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Concourse is a self-tuning database that is designed for both ad hoc analytics and high volume transactions at scale. Developers use Concourse to quickly build mission critical software while also benefiting from real time insight into their most important data. With Concourse, end-to-end data management requires no extra infrastructure, no prior configuration and no additional coding–all of which greatly reduce costs and allow developers to focus on core business problems.

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/*
 * Copyright (c) 2013-2019 Cinchapi Inc.
 *
 * 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.cinchapi.concourse.util;

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

import com.google.common.collect.Lists;

/**
 * Yet another utility class that deals with {@link Collection Collections}.
 * 
 * @author Jeff Nelson
 */
public final class Collections {

    /**
     * Convert the given {@code collection} to a {@link List}, if necessary.
     * 
     * @param collection
     * @return a List that contains all the elements in {@code collection}.
     */
    public static  List toList(Collection collection) {
        return collection instanceof List ? (List) collection
                : Lists.newArrayList(collection);
    }

    /**
     * Convert the given {@code collection} to a {@link List} of {@link Long}
     * values, if necessary. The client must attempt to do this for every
     * collection of records because CaSH always passes user input in as a
     * collection of {@link Integer integers}.
     * 
     * @param collection
     * @return a List that contains Long values
     */
    public static  List toLongList(Collection collection) {
        List list = Lists.newArrayListWithCapacity(collection.size());
        Iterator it = collection.iterator();
        while (it.hasNext()) {
            T elt = it.next();
            if(elt instanceof Number) {
                list.add(((Number) elt).longValue());
            }
            else {
                throw new ClassCastException("Cant convert object of type"
                        + elt.getClass() + " to java.lang.Long");
            }
        }
        return list;
    }

    private Collections() {/* noop */}

}