Implement Encoders for all config options

readme/Configuration.scalatex

@@ -910,8 +910,5 @@
       there are more configuration options if you visited nested fields
       like @code{spaces} and @code{newlines}.
 
-      @hl.ref(
-        wd / "scalafmt-core" / "shared" / "src" / "main" / "scala" / "org" / "scalafmt" / "config" / "ScalafmtConfig.scala",
-        start = "case class",
-        end = ") {"
-      )
+      @org.scalafmt.readme.Readme.allOptions
+

readme/src/main/scala/org/scalafmt/readme/Readme.scala

@@ -117,12 +117,13 @@ object Readme {
     //   a.b = 1
     //   a.c = 2
     // which means a simple line-by-line string diffing is sufficient for now.
-//    val defaultStrs = Config.toHocon(ScalafmtConfig.default).toSet
-//    val configStrs = Config.toHocon(style).toSet
-//    configStrs.diff(defaultStrs).mkString("\n")
-    "???"
+    val defaultStrs = Config.toHocon(ScalafmtConfig.default).toSet
+    val configStrs = Config.toHocon(style).toSet
+    configStrs.diff(defaultStrs).mkString("\n")
   }
 
+  def allOptions = hl.scala.apply(Config.toHocon(ScalafmtConfig.default))
+
   def configurationBlock(style: ScalafmtConfig) = {
     div(
       span(

scalafmt-core/shared/src/main/scala/org/scalafmt/config/Align.scala

@@ -94,6 +94,9 @@ object Align {
   val default = some
   val more: Align = some.copy(tokens = AlignToken.default)
   implicit lazy val surface: Surface[Align] = generic.deriveSurface[Align]
+  implicit lazy val encoder: ConfEncoder[Align] = generic.deriveEncoder
+  // TODO: metaconfig should handle iterables
+  implicit def encoderSet[T:ConfEncoder]: ConfEncoder[Set[T]] = implicitly[ConfEncoder[Seq[T]]].contramap(_.toSeq)
 
   // only for the truest vertical aligners, this setting is open for changes,
   // please open PR addding more stuff to it if you like.

scalafmt-core/shared/src/main/scala/org/scalafmt/config/AlignToken.scala

@@ -18,6 +18,7 @@ case class AlignToken(code: String, owner: String) {
 object AlignToken {
   implicit lazy val surface: Surface[AlignToken] =
     generic.deriveSurface[AlignToken]
+  implicit lazy val encoder: ConfEncoder[AlignToken] = generic.deriveEncoder
   val applyInfix = "Term.ApplyInfix"
   val caseArrow = AlignToken("=>", "Case")
   protected[scalafmt] val fallbackAlign = new AlignToken("<empty>", ".*")

scalafmt-core/shared/src/main/scala/org/scalafmt/config/BinPack.scala

@@ -45,4 +45,5 @@ case class BinPack(
 object BinPack {
   implicit lazy val surface: generic.Surface[BinPack] =
     generic.deriveSurface[BinPack]
+  implicit lazy val encoder: ConfEncoder[BinPack] = generic.deriveEncoder
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/config/ContinuationIndent.scala

@@ -19,4 +19,5 @@ case class ContinuationIndent(
 object ContinuationIndent {
   implicit lazy val surface: generic.Surface[ContinuationIndent] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[ContinuationIndent] = generic.deriveEncoder
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/config/Docstrings.scala

@@ -1,11 +1,11 @@
 package org.scalafmt.config
 
-import metaconfig.ConfDecoder
+import metaconfig.ConfCodec
 
 sealed abstract class Docstrings
 
 object Docstrings {
-  implicit val reader: ConfDecoder[Docstrings] =
+  implicit val reader: ConfCodec[Docstrings] =
     ReaderUtil.oneOf[Docstrings](JavaDoc, ScalaDoc, preserve)
   case object JavaDoc extends Docstrings
   case object ScalaDoc extends Docstrings

scalafmt-core/shared/src/main/scala/org/scalafmt/config/ImportSelectors.scala

@@ -45,9 +45,11 @@ sealed abstract class ImportSelectors
 
 object ImportSelectors {
 
-  val reader: ConfDecoder[ImportSelectors] =
+  val reader: ConfCodec[ImportSelectors] =
     ReaderUtil.oneOf[ImportSelectors](noBinPack, binPack, singleLine)
 
