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Event capture and querying framework for Java

There is a newer version: 0.4.6

/**
 * 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.index;

import com.eventsourcing.Entity;
import com.googlecode.cqengine.query.option.QueryOptions;

import java.util.function.BiFunction;

/**
 * Designates a multiple values index using a functional interface
 *
 * Typically, a definition will look like this:
 *
 *  * 
 * public static MultiValueIndex<TestEvent, UUID> REFERENCE_ID = (object) -> ...;
 * 
 * 
 *
 * However, there are cases when accessing {@link QueryOptions} is necessary. This can be achieved
 * using {@link MultiValueIndex#withQueryOptions(BiFunction)}:
 *
 *  * 
 * public static MultiValueIndex<TestEvent, UUID> REFERENCE_ID =
 *    MultiValueIndex.withQueryOptions((object, queryOptions) -> ...);
 * 
 * 
 *
 * @param  entity type
 * @param  attribute type
 */
@FunctionalInterface
public interface MultiValueIndex extends EntityIndex {
    default Iterable getValues(O object, QueryOptions queryOptions) {
        return getValues(object);
    }

    Iterable getValues(O object);

    /**
     * Creates a MultiValueIndex with a function that can access {@link QueryOptions}
     * @param function
     * @param 
     * @param 
     * @return
     */
    static  MultiValueIndex
        withQueryOptions(BiFunction> function) {
        return new MultiValueIndex() {
            @Override public Iterable getValues(O object, QueryOptions queryOptions) {
                return function.apply(object, queryOptions);
            }

            @Override public Iterable getValues(O object) {
                return function.apply(object, EntityQueryFactory.noQueryOptions());
            }
        };
    }

    default Attribute getAttribute() {
        throw new IllegalStateException("Index " + this + " hasn't been initialized yet");
    }
}