CheckedBiFunction.java

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package com.google.mu.function;

import static java.util.Objects.requireNonNull;

/** A binary function that can throw checked exceptions. */
@FunctionalInterface
public interface CheckedBiFunction<A, B, T, E extends Throwable> {
  T apply(A a, B b) throws E;

  /**
   * Returns a new {@code CheckedBiFunction} that maps the return value using {@code mapper}.
   * For example: {@code ((a, b) -> a + b).andThen(Object::toString).apply(1, 2) => "3"}.
   */
  default <R> CheckedBiFunction<A, B, R, E> andThen(
      CheckedFunction<? super T, ? extends R, ? extends E> mapper) {
    requireNonNull(mapper);
    return (a, b) -> mapper.apply(apply(a, b));
  }
}