--- /dev/null 2015-10-08 07:26:02.000000000 -1000 +++ new/src/jdk.vm.ci/share/classes/jdk.vm.ci.options/src/jdk/vm/ci/options/DerivedOptionValue.java 2015-10-08 07:26:02.000000000 -1000 @@ -0,0 +1,59 @@ +/* + * 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 { + + public interface OptionSupplier extends Supplier, Serializable { + } + + private final T initialValue; + private final OptionSupplier supplier; + + public DerivedOptionValue(OptionSupplier 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(); + } +}