ch.rasc.wampspring.demo.various.grid.PropertyComparatorFactory.java Source code

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Here is the source code for ch.rasc.wampspring.demo.various.grid.PropertyComparatorFactory.java

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/**
 * Copyright 2013-2015 Ralph Schaer <ralphschaer@gmail.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 ch.rasc.wampspring.demo.various.grid;

import java.util.Collection;
import java.util.Comparator;

import org.springframework.expression.ParseException;

public enum PropertyComparatorFactory {

    INSTANCE;

    public static <T> Comparator<T> createComparator(String propertyName, SortDirection sortDirection) {
        try {
            Comparator<T> comparator = new PropertyComparator<>(propertyName);

            if (sortDirection == SortDirection.DESC) {
                comparator = comparator.reversed();
            }

            return comparator;
        } catch (ParseException e) {
            return null;
        }
    }

    @SuppressWarnings("unchecked")
    public static <T> Comparator<T> createComparatorFromSorters(Collection<SortInfo> sortInfos) {
        Comparator<T> comparator = null;

        if (sortInfos != null) {
            comparator = sortInfos.stream()
                    .map(a -> (Comparator<T>) createComparator(a.getProperty(), a.getDirection()))
                    .reduce(comparator, (a, b) -> a != null ? a.thenComparing(b) : b);
        }

        return comparator;
    }

}