TransformerBenchmark

build.gradle

plugins {
  // https://github.com/melix/jmh-gradle-plugin
  id 'me.champeau.gradle.jmh' version '0.4.7'
}

wrapper {
  gradleVersion = '5.0'
}

apply plugin: 'java'
sourceCompatibility = 1.8

StringBox.java

package pl.tlinkowski.transformer;

import java.util.function.Function;

/**
 * @author Tomasz Linkowski
 */
final class StringBox implements Transformable {

  private final String string;

  StringBox(String string) {
    this.string = string;
  }

  StringBox toLowerCase() {
    return new StringBox(string.toLowerCase());
  }

  @Override
  public Transformer<StringBox> transformed() {
    return this::transform;
  }

  <R> R transform(Function<? super StringBox, ? extends R> f) {
    return f.apply(this);
  }
}

Transformable.java

package pl.tlinkowski.transformer;

/**
 * @author Tomasz Linkowski
 */
public interface Transformable {

  Transformer<?> transformed();
}

Transformer.java

package pl.tlinkowski.transformer;

import java.util.function.Function;

/**
 * @author Tomasz Linkowski
 */
@FunctionalInterface
public interface Transformer<T> {

  <R> R by(Function<? super T, ? extends R> f);
}

TransformerBenchmark.java

package pl.tlinkowski.transformer;

import org.openjdk.jmh.annotations.*;

import java.util.concurrent.TimeUnit;

/**
 * @author Tomasz Linkowski
 */
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Benchmark)
public class TransformerBenchmark {

  @Param({"no change", "Some Change"})
  public String string;
  public StringBox stringBox;

  @Setup
  public void setup() {
    stringBox = new StringBox(string);
  }

  @Benchmark
  public StringBox baseline() {
    return stringBox.toLowerCase();
  }

  @Benchmark
  public StringBox transform() {
    return stringBox.transform(StringBox::toLowerCase);
  }

  @Benchmark
  public StringBox transformed() {
    return stringBox.transformed().by(StringBox::toLowerCase);
  }
}