com.onthegomap.planetiler.util.Try Maven / Gradle / Ivy

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package com.onthegomap.planetiler.util;

import static com.onthegomap.planetiler.util.Exceptions.throwFatalException;

/**
 * A container for the result of an operation that may succeed or fail.
 *
 * @param  Type of the result value, if success
 */
public interface Try {
  /**
   * Calls {@code supplier} and wraps the result in {@link Success} if successful, or {@link Failure} if it throws an
   * exception.
   */
  static  Try apply(SupplierThatThrows supplier) {
    try {
      return success(supplier.get());
    } catch (Exception e) {
      return failure(e);
    }
  }

  static  Success success(T item) {
    return new Success<>(item);
  }

  static  Failure failure(Exception throwable) {
    return new Failure<>(throwable);
  }

  /**
   * Returns the result if success, or throws an exception if failure.
   *
   * @throws IllegalStateException wrapping the exception on failure
   */
  T get();

  default boolean isSuccess() {
    return !isFailure();
  }

  default boolean isFailure() {
    return exception() != null;
  }

  default Exception exception() {
    return null;
  }

  /** If success, then tries to cast the result to {@code clazz}, turning into a failure if not possible. */
  default  Try cast(Class clazz) {
    return map(clazz::cast);
  }

  /**
   * If this is a success, then maps the value through {@code fn}, returning the new value in a {@link Success} if
   * successful, or {@link Failure} if the mapping function threw an exception.
   */
   Try map(FunctionThatThrows fn);

  record Success (T get) implements Try {

    @Override
    public  Try map(FunctionThatThrows fn) {
      return Try.apply(() -> fn.apply(get));
    }
  }
  record Failure (@Override Exception exception) implements Try {

    @Override
    public T get() {
      return throwFatalException(exception);
    }

    @Override
    @SuppressWarnings("unchecked")
    public  Try map(FunctionThatThrows fn) {
      return (Try) this;
    }
  }

  @FunctionalInterface
  interface SupplierThatThrows {
    @SuppressWarnings("java:S112")
    T get() throws Exception;
  }
}