upickle.implicits.CaseClassReadWriters.scala Maven / Gradle / Ivy

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upickle-implicits
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package upickle.implicits

import scala.language.experimental.macros
import scala.language.higherKinds
import scala.reflect.ClassTag
import upickle.core.{Abort, AbortException, ArrVisitor, Config, NoOpVisitor, ObjVisitor, Visitor}

/**
* Basic functionality to be able to read and write objects. Kept as a trait so
* other internal files can use it, while also mixing it into the `upickle`
* package to form the public API1
*/
trait CaseClassReadWriters extends upickle.core.Types { self: Config =>
  abstract class CaseClassReader[V] extends SimpleReader[V] {
    override def expectedMsg = "expected dictionary"

    override def visitString(s: CharSequence, index: Int) = visitObject(0, true, index).visitEnd(index)
  }

  trait CaseClassWriter[V] extends ObjectWriter[V] {
    def length(v: V): Int

    @scala.annotation.nowarn
    def write0[R](out: Visitor[_, R], v: V): R = {
      if (v == null) out.visitNull(-1)
      else {
        val ctx = out.visitObject(length(v), true, -1)
        writeToObject(ctx, v)
        ctx.visitEnd(-1)
      }
    }

    def writeSnippetMappedName[R, V](ctx: _root_.upickle.core.ObjVisitor[_, R],
                                     mappedArgsI: CharSequence,
                                     w: Any,
                                     value: Any) = {
      val keyVisitor = ctx.visitKey(-1)
      ctx.visitKeyValue(
        keyVisitor.visitString(mappedArgsI, -1)
      )
      ctx.narrow.visitValue(w.asInstanceOf[Writer[Any]].write(ctx.subVisitor, value), -1)
    }
  }

  class SingletonReader[T](t: T) extends CaseClassReader[T] {
    override def expectedMsg = "expected string or dictionary"

    override def visitString(s: CharSequence, index: Int) = t

    override def visitObject(length: Int, jsonableKeys: Boolean, index: Int) = new ObjVisitor[Any, T] {
      def subVisitor = NoOpVisitor

      def visitKey(index: Int) = NoOpVisitor

      def visitKeyValue(s: Any) = ()

      def visitValue(v: Any, index: Int): Unit = ()

      def visitEnd(index: Int) = t
    }
  }

  class SingletonWriter[T](f: T) extends CaseClassWriter[T] {
    def length(v: T) = 0

    def writeToObject[R](ctx: ObjVisitor[_, R], v: T): Unit = () // do nothing
  }
}