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toml-scala

toml-scala is a feature-complete implementation of TOML for the Scala platform. It can parse TOML content into an AST or map it onto case class hierarchies. Furthermore, it can generate TOML back from an AST.

This project is an updated and maintained fork of the original sparsetech/toml-scala

• toml-scala
  • Features
  • Compatibility
    • Dependencies
  • Examples
    • AST parsing
    • Codec derivation (Scala 2 only)
      • Tables
      • Table lists
      • Optional values
      • Define custom codecs
      • Generate TOML
      • Language Extensions
  • Links
  • Licence
  • Credits
  • Contributors

Features

• Standard-compliant
• AST parsing
• Codec derivation
  • Optional values
  • Custom codecs
• Generating TOML from ASTs
• Error handling
• Property-based unit tests

Compatibility

• (1) On Scala.js and Scala Native we introduce dependency on https://index.scala-lang.org/cquiroz/scala-java-time to be able to parse date time values. At the moment there is no way to opt out of that dependency.

Dependencies

libraryDependencies += "com.indoorvivants" %%  "toml" % "<version>"  // JVM
libraryDependencies += "com.indoorvivants" %%% "toml" % "<version>"  // Scala.js, Scala Native

Examples

AST parsing

val table =
  """
    |a = 1
    |[table]
    |b = 2
  """.stripMargin

toml.Toml.parse(table) 

// Right(
//  value = Tbl(
//    values = Map("a" -> Num(value = 1L), "table" -> Tbl(values = Map("b" -> Num(value = 2L))))
//  )
// ) 

Codec derivation (Scala 2 only)

Currently only supported on Scala 2

The following import is needed:

import toml.derivation.auto._

Tables

case class Table(b: Int)
case class Root(a: Int, table: Table)

val table =
  """
    |a = 1
    |[table]
    |b = 2
  """.stripMargin

Toml.parseAs[Root](table)  // Right(Root(1, Table(2)))

Table lists

val tableList =
  """
    |points = [ { x = 1, y = 2, z = 3 },
    |           { x = 7, y = 8, z = 9 },
    |           { x = 2, y = 4, z = 8 } ]
  """.stripMargin

case class Point(x: Int, y: Int, z: Int)
case class Root(points: List[Point])

Toml.parseAs[Root](tableList)
// Right(Root(List(
//   Point(1, 2, 3),
//   Point(7, 8, 9),
//   Point(2, 4, 8))))

Lists can be mapped onto case classes as a shorter alternative. Therefore, the following notation would yield the same result:

points = [ [ 1, 2, 3 ],
           [ 7, 8, 9 ],
           [ 2, 4, 8 ] ]

Optional values

case class Table(b: Int)
case class Root(a: Int, table: Option[Table])

Toml.parseAs[Root]("a = 1")  // Right(Root(1, None))

Define custom codecs

case class Currency(name: String)
implicit val currencyCodec: Codec[Currency] = Codec {
  case (Value.Str(value), _, _) =>
    value match {
      case "EUR" => Right(Currency("EUR"))
      case "BTC" => Right(Currency("BTC"))
      case _     => Left((List(), s"Invalid currency: $value"))
    }

  case (value, _, _) => Left((List(), s"Currency expected, $value provided"))
}

case class Root(currency: Currency)
Toml.parseAs[Root]("""currency = "BTC"""")  // Right(Root(Currency(BTC)))

Generate TOML

val root = Root(List(Pair("scalaDeps", Arr(List(
  Arr(List(Str("io.monix"), Str("minitest"), Str("2.2.2"))),
  Arr(List(Str("org.scalacheck"), Str("scalacheck"), Str("1.14.0"))),
  Arr(List(Str("org.scalatest"), Str("scalatest"), Str("3.2.0-SNAP10")))
)))))

Toml.generate(root)

Returns:

scalaDeps = [
  ["io.monix", "minitest", "2.2.2"],
  ["org.scalacheck", "scalacheck", "1.14.0"],
  ["org.scalatest", "scalatest", "3.2.0-SNAP10"]
]

Language Extensions

toml-scala supports the following language extensions which are disabled by default:

• New lines and trailing commas in inline tables

To enable them, pass in a set of extensions to the parse() or parseAs() function as a second argument:

toml.Toml.parse("""key = {
  a = 23,
  b = 42,
}""", Set(toml.Extension.MultiLineInlineTables))

Links

• ScalaDoc

Licence

toml-scala is licensed under the terms of the Mozilla Public Licence v2.0.

Credits

The rules and their respective tests were derived from stoml by Jorge Vicente Cantero.

toml-scala is based on top of FastParse for defining the language rules. ScalaCheck allows us to test synthetic examples of TOML files. The codec derivation was implemented using Shapeless.

Contributors

• Tim Nieradzik