com.github.tonivade.purefun.MemoizedProducer Maven / Gradle / Ivy

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/*
 * Copyright (c) 2018-2020, Antonio Gabriel Muñoz Conejo 
 * Distributed under the terms of the MIT License
 */
package com.github.tonivade.purefun;

import static com.github.tonivade.purefun.Unit.unit;
import static java.util.Collections.synchronizedMap;
import static java.util.Objects.requireNonNull;

import java.util.HashMap;
import java.util.Map;

final class MemoizedProducer implements Producer {

  private final Map cache = synchronizedMap(new HashMap<>(1));
  private final Function1 function;

  MemoizedProducer(Producer producer) {
    this.function = requireNonNull(producer).asFunction();
  }

  @Override
  public T run() {
    return cache.computeIfAbsent(unit(), function::apply);
  }

  @Override
  public Producer memoized() {
    return this;
  }
}