Change Dependency API to Class[_ <: A]

This changes the Dependency API to specify dependencies in terms of
classes subtyping the DependencyAPI trait. Previously, this was
invariant which caused a bunch of ugly, unneeded .asInstanceOf jank.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

2 files changed, 29 insertions, 37 deletions

diff --git a/src/main/scala/firrtl/options/DependencyManager.scala b/src/main/scala/firrtl/options/DependencyManager.scala
index 2afc085d..7b49b074 100644
--- a/src/main/scala/firrtl/options/DependencyManager.scala
+++ b/src/main/scala/firrtl/options/DependencyManager.scala
@@ -22,15 +22,15 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
   /** Requested [[firrtl.options.TransformLike TransformLike]]s that should be run. Internally, this will be converted to
     * a set based on the ordering defined here.
     */
-  def targets: Seq[Class[B]]
-  private lazy val _targets: LinkedHashSet[Class[B]] = targets
-    .foldLeft(new LinkedHashSet[Class[B]]()){ case (a, b) => a += b }
+  def targets: Seq[Class[_ <: B]]
+  private lazy val _targets: LinkedHashSet[Class[_ <: B]] = targets
+    .foldLeft(new LinkedHashSet[Class[_ <: B]]()){ case (a, b) => a += b }
 
   /** A sequence of [[firrtl.Transform]]s that have been run. Internally, this will be converted to an ordered set.
     */
-  def currentState: Seq[Class[B]]
-  private lazy val _currentState: LinkedHashSet[Class[B]] = currentState
-    .foldLeft(new LinkedHashSet[Class[B]]()){ case (a, b) => a += b }
+  def currentState: Seq[Class[_ <: B]]
+  private lazy val _currentState: LinkedHashSet[Class[_ <: B]] = currentState
+    .foldLeft(new LinkedHashSet[Class[_ <: B]]()){ case (a, b) => a += b }
 
   /** Existing transform objects that have already been constructed */
   def knownObjects: Set[B]
@@ -42,8 +42,8 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
 
   /** Store of conversions between classes and objects. Objects that do not exist in the map will be lazily constructed.
     */
-  protected lazy val classToObject: LinkedHashMap[Class[B], B] = {
-    val init = LinkedHashMap[Class[B], B](knownObjects.map(x => x.getClass.asInstanceOf[Class[B]] -> x).toSeq: _*)
+  protected lazy val classToObject: LinkedHashMap[Class[_ <: B], B] = {
+    val init = LinkedHashMap[Class[_ <: B], B](knownObjects.map(x => x.getClass -> x).toSeq: _*)
     (_targets ++ _currentState)
       .filter(!init.contains(_))
       .map(x => init(x) = safeConstruct(x))
@@ -54,33 +54,33 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
     * requirements. This is used to solve sub-problems arising from invalidations.
     */
   protected def copy(
-    targets: Seq[Class[B]],
-    currentState: Seq[Class[B]],
+    targets: Seq[Class[_ <: B]],
+    currentState: Seq[Class[_ <: B]],
     knownObjects: ISet[B] = classToObject.values.toSet): B
 
   /** Implicit conversion from Class[B] to B */
-  private implicit def cToO(c: Class[B]): B = classToObject.getOrElseUpdate(c, safeConstruct(c))
+  private implicit def cToO(c: Class[_ <: B]): B = classToObject.getOrElseUpdate(c, safeConstruct(c))
 
   /** Implicit conversion from B to Class[B] */
-  private implicit def oToC(b: B): Class[B] = b.getClass.asInstanceOf[Class[B]]
+  private implicit def oToC(b: B): Class[_ <: B] = b.getClass
 
   /** Modified breadth-first search that supports multiple starting nodes and a custom extractor that can be used to
     * generate/filter the edges to explore. Additionally, this will include edges to previously discovered nodes.
     */
-  private def bfs( start: LinkedHashSet[Class[B]],
-                   blacklist: LinkedHashSet[Class[B]],
-                   extractor: B => Set[Class[B]] ): LinkedHashMap[B, LinkedHashSet[B]] = {
+  private def bfs( start: LinkedHashSet[Class[_ <: B]],
+                   blacklist: LinkedHashSet[Class[_ <: B]],
+                   extractor: B => Set[Class[_ <: B]] ): LinkedHashMap[B, LinkedHashSet[B]] = {
 
     val (queue, edges) = {
-      val a: Queue[Class[B]]                    = Queue(start.toSeq:_*)
+      val a: Queue[Class[_ <: B]]                    = Queue(start.toSeq:_*)
       val b: LinkedHashMap[B, LinkedHashSet[B]] = LinkedHashMap[B, LinkedHashSet[B]](
         start.map((cToO(_) -> LinkedHashSet[B]())).toSeq:_*)
       (a, b)
     }
 
     while (queue.nonEmpty) {
-      val u: Class[B] = queue.dequeue
-      for (v: Class[B] <- extractor(classToObject(u))) {
+      val u: Class[_ <: B] = queue.dequeue
+      for (v <- extractor(classToObject(u))) {
         if (!blacklist.contains(v) && !edges.contains(v)) {
           queue.enqueue(v)
         }
@@ -107,7 +107,7 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
     val edges = bfs(
       start = _targets -- _currentState,
       blacklist = _currentState,
-      extractor = (p: B) => new LinkedHashSet[Class[B]]() ++ p.prerequisites -- _currentState)
+      extractor = (p: B) => new LinkedHashSet[Class[_ <: B]]() ++ p.prerequisites -- _currentState)
     DiGraph(edges)
   }
 
