Block.java

/*
 * Copyright 2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ratpack.func;

import ratpack.exec.Operation;
import ratpack.util.Exceptions;

/**
 * A block of code.
 * <p>
 * Similar to {@link Runnable}, but allows throwing of checked exceptions.
 */
@FunctionalInterface
public interface Block {

  static Block noop() {
    return () -> {
    };
  }

  /**
   * Execute the action.
   *
   * @throws Exception any
   */
  void execute() throws Exception;

  /**
   * Returns an action that immediately throws the given exception.
   * <p>
   * The exception is thrown via {@link ratpack.util.Exceptions#toException(Throwable)}
   *
   * @param throwable the throwable to immediately throw when the returned action is executed
   * @return an action that immediately throws the given exception.
   */
  static Block throwException(final Throwable throwable) {
    return () -> {
      throw Exceptions.toException(throwable);
    };
  }

  /**
   * Converts this action to a runnable.
   * <p>
   * Any thrown exceptions will be {@link Exceptions#uncheck(Block) unchecked}.
   *
   * @return a runnable
   */
  default Runnable toRunnable() {
    return () -> Exceptions.uncheck(this);
  }

  /**
   * Creates an {@link Operation} from this block.
   *
   * @return an operation
   * @see Operation#of(Block)
   * @deprecated since 1.5
   */
  @Deprecated
  default Operation operation() {
    return Operation.of(this);
  }

  /**
   * Creates an {@link Action} from this block, where the argument is ignored.
   *
   * @return an action that executes this block
   * @since 1.1
   */
  default Action<Object> action() {
    return t -> execute();
  }

  /**
   * Maps a block onto a new object with the provided function.
   * <p>
   * The block is not implicitly handled and the mapping function must call {@link #execute()} if desired.
   *
   * @param function the mapping function
   * @param <T> the return type
   * @return the mapped block
   */
  default <T> T map(Function<? super Block, ? extends T> function) {
    return Exceptions.uncheck(() -> function.apply(this));
  }
}