io.circe.shapes.LabelledHListInstances.scala Maven / Gradle / Ivy
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/*
* Copyright 2024 circe
*
* 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 io.circe.shapes
import cats.data.Validated
import cats.kernel.Eq
import io.circe.Decoder
import io.circe.DecodingFailure
import io.circe.Encoder
import io.circe.HCursor
import io.circe.JsonObject
import io.circe.KeyDecoder
import io.circe.KeyEncoder
import shapeless.::
import shapeless.HList
import shapeless.Widen
import shapeless.Witness
import shapeless.labelled.FieldType
import shapeless.labelled.field
trait LabelledHListInstances extends LowPriorityLabelledHListInstances {
/**
* Decode a record element with a symbol key.
*
* This is provided as a special case because of type inference issues with
* `decodeRecord` for symbols.
*/
implicit final def decodeSymbolLabelledHCons[K <: Symbol, V, T <: HList](implicit
witK: Witness.Aux[K],
decodeV: Decoder[V],
decodeT: Decoder[T]
): Decoder[FieldType[K, V] :: T] = new Decoder[FieldType[K, V] :: T] {
def apply(c: HCursor): Decoder.Result[FieldType[K, V] :: T] = Decoder.resultInstance.map2(
c.get[V](witK.value.name),
decodeT(c)
)((h, t) => field[K](h) :: t)
override def decodeAccumulating(c: HCursor): Decoder.AccumulatingResult[FieldType[K, V] :: T] =
Decoder.accumulatingResultInstance.map2(
decodeV.tryDecodeAccumulating(c.downField(witK.value.name)),
decodeT.decodeAccumulating(c)
)((h, t) => field[K](h) :: t)
}
/**
* Encode a record element with a symbol key.
*
* This is provided as a special case because of type inference issues with
* `encodeRecord` for symbols.
*/
implicit final def encodeSymbolLabelledHCons[K <: Symbol, V, T <: HList](implicit
witK: Witness.Aux[K],
encodeV: Encoder[V],
encodeT: Encoder.AsObject[T]
): Encoder.AsObject[FieldType[K, V] :: T] = new Encoder.AsObject[FieldType[K, V] :: T] {
def encodeObject(a: FieldType[K, V] :: T): JsonObject =
encodeT.encodeObject(a.tail).add(witK.value.name, encodeV(a.head))
}
}
private[shapes] trait LowPriorityLabelledHListInstances extends HListInstances {
implicit final def decodeLabelledHCons[K, W >: K, V, T <: HList](implicit
witK: Witness.Aux[K],
widenK: Widen.Aux[K, W],
eqW: Eq[W],
decodeW: KeyDecoder[W],
decodeV: Decoder[V],
decodeT: Decoder[T]
): Decoder[FieldType[K, V] :: T] = new Decoder[FieldType[K, V] :: T] {
private[this] val widened = widenK(witK.value)
private[this] val isK: String => Boolean = decodeW(_).exists(eqW.eqv(widened, _))
def apply(c: HCursor): Decoder.Result[FieldType[K, V] :: T] = Decoder.resultInstance.map2(
c.keys
.flatMap(_.find(isK))
.fold[Decoder.Result[String]](
Left(DecodingFailure("Record", c.history))
)(Right(_))
.flatMap(c.get[V](_)),
decodeT(c)
)((h, t) => field[K](h) :: t)
override def decodeAccumulating(c: HCursor): Decoder.AccumulatingResult[FieldType[K, V] :: T] =
Decoder.accumulatingResultInstance.map2(
c.keys
.flatMap(_.find(isK))
.fold[Decoder.AccumulatingResult[String]](
Validated.invalidNel(DecodingFailure("Record", c.history))
)(Validated.valid)
.andThen(k => decodeV.tryDecodeAccumulating(c.downField(k))),
decodeT.decodeAccumulating(c)
)((h, t) => field[K](h) :: t)
}
implicit final def encodeLabelledHCons[K, W >: K, V, T <: HList](implicit
witK: Witness.Aux[K],
widenK: Widen.Aux[K, W],
encodeW: KeyEncoder[W],
encodeV: Encoder[V],
encodeT: Encoder.AsObject[T]
): Encoder.AsObject[FieldType[K, V] :: T] = new Encoder.AsObject[FieldType[K, V] :: T] {
private[this] val widened = widenK(witK.value)
def encodeObject(a: FieldType[K, V] :: T): JsonObject =
encodeT.encodeObject(a.tail).add(encodeW(widened), encodeV(a.head))
}
}