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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.gds.collections.hsa;

import org.neo4j.gds.collections.DrainingIterator;
import org.neo4j.gds.collections.HugeSparseArray;

/**
 * A long-indexable version of an array of primitive double arrays ({@code
 * double[][]}) that can contain more than 2bn. elements.
 * 
 * It is implemented by paging of smaller arrays where each array, a so-called
 * page, can store up to 4096 elements. Using small pages can lead to fewer
 * array allocations if the value distribution is sparse. For indices for which
 * no value has been inserted, a user-defined default value is returned.
 * 
 * The array is immutable and needs to be constructed using a thread-safe,
 * growing builder.
 */
@HugeSparseArray(valueType = double[].class)
public interface HugeSparseDoubleArrayArray {

    /**
     * @return the maximum number of values stored in the array
     */
    long capacity();

    /**
     * @return the double[] value at the given index
     */
    double[] get(long index);

    /**
     * @return true, iff the value at the given index is not the default value
     */
    boolean contains(long index);

    /**
     * Returns an iterator that consumes the underlying pages of this array.
     * Once the iterator has been consumed, the array is empty and will return
     * the default value for each index.
     */
    DrainingIterator drainingIterator();

    /**
     * @return a thread-safe array builder that grows dynamically on inserts
     */
    static Builder builder(double[] defaultValue) {
        return builder(defaultValue, 0);
    }

    /**
     * @return a thread-safe array builder that grows dynamically on inserts
     */
    static Builder builder(double[] defaultValue, long initialCapacity) {
        return new HugeSparseDoubleArrayArraySon.GrowingBuilder(defaultValue, initialCapacity);
    }

    interface Builder {
        /**
         * Sets the value at the given index.
         */
        void set(long index, double[] value);

        /**
         * @return an immutable array
         */
        HugeSparseDoubleArrayArray build();
    }
}