fs2.data.csv.internals.CsvRowParser.scala Maven / Gradle / Ivy

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/*
 * Copyright 2024 fs2-data Project
 *
 * 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 fs2
package data
package csv
package internals

import cats.syntax.all._

private[csv] object CsvRowParser {

  def pipe[F[_], Header](implicit
      F: RaiseThrowable[F],
      Header: ParseableHeader[Header]
  ): Pipe[F, Row, CsvRow[Header]] =
    _.through(pipeAttempt[F, Header]).rethrow

  /** Like `pipe` except that instead of failing the stream on parse errors, it emits `Left` elements for bad rows */
  def pipeAttempt[F[_], Header](implicit
      Header: ParseableHeader[Header]): Pipe[F, Row, Either[CsvException, CsvRow[Header]]] =
    _.pull.uncons1
      .flatMap {
        case Some((firstRow, tail)) =>
          Header(firstRow.values) match {
            case Left(error) => Pull.output1(Left(error))
            case Right(headers) if headers.length =!= firstRow.values.length =>
              val error = new HeaderError(
                s"Got ${headers.length} headers, but ${firstRow.values.length} columns. Both numbers must match!",
                firstRow.line)
              Pull.output1(Left(error))
            case Right(headers) =>
              tail
                .map(CsvRow.liftRow(headers))
                .pull
                .echo
          }
        case None => Pull.done
      }
      .stream

}