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// Copyright 2016 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.skylarkinterface;
import java.lang.reflect.Method;
import javax.annotation.Nullable;
/**
* Helpers for accessing Skylark interface annotations.
*/
public class SkylarkInterfaceUtils {
/**
* Returns the {@link SkylarkCallable} annotation for the given method, if it exists, and
* null otherwise. The method must be declared in {@code classObj} or one of its base classes
* or interfaces. The first annotation of an overridden version of the method that is found
* will be returned, starting with {@code classObj} and following its base classes and
* interfaces recursively.
*/
@Nullable
public static SkylarkCallable getSkylarkCallable(Class<?> classObj, Method method) {
boolean keepLooking = false;
try {
Method superMethod = classObj.getMethod(method.getName(), method.getParameterTypes());
if (classObj.isAnnotationPresent(SkylarkModule.class)
&& superMethod.isAnnotationPresent(SkylarkCallable.class)) {
return superMethod.getAnnotation(SkylarkCallable.class);
} else {
keepLooking = true;
}
} catch (NoSuchMethodException e) {
// The class might not have the specified method, so an exceptions is OK.
keepLooking = true;
}
if (keepLooking) {
if (classObj.getSuperclass() != null) {
SkylarkCallable annotation =
getSkylarkCallable(classObj.getSuperclass(), method);
if (annotation != null) {
return annotation;
}
}
for (Class<?> interfaceObj : classObj.getInterfaces()) {
SkylarkCallable annotation = getSkylarkCallable(interfaceObj, method);
if (annotation != null) {
return annotation;
}
}
}
return null;
}
/**
* Convenience version of {@code getAnnotationsFromParentClass(Class, Method)} that uses
* the declaring class of the method.
*/
@Nullable
public static SkylarkCallable getSkylarkCallable(Method method) {
return getSkylarkCallable(method.getDeclaringClass(), method);
}
}
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