/*

 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.vm.ci.options;

import java.io.*;

import java.util.function.*;

import jdk.vm.ci.options.OptionValue.*;

/**

 * A cached value that needs to be recomputed when an option changes.

 */

public class DerivedOptionValue<T> {

    public interface OptionSupplier<T> extends Supplier<T>, Serializable {

    }

    private final T initialValue;

    private final OptionSupplier<T> supplier;

    public DerivedOptionValue(OptionSupplier<T> supplier) {

        this.supplier = supplier;

        assert OptionValue.getOverrideScope() == null : "derived option value should be initialized outside any override scope";

        this.initialValue = createValue();

    }

    public T getValue() {

        OverrideScope overrideScope = OptionValue.getOverrideScope();

        if (overrideScope != null) {

            return overrideScope.getDerived(this);

        } else {

            return initialValue;

        }

    }

    T createValue() {

        return supplier.get();

    }

}