Move compiler and compiler tests to compiler dir

1 files changed, 78 insertions, 0 deletions

diff --git a/compiler/src/dotty/tools/dotc/core/DenotTransformers.scala b/compiler/src/dotty/tools/dotc/core/DenotTransformers.scala
new file mode 100644
index 000000000..02d27ea33
--- /dev/null
+++ b/compiler/src/dotty/tools/dotc/core/DenotTransformers.scala
@@ -0,0 +1,78 @@
+package dotty.tools.dotc
+package core
+
+import Periods._
+import SymDenotations._
+import Contexts._
+import Types._
+import Symbols._
+import Denotations._
+import Phases._
+import java.lang.AssertionError
+import dotty.tools.dotc.util.DotClass
+
+object DenotTransformers {
+
+  /** A transformer group contains a sequence of transformers,
+   *  ordered by the phase where they apply. Transformers are added
+   *  to a group via `install`.
+   */
+
+  /** A transformer transforms denotations at a given phase */
+  trait DenotTransformer extends Phase {
+
+    /** The last phase during which the transformed denotations are valid */
+    def lastPhaseId(implicit ctx: Context) = ctx.nextDenotTransformerId(id + 1)
+
+    /** The validity period of the transformer in the given context */
+    def validFor(implicit ctx: Context): Period =
+      Period(ctx.runId, id, lastPhaseId)
+
+    /** The transformation method */
+    def transform(ref: SingleDenotation)(implicit ctx: Context): SingleDenotation
+  }
+
+  /** A transformer that only transforms the info field of denotations */
+  trait InfoTransformer extends DenotTransformer {
+
+    def transformInfo(tp: Type, sym: Symbol)(implicit ctx: Context): Type
+
+    def transform(ref: SingleDenotation)(implicit ctx: Context): SingleDenotation = {
+      val sym = ref.symbol
+      if (sym.exists && !mayChange(sym)) ref
+      else {
+        val info1 = transformInfo(ref.info, ref.symbol)
+        if (info1 eq ref.info) ref
+        else ref match {
+          case ref: SymDenotation => ref.copySymDenotation(info = info1)
+          case _ => ref.derivedSingleDenotation(ref.symbol, info1)
+        }
+      }
+    }
+
+    /** Denotations with a symbol where `mayChange` is false are guaranteed to be
+     *  unaffected by this transform, so `transformInfo` need not be run. This
+     *  can save time, and more importantly, can help avoid forcing symbol completers.
+     */
+    protected def mayChange(sym: Symbol)(implicit ctx: Context): Boolean = true
+  }
+
+  /** A transformer that only transforms SymDenotations */
+  trait SymTransformer extends DenotTransformer {
+
+    def transformSym(sym: SymDenotation)(implicit ctx: Context): SymDenotation
+
+    def transform(ref: SingleDenotation)(implicit ctx: Context): SingleDenotation = ref match {
+      case ref: SymDenotation => transformSym(ref)
+      case _ => ref
+    }
+  }
+
+  /** A `DenotTransformer` trait that has the identity as its `transform` method.
+   *  You might want to inherit from this trait so that new denotations can be
+   *  installed using `installAfter` and `enteredAfter` at the end of the phase.
+   */
+  trait IdentityDenotTransformer extends DenotTransformer {
+    def transform(ref: SingleDenotation)(implicit ctx: Context): SingleDenotation = ref
+  }
+}