org.jclouds.collect.FindResourceInSet.java Source code

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Here is the source code for org.jclouds.collect.FindResourceInSet.java

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/**
 *
 * Copyright (C) 2010 Cloud Conscious, LLC. <info@cloudconscious.com>
 *
 * ====================================================================
 * 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 org.jclouds.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.NoSuchElementException;
import java.util.Set;

import javax.annotation.Resource;
import javax.inject.Inject;
import javax.inject.Singleton;

import org.jclouds.logging.Logger;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.base.Supplier;
import com.google.common.collect.Iterables;

/**
 * @author Adrian Cole
 */
@Singleton
public abstract class FindResourceInSet<F, T> implements Function<F, T> {
    @Resource
    protected Logger logger = Logger.NULL;

    private final Supplier<Set<? extends T>> set;

    @Inject
    public FindResourceInSet(@Memoized Supplier<Set<? extends T>> set) {
        this.set = checkNotNull(set, "set");
    }

    public abstract boolean matches(F from, T input);

    public T apply(final F from) {
        try {
            return Iterables.find(set.get(), new Predicate<T>() {

                @Override
                public boolean apply(T input) {
                    return matches(from, input);
                }

            });
        } catch (NoSuchElementException e) {
            logger.warn("could not find a match in set for %s", from);
        }
        return null;
    }
}