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Neo4j property value system.

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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://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.values;

import org.neo4j.values.storable.HashMemoizingScalarValue;
import org.neo4j.values.storable.HashMemoizingValue;

/**
 * AnyValue that caches the hash code so that it doesn't require recomputation.
 * 
 * In order for the hierarchy to work out this is a duplicate of {@link HashMemoizingValue} and {@link HashMemoizingScalarValue}
 */
public abstract class HashMemoizingAnyValue extends AnyValue {
    private int hash;

    @Override
    protected final int computeHash() {
        // We will always recompute hashcode for values
        // where `hashCode == 0`, e.g. empty strings and empty lists
        // however that shouldn't be shouldn't be too costly
        if (hash == 0) {
            hash = computeHashToMemoize();
        }
        return hash;
    }

    @Override
    protected boolean internalEquals(Object other) {
        if (this == other) {
            return true;
        } else if (hash != 0 && other instanceof HashMemoizingAnyValue o && o.hash == hash) {
            return equalTo(other);
        } else {
            return other != null && equalTo(other);
        }
    }

    protected abstract int computeHashToMemoize();
}