1 files changed, 56 insertions, 0 deletions
diff --git a/main/core/src/mill/util/Ctx.scala b/main/core/src/mill/util/Ctx.scala
new file mode 100644
index 00000000..6c8b2afb
--- /dev/null
+++ b/main/core/src/mill/util/Ctx.scala
@@ -0,0 +1,56 @@
+package mill.util
+
+import ammonite.ops.Path
+import mill.define.Applicative.ImplicitStub
+
+import scala.annotation.compileTimeOnly
+import scala.language.implicitConversions
+
+object Ctx{
+  @compileTimeOnly("Target.ctx() can only be used with a T{...} block")
+  @ImplicitStub
+  implicit def taskCtx: Ctx = ???
+
+  object Dest {
+    implicit def pathToCtx(path: Path): Dest = new Dest { def dest = path }
+  }
+  trait Dest{
+    def dest: Path
+  }
+  trait Log{
+    def log: Logger
+  }
+  trait Home{
+    def home: Path
+  }
+  trait Env{
+    def env: Map[String, String]
+  }
+  object Log{
+    implicit def logToCtx(l: Logger): Log = new Log { def log = l }
+  }
+  trait Args{
+    def args: IndexedSeq[_]
+  }
+
+  def defaultHome = ammonite.ops.home / ".mill" / "ammonite"
+
+}
+class Ctx(val args: IndexedSeq[_],
+          dest0: () => Path,
+          val log: Logger,
+          val home: Path,
+          val env : Map[String, String])
+  extends Ctx.Dest
+  with Ctx.Log
+  with Ctx.Args
+  with Ctx.Home
+  with Ctx.Env {
+
+  def dest = dest0()
+  def length = args.length
+  def apply[T](index: Int): T = {
+    if (index >= 0 && index < args.length) args(index).asInstanceOf[T]
+    else throw new IndexOutOfBoundsException(s"Index $index outside of range 0 - ${args.length}")
+  }
+}