org.elasticsearch.common.inject.Key Maven / Gradle / Ivy
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/*
* Copyright (C) 2006 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 org.elasticsearch.common.inject;
import org.elasticsearch.common.inject.internal.Annotations;
import org.elasticsearch.common.inject.internal.MoreTypes;
import org.elasticsearch.common.inject.internal.ToStringBuilder;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.Objects;
/**
* Binding key consisting of an injection type and an optional annotation.
* Matches the type and annotation at a point of injection.
*
* For example, {@code Key.get(Service.class, Transactional.class)} will
* match:
*
* {@literal @}Inject
* public void setService({@literal @}Transactional Service service) {
* ...
* }
*
*
* {@code Key} supports generic types via subclassing just like {@link
* TypeLiteral}.
*
* Keys do not differentiate between primitive types (int, char, etc.) and
* their corresponding wrapper types (Integer, Character, etc.). Primitive
* types will be replaced with their wrapper types when keys are created.
*
* @author [email protected] (Bob Lee)
*/
public class Key {
private final AnnotationStrategy annotationStrategy;
private final TypeLiteral typeLiteral;
private final int hashCode;
/**
* Constructs a new key. Derives the type from this class's type parameter.
*
* Clients create an empty anonymous subclass. Doing so embeds the type
* parameter in the anonymous class's type hierarchy so we can reconstitute it
* at runtime despite erasure.
*
* Example usage for a binding of type {@code Foo}:
*
* {@code new Key() {}}.
*/
@SuppressWarnings("unchecked")
protected Key() {
this.annotationStrategy = NullAnnotationStrategy.INSTANCE;
this.typeLiteral = (TypeLiteral) TypeLiteral.fromSuperclassTypeParameter(getClass());
this.hashCode = computeHashCode();
}
/**
* Unsafe. Constructs a key from a manually specified type.
*/
@SuppressWarnings("unchecked")
private Key(Type type, AnnotationStrategy annotationStrategy) {
this.annotationStrategy = annotationStrategy;
this.typeLiteral = MoreTypes.makeKeySafe((TypeLiteral) TypeLiteral.get(type));
this.hashCode = computeHashCode();
}
/**
* Constructs a key from a manually specified type.
*/
private Key(TypeLiteral typeLiteral, AnnotationStrategy annotationStrategy) {
this.annotationStrategy = annotationStrategy;
this.typeLiteral = MoreTypes.makeKeySafe(typeLiteral);
this.hashCode = computeHashCode();
}
private int computeHashCode() {
return typeLiteral.hashCode() * 31 + annotationStrategy.hashCode();
}
/**
* Gets the key type.
*/
public final TypeLiteral getTypeLiteral() {
return typeLiteral;
}
/**
* Gets the annotation type.
*/
public final Class getAnnotationType() {
return annotationStrategy.getAnnotationType();
}
/**
* Gets the annotation.
*/
public final Annotation getAnnotation() {
return annotationStrategy.getAnnotation();
}
boolean hasAnnotationType() {
return annotationStrategy.getAnnotationType() != null;
}
Class getRawType() {
return typeLiteral.getRawType();
}
@Override
public final boolean equals(Object o) {
if (o == this) {
return true;
}
if ((o instanceof Key) == false) {
return false;
}
Key other = (Key) o;
return annotationStrategy.equals(other.annotationStrategy) && typeLiteral.equals(other.typeLiteral);
}
@Override
public final int hashCode() {
return this.hashCode;
}
@Override
public final String toString() {
return new ToStringBuilder(Key.class).add("type", typeLiteral).add("annotation", annotationStrategy).toString();
}
/**
* Gets a key for an injection type.
*/
public static Key get(Class type) {
return new Key<>(type, NullAnnotationStrategy.INSTANCE);
}
/**
* Gets a key for an injection type.
*/
public static Key get(TypeLiteral typeLiteral) {
return new Key<>(typeLiteral, NullAnnotationStrategy.INSTANCE);
}
/**
* Gets a key for an injection type and an annotation.
*/
public static Key get(TypeLiteral typeLiteral, Annotation annotation) {
return new Key<>(typeLiteral, strategyFor(annotation));
}
/**
* Returns a new key of the {@link String} type with the same annotation as this
* key.
*/
Key ofStringType() {
return new Key<>(String.class, annotationStrategy);
}
/**
* Returns a new key of the specified type with the same annotation as this
* key.
