001/*
002 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package jdk.internal.jvmci.options;
024
025import java.io.*;
026import java.util.function.*;
027
028import jdk.internal.jvmci.options.OptionValue.*;
029
030/**
031 * A cached value that needs to be recomputed when an option changes.
032 */
033public class DerivedOptionValue<T> {
034
035    public interface OptionSupplier<T> extends Supplier<T>, Serializable {
036    }
037
038    private final T initialValue;
039    private final OptionSupplier<T> supplier;
040
041    public DerivedOptionValue(OptionSupplier<T> supplier) {
042        this.supplier = supplier;
043        assert OptionValue.getOverrideScope() == null : "derived option value should be initialized outside any override scope";
044        this.initialValue = createValue();
045    }
046
047    public T getValue() {
048        OverrideScope overrideScope = OptionValue.getOverrideScope();
049        if (overrideScope != null) {
050            return overrideScope.getDerived(this);
051        } else {
052            return initialValue;
053        }
054    }
055
056    T createValue() {
057        return supplier.get();
058    }
059}