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/*
* Copyright (C) 2014 Google, Inc.
*
* 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.auto.common;
import static com.google.auto.common.MoreElements.isAnnotationPresent;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.base.Equivalence;
import com.google.common.base.Predicate;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.lang.annotation.Annotation;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.util.ElementFilter;
import javax.lang.model.util.Elements;
/**
* A utility class for working with {@link AnnotationMirror} instances.
*
* @author Gregory Kick
*/
public final class AnnotationMirrors {
private static final Equivalence ANNOTATION_MIRROR_EQUIVALENCE =
new Equivalence() {
@Override
protected boolean doEquivalent(AnnotationMirror left, AnnotationMirror right) {
return MoreTypes.equivalence().equivalent(left.getAnnotationType(),
right.getAnnotationType()) && AnnotationValues.equivalence().pairwise().equivalent(
getAnnotationValuesWithDefaults(left).values(),
getAnnotationValuesWithDefaults(right).values());
}
@Override
protected int doHash(AnnotationMirror annotation) {
DeclaredType type = annotation.getAnnotationType();
Iterable annotationValues =
getAnnotationValuesWithDefaults(annotation).values();
return Arrays.hashCode(new int[] {MoreTypes.equivalence().hash(type),
AnnotationValues.equivalence().pairwise().hash(annotationValues)});
}
};
/**
* Returns an {@link Equivalence} for {@link AnnotationMirror} as some implementations
* delegate equality tests to {@link Object#equals} whereas the documentation explicitly
* states that instance/reference equality is not the proper test.
*/
public static Equivalence equivalence() {
return ANNOTATION_MIRROR_EQUIVALENCE;
}
/**
* Returns the {@link AnnotationMirror}'s map of {@link AnnotationValue} indexed by {@link
* ExecutableElement}, supplying default values from the annotation if the annotation property has
* not been set. This is equivalent to {@link
* Elements#getElementValuesWithDefaults(AnnotationMirror)} but can be called statically without
* an {@link Elements} instance.
*
* The iteration order of elements of the returned map will be the order in which the {@link
* ExecutableElement}s are defined in {@code annotation}'s {@linkplain
* AnnotationMirror#getAnnotationType() type}.
*/
public static ImmutableMap getAnnotationValuesWithDefaults(
AnnotationMirror annotation) {
ImmutableMap.Builder values = ImmutableMap.builder();
Map declaredValues =
annotation.getElementValues();
for (ExecutableElement method :
ElementFilter.methodsIn(annotation.getAnnotationType().asElement().getEnclosedElements())) {
// Must iterate and put in this order, to ensure consistency in generated code.
if (declaredValues.containsKey(method)) {
values.put(method, declaredValues.get(method));
} else if (method.getDefaultValue() != null) {
values.put(method, method.getDefaultValue());
} else {
throw new IllegalStateException(
"Unset annotation value without default should never happen: "
+ MoreElements.asType(method.getEnclosingElement()).getQualifiedName()
+ '.' + method.getSimpleName() + "()");
}
}
return values.build();
}
/**
* Returns an {@link AnnotationValue} for the named element if such an element was
* either declared in the usage represented by the provided {@link AnnotationMirror}, or if
* such an element was defined with a default.
*
* @throws IllegalArgumentException if no element is defined with the given elementName.
*/
public static AnnotationValue getAnnotationValue(
AnnotationMirror annotationMirror, String elementName) {
return getAnnotationElementAndValue(annotationMirror, elementName).getValue();
}
/**
* Returns a {@link ExecutableElement} and its associated {@link AnnotationValue} if such
* an element was either declared in the usage represented by the provided
* {@link AnnotationMirror}, or if such an element was defined with a default.
*
* @throws IllegalArgumentException if no element is defined with the given elementName.
*/
public static Map.Entry getAnnotationElementAndValue(
AnnotationMirror annotationMirror, final String elementName) {
checkNotNull(annotationMirror);
checkNotNull(elementName);
for (Map.Entry entry :
getAnnotationValuesWithDefaults(annotationMirror).entrySet()) {
if (entry.getKey().getSimpleName().contentEquals(elementName)) {
return entry;
}
}
throw new IllegalArgumentException(String.format("@%s does not define an element %s()",
MoreElements.asType(annotationMirror.getAnnotationType().asElement()).getQualifiedName(),
elementName));
}
/**
* Returns all {@linkplain AnnotationMirror annotations} that are present on the given
* {@link Element} which are themselves annotated with {@code annotationType}.
*/
public static ImmutableSet getAnnotatedAnnotations(Element element,
final Class annotationType) {
List annotations = element.getAnnotationMirrors();
return FluentIterable.from(annotations)
.filter(new Predicate() {
@Override public boolean apply(AnnotationMirror input) {
return isAnnotationPresent(input.getAnnotationType().asElement(), annotationType);
}
})
.toSet();
}
private AnnotationMirrors() {}
}