com.spotify.scio.coders.KryoRegistrar.scala Maven / Gradle / Ivy
/*
* Copyright 2019 Spotify AB.
*
* 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.spotify.scio.coders
import scala.annotation.{compileTimeOnly, StaticAnnotation}
import scala.reflect.macros._
/**
* Annotation for custom Kryo registrar classes.
*
* Annotated class must extend `IKryoRegistrar` and has name that ends with "KryoRegistrar".
*/
@compileTimeOnly(
"enable macro paradise (2.12) or -Ymacro-annotations (2.13) to expand macro annotations"
)
class KryoRegistrar extends StaticAnnotation {
def macroTransform(annottees: Any*): Any = macro KryoRegistrarMacro.impl
}
private object KryoRegistrarMacro {
def impl(c: blackbox.Context)(annottees: c.Expr[Any]*): c.Expr[Any] = {
import c.universe._
val traitT = tq"_root_.com.spotify.scio.coders.AnnotatedKryoRegistrar"
annottees.map(_.tree) match {
case List(q"$mod class $name extends ..$parents { ..$body }") =>
if (!parents.exists(_.toString() == "IKryoRegistrar")) {
c.abort(c.enclosingPosition, s"Registrar class must extend IKryoRegistrar")
}
if (!name.toString().endsWith("KryoRegistrar")) {
c.abort(c.enclosingPosition, s"Registrar class name must end with KryoRegistrar")
}
c.Expr[Any](q"$mod class $name extends ..$parents with $traitT { ..$body }")
case t => c.abort(c.enclosingPosition, s"Invalid annotation $t")
}
}
}
/** Trait to be added to Kryo registrar class annotated with `@KryoRegistrar`. */
trait AnnotatedKryoRegistrar