content: /*
   * Copyright (C) 2020 ActiveJ LLC.
   *
   * 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 io.activej.promise;
  
  import org.jetbrains.annotations.Async;
  import org.jetbrains.annotations.Nullable;
  
  /**
   * Represents a {@link Promise} which can be completed or completedExceptionally
   * manually at once or later in the future.
   * <p>
   * Can be used as root {@code Promise} to start execution of chain of
   * {@code Promises} or when you want wrap your actions in {@code Promise}.
   *
   * @param <T> result type
   */
  public final class SettablePromise<T> extends AbstractPromise<T> implements SettableCallback<T> {
  	/**
  	 * Accepts the provided values and performs this operation
  	 * on them. If the {@code Exception e} is {@code null},
  	 * provided {@code result} will be set to this
  	 * {@code SettablePromise}.
  	 * <p>
  	 * Otherwise, {@code Exception e} will be set.
  	 *
  	 * @param result a value to be set to this
  	 *               {@code SettablePromise} if
  	 *               {@code e} is {@code null}
  	 * @param e      a {@code Exception}, which will
  	 *               be set to this {@code SettablePromise}
  	 *               if not {@code null}
  	 */
  	@Override
  	public void set(T result, @Nullable Exception e) {
  		complete(result, e);
  	}
  
  	/**
  	 * Sets the result of this {@code SettablePromise} and
  	 * completes it. {@code AssertionError} is thrown when you
  	 * try to set result for an already completed {@code Promise}.
  	 */
  	@Override
  	@Async.Execute
  	public void set(T result) {
  		complete(result);
  	}
  
  	/**
  	 * Sets exception and completes this {@code SettablePromise} exceptionally.
  	 * {@code AssertionError} is thrown when you try to set exception for
  	 * an already completed {@code Promise}.
  	 *
  	 * @param e exception
  	 */
  	@Override
  	@Async.Execute
  	public void setException(Exception e) {
  		completeExceptionally(e);
  	}
  
  	/**
  	 * Tries to set result or exception for this {@code SettablePromise}
  	 * if it is not completed yet. Otherwise, does nothing.
  	 */
  	@Override
  	@Async.Execute
  	public boolean trySet(T result, @Nullable Exception e) {
  		return tryComplete(result, e);
  	}
  
  	/**
  	 * Tries to set provided {@code result} for this
  	 * {@code SettablePromise} if it is not completed yet.
  	 * Otherwise, does nothing.
  	 */
  	@Override
  	@Async.Execute
  	public boolean trySet(T result) {
  		return tryComplete(result);
  	}
  
  	/**
  	 * Tries to set provided {@code e} exception for this
  	 * {@code SettablePromise} if it is not completed yet.
  	 * Otherwise, does nothing.
  	 */
  	@Override
  	@Async.Execute
  	public boolean trySetException(Exception e) {
  		return tryCompleteExceptionally(e);
  	}
  
  	@Override
  	public String describe() {
  		return "SettablePromise";
  	}
  }
  