Add DataView (#1955)

DataView is a mechanism for "viewing" Scala objects as a subtype of
`Data`. Often, this is useful for viewing one subtype of `Data`, as
another. One can think about a DataView as a cross between a
customizable cast and an untagged union.

A DataView has a Target type `T`, and a View type `V`. DataView requires
that an implementation of `DataProduct` is available for Target types.
DataProduct is a type class that provides a way to iterate on `Data`
children of objects of implementing types.

If a DataView is provided for a type T to a type V, then the function
.viewAs[V] (of type T => V) is available. The object (of type T) returned
by .viewAs is called a "View" and can be used as both an rvalue and an
lvalue. Unlike when using an .asTypeOf cast, connecting to a "View" will
connect to the associated field or fields of the underlying Target.

DataView also enables .viewAsSupertype which is available for viewing
Bundles as a parent Bundle type. It is similar to .viewAs but requires
a prototype object of the Target type which will be cloned in order to
create the returned View. .viewAsSupertype maps between the
corresponding fields of the parent and child Bundle types.

1 files changed, 5 insertions, 2 deletions

diff --git a/core/src/main/scala/chisel3/internal/firrtl/IR.scala b/core/src/main/scala/chisel3/internal/firrtl/IR.scala
index 5796522c..f8a3cf7f 100644
--- a/core/src/main/scala/chisel3/internal/firrtl/IR.scala
+++ b/core/src/main/scala/chisel3/internal/firrtl/IR.scala
@@ -8,7 +8,8 @@ import chisel3.internal._
 import chisel3.internal.sourceinfo.SourceInfo
 import chisel3.experimental._
 import _root_.firrtl.{ir => firrtlir}
-import _root_.firrtl.PrimOps
+import _root_.firrtl.{PrimOps, RenameMap}
+import _root_.firrtl.annotations.Annotation
 
 import scala.collection.immutable.NumericRange
 import scala.math.BigDecimal.RoundingMode
@@ -789,4 +790,6 @@ abstract class Component extends Arg {
 case class DefModule(id: RawModule, name: String, ports: Seq[Port], commands: Seq[Command]) extends Component
 case class DefBlackBox(id: BaseBlackBox, name: String, ports: Seq[Port], topDir: SpecifiedDirection, params: Map[String, Param]) extends Component
 
-case class Circuit(name: String, components: Seq[Component], annotations: Seq[ChiselAnnotation] = Seq.empty)
+case class Circuit(name: String, components: Seq[Component], annotations: Seq[ChiselAnnotation], renames: RenameMap) {
+  def firrtlAnnotations: Iterable[Annotation] = annotations.flatMap(_.toFirrtl.update(renames))
+}