Add support for nested builds and use it to replace cross compilation

command which was previously hard-coded

This will allow multi-project builds, too but we should first fix
caching across instances and GitDependencies on sub-builds within
other repositories.

8 files changed, 38 insertions, 16 deletions

diff --git a/compatibility/BuildInterface.java b/compatibility/BuildInterface.java
index f061832..e2b5f36 100644
--- a/compatibility/BuildInterface.java
+++ b/compatibility/BuildInterface.java
@@ -4,7 +4,9 @@ import java.io.*;
 public abstract class BuildInterface implements Dependency{
   public abstract BuildInterface copy(Context context);  // needed to configure builds
   public abstract String scalaVersion(); // needed to propagate scalaVersion to dependent builds
-  public abstract String[] crossScalaVersionsArray(); // FIXME: this probably can't use Scala classes
   public abstract BuildInterface finalBuild(); // needed to propagage through build builds. Maybe we can get rid of this.
   public abstract File[] triggerLoopFilesArray(); // needed for watching files across composed builds
+
+  // deprecated methods, which clients are still allowed to implement, but not required
+  public abstract String[] crossScalaVersionsArray();
 }
diff --git a/examples/cross-build-example/build/build.scala b/examples/cross-build-example/build/build.scala
new file mode 100644
index 0000000..e1df645
--- /dev/null
+++ b/examples/cross-build-example/build/build.scala
@@ -0,0 +1,4 @@
+import cbt._
+class Build(val context: Context) extends MultipleScalaVersions{
+  override def scalaVersions = Seq("2.10.5","2.11.7")
+}
diff --git a/examples/cross-build-example/src/Main.scala b/examples/cross-build-example/src/Main.scala
new file mode 100644
index 0000000..88a18d3
--- /dev/null
+++ b/examples/cross-build-example/src/Main.scala
@@ -0,0 +1,3 @@
+object Main extends App {
+  println("Hello World")
+}
diff --git a/plugins/essentials/MultipleScalaVersions.scala b/plugins/essentials/MultipleScalaVersions.scala
new file mode 100644
index 0000000..5d896dd
--- /dev/null
+++ b/plugins/essentials/MultipleScalaVersions.scala
@@ -0,0 +1,9 @@
+package cbt
+
+trait MultipleScalaVersions extends DynamicOverrides{
+  def scalaVersions: Seq[String] = Seq(scalaVersion, "2.10.6")
+  def cross: Seq[MultipleScalaVersions] =
+    scalaVersions.map{ v =>
+      newBuild[MultipleScalaVersions](context.copy(scalaVersion = Some(v)))("")
+    }
+}
diff --git a/stage1/cbt.scala b/stage1/cbt.scala
index 8520be4..dd06d81 100644
--- a/stage1/cbt.scala
+++ b/stage1/cbt.scala
@@ -44,7 +44,6 @@ object `package`{
     // then we wouldn't need this and could provide this method from a 
     // plugin rather than hard-coding trigger files stuff in cbt
     def triggerLoopFiles: Seq[File] = triggerLoopFilesArray.to
-    def crossScalaVersions: Seq[String] = crossScalaVersionsArray.to
   }
   implicit class ArtifactInfoExtensions(subject: ArtifactInfo){
     import subject._
diff --git a/stage2/BasicBuild.scala b/stage2/BasicBuild.scala
index ed03de2..b7b0854 100644
--- a/stage2/BasicBuild.scala
+++ b/stage2/BasicBuild.scala
@@ -41,8 +41,6 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with Trigge
   def defaultScalaVersion: String = constants.scalaVersion
   final def scalaVersion = context.scalaVersion getOrElse defaultScalaVersion
   final def scalaMajorVersion: String = lib.libMajorVersion(scalaVersion)
-  def crossScalaVersions: Seq[String] = Seq(scalaVersion, "2.10.6")
-  final def crossScalaVersionsArray: Array[String] = crossScalaVersions.to
   def projectName = "default"
 
   // TODO: get rid of this in favor of newBuild.
@@ -285,4 +283,7 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with Trigge
 
   // a method that can be called only to trigger any side-effects
   final def `void` = ()
+
+  @deprecated("use the MultipleScalaVersions plugin instead","")
+  final def crossScalaVersionsArray = Array(scalaVersion)
 }
diff --git a/stage2/Lib.scala b/stage2/Lib.scala
index 47e1635..dfb7ef3 100644
--- a/stage2/Lib.scala
+++ b/stage2/Lib.scala
@@ -181,6 +181,20 @@ final class Lib(val logger: Logger) extends Stage1Lib(logger) with Scaffold{
                 case code if code.getClass.getSimpleName == "ExitCode" =>
                   // FIXME: ExitCode needs to be part of the compatibility interfaces
                   ExitCode(Stage0Lib.get(code,"integer").asInstanceOf[Int])
+                case Seq(b:BaseBuild) =>
+                  val context = b.context.copy(args=b.context.args.drop(1))
+                  val task = b.context.args.lift(0)
+                  new ReflectBuild( b.copy(context=context) ).callNullary( task )
+                case Seq(b: BaseBuild, bs @ _*) if bs.forall(_.isInstanceOf[BaseBuild]) =>
+                  (b +: bs)
+                    .map( _.asInstanceOf[BaseBuild] )
+                    .map{ b =>
+                      val task = b.context.args.lift(0)
+                      new ReflectBuild(
+                        b.copy( context = b.context.copy(args=b.context.args.drop(1)) )
+                      ).callNullary( task )
+                    }
+                    .head
                 case other =>
                   println( other.toString ) // no method .toConsole, using to String
                   ExitCode.Success
diff --git a/stage2/Stage2.scala b/stage2/Stage2.scala
index 0f5b557..25cd0ae 100644
--- a/stage2/Stage2.scala
+++ b/stage2/Stage2.scala
@@ -12,12 +12,10 @@ object Stage2 extends Stage2Base{
     val paths = CbtPaths(args.cbtHome,args.cache)
     import paths._
     val lib = new Lib(args.logger)
-
     logger.stage2(s"Stage2 start")
     val loop = args.args.lift(0) == Some("loop")
-    val cross = args.args.lift(0) == Some("cross")
 
-    val taskIndex = if (loop || cross) {
+    val taskIndex = if (loop) {
       1
     } else {
       0
@@ -44,15 +42,7 @@ object Stage2 extends Stage2Base{
     val build = first.finalBuild
 
     def call(build: BuildInterface): ExitCode = {
-      if(cross){
-        build.crossScalaVersions.map{
-          v => new lib.ReflectBuild(
-            build.copy(context.copy(scalaVersion = Some(v)))
-          ).callNullary(task)
-        }.filter(_ != ExitCode.Success).headOption getOrElse ExitCode.Success
-      } else {
-        new lib.ReflectBuild(build).callNullary(task)
-      }
+      new lib.ReflectBuild(build).callNullary(task)
     }
 
     val res =