Switch from scalafmt-cli to scalafmt-dynamic (#600)

5 files changed, 32 insertions, 30 deletions

diff --git a/build.sc b/build.sc
index 215e8d37..c51e8195 100755
--- a/build.sc
+++ b/build.sc
@@ -143,7 +143,8 @@ object scalalib extends MillModule {
   def moduleDeps = Seq(main, scalalib.api)
 
   def ivyDeps = Agg(
-    ivy"org.scala-sbt:test-interface:1.0"
+    ivy"org.scala-sbt:test-interface:1.0",
+    ivy"org.scalameta::scalafmt-dynamic:2.0.0-RC6"
   )
 
   def genTask(m: ScalaModule) = T.task{
diff --git a/docs/pages/2 - Configuring Mill.md b/docs/pages/2 - Configuring Mill.md
index dbcbcee4..f6ca86a0 100644
--- a/docs/pages/2 - Configuring Mill.md
+++ b/docs/pages/2 - Configuring Mill.md
@@ -237,6 +237,12 @@ Now you can reformat code with `mill foo.reformat` command.
 You can also reformat your project's code globally with `mill mill.scalalib.scalafmt.ScalafmtModule/reformatAll __.sources` command.
 It will reformat all sources that matches `__.sources` query.
 
+If you add a `.scalafmt.conf` file at the root of you project, it will be used
+to configure formatting. It can contain a `version` key to specify the scalafmt
+version used to format your code. See the
+[scalafmt configuration documentation](https://scalameta.org/scalafmt/docs/configuration.html)
+for details.
+
 ## Common Configuration
 
 ```scala
diff --git a/scalalib/resources/mill/scalalib/scalafmt/default.scalafmt.conf b/scalalib/resources/mill/scalalib/scalafmt/default.scalafmt.conf
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/scalalib/resources/mill/scalalib/scalafmt/default.scalafmt.conf
diff --git a/scalalib/src/scalafmt/ScalafmtModule.scala b/scalalib/src/scalafmt/ScalafmtModule.scala
index 6a81d975..ea254e6d 100644
--- a/scalalib/src/scalafmt/ScalafmtModule.scala
+++ b/scalalib/src/scalafmt/ScalafmtModule.scala
@@ -11,23 +11,12 @@ trait ScalafmtModule extends JavaModule {
       .worker()
       .reformat(
         filesToFormat(sources()),
-        scalafmtConfig().head,
-        scalafmtDeps().map(_.path)
+        scalafmtConfig().head
       )
   }
 
-  def scalafmtVersion: T[String] = "1.5.1"
-
   def scalafmtConfig: Sources = T.sources(os.pwd / ".scalafmt.conf")
 
-  def scalafmtDeps: T[Agg[PathRef]] = T {
-    Lib.resolveDependencies(
-      zincWorker.repositories,
-      Lib.depToDependency(_, "2.12.4"),
-      Seq(ivy"com.geirsson::scalafmt-cli:${scalafmtVersion()}")
-    )
-  }
-
   protected def filesToFormat(sources: Seq[PathRef]) = {
     for {
       pathRef <- sources if os.exists(pathRef.path)
@@ -46,8 +35,7 @@ object ScalafmtModule extends ExternalModule with ScalafmtModule {
         .worker()
         .reformat(
           files,
-          scalafmtConfig().head,
-          scalafmtDeps().map(_.path)
+          scalafmtConfig().head
         )
     }
 
diff --git a/scalalib/src/scalafmt/ScalafmtWorker.scala b/scalalib/src/scalafmt/ScalafmtWorker.scala
index 47d8375f..f9c7e9b4 100644
--- a/scalalib/src/scalafmt/ScalafmtWorker.scala
+++ b/scalalib/src/scalafmt/ScalafmtWorker.scala
@@ -1,9 +1,11 @@
 package mill.scalalib.scalafmt
 
+import java.nio.file.{Paths => JPaths}
+
 import mill._
 import mill.define.{Discover, ExternalModule, Worker}
-import mill.modules.Jvm
 import mill.api.Ctx
+import org.scalafmt.interfaces.Scalafmt
 
 import scala.collection.mutable
 
@@ -18,8 +20,7 @@ private[scalafmt] class ScalafmtWorker {
   private var configSig: Int = 0
 
   def reformat(input: Seq[PathRef],
-               scalafmtConfig: PathRef,
-               scalafmtClasspath: Agg[os.Path])(implicit ctx: Ctx): Unit = {
+               scalafmtConfig: PathRef)(implicit ctx: Ctx): Unit = {
     val toFormat =
       if (scalafmtConfig.sig != configSig) input
       else
@@ -28,8 +29,7 @@ private[scalafmt] class ScalafmtWorker {
     if (toFormat.nonEmpty) {
       ctx.log.info(s"Formatting ${toFormat.size} Scala sources")
       reformatAction(toFormat.map(_.path),
-                     scalafmtConfig.path,
-                     scalafmtClasspath)
+                     scalafmtConfig.path)
       reformatted ++= toFormat.map { ref =>
         val updRef = PathRef(ref.path)
         updRef.path -> updRef.sig
@@ -43,15 +43,22 @@ private[scalafmt] class ScalafmtWorker {
   private val cliFlags = Seq("--non-interactive", "--quiet")
 
   private def reformatAction(toFormat: Seq[os.Path],
-                             config: os.Path,
-                             classpath: Agg[os.Path])(implicit ctx: Ctx) = {
-    val configFlags =
-      if (os.exists(config)) Seq("--config", config.toString) else Seq.empty
-    Jvm.runSubprocess(
-      "org.scalafmt.cli.Cli",
-      classpath,
-      mainArgs = toFormat.map(_.toString) ++ configFlags ++ cliFlags
-    )
-  }
+                             config: os.Path)(implicit ctx: Ctx) = {
+    val scalafmt =
+      Scalafmt
+        .create(this.getClass.getClassLoader)
+        .withRespectVersion(false)
+
+    val configPath =
+      if (os.exists(config))
+        config.toNIO
+      else
+        JPaths.get(getClass.getResource("default.scalafmt.conf").toURI)
 
+    toFormat.foreach { pathToFormat =>
+      val code = os.read(pathToFormat)
+      val formatteCode = scalafmt.format(configPath, pathToFormat.toNIO, code)
+      os.write.over(pathToFormat, formatteCode)
+    }
+  }
 }