| // Copyright (c) 2019, the R8 project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| package com.android.tools.r8.ir.analysis.type; |
| |
| import java.util.function.BiFunction; |
| import java.util.function.Function; |
| |
| public class NullabilityVariants<T extends ReferenceTypeElement> { |
| |
| private T maybeNullVariant; |
| private T definitelyNullVariant; |
| private T definitelyNotNullVariant; |
| private T bottomVariant; |
| |
| public static <T extends ReferenceTypeElement> T create( |
| Nullability nullability, Function<NullabilityVariants<T>, T> callback) { |
| NullabilityVariants<T> variants = new NullabilityVariants<>(); |
| T newElement = callback.apply(variants); |
| variants.set(nullability, newElement); |
| return newElement; |
| } |
| |
| private void set(Nullability nullability, T element) { |
| if (nullability == Nullability.maybeNull()) { |
| maybeNullVariant = element; |
| } else if (nullability == Nullability.definitelyNull()) { |
| definitelyNullVariant = element; |
| } else if (nullability == Nullability.definitelyNotNull()) { |
| definitelyNotNullVariant = element; |
| } else { |
| assert nullability == Nullability.bottom(); |
| bottomVariant = element; |
| } |
| } |
| |
| T get(Nullability nullability) { |
| if (nullability == Nullability.maybeNull()) { |
| return maybeNullVariant; |
| } else if (nullability == Nullability.definitelyNull()) { |
| return definitelyNullVariant; |
| } else if (nullability == Nullability.definitelyNotNull()) { |
| return definitelyNotNullVariant; |
| } else { |
| assert nullability == Nullability.bottom(); |
| return bottomVariant; |
| } |
| } |
| |
| T getOrCreateElement( |
| Nullability nullability, BiFunction<Nullability, NullabilityVariants<T>, T> creator) { |
| T element = get(nullability); |
| if (element != null) { |
| return element; |
| } |
| synchronized (this) { |
| element = get(nullability); |
| if (element != null) { |
| return element; |
| } |
| element = creator.apply(nullability, this); |
| assert element != null; |
| set(nullability, element); |
| return element; |
| } |
| } |
| } |