Scond step to typer reorg: Introduce TypeAssigners.

TypeAssigners assign a toplevel type to a node. They are mixed into Typer, and can be accessed from tpd using
ctx.typeAssigner.

Author: odersky

src/dotty/tools/dotc/ast/tpd.scala

@@ -11,6 +11,8 @@ import config.Printers._
 /** Some creators for typed trees */
 object tpd extends Trees.Instance[Type] with TypedTreeInfo {
 
+  private def ta(implicit ctx: Context) = ctx.typeAssigner
+
   def Modifiers(sym: Symbol)(implicit ctx: Context): Modifiers = Modifiers(
     sym.flags & ModifierFlags,
     if (sym.privateWithin.exists) sym.privateWithin.asType.name else tpnme.EMPTY,
@@ -68,27 +70,13 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   }
 
   def Literal(const: Constant)(implicit ctx: Context): Literal =
-    typedLiteral(untpd.Literal(const))
-
-  def typedLiteral(tree: untpd.Literal)(implicit ctx: Context) =
-    tree.withType {
-      tree.const.tag match {
-        case UnitTag => defn.UnitType
-        case NullTag => defn.NullType
-        case _ => ConstantType(tree.const)
-      }
-    }
+    ta.assignType(untpd.Literal(const))
 
   def unitLiteral(implicit ctx: Context): Literal =
     Literal(Constant(()))
 
   def New(tpt: Tree)(implicit ctx: Context): New =
-    untpd.New(tpt).withType(tpt.tpe).checked
-
-  def typedNew(tree: untpd.New)(implicit ctx: Context) = {
-    ctx.typer.checkClassTypeWithStablePrefix(tree.tpt.tpe, tree.tpt.pos, traitReq = false)
-    tree.withType(tree.tpt.tpe)
-  }
+    ta.assignType(untpd.New(tpt))
 
   def New(tp: Type)(implicit ctx: Context): New = New(TypeTree(tp))
 

src/dotty/tools/dotc/core/Contexts.scala

@@ -119,10 +119,11 @@ object Contexts {
     protected def scope_=(scope: Scope) = _scope = scope
     def scope: Scope = _scope
 
-    /** The current typer */
-    private[this] var _typer: Typer = _
-    protected def typer_=(typer: Typer) = _typer = typer
-    def typer: Typer = _typer
+    /** The current type assigner ot typer */
+    private[this] var _typeAssigner: TypeAssigner = _
+    protected def typeAssigner_=(typeAssigner: TypeAssigner) = _typeAssigner = typeAssigner
+    def typeAssigner: TypeAssigner = _typeAssigner
+    def typer: Typer = _typeAssigner.asInstanceOf[Typer]
 
     /** The currently active import info */
     private[this] var _importInfo: ImportInfo = _
@@ -312,7 +313,8 @@ object Contexts {
     def withTree(tree: Tree[_ >: Untyped]): this.type = { this.tree = tree; this }
     def withScope(scope: Scope): this.type = { this.scope = scope; this }
     def withNewScope: this.type = { this.scope = newScope; this }
-    def withTyper(typer: Typer): this.type = { this.typer = typer; this.scope = typer.scope; this }
+    def withTypeAssigner(typeAssigner: TypeAssigner): this.type = { this.typeAssigner = typeAssigner; this }
+    def withTyper(typer: Typer): this.type = { this.scope = typer.scope; withTypeAssigner(typer) }
     def withImportInfo(importInfo: ImportInfo): this.type = { this.importInfo = importInfo; this }
     def withRunInfo(runInfo: RunInfo): this.type = { this.runInfo = runInfo; this }
     def withDiagnostics(diagnostics: Option[StringBuilder]): this.type = { this.diagnostics = diagnostics; this }
@@ -342,6 +344,7 @@ object Contexts {
     owner = NoSymbol
     sstate = settings.defaultState
     tree = untpd.EmptyTree
+    typeAssigner = TypeAssigner
     runInfo = new RunInfo(this)
     diagnostics = None
     moreProperties = Map.empty

src/dotty/tools/dotc/typer/Checking.scala

@@ -18,12 +18,23 @@ import ErrorReporting.{errorType, InfoString}
 import config.Printers._
 import collection.mutable
 
