com.google.auto.value.extension.serializable.serializer.interfaces.SerializerExtension Maven / Gradle / Ivy
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/*
* Copyright 2020 Google LLC
*
* 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.value.extension.serializable.serializer.interfaces;
import java.util.Optional;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.type.TypeMirror;
/**
* A SerializerExtension allows unserializable types to be serialized by SerializableAutoValue.
*
* Extensions are discovered at compile time using the {@link java.util.ServiceLoader} APIs,
* allowing them to run without any additional annotations. To be found by {@code ServiceLoader}, an
* extension class must be public with a public no-arg constructor, and its fully-qualified name
* must appear in a file called {@code
* META-INF/services/com.google.auto.value.extension.serializable.serializer.interfaces.SerializerExtension}
* in a jar that is on the compiler's {@code -classpath} or {@code -processorpath}.
*
*
When SerializableAutoValue maps each field in an AutoValue to a serializable proxy object, it
* asks each SerializerExtension whether it can generate code to make the given type serializable. A
* SerializerExtension replies that it can by returning a non-empty {@link Serializer}.
*
*
A SerializerExtension is also provided with a SerializerFactory, which it can use to query
* nested types.
*/
public interface SerializerExtension {
/**
* Returns a {@link Serializer} if this {@link SerializerExtension} applies to the given {@code
* type}. Otherwise, {@code Optional.empty} is returned.
*
* @param type the type being serialized
* @param factory a {@link SerializerFactory} that can be used to serialize nested types
* @param processingEnv the processing environment provided by the annotation processing framework
*/
Optional getSerializer(
TypeMirror type, SerializerFactory factory, ProcessingEnvironment processingEnv);
}