+  implicit val encoder: ConfEncoder[ImportSelectors] = reader
+
   // This reader is backwards compatible with the old import selector
   // configuration, which used the boolean flag binPackImportSelectors to
   // decide between (what are now) the `binPack` and `noBinPack` strategies.
@@ -56,7 +58,7 @@ object ImportSelectors {
   // limitations in the current version of scalameta/paradise, but these will
   // likely be fixed in the future, at which point this reader could be moved
   // to ScalafmtConfig
-  implicit val backwardsCompatibleReader =
+  implicit val backwardsCompatibleReader: ConfDecoder[ImportSelectors] =
     ConfDecoder.instance[ImportSelectors] {
       case Conf.Bool(true) => Ok(ImportSelectors.binPack)
       case Conf.Bool(false) => Ok(ImportSelectors.noBinPack)

scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala

@@ -43,6 +43,8 @@ case class IndentOperator(
 object IndentOperator {
   implicit lazy val surface: generic.Surface[IndentOperator] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[IndentOperator] =
+    generic.deriveEncoder
   val default = IndentOperator()
   val akka = IndentOperator(
     ScalafmtConfig.indentOperatorsIncludeAkka,

scalafmt-core/shared/src/main/scala/org/scalafmt/config/LineEndings.scala

@@ -1,11 +1,11 @@
 package org.scalafmt.config
 
-import metaconfig.ConfDecoder
+import metaconfig.ConfCodec
 
 sealed abstract class LineEndings
 
 object LineEndings {
-  implicit val reader: ConfDecoder[LineEndings] =
+  implicit val reader: ConfCodec[LineEndings] =
     ReaderUtil.oneOf[LineEndings](unix, windows, preserve)
   case object unix extends LineEndings
   case object windows extends LineEndings

scalafmt-core/shared/src/main/scala/org/scalafmt/config/Newlines.scala

@@ -98,19 +98,17 @@ case class Newlines(
 
 object Newlines {
   implicit lazy val surface: Surface[Newlines] = generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[Newlines] = generic.deriveEncoder
 }
 
 sealed abstract class NewlineCurlyLambda
 
 object NewlineCurlyLambda {
 
-  implicit lazy val surface: generic.Surface[Newlines] =
-    generic.deriveSurface
-
   case object preserve extends NewlineCurlyLambda
   case object always extends NewlineCurlyLambda
   case object never extends NewlineCurlyLambda
 
-  implicit val newlineCurlyLambdaReader: ConfDecoder[NewlineCurlyLambda] =
+  implicit val newlineCurlyLambdaReader: ConfCodec[NewlineCurlyLambda] =
     ReaderUtil.oneOf[NewlineCurlyLambda](preserve, always, never)
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/config/OptIn.scala

@@ -84,4 +84,5 @@ case class OptIn(
 
 object OptIn {
   implicit lazy val surface: Surface[OptIn] = generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[OptIn] = generic.deriveEncoder
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/config/Pattern.scala

@@ -15,7 +15,10 @@ case class Pattern(
 }
 
 object Pattern {
-  implicit lazy val surface: Surface[Pattern] = generic.deriveSurface
+  implicit lazy val surface: Surface[Pattern] =
+    generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[Pattern] =
+    generic.deriveEncoder
   val neverInfix = Pattern(
     Seq("[\\w\\d_]+"),
     Seq(

scalafmt-core/shared/src/main/scala/org/scalafmt/config/ProjectFiles.scala

@@ -18,4 +18,6 @@ case class ProjectFiles(
 object ProjectFiles {
   implicit lazy val surface: generic.Surface[ProjectFiles] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[ProjectFiles] =
+    generic.deriveEncoder
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/config/ReaderUtil.scala

