Added substThis to substituters

2 files changed, 58 insertions, 5 deletions

diff --git a/src/dotty/tools/dotc/core/Substituters.scala b/src/dotty/tools/dotc/core/Substituters.scala
index 55e3591a3..539d12310 100644
--- a/src/dotty/tools/dotc/core/Substituters.scala
+++ b/src/dotty/tools/dotc/core/Substituters.scala
@@ -129,6 +129,49 @@ object Substituters {
           }
       }
     }
+
+    def substThis(from: ClassSymbol, to: Type, map: SubstThisMap)(implicit ctx: Context): Type =
+      tp match {
+        case tp @ ThisType(clazz) =>
+          if (clazz eq from) to else tp
+        case tp: NamedType =>
+          if (tp.symbol.isStatic) tp
+          else tp.derivedNamedType(tp.prefix.substThis(from, to, map), tp.name)
+        case MethodParam(_, _)
+           | PolyParam(_, _)
+           | NoPrefix => tp
+        case _ =>
+          val substMap = if (map != null) map else new SubstThisMap(from, to)
+          tp match {
+            case tp: AppliedType =>
+              tp.derivedAppliedType(
+                substMap(tp.tycon), tp.typeArgs mapConserve substMap)
+            case _ =>
+              substMap mapOver tp
+          }
+      }
+
+    def substThis(from: RefinedType, to: Type, map: SubstRefinedThisMap)(implicit ctx: Context): Type =
+      tp match {
+        case tp @ RefinedThis(rt) =>
+          if (rt eq from) to else tp
+        case tp: NamedType =>
+          if (tp.symbol.isStatic) tp
+          else tp.derivedNamedType(tp.prefix.substThis(from, to, map), tp.name)
+        case ThisType(_)
+           | MethodParam(_, _)
+           | PolyParam(_, _)
+           | NoPrefix => tp
+        case _ =>
+          val substMap = if (map != null) map else new SubstRefinedThisMap(from, to)
+          tp match {
+            case tp: AppliedType =>
+              tp.derivedAppliedType(
+                substMap(tp.tycon), tp.typeArgs mapConserve substMap)
+            case _ =>
+              substMap mapOver tp
+          }
+      }
   }
 
   class SubstPolyMap(from: PolyType, to: PolyType)(implicit ctx: Context) extends TypeMap {
@@ -150,4 +193,12 @@ object Substituters {
   class SubstMap(from: List[Symbol], to: List[Type])(implicit ctx: Context) extends TypeMap {
     def apply(tp: Type): Type = tp.subst(from, to, this)
   }
+
+  class SubstThisMap(from: ClassSymbol, to: Type)(implicit ctx: Context) extends TypeMap {
+    def apply(tp: Type): Type = tp.substThis(from, to, this)
+  }
+
+  class SubstRefinedThisMap(from: RefinedType, to: Type)(implicit ctx: Context) extends TypeMap {
+    def apply(tp: Type): Type = tp.substThis(from, to, this)
+  }
 }
\ No newline at end of file
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index fd0318c97..258844467 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -118,6 +118,12 @@ object Types {
       if (from.isDependent) new SubstOps(this).subst(from, to, null)
       else this
 
+    def substThis(clazz: ClassSymbol, tp: Type)(implicit ctx: Context): Type =
+      new SubstOps(this).substThis(clazz, tp, null)
+
+    def substThis(from: RefinedType, tp: Type)(implicit ctx: Context): Type =
+      new SubstOps(this).substThis(from, tp, null)
+
     /** For a class or intersection type, its parents.
      *  For a TypeBounds type, the parents of its hi bound.
      *  inherited by typerefs, singleton types, and refinement types,
@@ -167,10 +173,6 @@ object Types {
       if (this.isTrivial || clazz.isStaticMono) this
       else new AsSeenFromMap(pre, clazz) apply (this)
 
-    def substSym(from: List[Symbol], to: List[Symbol]): Type = ???
-    def substThis(clazz: ClassSymbol, tp: Type): Type = ???
-    def substThis(from: RefinedType, tp: Type): Type = ???
-
     def signature: Signature = NullSignature
     def subSignature: Signature = List()
 
@@ -523,7 +525,7 @@ object Types {
 
     lazy val infos = infosExpr(this)
 
-    def derivedRefinedType(parent1: Type, names1: List[Name], infos1: List[Type]): RefinedType =
+    def derivedRefinedType(parent1: Type, names1: List[Name], infos1: List[Type])(implicit ctx: Context): RefinedType =
       if ((parent1 eq parent) && (names1 eq names) && (infos1 eq infos)) this
       else
         RefinedType(parent1, names1) { rt =>