Fleshed out transformer architecture.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/Transformers.scala b/src/dotty/tools/dotc/core/Transformers.scala
new file mode 100644
index 000000000..2bc475104
--- /dev/null
+++ b/src/dotty/tools/dotc/core/Transformers.scala
@@ -0,0 +1,51 @@
+package dotty.tools.dotc
+package core
+
+import Periods._, Denotations._, Contexts._, Types._, References._
+import java.lang.AssertionError
+
+trait Transformers { self: RootContext =>
+
+  import Transformers._
+
+  def transformersFor(ref: SymRef): TransformerGroup = ref match {
+    case _: Denotation => denotTransformers
+    case _ => refTransformers
+  }
+
+  val denotTransformers = new TransformerGroup
+  val refTransformers = new TransformerGroup
+}
+
+object Transformers {
+
+  val lastPhaseId = 31
+
+  class TransformerGroup {
+
+    abstract class Transformer extends DotClass {
+      val phaseId: Int
+      def lastPhaseId = nextTransformer(phaseId).phaseId - 1
+      def validFor(implicit ctx: Context): Period =
+        Period(ctx.runId, phaseId, lastPhaseId)
+      def transform(ref: SymRef)(implicit ctx: Context): SymRef
+    }
+
+    object NoTransformer extends Transformer {
+      val phaseId = lastPhaseId + 1
+      def transform(ref: SymRef)(implicit ctx: Context): SymRef =
+        unsupported("transform")
+    }
+
+    private val nxTransformer =
+      Array.fill[Transformer](lastPhaseId + 1)(NoTransformer)
+
+    def nextTransformer(i: Int) = nxTransformer(i)
+
+    def install(pid: PhaseId, trans: Transformer): Unit =
+      if ((pid > NoPhaseId) && (nxTransformer(pid).phaseId > pid)) {
+        nxTransformer(pid) = trans
+        install(pid - 1, trans)
+      }
+  }
+}
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