First pass at generating CLI output when you run `Target`s, based on their return values, converted to JSON

3 files changed, 59 insertions, 17 deletions

diff --git a/core/src/main/scala/mill/Main.scala b/core/src/main/scala/mill/Main.scala
index 97499db6..470d9cbc 100644
--- a/core/src/main/scala/mill/Main.scala
+++ b/core/src/main/scala/mill/Main.scala
@@ -12,6 +12,7 @@ object Main {
 
     import ammonite.main.Cli
     var repl = false
+    var show = false
     val replCliArg = Cli.Arg[Cli.Config, Unit](
       "repl",
       None,
@@ -21,9 +22,18 @@ object Main {
         x
       }
     )
+    val showCliArg = Cli.Arg[Cli.Config, Unit](
+      "show",
+      None,
+      "Display the json-formatted value of the given target, if any",
+      (x, _) => {
+        show = true
+        x
+      }
+    )
     Cli.groupArgs(
       args.toList,
-      Cli.ammoniteArgSignature :+ replCliArg,
+      Cli.ammoniteArgSignature :+ replCliArg :+ showCliArg,
       Cli.Config()
     ) match{
       case Left(msg) =>
@@ -41,7 +51,7 @@ object Main {
             welcomeBanner = None
           )
 
-        val runner = new mill.main.MainRunner(config)
+        val runner = new mill.main.MainRunner(config, show)
         if (repl){
           runner.printInfo("Loading...")
           runner.runRepl()
diff --git a/core/src/main/scala/mill/main/MainRunner.scala b/core/src/main/scala/mill/main/MainRunner.scala
index 28d0a284..f354e838 100644
--- a/core/src/main/scala/mill/main/MainRunner.scala
+++ b/core/src/main/scala/mill/main/MainRunner.scala
@@ -4,13 +4,15 @@ import ammonite.ops.Path
 import ammonite.util.{Imports, Name, Res, Util}
 import mill.discover.Discovered
 import mill.eval.Evaluator
+import upickle.Js
 
 /**
   * Customized version of [[ammonite.MainRunner]], allowing us to run Mill
   * `build.sc` scripts with mill-specific tweaks such as a custom
   * `scriptCodeWrapper` or with a persistent evaluator between runs.
   */
-class MainRunner(config: ammonite.main.Cli.Config)
+class MainRunner(config: ammonite.main.Cli.Config,
+                 show: Boolean)
   extends ammonite.MainRunner(
     config,
     System.out, System.err, System.in, System.out, System.err
@@ -31,9 +33,9 @@ class MainRunner(config: ammonite.main.Cli.Config)
             )
             result match{
               case Res.Success(data) =>
-                val (eval, evaluationWatches) = data
+                val (eval, evaluationWatches, res) = data
                 lastEvaluator = Some((interpWatched, eval))
-                (result, interpWatched ++ evaluationWatches)
+                (Res.Success(res.flatMap(_._2)), interpWatched ++ evaluationWatches)
               case _ =>
                 (result, interpWatched)
             }
@@ -42,12 +44,25 @@ class MainRunner(config: ammonite.main.Cli.Config)
         }
       }
     )
+
+  override def handleWatchRes[T](res: Res[T], printing: Boolean) = {
+    res match{
+      case Res.Success(value) =>
+        if (show){
+          for(json <- value.asInstanceOf[Seq[Js.Value]]){
+            System.out.println(json)
+          }
+        }
+
+        true
+
+      case _ => super.handleWatchRes(res, printing)
+    }
+
+  }
   override def initMain(isRepl: Boolean) = {
     super.initMain(isRepl).copy(scriptCodeWrapper = mill.main.MainRunner.CustomCodeWrapper)
   }
-  override def handleWatchRes[T](res: Res[T], printing: Boolean) = {
-    super.handleWatchRes(res, printing = false)
-  }
 }
 
 object MainRunner{
diff --git a/core/src/main/scala/mill/main/RunScript.scala b/core/src/main/scala/mill/main/RunScript.scala
index ad6ad327..f58cf5c0 100644
--- a/core/src/main/scala/mill/main/RunScript.scala
+++ b/core/src/main/scala/mill/main/RunScript.scala
@@ -11,6 +11,7 @@ import mill.define.Task
 import mill.discover.{Discovered, Mirror}
 import mill.eval.{Evaluator, Result}
 import mill.util.{OSet, PrintLogger}
+import upickle.Js
 
 import scala.collection.mutable
 
@@ -26,7 +27,7 @@ object RunScript{
                 interp: ammonite.interp.Interpreter,
                 scriptArgs: Seq[String],
                 lastEvaluator: Option[(Seq[(Path, Long)], Evaluator[_])])
-  : Res[(Evaluator[_], Seq[(Path, Long)])] = {
+  : Res[(Evaluator[_], Seq[(Path, Long)], Seq[(Any, Option[Js.Value])])] = {
 
     val log = new PrintLogger(true)
     for{
@@ -41,12 +42,12 @@ object RunScript{
           yield new Evaluator(pwd / 'out, mapping, log)
       }
       evaluationWatches = mutable.Buffer.empty[(Path, Long)]
-      _ <- Res(evaluateTarget(
+      res <- Res(evaluateTarget(
         evaluator,
         scriptArgs,
         p => evaluationWatches.append((p, Interpreter.pathSignature(p)))
       ))
-    } yield (evaluator, evaluationWatches)
+    } yield (evaluator, evaluationWatches, res)
   }
 
   def watchedSigUnchanged(sig: Seq[(Path, Long)]) = {
@@ -106,13 +107,16 @@ object RunScript{
         case Mirror.Segment.Cross(x) => x.toList.map(_.toString)
         case _ => Nil
       }
-      target <- mill.main.Resolve.resolve(sel, evaluator.mapping.mirror, evaluator.mapping.base, rest, crossSelectors, Nil)
-      _ <- evaluate(evaluator, target, watch).toLeft(())
-    } yield ()
+      target <- mill.main.Resolve.resolve(
+        sel, evaluator.mapping.mirror, evaluator.mapping.base,
+        rest, crossSelectors, Nil
+      )
+      res <- evaluate(evaluator, target, watch)
+    } yield res
   }
   def evaluate(evaluator: Evaluator[_],
                target: Task[Any],
-               watch: Path => Unit): Option[String] = {
+               watch: Path => Unit): Either[String, Seq[(Any, Option[upickle.Js.Value])]] = {
     val evaluated = evaluator.evaluate(OSet(target))
     evaluated.transitive.foreach {
       case t: define.Source => watch(t.handle.path)
@@ -133,8 +137,21 @@ object RunScript{
       }).mkString("\n")
 
     evaluated.failing.keyCount match {
-      case 0 => None
-      case n => Some(s"$n targets failed\n$errorStr")
+      case 0 =>
+        val json = for(t <- Seq(target)) yield {
+          t match {
+            case t: mill.define.Target[_] =>
+              for (labelled <- evaluator.labeling.get(t)) yield {
+                val jsonFile = Evaluator.resolveDestPaths(evaluator.workspacePath, labelled)._2
+                val metadata = upickle.json.read(jsonFile.toIO)
+                metadata(1)
+              }
+            case _ => None
+          }
+        }
+
+        Right(evaluated.values.zip(json))
+      case n => Left(s"$n targets failed\n$errorStr")
     }
   }