Add support for dynamic re-configuration.

The exact precedence rule of override code vs original code may still
need to be tweaked as we go along.

4 files changed, 100 insertions, 0 deletions

diff --git a/plugins/essentials/CommandLineOverrides.scala b/plugins/essentials/CommandLineOverrides.scala
new file mode 100644
index 0000000..32b8403
--- /dev/null
+++ b/plugins/essentials/CommandLineOverrides.scala
@@ -0,0 +1,25 @@
+package cbt
+trait CommandLineOverrides extends DynamicOverrides{
+  def `with`: Any = {
+    new lib.ReflectObject(
+      newBuild[DynamicOverrides](
+        context.copy(
+          args = context.args.drop(2)
+        )
+      )( s"""
+        ${context.args.lift(0).getOrElse("")}
+      """ )
+    ){
+      def usage = ""
+    }.callNullary(context.args.lift(1) orElse Some("void"))
+  }
+  def eval = {
+    new lib.ReflectObject(
+      newBuild[CommandLineOverrides](
+        context.copy(
+          args = ( context.args.lift(0).map("println{ "+_+" }") ).toSeq
+        )
+      ){""}
+    ){def usage = ""}.callNullary(Some("with"))
+  }
+}
diff --git a/plugins/essentials/DynamicOverrides.scala b/plugins/essentials/DynamicOverrides.scala
new file mode 100644
index 0000000..0826f12
--- /dev/null
+++ b/plugins/essentials/DynamicOverrides.scala
@@ -0,0 +1,66 @@
+package cbt
+import cbt.eval.Eval
+trait DynamicOverrides extends BaseBuild{
+  private val twitterEval = cached("eval"){
+    new Eval{
+      override lazy val impliedClassPath: List[String] = context.parentBuild.get.classpath.strings.toList//new ScalaCompilerDependency( context.cbtHasChanged, context.paths.mavenCache, scalaVersion ).classpath.strings.toList
+      override def classLoader = DynamicOverrides.this.getClass.getClassLoader
+    }
+  }
+
+  protected [cbt] def overrides: String = ""
+
+  // TODO: add support for Build inner classes
+  def newBuild[T <: DynamicOverrides:scala.reflect.ClassTag]: DynamicOverrides with T = newBuild[T](context)("")
+  def newBuild[T <: DynamicOverrides:scala.reflect.ClassTag](body: String): DynamicOverrides with T = newBuild[T](context)(body)
+  def newBuild[T <: DynamicOverrides:scala.reflect.ClassTag](context: Context)(body: String): DynamicOverrides with T = {
+    val mixinClass = scala.reflect.classTag[T].runtimeClass
+    assert(mixinClass.getTypeParameters.size == 0)
+    val mixin = if(
+      mixinClass == classOf[Nothing]
+      || mixinClass.getSimpleName == "Build"
+    ) "" else " with "+mixinClass.getName
+    import scala.collection.JavaConverters._
+    val parent = Option(
+      if(this.getClass.getName.startsWith("Evaluator__"))
+        this.getClass.getName.dropWhile(_ != '$').drop(1).stripSuffix("$1")
+      else
+        this.getClass.getName
+    ).getOrElse(
+      throw new Exception( "You cannot have more than one newBuild call on the Stack right now." )
+    )
+    val overrides = "" // currently disables, but can be used to force overrides everywhere
+    val name = if(mixin == "" && overrides == "" && body == ""){
+      "Build"
+    } else if(overrides == ""){
+      val name = "DynamicBuild" + System.currentTimeMillis
+      val code = s"""
+        class $name(context: _root_.cbt.Context)
+          extends $parent(context)$mixin{
+            $body
+        }
+      """
+      logger.dynamic("Dynamically generated code:\n" ++ code)
+      twitterEval.compile(code)
+      name
+    } else {
+      val name = "DynamicBuild" + System.currentTimeMillis
+      val code = s"""
+        class $name(context: _root_.cbt.Context)
+          extends $parent(context)$mixin{
+            $body
+        }
+        class ${name}Overrides(context: _root_.cbt.Context)
+          extends $name(context){
+            $overrides
+        }
+      """
+      logger.dynamic("Dynamically generated code:\n" ++ code)
+      twitterEval.compile(code)
+      name+"Overrides"
+    }
+
+    val createBuild = twitterEval.apply[Context => T](s"new $name(_: _root_.cbt.Context)",false)
+    createBuild( context ).asInstanceOf[DynamicOverrides with T]
+  }
+}
diff --git a/plugins/essentials/Readme.md b/plugins/essentials/Readme.md
new file mode 100644
index 0000000..76d3756
--- /dev/null
+++ b/plugins/essentials/Readme.md
@@ -0,0 +1,3 @@
+Essential CBT plugins
+
+Not part of CBT's core to keep it slim and so they can have dependencies if needed.
diff --git a/plugins/essentials/build/build.scala b/plugins/essentials/build/build.scala
new file mode 100644
index 0000000..1288367
--- /dev/null
+++ b/plugins/essentials/build/build.scala
@@ -0,0 +1,6 @@
+import cbt._
+class Build(val context: Context) extends Plugin{
+  override def dependencies =
+    super.dependencies :+ // don't forget super.dependencies here for scala-library, etc.
+    DirectoryDependency( context.cbtHome ++ "/libraries/eval" )
+}