CheckedSupplier.java

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package com.google.mu.function;

import static java.util.Objects.requireNonNull;

/** A supplier that can throw checked exceptions. */
@FunctionalInterface
public interface CheckedSupplier<T, E extends Throwable> {
  T get() throws E;

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