| // Copyright 2020 The Bazel Authors. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| package com.google.devtools.build.lib.analysis.config; |
| |
| import com.google.common.collect.ImmutableSet; |
| import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable; |
| import com.google.devtools.build.lib.events.EventHandler; |
| import java.util.List; |
| import javax.annotation.Nullable; |
| import net.starlark.java.eval.StarlarkValue; |
| |
| /** |
| * An interface for language-specific configurations. |
| * |
| * <p>Implementations must have a constructor that takes a single {@link BuildOptions} argument. If |
| * the constructor reads any {@link FragmentOptions} from this argument, the fragment must declare |
| * them via {@link RequiresOptions}. |
| * |
| * <p>All implementations must be immutable and communicate this as clearly as possible (e.g. |
| * declare {@link com.google.common.collect.ImmutableList} signatures on their interfaces vs. {@link |
| * List}). This is because fragment instances may be shared across configurations. |
| * |
| * <p>Fragments are Starlark values, as returned by {@code ctx.fragments.android}, for example. |
| */ |
| @Immutable |
| public abstract class Fragment implements StarlarkValue { |
| |
| /** |
| * When a fragment doesn't want to be part of the configuration (for example, when its required |
| * options are missing and the fragment determines this means the configuration doesn't need it), |
| * it should override this method. |
| */ |
| public boolean shouldInclude() { |
| return true; |
| } |
| |
| @Override |
| public boolean isImmutable() { |
| return true; // immutable and Starlark-hashable |
| } |
| |
| /** |
| * Validates the options for this Fragment. Issues warnings for the use of deprecated options, and |
| * warnings or errors for any option settings that conflict. |
| */ |
| @SuppressWarnings("unused") |
| public void reportInvalidOptions(EventHandler reporter, BuildOptions buildOptions) {} |
| |
| /** |
| * Returns a fragment of the output directory name for this configuration. The output directory |
| * for the whole configuration contains all the short names by all fragments. |
| */ |
| @Nullable |
| public String getOutputDirectoryName() { |
| return null; |
| } |
| |
| /** Returns the option classes needed to create a fragment. */ |
| public static ImmutableSet<Class<? extends FragmentOptions>> requiredOptions( |
| Class<? extends Fragment> fragmentClass) { |
| return fragmentClass.isAnnotationPresent(RequiresOptions.class) |
| ? ImmutableSet.copyOf(fragmentClass.getAnnotation(RequiresOptions.class).options()) |
| : ImmutableSet.of(); |
| } |
| } |