBinaryFunction = binaryFunction;
  }

  /**
   * Builds and returns a new binary operator invocation factory backed by the specified
   * bi-function instance.
   *
   * @param binaryFunction the operator bi-function instance.
   * @param          the data type.
   * @return the invocation factory.
   */
  @NotNull
  static  InvocationFactory functionFactory(
      @NotNull final BiFunction binaryFunction) {
    return new BinaryOperatorInvocationFactory(Functions.decorate(binaryFunction));
  }

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

  @Override
  public void onInput(final DATA input, @NotNull final Channel result) throws Exception {
    if (mIsFirst) {
      mIsFirst = false;
      mResult = input;

    } else {
      mResult = mBinaryFunction.apply(mResult, input);
    }
  }

  @Override
  public void onRecycle(final boolean isReused) {
    mResult = null;
  }

  @Override
  public void onRestart() {
    mIsFirst = true;
  }

  /**
   * Class implementing a binary operator invocation factory.
   *
   * @param  the data type.
   */
  private static class BinaryOperatorInvocationFactory extends InvocationFactory {

    private final BiFunctionDecorator mBinaryFunction;

    /**
     * Constructor.
     *
     * @param binaryFunction the operator bi-function instance.
     */
    private BinaryOperatorInvocationFactory(
        @NotNull final BiFunctionDecorator binaryFunction) {
      super(asArgs(binaryFunction));
      mBinaryFunction = binaryFunction;
    }

    @NotNull
    @Override
    public Invocation newInvocation() {
      return new BinaryOperatorInvocation(mBinaryFunction);
    }
  }
}