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// Copyright: 2010 - 2018 https://github.com/ensime/ensime-server/graphs
// License: http://www.gnu.org/licenses/lgpl-3.0.en.html
package spray.json

import annotation.implicitNotFound
import shapeless._

/**
 * Provides the JSON deserialization for type T.
 */
@implicitNotFound(
  msg = "Cannot find JsonReader or JsonFormat type class for ${T}"
)
trait JsonReader[T] {
  def read(json: JsValue): T
}

object JsonReader {
  def apply[T](implicit reader: JsonReader[T]): JsonReader[T] = reader
  implicit def func2Reader[T](f: JsValue => T): JsonReader[T] =
    new JsonReader[T] {
      def read(json: JsValue) = f(json)
    }
}

/**
 * Provides the JSON serialization for type T.
 */
@implicitNotFound(
  msg = "Cannot find JsonWriter or JsonFormat type class for ${T}"
)
trait JsonWriter[T] {
  def write(obj: T): JsValue
}

object JsonWriter {
  def apply[T](implicit writer: JsonWriter[T]): JsonWriter[T] = writer
  implicit def func2Writer[T](f: T => JsValue): JsonWriter[T] =
    new JsonWriter[T] {
      def write(obj: T) = f(obj)
    }
}

/**
 * Provides the JSON deserialization and serialization for type T.
 */
trait JsonFormat[T] extends JsonReader[T] with JsonWriter[T]
object JsonFormat {
  def apply[T](implicit f: Strict[JsonFormat[T]]): JsonFormat[T] = f.value
}

/**
 * A special JsonReader capable of reading a legal JSON root object, i.e. either a JSON array or a JSON object.
 */
@implicitNotFound(
  msg = "Cannot find RootJsonReader or RootJsonFormat type class for ${T}"
)
trait RootJsonReader[T] extends JsonReader[T]

/**
 * A special JsonWriter capable of writing a legal JSON root object, i.e. either a JSON array or a JSON object.
 */
@implicitNotFound(
  msg = "Cannot find RootJsonWriter or RootJsonFormat type class for ${T}"
)
trait RootJsonWriter[T] extends JsonWriter[T]

/**
 * A special JsonFormat signaling that the format produces a legal JSON root object, i.e. either a JSON array
 * or a JSON object.
 */
trait RootJsonFormat[T]
    extends JsonFormat[T]
    with RootJsonReader[T]
    with RootJsonWriter[T]
object RootJsonFormat {
  def apply[T](implicit f: Strict[RootJsonFormat[T]]): RootJsonFormat[T] =
    f.value
}