1 files changed, 105 insertions, 0 deletions
diff --git a/src/main/scala/hbt/Hbt.scala b/src/main/scala/hbt/Hbt.scala
new file mode 100644
index 00000000..c6035e55
--- /dev/null
+++ b/src/main/scala/hbt/Hbt.scala
@@ -0,0 +1,105 @@
+package hbt
+
+import java.io.FileOutputStream
+
+import collection.JavaConverters._
+import java.nio.{file => jnio}
+import java.util.jar.JarEntry
+
+import sourcecode.Enclosing
+
+import scala.collection.mutable
+class Args(val args: IndexedSeq[_]){
+  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}")
+  }
+}
+sealed trait Target[T]{
+  val label: String
+  def evaluate(args: Args): T
+  val inputs: Seq[Target[_]]
+
+  def map[V](f: T => V)(implicit path: Enclosing) = {
+    Target.Mapped(this, f, path.value)
+  }
+  def zip[V](other: Target[V])(implicit path: Enclosing) = {
+    Target.Zipped(this, other, path.value)
+  }
+  def ~[V, R](other: Target[V])
+             (implicit s: Implicits.Sequencer[T, V, R]): Target[R] = {
+    this.zip(other).map(s.apply _ tupled)
+  }
+
+}
+
+object Target{
+  def traverse[T](source: Seq[Target[T]])(implicit path: Enclosing) = {
+    Traverse(source, path.value)
+  }
+  case class Traverse[T](inputs: Seq[Target[T]], label: String) extends Target[Seq[T]]{
+    def evaluate(args: Args) = {
+      for (i <- 0 until args.length)
+      yield args(i)
+    }
+
+  }
+  case class Mapped[T, V](source: Target[T], f: T => V,
+                          label: String) extends Target[V]{
+    def evaluate(args: Args) = f(args(0))
+    val inputs = List(source)
+  }
+  case class Zipped[T, V](source1: Target[T],
+                          source2: Target[V],
+                          label: String) extends Target[(T, V)]{
+    def evaluate(args: Args) = (args(0), args(0))
+    val inputs = List(source1, source1)
+  }
+  case class Path(path: jnio.Path, label: String) extends Target[jnio.Path]{
+    def evaluate(args: Args) = path
+    val inputs = Nil
+  }
+//  case class Command(inputs: Seq[Target[jnio.Path]],
+//                     output: Seq[Target[jnio.Path]],
+//                     label: String) extends Target[Command.Result]
+//  object Command{
+//    case class Result(stdout: String,
+//                      stderr: String,
+//                      writtenFiles: Seq[jnio.Path])
+//  }
+}
+object Hbt{
+
+
+  def evaluateTargetGraph[T](t: Target[T]): T = {
+    val targetSet = mutable.Set.empty[Target[_]]
+    def rec(t: Target[_]): Unit = {
+      if (targetSet.contains(t)) () // do nothing
+      else {
+        targetSet.add(t)
+        t.inputs.foreach(rec)
+      }
+    }
+    rec(t)
+    val targets = targetSet.toIndexedSeq
+    val targetIndices = targets.zipWithIndex.toMap
+
+    val numberedEdges =
+      for(i <- targets.indices)
+      yield targets(i).inputs.map(targetIndices)
+
+    val sortedClusters = Tarjans(numberedEdges)
+    val nonTrivialClusters = sortedClusters.filter(_.length > 1)
+    assert(nonTrivialClusters.isEmpty, nonTrivialClusters)
+
+    val results = mutable.Map.empty[Target[_], Any]
+    for (cluster <- sortedClusters){
+      val Seq(singletonIndex) = cluster
+      val singleton = targets(singletonIndex)
+      val inputResults = singleton.inputs.map(results)
+      results(singleton) = singleton.evaluate(new Args(inputResults.toIndexedSeq))
+    }
+    results(t).asInstanceOf[T]
+  }
+}
+\ No newline at end of file