com.intel.podm.allocation.mappers.Sorter.java Source code

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Here is the source code for com.intel.podm.allocation.mappers.Sorter.java

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/*
 * Copyright (c) 2016 Intel Corporation
 *
 * 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 com.intel.podm.allocation.mappers;

import com.google.common.base.Function;
import com.google.common.collect.Ordering;
import com.intel.podm.business.dto.redfish.ContextPossessor;

import java.util.Collection;
import java.util.List;

import static com.google.common.collect.Ordering.natural;
import static java.util.Objects.isNull;

public final class Sorter {
    private Sorter() {
    }

    @SafeVarargs
    public static <T> List<T> sort(Collection<T> toBeSorted, Ordering<T>... orderings) {
        if (orderings == null || orderings.length == 0) {
            throw new IllegalArgumentException("At least one ordering method must be passed to sort.");
        }

        Ordering<T> ordering = orderings[0];
        for (int i = 1; i < orderings.length; i++) {
            ordering = ordering.compound(orderings[i]);
        }

        return ordering.sortedCopy(toBeSorted);
    }

    public static <T, U extends Comparable> Ordering<T> ascendingWhereNullsFirst(Function<T, U> comparingFunction) {
        return natural().nullsFirst().onResultOf(comparingFunction);
    }

    public static <T, U extends Comparable> Ordering<T> ascendingWhereNullsLast(Function<T, U> comparingFunction) {
        return natural().nullsLast().onResultOf(comparingFunction);
    }

    public static <T extends ContextPossessor> Ordering<T> contextsAscendingWhereNullsLast() {
        return natural().nullsLast()
                .onResultOf(addressPossessor -> isNull(addressPossessor.getResourceContext()) ? null
                        : addressPossessor.getResourceContext().getId());
    }
}