Renaming core.Transformer(s) -> core.DenotTransformer(s)

To bring in line with TreeTransformer terminology.

1 files changed, 69 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/DenotTransformers.scala b/src/dotty/tools/dotc/core/DenotTransformers.scala
new file mode 100644
index 000000000..f41f1d171
--- /dev/null
+++ b/src/dotty/tools/dotc/core/DenotTransformers.scala
@@ -0,0 +1,69 @@
+package dotty.tools.dotc
+package core
+
+import Periods._
+import SymDenotations._
+import Contexts._
+import Types._
+import Denotations._
+import java.lang.AssertionError
+import dotty.tools.dotc.util.DotClass
+
+object DenotTransformers {
+
+  trait DenotTransformerBase { self: ContextBase =>
+    val denotTransformers = new DenotTransformerGroup
+  }
+
+  /** A transformer group contains a sequence of transformers,
+   *  ordered by the phase where they apply. Transformers are added
+   *  to a group via `install`.
+   *
+   *  There are two transformerGroups in a context base:
+   *  symTransformers and refTransformers. symTransformers translate
+   *  full symbol denotations, refTransformers translate only symbol references
+   *  of type Unique/JointRefDenotation.
+   */
+  class DenotTransformerGroup {
+
+    private val nxTransformer =
+      Array.fill[DenotTransformer](MaxPossiblePhaseId + 1)(NoTransformer)
+
+    def nextTransformer(pid: PhaseId) = nxTransformer(pid)
+
+    def install(pid: PhaseId, transFn: DenotTransformerGroup => DenotTransformer): Unit =
+      if ((pid > NoPhaseId) && (nxTransformer(pid).phaseId > pid)) {
+        val trans = transFn(this)
+        trans._phaseId = pid
+        nxTransformer(pid) = transFn(this)
+        install(pid - 1, transFn)
+      }
+
+    /** A sentinel transformer object */
+    object NoTransformer extends DenotTransformer(this) {
+      _phaseId = MaxPossiblePhaseId + 1
+      override def lastPhaseId = phaseId - 1 // TODO JZ Probably off-by-N error here. MO: Don't think so: we want empty validity period.
+      def transform(ref: SingleDenotation)(implicit ctx: Context): SingleDenotation =
+        unsupported("transform")
+    }
+  }
+
+  /** A transformer transforms denotations at a given phase */
+  abstract class DenotTransformer(group: DenotTransformerGroup) extends DotClass {
+
+    private[DenotTransformers] var _phaseId: PhaseId = _
+
+    /** The phase at the start of which the denotations are transformed */
+    def phaseId: PhaseId = _phaseId
+
+    /** The last phase during which the transformed denotations are valid */
+    def lastPhaseId = group.nextTransformer(phaseId).phaseId - 1
+
+    /** The validity period of the transformer in the given context */
+    def validFor(implicit ctx: Context): Period =
+      Period(ctx.runId, phaseId, lastPhaseId)
+
+    /** The transformation method */
+    def transform(ref: SingleDenotation)(implicit ctx: Context): SingleDenotation
+  }
+}