@@ -145,7 +145,7 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
       bfs(
         start = _targets -- _currentState,
         blacklist = _currentState,
-        extractor = (p: B) => v.filter(p.invalidates).map(_.asClass).toSet))
+        extractor = (p: B) => v.filter(p.invalidates).map(_.getClass).toSet))
       .reverse
   }
 
@@ -158,7 +158,7 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
   }
 
   /** Wrap an [[IllegalAccessException]] due to attempted object construction in a [[DependencyManagerException]] */
-  private def safeConstruct[A](a: Class[A]): A = try { a.newInstance } catch {
+  private def safeConstruct[A](a: Class[_ <: A]): A = try { a.newInstance } catch {
     case e: IllegalAccessException => throw new DependencyManagerException(
       s"Failed to construct '$a'! (Did you try to construct an object?)", e)
     case e: InstantiationException => throw new DependencyManagerException(
@@ -230,7 +230,7 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
   final override def transform(annotations: A): A = {
 
     /* A local store of each wrapper to it's underlying class. */
-    val wrapperToClass = new HashMap[B, Class[B]]
+    val wrapperToClass = new HashMap[B, Class[_ <: B]]
 
     /* The determined, flat order of transforms is wrapped with surrounding transforms while populating wrapperToClass so
      * that each wrapped transform object can be dereferenced to its underlying class. Each wrapped transform is then
@@ -354,10 +354,10 @@ trait DependencyManager[A, B <: TransformLike[A] with DependencyAPI[B]] extends
   * @param targets the [[Phase]]s you want to run
   */
 class PhaseManager(
-  val targets: Seq[Class[Phase]],
-  val currentState: Seq[Class[Phase]] = Seq.empty,
+  val targets: Seq[Class[_ <: Phase]],
+  val currentState: Seq[Class[_ <: Phase]] = Seq.empty,
   val knownObjects: Set[Phase] = Set.empty) extends Phase with DependencyManager[AnnotationSeq, Phase] {
 
-  protected def copy(a: Seq[Class[Phase]], b: Seq[Class[Phase]], c: ISet[Phase]) = new PhaseManager(a, b, c)
+  protected def copy(a: Seq[Class[_ <: Phase]], b: Seq[Class[_ <: Phase]], c: ISet[Phase]) = new PhaseManager(a, b, c)
 
 }
diff --git a/src/main/scala/firrtl/options/Phase.scala b/src/main/scala/firrtl/options/Phase.scala
index e5aa87ec..66a47f45 100644
--- a/src/main/scala/firrtl/options/Phase.scala
+++ b/src/main/scala/firrtl/options/Phase.scala
@@ -45,8 +45,8 @@ trait DependencyAPI[A <: DependencyAPI[A]] { this: TransformLike[_] =>
   /** All transform that must run before this transform
     * $seqNote
     */
-  def prerequisites: Seq[Class[A]] = Seq.empty
-  private[options] lazy val _prerequisites: LinkedHashSet[Class[A]] = new LinkedHashSet() ++ prerequisites.toSet
+  def prerequisites: Seq[Class[_ <: A]] = Seq.empty
+  private[options] lazy val _prerequisites: LinkedHashSet[Class[_ <: A]] = new LinkedHashSet() ++ prerequisites.toSet
 
   /** All transforms that must run ''after'' this transform
     *
@@ -67,8 +67,8 @@ trait DependencyAPI[A <: DependencyAPI[A]] { this: TransformLike[_] =>
     * @see [[firrtl.passes.CheckTypes]] for an example of an optional checking [[firrtl.Transform]]
     * $seqNote
     */
-  def dependents: Seq[Class[A]] = Seq.empty
-  private[options] lazy val _dependents: LinkedHashSet[Class[A]] = new LinkedHashSet() ++ dependents.toSet
+  def dependents: Seq[Class[_ <: A]] = Seq.empty
+  private[options] lazy val _dependents: LinkedHashSet[Class[_ <: A]] = new LinkedHashSet() ++ dependents.toSet
 
   /** A function that, given a transform will return true if this transform invalidates/undos the effects of the input
     * transform
@@ -76,14 +76,6 @@ trait DependencyAPI[A <: DependencyAPI[A]] { this: TransformLike[_] =>
     */
   def invalidates(a: A): Boolean = true
 
-  /** Helper method to return the underlying class */
-  final def asClass: Class[A] = this.getClass.asInstanceOf[Class[A]]
-
-  /** Implicit conversion that allows for terser specification of [[DependencyAPI.prerequisites prerequisites]] and
-    * [[DependencyAPI.dependents dependents]].
-    */
-  implicit def classHelper(a: Class[_ <: A]): Class[A] = a.asInstanceOf[Class[A]]
-
 }
 
 /** A trait indicating that no invalidations occur, i.e., all previous transforms are preserved