Add a module to support julienrf's enum library

build.sbt

@@ -8,6 +8,10 @@ lazy val enumeratum = (project in file("modules/enumeratum")).
   settings(settings).
   dependsOn(core)
 
+lazy val enum = (project in file("modules/enum")).
+  settings(settings).
+  dependsOn(core)
+
 lazy val joda = (project in file("modules/joda")).
   settings(settings).
   dependsOn(core).

modules/enum/README.md

@@ -0,0 +1,49 @@
+# Enum module for PureConfig
+Add support for [julienrf's enum](https://github.com/julienrf/enum) library to pureconfig.
+
+## Why
+
+Automatically create a converter to read [enum](https://github.com/julienrf/enum) elements from a configuration.
+
+## Add pureconfig-enum to your project
+
+In addition to [core pureconfig](https://github.com/melrief/pureconfig), you'll need:
+
+```scala
+libraryDependencies += "com.github.melrief" %% "pureconfig-enum" % "0.5.1"
+```
+
+## Example
+
+```scala
+// Given a Greeting ADT composed of `case object`s with an `implicit` `Enum` instance:
+sealed trait Greeting
+
+object Greeting {
+  case object Hello extends Greeting
+  case object WhisperHello extends Greeting
+  case object GoodBye extends Greeting
+  case object ShoutGoodBye extends Greeting
+
+  final implicit val EnumInstance: Enum[Greeting] = Enum.derived[Greeting]
+}
+
+// And a class to hold the configuration:
+case class GreetingConf(start: Greeting, end: Greeting)
+
+// We can read a GreetingConf like:
+import pureconfig.loadConfig
+import pureconfig.module.enum._
+import com.typesafe.config.ConfigFactory.parseString
+
+val conf = parseString("""{ 
+  start: WhisperHello
+  end: ShoutGoodBye
+}""")
+loadConfig(conf)
+// GreetingConf(WhisperHello, ShoutGoodBye)
+```
+
+## Can I configure how the elements are read?
+
+Nope. If you need more flexibility, look at [enumeratum](https://github.com/lloydmeta/enumeratum) and its companion pureconfig library, [pureconfig-enumeratum](https://github.com/leifwickland/pureconfig/tree/master/modules/enumeratum).

modules/enum/build.sbt

@@ -0,0 +1,57 @@
+name := "pureconfig-enum"
+
+organization := "com.github.melrief"
+
+homepage := Some(url("https://github.com/melrief/pureconfig"))
+
+licenses := Seq("Mozilla Public License, version 2.0" -> url("https://www.mozilla.org/MPL/2.0/"))
+
+resolvers ++= Seq(
+  Resolver.sonatypeRepo("releases"),
+  Resolver.sonatypeRepo("snapshots")
+)
+
+libraryDependencies ++= Seq(
+  "org.julienrf" %% "enum" % "3.1",
+  Dependencies.scalaMacrosParadise,
+  Dependencies.scalaTest
+)
+
+publishMavenStyle := true
+
+publishTo := {
+  val nexus = "https://oss.sonatype.org/"
+  if (isSnapshot.value)
+    Some("snapshots" at nexus + "content/repositories/snapshots")
+  else
+    Some("releases"  at nexus + "service/local/staging/deploy/maven2")
+}
+
+publishArtifact in Test := false
+
+pomExtra := (
+    <scm>
+      <url>git@github.com:melrief/pureconfig.git</url>
+      <connection>scm:git:git@github.com:melrief/pureconfig.git</connection>
+    </scm>
+    <developers>
+      <developer>
+        <id>melrief</id>
+        <name>Mario Pastorelli</name>
+        <url>https://github.com/melrief</url>
+      </developer>
+      <developer>
+        <id>leifwickland</id>
+        <name>Leif Wickland</name>
+        <url>https://github.com/leifwickland</url>
+      </developer>
+    </developers>)
+
+osgiSettings
+
+OsgiKeys.exportPackage := Seq("pureconfig.module.enum.*")
+
+OsgiKeys.privatePackage := Seq()
+
+OsgiKeys.importPackage := Seq(s"""scala.*;version="[${scalaBinaryVersion.value}.0,${scalaBinaryVersion.value}.50)"""", "*")
+

modules/enum/src/main/scala/pureconfig/module/enum.scala

@@ -0,0 +1,22 @@
+package pureconfig.module
+
+import _root_.enum.Enum
+import pureconfig.ConfigConvert
+import pureconfig.ConfigConvert.{ nonEmptyStringConvert }
+
+import scala.reflect.ClassTag
+import scala.util.{ Success, Failure }
+
+package object enum {
+  implicit def enumConfigConvert[T](implicit e: Enum[T], ct: ClassTag[T]): ConfigConvert[T] = {
+    nonEmptyStringConvert(
+      s =>
+        e.decodeOpt(s)
+          .map(new Success(_))
+          .getOrElse {
+            val err = s"Could not interpret '$s' as a member of ${ct.runtimeClass.getSimpleName}."
+            new Failure(new IllegalArgumentException(err))
+          },
+      e.encode)
+  }
+}

modules/enum/src/test/scala/pureconfig/module/enum/EnumTest.scala

@@ -0,0 +1,33 @@
+package pureconfig.module.enum
+
+import com.typesafe.config.ConfigFactory
+import org.scalatest.{ FlatSpec, Matchers, TryValues }
+import pureconfig.syntax._
+import org.scalatest.Inspectors._
+import _root_.enum.Enum
+
+sealed trait Greeting
+
+object Greeting {
+  case object Hello extends Greeting
+  case object GoodBye extends Greeting
+  case object ShoutGoodBye extends Greeting
+
+  final implicit val EnumInstance: Enum[Greeting] = Enum.derived[Greeting]
+}
+
+class EnumTest extends FlatSpec with Matchers with TryValues {
+  "enum config convert" should "parse an enum" in forAll(Greeting.EnumInstance.values) { greeting =>
+    val conf = ConfigFactory.parseString(s"""{greeting:"$greeting"}""")
+    case class Conf(greeting: Greeting)
+    conf.to[Conf].success.value shouldEqual Conf(greeting)
+  }
+
+  it should "politely refuse an invalid member" in {
+    val conf = ConfigFactory.parseString(s"""{greeting:"Psych"}""")
+    case class Conf(greeting: Greeting)
+    conf.to[Conf].failure.exception.getMessage should include regex "'Psych' as a member of Greeting"
+  }
+
+}
+