spray.json.derived.DiscriminatorMacro.scala Maven / Gradle / Ivy

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/*
 * Copyright 2021 Paolo Boni
 *
 * 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 spray.json.derived

import scala.quoted.*

object DiscriminatorMacro {
  inline def getDiscriminator[A]: Option[String] = ${ getDiscriminatorImpl[A] }

  def getDiscriminatorImpl[A: Type](using Quotes): Expr[Option[String]] = {
    import quotes.reflect.*
    val annotations = TypeRepr.of[A].typeSymbol.annotations.collectFirst {
      case ann @ Apply(Select(New(ident), _), List(tpe)) if ann.tpe.show == "spray.json.derived.Discriminator" =>
        tpe.show.replaceAll("\"", "")
    }
    Expr(annotations)
  }
}