tethys.JsonStreaming.scala Maven / Gradle / Ivy

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package tethys

import tethys.readers.{FieldName, ReaderError}
import tethys.readers.tokens.TokenIterator
import tethys.writers.tokens.TokenWriter

object JsonStreaming {

  def streamValue(from: TokenIterator, to: TokenWriter)(implicit
      fieldName: FieldName
  ): Unit = writeCurrentValue(from, to)

  private def writeCurrentValue(it: TokenIterator, writer: TokenWriter)(implicit
      fieldName: FieldName
  ): Unit = {
    val token = it.currentToken()
    if (token.isArrayStart) writeArray(it, writer)
    else if (token.isObjectStart) writeObject(it, writer)
    else if (token.isStringValue) writer.writeString(it.string())
    else if (token.isNumberValue) writer.writeRawNumber(it.number())
    else if (token.isBooleanValue) writer.writeBoolean(it.boolean())
    else if (token.isNullValue) writer.writeNull()
    else ReaderError.wrongJson(s"Expects value start but $token found")
    it.next()
  }

  private def writeArray(it: TokenIterator, writer: TokenWriter)(implicit
      fieldName: FieldName
  ): Unit = {
    it.next()
    writer.writeArrayStart()
    var index: Int = 0
    while (!it.currentToken().isArrayEnd) {
      writeCurrentValue(it, writer)(fieldName.appendArrayIndex(index))
      index = index + 1
    }
    writer.writeArrayEnd()
  }

  private def writeObject(it: TokenIterator, writer: TokenWriter)(implicit
      fieldName: FieldName
  ): Unit = {
    it.next()
    writer.writeObjectStart()
    while (!it.currentToken().isObjectEnd) {
      val token = it.currentToken()
      if (token.isFieldName) {
        val name = it.fieldName()
        writer.writeFieldName(name)
        writeCurrentValue(it.next(), writer)(fieldName.appendFieldName(name))
      } else {
        ReaderError.wrongJson(s"Expects field name but $token found")
      }
    }
    writer.writeObjectEnd()
  }
}