com.eucalyptus.util.FUtils.java Source code

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Here is the source code for com.eucalyptus.util.FUtils.java

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/*************************************************************************
 * Copyright 2009-2015 Eucalyptus Systems, Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/.
 *
 * Please contact Eucalyptus Systems, Inc., 6755 Hollister Ave., Goleta
 * CA 93117, USA or visit http://www.eucalyptus.com/licenses/ if you need
 * additional information or have any questions.
 ************************************************************************/
package com.eucalyptus.util;

import java.util.concurrent.Callable;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import com.google.common.base.Function;
import com.google.common.base.Optional;

/**
 * Functional utility methods
 */
public class FUtils {

    /**
     * Partially apply the function using the given parameter.
     *
     * @return Callable type thunk
     */
    public static <R, P> Callable<R> cpartial(final Function<? super P, ? extends R> function, final P param) {
        return new Callable<R>() {
            @Override
            public R call() throws Exception {
                return function.apply(param);
            }
        };
    }

    /**
     * Flatten a nested optional.
     *
     * @param option The optional to flatten
     * @param <T> The resulting optional type
     * @return The optional
     */
    @Nonnull
    public static <T> Optional<T> flatten(@Nullable final Optional<? extends Optional<T>> option) {
        if (option != null && option.isPresent()) {
            return option.get();
        }
        return Optional.absent();
    }

}