com.mobimeo.gtfs.model.CsvEnum.scala Maven / Gradle / Ivy

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/*
 * Copyright 2021 Mobimeo GmbH
 *
 * 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.mobimeo.gtfs.model

import cats.syntax.all._
import fs2.data.csv.{CellDecoder, CellEncoder, DecoderError}

import scala.util.Try

trait EnumEntry {
  def entryName: String
}

trait CsvEnum[T <: EnumEntry] {

  def values: Array[T]

  lazy val byEntryName: Map[String, T] = values.toList.groupMapReduce(_.entryName)(identity)((e, _) => e)

  implicit val cellDecoder: CellDecoder[T] =
    CellDecoder.stringDecoder.emap(s => byEntryName.get(s).toRight(new DecoderError(s"Unknown enum value $s")))

  implicit val cellEncoder: CellEncoder[T] =
    CellEncoder.stringEncoder.contramap(_.entryName)

}

trait IntEnumEntry {
  def value: Int
}

trait CsvIntEnum[T <: IntEnumEntry] {

  def values: Array[T]

  // Build an array for quick int->value lookup using the fact GTFS has small known key spaces
  // Performance optimization for decoding a lot of T instances as we don't have to search the value space each time
  private lazy val valueLookup: Array[Option[T]] = {
    val grouped = values.toList.groupBy(_.value)
    Array.tabulate(grouped.keySet.max + 1)(grouped.get(_).flatMap(_.headOption))
  }

  def valueOf(n: Int): Option[T] = valueLookup(n)

  implicit val cellDecoder: CellDecoder[T] =
    CellDecoder.intDecoder.emap(n => valueOf(n).toRight(new DecoderError(s"Unknown enum value $n")))

  implicit val cellEncoder: CellEncoder[T] =
    CellEncoder.intEncoder.contramap(_.value)

}

trait OrdinalBasedCsvIntEnum[T <: IntEnumEntry] extends CsvIntEnum[T] {
  def fromOrdinal(n: Int): T

  override def valueOf(n: Int): Option[T] = Try(fromOrdinal(n)).toOption
}