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JsonMergePatch.scala
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JsonMergePatch.scala
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/*
* Copyright 2022 Lucas Satabin
*
* 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 diffson
package jsonmergepatch
import cats._
import cats.implicits._
import scala.language.higherKinds
sealed trait JsonMergePatch[Json] {
/** Applies this patch to the given Json valued and returns the patched value */
def apply[F[_]](original: Json)(implicit F: MonadError[F, Throwable]): F[Json]
def toJson: Json
}
object JsonMergePatch {
case class Value[Json](toJson: Json) extends JsonMergePatch[Json] {
def apply[F[_]](original: Json)(implicit F: MonadError[F, Throwable]): F[Json] =
F.pure(toJson)
}
case class Object[Json](fields: Map[String, Json])(implicit Json: Jsony[Json]) extends JsonMergePatch[Json] {
def toJson = JsObject(fields)
def apply[F[_]](json: Json)(implicit F: MonadError[F, Throwable]): F[Json] = {
val toPatch =
json match {
case JsObject(toPatch) => toPatch
case _ => Map.empty[String, Json]
}
val patched =
fields.toList.foldM(toPatch) {
case (acc, (k, n)) if n === Json.Null =>
F.pure(acc - k)
case (acc, (k, JsObject(flds))) =>
Object(flds).apply[F](acc.getOrElse(k, Json.Null)).map(acc.updated(k, _))
case (acc, (k, v)) =>
F.pure(acc.updated(k, v))
}
patched.map(JsObject(_))
}
}
}