@@ -11,7 +11,7 @@ object ReaderUtil {
     oneOfImpl((lowerCase _).compose(lowerCaseNoBackticks), options)
 
   def oneOfIgnoreBackticks[T: ClassTag](
-      options: sourcecode.Text[T]*): ConfDecoder[T] =
+      options: sourcecode.Text[T]*): ConfCodec[T] =
     oneOfImpl(lowerCaseNoBackticks, options)
 
   private def lowerCase(s: String): String = s.toLowerCase

scalafmt-core/shared/src/main/scala/org/scalafmt/config/RedundantBracesSettings.scala

@@ -18,4 +18,6 @@ case class RedundantBracesSettings(
 object RedundantBracesSettings {
   implicit lazy val surface: generic.Surface[RedundantBracesSettings] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[RedundantBracesSettings] =
+    generic.deriveEncoder
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/config/RewriteSettings.scala

@@ -28,4 +28,7 @@ case class RewriteSettings(
 object RewriteSettings {
   implicit lazy val surface: generic.Surface[RewriteSettings] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[RewriteSettings] =
+    generic.deriveEncoder
+
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/config/ScalafmtConfig.scala

@@ -165,6 +165,11 @@ case class ScalafmtConfig(
 object ScalafmtConfig {
   implicit lazy val surface: generic.Surface[ScalafmtConfig] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[ScalafmtConfig] =
+    generic.deriveEncoder[ScalafmtConfig]
+
+  implicit lazy val codecEncoder: ConfEncoder[Codec] =
+    ConfEncoder.StringEncoder.contramap(_.name)
 
   val indentOperatorsIncludeAkka = "^.*=$"
   val indentOperatorsExcludeAkka = "^$"

scalafmt-core/shared/src/main/scala/org/scalafmt/config/ScalafmtOptimizer.scala

@@ -81,6 +81,8 @@ case class ScalafmtOptimizer(
 object ScalafmtOptimizer {
   implicit lazy val surface: generic.Surface[ScalafmtOptimizer] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[ScalafmtOptimizer] =
+    generic.deriveEncoder
   val default = ScalafmtOptimizer()
 
   // TODO(olafur) uncomment once scala.meta converter supports default args.

scalafmt-core/shared/src/main/scala/org/scalafmt/config/ScalafmtRunner.scala

@@ -23,7 +23,7 @@ import scala.meta.dialects.Scala211
 case class ScalafmtRunner(
     debug: Boolean = false,
     eventCallback: FormatEvent => Unit = _ => Unit,
-    parser: MetaParser = Parse.parseSource,
+    parser: Parse[_ <: Tree] = Parse.parseSource,
     optimizer: ScalafmtOptimizer = ScalafmtOptimizer.default,
     maxStateVisits: Int = 1000000,
     dialect: Dialect = ScalafmtRunner.defaultDialect,
@@ -43,6 +43,14 @@ case class ScalafmtRunner(
 object ScalafmtRunner {
   implicit lazy val surface: generic.Surface[ScalafmtRunner] =
     generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[ScalafmtRunner] =
+    generic.deriveEncoder
+  implicit lazy val formatEventEncoder: ConfEncoder[FormatEvent => Unit] =
+    ConfEncoder.StringEncoder.contramap(_ => "FormatEvent => Unit")
+  implicit lazy val parseEncoder: ConfEncoder[Parse[_ <: Tree]] =
+    ConfEncoder.StringEncoder.contramap(_ => "Parse[Tree]")
+  implicit lazy val dialectEncoder: ConfEncoder[Dialect] =
+    ConfEncoder.StringEncoder.contramap(_.toString())
   val defaultDialect = Scala211.copy(
     // Are `&` intersection types supported by this dialect?
     allowAndTypes = true,

