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// Copyright 2014 Google Inc. 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;
import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import java.util.Set;
/**
* Transitive info provider for rules that behave differently when used from
* different languages.
*
* <p>Most rules generate code for a particular language or are totally language independent.
* Some rules, however, behave differently when depended upon from different languages.
* They might generate different libraries when used from different languages (and with
* different API versions). This interface allows code sharing between implementations.
*
* <p>This provider is not really a roll-up of transitive information.
*/
@Immutable
public final class LanguageDependentFragment implements TransitiveInfoProvider {
/**
* A language that can be supported by a multi-language configured target.
*
* <p>Note that no {@code hashCode}/{@code equals} methods are provided, because these
* objects are expected to be compared for object identity, which is the default.
*/
public static final class LibraryLanguage {
private final String displayName;
public LibraryLanguage(String displayName) {
this.displayName = displayName;
}
@Override
public String toString() {
return displayName;
}
}
private final Label label;
private final ImmutableSet<LibraryLanguage> languages;
public LanguageDependentFragment(Label label, Set<LibraryLanguage> languages) {
this.label = label;
this.languages = ImmutableSet.copyOf(languages);
}
/**
* Returns the label that is associated with this piece of information.
*
* <p>This is usually the label of the target that provides the information.
*/
public Label getLabel() {
return label;
}
/**
* Returns a set of the languages the ConfiguredTarget generates output for.
* For use only by rules that directly depend on this library via a "deps" attribute.
*/
public ImmutableSet<LibraryLanguage> getSupportedLanguages() {
return languages;
}
/**
* Routines for verifying that dependency provide the right output.
*/
public static final class Checker {
/**
* Checks that given dep supports the given language.
*/
public static boolean depSupportsLanguage(
RuleContext context, LanguageDependentFragment dep, LibraryLanguage language) {
if (dep.getSupportedLanguages().contains(language)) {
return true;
} else {
context.attributeError(
"deps", String.format("'%s' does not produce output for %s", dep.getLabel(), language));
return false;
}
}
/**
* Checks that all LanguageDependentFragment support the given language.
*/
public static void depsSupportsLanguage(RuleContext context, LibraryLanguage language) {
for (LanguageDependentFragment dep :
context.getPrerequisites("deps", Mode.TARGET, LanguageDependentFragment.class)) {
depSupportsLanguage(context, dep, language);
}
}
}
}
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