com.sksamuel.avro4s.FieldMapper.scala Maven / Gradle / Ivy

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package com.sksamuel.avro4s

import scala.collection.mutable.ListBuffer

/**
  * We may have a schema with a field in snake case like say { "first_name": "sam" } and
  * that schema needs to be used for a case class field `firstName`.
  *
  * The [[FieldMapper]] is used to map fields in a schema to fields in a class by
  * transforming the class field name to the wire name format.
  */
trait FieldMapper {

  /**
    * Takes a field name from a type and converts it to the wire format.
    * Eg, `case class Foo(wibbleWobble: String)` with a SnakeCase instance
    * would result in `wibble_wobble`
    */
  def to(name: String): String = name

  protected def fromDelimited(sep: String, s: String): String = {
    val head :: tail = s.split(sep).toList
    head ++ tail.foldLeft("")((acc, word) => acc ++ word.capitalize)
  }

  protected def toDelimited(delim: Char, s: String): String = {
    val word = ListBuffer.empty[Char]
    word += s.head.toLower
    s.tail.toCharArray.foreach { char =>
      if (char.isUpper) {
        word.+=(delim)
      }
      word.+=(char.toLower)
    }
    word.result.mkString
  }
}

object FieldMapper {
  val default = DefaultFieldMapper
}

case object DefaultFieldMapper extends FieldMapper {
  override def to(name: String): String = name
}

case object PascalCase extends FieldMapper {
  override def to(name: String): String = {
    if (name.length == 1) name.toUpperCase else {
      val chars = name.toCharArray
      chars(0) = chars(0).toUpper
      new String(chars)
    }
  }
}

case object SnakeCase extends FieldMapper {
  override def to(name: String): String = toDelimited('_', name)
}

case object LispCase extends FieldMapper {
  override def to(name: String): String = toDelimited('-', name)
}