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Event capture and querying framework for Java

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/**
 * Copyright (c) 2016, All Contributors (see CONTRIBUTORS file)
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
package com.eventsourcing.queries;

import com.eventsourcing.Entity;
import com.eventsourcing.EntityHandle;
import com.eventsourcing.Model;
import com.eventsourcing.Repository;
import com.eventsourcing.index.EntityIndex;
import com.googlecode.cqengine.resultset.ResultSet;

import java.util.Optional;
import java.util.UUID;

import static com.eventsourcing.index.EntityQueryFactory.equal;

/**
 * Combines all standard queries into one:
 * 
 *     {@link LatestAssociatedEntryQuery}
 * 
 */
public interface ModelQueries extends Model, LatestAssociatedEntryQuery {

    /**
     * Lookup an entity by a unique ID.
     *
     * @param repository repository
     * @param klass entity klass
     * @param keyAttribute entity ID attribute
     * @param id ID
     * @param  entity type
     * @return Non-empty {@link Optional} if the entity is found, empty otherwise
     */
    static  Optional
            lookup(Repository repository, Class klass, EntityIndex keyAttribute, UUID id) {
        try (ResultSet> resultSet = repository.query(klass, equal(keyAttribute, id))) {
            if (resultSet.isEmpty()) {
                return Optional.empty();
            } else {
                return Optional.of(resultSet.uniqueResult().get());
            }
        }
    }

}