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Expose current repository name to Java with @AutoBazelRepository
Java targets depending on `@bazel_tools//tools/java/runfiles` can add the new `@AutoBazelRepository` to a class to have an annotation processor generate a companion class with a `BAZEL_REPOSITORY` constant containing the repository name of the target that compiled the class. This requires a small addition to JavaBuilder to parse the repository name out of the target label and pass it to javac as a processor option.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,32 @@ | ||
| // Copyright 2022 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.runfiles; | ||
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|
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| import java.lang.annotation.ElementType; | ||
| import java.lang.annotation.Retention; | ||
| import java.lang.annotation.RetentionPolicy; | ||
| import java.lang.annotation.Target; | ||
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|
||
| /** | ||
| * Annotating a class {@code Fooer} with this annotation generates a class | ||
| * {@code AutoBazelRepository_Fooer} defining a {@link String} constant {@code BAZEL_REPOSITORY} | ||
| * containing the canonical name of the repository containing the Bazel target that compiled the | ||
| * annotated class. | ||
| */ | ||
| @Retention(RetentionPolicy.SOURCE) | ||
| @Target(ElementType.TYPE) | ||
| public @interface AutoBazelRepository { | ||
|
|
||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,102 @@ | ||
| // Copyright 2022 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. | ||
|
|
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| package com.google.devtools.build.runfiles; | ||
|
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| import static java.util.stream.Collectors.joining; | ||
| import static java.util.stream.Collectors.toList; | ||
|
|
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| import java.io.IOException; | ||
| import java.io.PrintWriter; | ||
| import java.util.Collections; | ||
| import java.util.List; | ||
| import java.util.Set; | ||
| import java.util.stream.Stream; | ||
| import javax.annotation.processing.AbstractProcessor; | ||
| import javax.annotation.processing.RoundEnvironment; | ||
| import javax.annotation.processing.SupportedAnnotationTypes; | ||
| import javax.annotation.processing.SupportedOptions; | ||
| import javax.annotation.processing.SupportedSourceVersion; | ||
| import javax.lang.model.SourceVersion; | ||
| import javax.lang.model.element.Element; | ||
| import javax.lang.model.element.Name; | ||
| import javax.lang.model.element.TypeElement; | ||
| import javax.tools.Diagnostic.Kind; | ||
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| @SupportedAnnotationTypes("com.google.devtools.build.runfiles.AutoBazelRepository") | ||
| @SupportedOptions("bazel.repository") | ||
| @SupportedSourceVersion(SourceVersion.RELEASE_8) | ||
| public final class AutoBazelRepositoryProcessor extends AbstractProcessor { | ||
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| @Override | ||
| public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) { | ||
| annotations.stream() | ||
| .flatMap(element -> roundEnv.getElementsAnnotatedWith(element).stream()) | ||
| .map(element -> (TypeElement) element) | ||
| .forEach(this::emitClass); | ||
| return true; | ||
| } | ||
|
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| private void emitClass(TypeElement annotatedClass) { | ||
| // This option is always provided by JavaBuilder. | ||
| String repositoryName = processingEnv.getOptions() | ||
| .getOrDefault("bazel.repository", "@for testing only"); | ||
| if (!repositoryName.startsWith("@")) { | ||
| processingEnv.getMessager() | ||
| .printMessage(Kind.ERROR, "Expected value of bazel.repository option to start with '@'", | ||
| annotatedClass); | ||
| return; | ||
| } | ||
| repositoryName = repositoryName.substring(1); | ||
|
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| // For a nested class Outer.Middle.Inner, generate a class with simple name | ||
| // AutoBazelRepository_Outer_Middle_Inner. | ||
| // Note: There can be collisions when local classes are involved, but since the definition of a | ||
| // class depends only on the containing Bazel target, this does not result in ambiguity. | ||
| List<String> nestedClassNames = Stream.iterate(annotatedClass, | ||
| element -> element instanceof TypeElement, | ||
| Element::getEnclosingElement) | ||
| .map(Element::getSimpleName) | ||
| .map(Name::toString) | ||
| .collect(toList()); | ||
| Collections.reverse(nestedClassNames); | ||
| String generatedClassSimpleName = Stream.concat(Stream.of("AutoBazelRepository"), | ||
| nestedClassNames.stream()).collect(joining("_")); | ||
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| String generatedClassPackage = processingEnv.getElementUtils().getPackageOf(annotatedClass) | ||
| .getQualifiedName().toString(); | ||
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| String generatedClassName = generatedClassPackage.isEmpty() ? generatedClassSimpleName | ||
| : generatedClassPackage + "." + generatedClassSimpleName; | ||
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| try (PrintWriter out = new PrintWriter( | ||
| processingEnv.getFiler().createSourceFile(generatedClassName).openWriter())) { | ||
| out.printf("package %s;\n", generatedClassPackage); | ||
| out.printf("\n"); | ||
| out.printf("class %s {\n", generatedClassSimpleName); | ||
| out.printf(" /**\n"); | ||
| out.printf(" * The canonical name of the repository containing the Bazel target that\n"); | ||
| out.printf(" * compiled {@link %s}.\n", annotatedClass.getQualifiedName().toString()); | ||
| out.printf(" */\n"); | ||
| out.printf(" static final String BAZEL_REPOSITORY = \"%s\";\n", repositoryName); | ||
| out.printf("\n"); | ||
| out.printf(" private %s() {}\n", generatedClassSimpleName); | ||
| out.printf("}\n"); | ||
| } catch (IOException e) { | ||
| processingEnv.getMessager().printMessage(Kind.ERROR, | ||
| String.format("Failed to generate %s: %s", generatedClassName, e.getMessage()), | ||
| annotatedClass); | ||
| } | ||
| } | ||
| } |
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