/****************************************************************************
* Sangria *
* Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com> *
* *
* 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.tavianator.sangria.core;
import java.lang.annotation.Annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.concurrent.atomic.AtomicLong;
import javax.inject.Qualifier;
import com.google.common.annotations.VisibleForTesting;
/**
* Re-implementation of Guice's internal UniqueAnnotations utility.
*
* @author Tavian Barnes (tavianator@tavianator.com)
* @version 1.0
* @since 1.0
*/
public class UniqueAnnotations {
private static final AtomicLong SEQUENCE = new AtomicLong();
private UniqueAnnotations() {
// Not for instantiating
}
@Retention(RetentionPolicy.RUNTIME)
@Qualifier
@VisibleForTesting
@interface UniqueAnnotation {
long value();
}
/**
* Actual implementation of {@link UniqueAnnotation}.
*/
@SuppressWarnings("ClassExplicitlyAnnotation")
private static class UniqueAnnotationImpl implements UniqueAnnotation {
private final long value;
UniqueAnnotationImpl(long value) {
this.value = value;
}
@Override
public long value() {
return value;
}
public Class<? extends Annotation> annotationType() {
return UniqueAnnotation.class;
}
@Override
public String toString() {
return "@" + UniqueAnnotation.class.getName() + "(value=" + value + ")";
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
} else if (!(obj instanceof UniqueAnnotation)) {
return false;
}
UniqueAnnotation other = (UniqueAnnotation)obj;
return value == other.value();
}
@Override
public int hashCode() {
return (127*"value".hashCode()) ^ Long.valueOf(value).hashCode();
}
}
/**
* @return An {@link Annotation} that will be unequal to every other annotation.
*/
public static Annotation create() {
return create(SEQUENCE.getAndIncrement());
}
@VisibleForTesting
static Annotation create(long value) {
return new UniqueAnnotationImpl(value);
}
}