*/
Key ofType(Type type) {
return new Key<>(type, annotationStrategy);
}
/**
* Returns true if this key has annotation attributes.
*/
boolean hasAttributes() {
return annotationStrategy.hasAttributes();
}
/**
* Returns this key without annotation attributes, i.e. with only the
* annotation type.
*/
Key withoutAttributes() {
return new Key<>(typeLiteral, annotationStrategy.withoutAttributes());
}
interface AnnotationStrategy {
Annotation getAnnotation();
Class getAnnotationType();
boolean hasAttributes();
AnnotationStrategy withoutAttributes();
}
/**
* Gets the strategy for an annotation.
*/
static AnnotationStrategy strategyFor(Annotation annotation) {
Objects.requireNonNull(annotation, "annotation");
Class annotationType = annotation.annotationType();
ensureRetainedAtRuntime(annotationType);
ensureIsBindingAnnotation(annotationType);
if (annotationType.getMethods().length == 0) {
return new AnnotationTypeStrategy(annotationType, annotation);
}
return new AnnotationInstanceStrategy(annotation);
}
private static void ensureRetainedAtRuntime(Class annotationType) {
if (Annotations.isRetainedAtRuntime(annotationType) == false) {
throw new IllegalArgumentException(
annotationType.getName() + " is not retained at runtime. Please annotate it with @Retention(RUNTIME)."
);
}
}
private static void ensureIsBindingAnnotation(Class annotationType) {
if (isBindingAnnotation(annotationType) == false) {
throw new IllegalArgumentException(
annotationType.getName() + " is not a binding annotation. Please annotate it with @BindingAnnotation."
);
}
}
enum NullAnnotationStrategy implements AnnotationStrategy {
INSTANCE;
@Override
public boolean hasAttributes() {
return false;
}
@Override
public AnnotationStrategy withoutAttributes() {
throw new UnsupportedOperationException("Key already has no attributes.");
}
@Override
public Annotation getAnnotation() {
return null;
}
@Override
public Class getAnnotationType() {
return null;
}
@Override
public String toString() {
return "[none]";
}
}
// this class not test-covered
static class AnnotationInstanceStrategy implements AnnotationStrategy {
final Annotation annotation;
AnnotationInstanceStrategy(Annotation annotation) {
this.annotation = Objects.requireNonNull(annotation, "annotation");
}
@Override
public boolean hasAttributes() {
return true;
}
@Override
public AnnotationStrategy withoutAttributes() {
return new AnnotationTypeStrategy(getAnnotationType(), annotation);
}
@Override
public Annotation getAnnotation() {
return annotation;
}
@Override
public Class getAnnotationType() {
return annotation.annotationType();
}
@Override
public boolean equals(Object o) {
if ((o instanceof AnnotationInstanceStrategy) == false) {
return false;
}
AnnotationInstanceStrategy other = (AnnotationInstanceStrategy) o;
return annotation.equals(other.annotation);
}
@Override
public int hashCode() {
return annotation.hashCode();
}
@Override
public String toString() {
return annotation.toString();
}
}
static class AnnotationTypeStrategy implements AnnotationStrategy {
final Class annotationType;
// Keep the instance around if we have it so the client can request it.
final Annotation annotation;
AnnotationTypeStrategy(Class annotationType, Annotation annotation) {
this.annotationType = Objects.requireNonNull(annotationType, "annotation type");
this.annotation = annotation;
}
@Override
public boolean hasAttributes() {
return false;
}
@Override
public AnnotationStrategy withoutAttributes() {
throw new UnsupportedOperationException("Key already has no attributes.");
}
@Override
public Annotation getAnnotation() {
return annotation;
}
@Override
public Class getAnnotationType() {
return annotationType;
}
@Override
public boolean equals(Object o) {
if ((o instanceof AnnotationTypeStrategy) == false) {
return false;
}
AnnotationTypeStrategy other = (AnnotationTypeStrategy) o;
return annotationType.equals(other.annotationType);
}
@Override
public int hashCode() {
return annotationType.hashCode();
}
@Override
public String toString() {
return "@" + annotationType.getName();
}
}
static boolean isBindingAnnotation(Class annotationType) {
return annotationType.getAnnotation(BindingAnnotation.class) != null;
}
}