tethys.readers.instances.IterableReaders.scala Maven / Gradle / Ivy

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package tethys.readers.instances

import tethys.JsonReader
import tethys.compat.CollectionBuilder
import tethys.readers.tokens.TokenIterator
import tethys.readers.{FieldName, ReaderError}

import scala.annotation.tailrec
import scala.collection.mutable
import scala.language.higherKinds

private[tethys] trait IterableReaders extends LowPriorityIterableReaders {

  implicit def byteIterableReader[C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[Byte, C[Byte]]
  ): JsonReader[C[Byte]] = new TraversableReader[Byte, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[Byte, C[Byte]]
    )(implicit fieldName: FieldName): Unit = {
      builder += PrimitiveReaders.ByteJsonReader.read(it)
    }
  }

  implicit def shortIterableReader[C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[Short, C[Short]]
  ): JsonReader[C[Short]] = new TraversableReader[Short, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[Short, C[Short]]
    )(implicit fieldName: FieldName): Unit = {
      builder += PrimitiveReaders.ShortJsonReader.read(it)
    }
  }

  implicit def intIterableReader[C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[Int, C[Int]]
  ): JsonReader[C[Int]] = new TraversableReader[Int, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[Int, C[Int]]
    )(implicit fieldName: FieldName): Unit = {
      builder += PrimitiveReaders.IntJsonReader.read(it)
    }
  }

  implicit def longIterableReader[C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[Long, C[Long]]
  ): JsonReader[C[Long]] = new TraversableReader[Long, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[Long, C[Long]]
    )(implicit fieldName: FieldName): Unit = {
      builder += PrimitiveReaders.LongJsonReader.read(it)
    }
  }

  implicit def floatIterableReader[C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[Float, C[Float]]
  ): JsonReader[C[Float]] = new TraversableReader[Float, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[Float, C[Float]]
    )(implicit fieldName: FieldName): Unit = {
      builder += PrimitiveReaders.FloatJsonReader.read(it)
    }
  }

  implicit def doubleIterableReader[C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[Double, C[Double]]
  ): JsonReader[C[Double]] = new TraversableReader[Double, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[Double, C[Double]]
    )(implicit fieldName: FieldName): Unit = {
      builder += PrimitiveReaders.DoubleJsonReader.read(it)
    }
  }

  implicit def booleanIterableReader[C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[Boolean, C[Boolean]]
  ): JsonReader[C[Boolean]] = new TraversableReader[Boolean, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[Boolean, C[Boolean]]
    )(implicit fieldName: FieldName): Unit = {
      builder += PrimitiveReaders.BooleanJsonReader.read(it)
    }
  }
}

private[tethys] trait LowPriorityIterableReaders
    extends LowPriorityJsonReaders {

  implicit def iterableReader[A, C[X] <: Iterable[X]](implicit
      jsonReader: JsonReader[A],
      collectionBuilder: CollectionBuilder[A, C[A]]
  ): JsonReader[C[A]] = new TraversableReader[A, C] {
    override protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[A, C[A]]
    )(implicit fieldName: FieldName): Unit = {
      builder += jsonReader.read(it)
    }
  }

  protected abstract class TraversableReader[A, C[X] <: Iterable[X]](implicit
      cb: CollectionBuilder[A, C[A]]
  ) extends JsonReader[C[A]] {
    protected def appendBuilder(
        it: TokenIterator,
        builder: mutable.Builder[A, C[A]]
    )(implicit fieldName: FieldName): Unit

    override def read(
        it: TokenIterator
    )(implicit fieldName: FieldName): C[A] = {
      if (it.currentToken().isArrayStart) recRead(0, it.next(), cb.newBuilder)
      else
        ReaderError.wrongJson(
          s"Expected array start but found: ${it.currentToken()}"
        )
    }

    @tailrec
    private def recRead(
        i: Int,
        it: TokenIterator,
        builder: mutable.Builder[A, C[A]]
    )(implicit fieldName: FieldName): C[A] = {
      it.currentToken() match {
        case token if token.isEmpty =>
          ReaderError.wrongJson("Unexpected end of input")
        case token if token.isArrayEnd =>
          it.nextToken()
          builder.result()
        case _ =>
          appendBuilder(it, builder)(fieldName.appendArrayIndex(i))
          recRead(i + 1, it, builder)
      }
    }
  }
}