Add trait-based Dependency API migration path

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

1 files changed, 38 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/DependencyAPIMigration.scala b/src/main/scala/firrtl/DependencyAPIMigration.scala
new file mode 100644
index 00000000..8dabe849
--- /dev/null
+++ b/src/main/scala/firrtl/DependencyAPIMigration.scala
@@ -0,0 +1,38 @@
+// See LICENSE for license details.
+
+package firrtl
+
+import firrtl.stage.TransformManager.TransformDependency
+
+/** This trait helps ease migration from old [[firrtl.CircuitForm CircuitForm]] specification of dependencies to
+  * Dependency API specification of dependencies. This trait implements deprecated, abstract [[Transform]] methods
+  * (`inputForm` and `outputForm`) for you and sets default values for dependencies:
+  *
+  *    - `prerequisites` are empty
+  *    - `optionalPrerequisites` are empty
+  *    - `dependents` are empty
+  *    - all transforms are invalidated
+  *
+  * For more information, see: https://bit.ly/2Voppre
+  */
+trait DependencyAPIMigration { this: Transform =>
+
+  @deprecated(
+    "Use Dependency API methods for equivalent functionality. See: https://bit.ly/2Voppre",
+    "FIRRTL 1.3")
+  final override def inputForm: CircuitForm = UnknownForm
+
+  @deprecated(
+    "Use Dependency API methods for equivalent functionality. See: https://bit.ly/2Voppre",
+    "FIRRTL 1.3")
+  final override def outputForm: CircuitForm = UnknownForm
+
+  override def prerequisites: Seq[TransformDependency] = Seq.empty
+
+  override def optionalPrerequisites: Seq[TransformDependency] = Seq.empty
+
+  override def dependents: Seq[TransformDependency] = Seq.empty
+
+  override def invalidates(a: Transform): Boolean = true
+
+}