-trait Checking {
+trait NoChecking {
+  import tpd._
+  def checkBounds(args: List[tpd.Tree], poly: PolyType, pos: Position)(implicit ctx: Context): Unit = ()
+  def checkStable(tp: Type, pos: Position)(implicit ctx: Context): Unit = ()
+  def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean)(implicit ctx: Context): Type = tp
+  def checkImplicitTptNonEmpty(defTree: untpd.ValOrDefDef)(implicit ctx: Context): Unit = ()
+  def checkImplicitParamsNotSingletons(vparamss: List[List[ValDef]])(implicit ctx: Context): Unit = ()
+  def checkFeasible(tp: Type, pos: Position, where: => String = "")(implicit ctx: Context): Type = tp
+  def checkNoDoubleDefs(cls: Symbol)(implicit ctx: Context): Unit = ()
+}
+
+trait Checking extends NoChecking {
 
   import tpd._
 
   /** Check that type arguments `args` conform to corresponding bounds in `poly` */
-  def checkBounds(args: List[tpd.Tree], poly: PolyType, pos: Position)(implicit ctx: Context): Unit =
+  override def checkBounds(args: List[tpd.Tree], poly: PolyType, pos: Position)(implicit ctx: Context): Unit =
     for ((arg, bounds) <- args zip poly.paramBounds) {
       def notConforms(which: String, bound: Type) =
         ctx.error(i"Type argument ${arg.tpe} does not conform to $which bound $bound", arg.pos)
@@ -34,14 +45,14 @@ trait Checking {
   /** Check that type `tp` is stable.
    *  @return The type itself
    */
-  def checkStable(tp: Type, pos: Position)(implicit ctx: Context): Unit =
+  override def checkStable(tp: Type, pos: Position)(implicit ctx: Context): Unit =
     if (!tp.isStable) ctx.error(i"Prefix of type ${tp.widenIfUnstable} is not stable", pos)
 
   /** Check that `tp` is a class type with a stable prefix. Also, if `isFirst` is
    *  false check that `tp` is a trait.
    *  @return  `tp` itself if it is a class or trait ref, ObjectClass.typeRef if not.
    */
-  def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean)(implicit ctx: Context): Type =
+  override def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean)(implicit ctx: Context): Type =
     tp.underlyingClassRef match {
       case tref: TypeRef =>
         checkStable(tref.prefix, pos)
@@ -53,7 +64,7 @@ trait Checking {
   }
 
   /** Check that (return) type of implicit definition is not empty */
-  def checkImplicitTptNonEmpty(defTree: untpd.ValOrDefDef)(implicit ctx: Context): Unit = defTree.tpt match {
+  override def checkImplicitTptNonEmpty(defTree: untpd.ValOrDefDef)(implicit ctx: Context): Unit = defTree.tpt match {
     case TypeTree(original) if original.isEmpty =>
       val resStr = if (defTree.isInstanceOf[untpd.DefDef]) "result " else ""
       ctx.error(i"${resStr}type of implicit definition needs to be given explicitly", defTree.pos)
@@ -63,7 +74,7 @@ trait Checking {
   /** Check that a non-implicit parameter making up the first parameter section of an
    *  implicit conversion is not a singleton type.
    */
-  def checkImplicitParamsNotSingletons(vparamss: List[List[ValDef]])(implicit ctx: Context): Unit = vparamss match {
+  override def checkImplicitParamsNotSingletons(vparamss: List[List[ValDef]])(implicit ctx: Context): Unit = vparamss match {
     case (vparam :: Nil) :: _ if !(vparam.symbol is Implicit) =>
       if (vparam.tpt.tpe.isInstanceOf[SingletonType])
         ctx.error(s"implicit conversion may not have a parameter of singleton type", vparam.tpt.pos)
@@ -74,7 +85,7 @@ trait Checking {
    *  their lower bound conforms to their upper cound. If a type argument is
    *  infeasible, issue and error and continue with upper bound.
    */
-  def checkFeasible(tp: Type, pos: Position, where: => String = "")(implicit ctx: Context): Type = tp match {
+  override def checkFeasible(tp: Type, pos: Position, where: => String = "")(implicit ctx: Context): Type = tp match {
     case tp: RefinedType =>
       tp.derivedRefinedType(tp.parent, tp.refinedName, checkFeasible(tp.refinedInfo, pos, where))
     case tp @ TypeBounds(lo, hi) if !(lo <:< hi) =>
@@ -85,7 +96,7 @@ trait Checking {
   }
 
