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// Copyright 2017 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;
import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.base.Verify;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import java.util.LinkedHashSet;
import java.util.Set;
/**
* Provides the effective class for the provider. The effective class is inferred as the sole class
* in the provider's inheritence hierarchy that implements {@link TransitiveInfoProvider} directly.
* This allows for simple subclasses such as those created by AutoValue, but will fail if there's
* any ambiguity as to which implementor of the {@link TransitiveInfoProvider} is intended. If the
* provider implements multiple TransitiveInfoProvider interfaces, prefer the explicit put builder
* methods.
*/
class TransitiveInfoProviderEffectiveClassHelper {
private TransitiveInfoProviderEffectiveClassHelper() {}
private static final LoadingCache<
Class<? extends TransitiveInfoProvider>, Class<? extends TransitiveInfoProvider>>
EFFECTIVE_PROVIDER_CLASS_CACHE =
CacheBuilder.newBuilder()
.build(
new CacheLoader<
Class<? extends TransitiveInfoProvider>,
Class<? extends TransitiveInfoProvider>>() {
private Set<Class<? extends TransitiveInfoProvider>> getDirectImplementations(
Class<? extends TransitiveInfoProvider> providerClass) {
Set<Class<? extends TransitiveInfoProvider>> result = new LinkedHashSet<>();
for (Class<?> clazz : providerClass.getInterfaces()) {
if (TransitiveInfoProvider.class.equals(clazz)) {
result.add(providerClass);
} else if (TransitiveInfoProvider.class.isAssignableFrom(clazz)) {
result.addAll(
getDirectImplementations(
(Class<? extends TransitiveInfoProvider>) clazz));
}
}
Class<?> superclass = providerClass.getSuperclass();
if (superclass != null
&& TransitiveInfoProvider.class.isAssignableFrom(superclass)) {
result.addAll(
getDirectImplementations(
(Class<? extends TransitiveInfoProvider>) superclass));
}
return result;
}
@Override
public Class<? extends TransitiveInfoProvider> load(
Class<? extends TransitiveInfoProvider> providerClass) {
Set<Class<? extends TransitiveInfoProvider>> result =
getDirectImplementations(providerClass);
Verify.verify(!result.isEmpty()); // impossible
Preconditions.checkState(
result.size() == 1,
"Effective provider class for %s is ambiguous (%s), specify explicitly.",
providerClass,
Joiner.on(',').join(result));
return result.iterator().next();
}
});
// TODO(arielb): see if these can be made private?
static <T extends TransitiveInfoProvider> Class<T> get(T provider) {
return get((Class<T>) provider.getClass());
}
static <T extends TransitiveInfoProvider> Class<T> get(Class<T> providerClass) {
return (Class<T>) EFFECTIVE_PROVIDER_CLASS_CACHE.getUnchecked(providerClass);
}
}
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