scalafmt-core/shared/src/main/scala/org/scalafmt/config/SortSettings.scala

@@ -8,7 +8,7 @@ case class SortSettings(
 
 object SortSettings {
 
-  implicit val SortSettingsModKeyReader: ConfDecoder[ModKey] =
+  implicit val SortSettingsModKeyReader: ConfCodec[ModKey] =
     ReaderUtil.oneOfIgnoreBackticks[ModKey](
       `implicit`,
       `final`,
@@ -36,6 +36,8 @@ object SortSettings {
   )
 
   implicit val surface: generic.Surface[SortSettings] = generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[SortSettings] =
+    generic.deriveEncoder
   implicit val reader: ConfDecoder[SortSettings] =
     generic.deriveDecoder(SortSettings(defaultOrder)).flatMap { result =>
       if (result.order.distinct.length != 8) {

scalafmt-core/shared/src/main/scala/org/scalafmt/config/SpaceBeforeContextBound.scala

@@ -1,25 +1,30 @@
 package org.scalafmt.config
 
+import metaconfig.ConfCodec
+import metaconfig.ConfEncoder
 import metaconfig.Configured.Ok
 import metaconfig.{Conf, ConfDecoder}
 import org.scalafmt.config.SpaceBeforeContextBound.{Always, IfMultipleBounds}
 
+sealed trait SpaceBeforeContextBound {
+  def isIfMultipleBounds = this == IfMultipleBounds
+  def isAlways = this == Always
+}
+
 object SpaceBeforeContextBound {
 
-  implicit val reader = ConfDecoder.instance[SpaceBeforeContextBound] {
-    case Conf.Bool(true) => Ok(Always)
-    case Conf.Bool(false) => Ok(Never)
-    case x =>
-      ReaderUtil
-        .oneOf[SpaceBeforeContextBound](Always, Never, IfMultipleBounds)
-        .read(x)
-  }
+  val codec: ConfCodec[SpaceBeforeContextBound] =
+    ReaderUtil.oneOf[SpaceBeforeContextBound](Always, Never, IfMultipleBounds)
+
+  implicit val encoder: ConfEncoder[SpaceBeforeContextBound] = codec
+  implicit val reader: ConfDecoder[SpaceBeforeContextBound] =
+    ConfDecoder.instance[SpaceBeforeContextBound] {
+      case Conf.Bool(true) => Ok(Always)
+      case Conf.Bool(false) => Ok(Never)
+      case x => codec.read(x)
+    }
 
   case object Always extends SpaceBeforeContextBound
   case object Never extends SpaceBeforeContextBound
   case object IfMultipleBounds extends SpaceBeforeContextBound
 }
-sealed trait SpaceBeforeContextBound {
-  def isIfMultipleBounds = this == IfMultipleBounds
-  def isAlways = this == Always
-}

scalafmt-core/shared/src/main/scala/org/scalafmt/config/Spaces.scala

@@ -35,4 +35,5 @@ case class Spaces(
 }
 object Spaces {
   implicit lazy val surface: generic.Surface[Spaces] = generic.deriveSurface
+  implicit lazy val encoder: ConfEncoder[Spaces] = generic.deriveEncoder
 }

scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/Rewrite.scala

@@ -1,12 +1,11 @@
 package org.scalafmt.rewrite
 
+import metaconfig.ConfCodec
 import scala.meta._
-import metaconfig.ConfDecoder
 import org.scalafmt.config.ReaderUtil
 import org.scalafmt.config.ScalafmtConfig
 import org.scalafmt.util.TokenOps.TokenHash
 import org.scalafmt.util.{TokenOps, TokenTraverser, TreeOps}
-import org.scalameta.logger
 
 case class RewriteCtx(
     style: ScalafmtConfig,
@@ -23,7 +22,7 @@ abstract class Rewrite {
 }
 
 object Rewrite {
-  implicit val reader: ConfDecoder[Rewrite] =
+  implicit val reader: ConfCodec[Rewrite] =
     ReaderUtil.oneOf[Rewrite](
       RedundantBraces,
       RedundantParens,