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Partly generated model of the fields that represent columns in the database. Fields can be used to produce special predicates and functions that contain metadata that Speedment can analyze runtime.

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/**
 *
 * Copyright (c) 2006-2017, Speedment, Inc. All Rights Reserved.
 *
 * 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.speedment.runtime.field.internal.util;

import java.util.*;

import static java.util.Collections.*;

/**
 * Utility class for constructing temporary collections.
 *
 * @author Emil Forslund
 * @since  3.0.11
 */
public final class CollectionUtil {

    /**
     * Returns a {@link Set} with the values in the specified collection. If the
     * specified collection is already a {@link Set}, it might be returned. This
     * method makes no guarantees regarding mutability or iteration order of the
     * returned set.
     *
     * @param          the element type
     * @param collection  the collection
     * @return            a set with the same elements as the collection
     */
    public static  Set collectionToSet(Collection collection) {
        if (collection instanceof Set) {
            return (Set) collection;
        } else {
            switch (collection.size()) {
                case 0  : return emptySet();
                case 1  : return singleton(collection.iterator().next());
                default : return new HashSet<>(collection);
            }
        }
    }

    /**
     * Creates a copy of the specified list and adds the specified elements to
     * it before returning it as an immutable list.
     *
     * @param        the element type
     * @param original  the original list
     * @param element   elements to add
     * @return          the new immutable list
     */
    @SafeVarargs
    public static  List copyAndAdd(List original, T... element) {
        switch (original.size() + element.length) {
            case 0 : return emptyList();
            case 1 : return singletonList(
                original.isEmpty() ? element[0] : original.get(0)
            );
            default : {
                final List copy = new ArrayList<>(original);
                addAll(copy, element);
                return unmodifiableList(copy);
            }
        }
    }

    /**
     * Should not be instantiated.
     */
    private CollectionUtil() {}
}