| /* |
| * Copyright (c) 2016, 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 org.graalvm.compiler.phases.common; |
| |
| import java.util.function.Supplier; |
| |
| /** |
| * A {@link Supplier} which always returns the same value, computed from an other supplier on the |
| * first access. |
| * |
| * <p> |
| * This implementation is not thread-safe and assumes the underlying supplier does not return null. |
| * If the underlying supplier returns null it will be called on each access until it returns a |
| * non-null value. |
| * </p> |
| */ |
| public class LazyValue<T> implements Supplier<T> { |
| private final Supplier<T> supplier; |
| private T value; |
| |
| public LazyValue(Supplier<T> supplier) { |
| this.supplier = supplier; |
| } |
| |
| @Override |
| public T get() { |
| if (value == null) { |
| value = supplier.get(); |
| } |
| return value; |
| } |
| } |