   /** Check that class does not define */
-  def checkNoDoubleDefs(cls: Symbol)(implicit ctx: Context): Unit = {
+  override def checkNoDoubleDefs(cls: Symbol)(implicit ctx: Context): Unit = {
     val seen = new mutable.HashMap[Name, List[Symbol]] {
       override def default(key: Name) = Nil
     }

src/dotty/tools/dotc/typer/Namer.scala

@@ -58,14 +58,16 @@ trait NamerContextOps { this: Context =>
   /** The symbol (stored in some typer's symTree) of an enclosing context definition */
   def symOfContextTree(tree: untpd.Tree) = {
     def go(ctx: Context): Symbol = {
-      val typer = ctx.typer
-      if (typer == null) NoSymbol
-      else tree.getAttachment(typer.SymOfTree) match {
-        case Some(sym) => sym
-        case None =>
-          var cx = ctx.outer
-          while (cx.typer eq typer) cx = cx.outer
-          go(cx)
+      ctx.typeAssigner match {
+        case typer: Typer =>
+          tree.getAttachment(typer.SymOfTree) match {
+            case Some(sym) => sym
+            case None =>
+              var cx = ctx.outer
+              while (cx.typeAssigner eq typer) cx = cx.outer
+              go(cx)
+          }
+        case _ => NoSymbol
       }
     }
     go(this)

src/dotty/tools/dotc/typer/ProtoTypes.scala

@@ -103,7 +103,7 @@ object ProtoTypes {
     def map(tm: TypeMap)(implicit ctx: Context) = derivedSelectionProto(name, tm(memberProto), compat)
     def fold[T](x: T, ta: TypeAccumulator[T])(implicit ctx: Context) = ta(x, memberProto)
 
-    override def computeHash = addDelta(doHash(name, memberProto), if (compat == NoViewsAllowed) 1 else 0)
+    override def computeHash = addDelta(doHash(name, memberProto), if (compat eq NoViewsAllowed) 1 else 0)
   }
 
   class CachedSelectionProto(name: Name, memberProto: Type, compat: Compatibility) extends SelectionProto(name, memberProto, compat)

src/dotty/tools/dotc/typer/TypeAssigner.scala

@@ -0,0 +1,27 @@
+package dotty.tools
+package dotc
+package typer
+
+import core._
+import ast._
+import Scopes._, Contexts._, Constants._, Types._, Symbols._
+
+trait TypeAssigner extends NoChecking {
+
+  def assignType(tree: untpd.New)(implicit ctx: Context) = {
+    checkClassTypeWithStablePrefix(tree.tpt.tpe, tree.tpt.pos, traitReq = false)
+    tree.withType(tree.tpt.tpe)
+  }
+
+  def assignType(tree: untpd.Literal)(implicit ctx: Context) =
+    tree.withType {
+      tree.const.tag match {
+        case UnitTag => defn.UnitType
+        case NullTag => defn.NullType
+        case _ => ConstantType(tree.const)
+      }
+    }
+}
+
+object TypeAssigner extends TypeAssigner
+

src/dotty/tools/dotc/typer/Typer.scala

@@ -48,7 +48,7 @@ object Typer {
   }
 }
 
-class Typer extends Namer with Applications with Implicits with Inferencing with Checking {
+class Typer extends Namer with TypeAssigner with Applications with Implicits with Inferencing with Checking {
 
   import Typer._
   import tpd.{cpy => _, _}
@@ -413,7 +413,7 @@ class Typer extends Namer with Applications with Implicits with Inferencing with
   }
 
   def typedLiteral(tree: untpd.Literal)(implicit ctx: Context) = track("typedLiteral") {
-    tpd.typedLiteral(tree)
+    assignType(tree)
   }
 
   def typedNew(tree: untpd.New, pt: Type)(implicit ctx: Context) = track("typedNew") {
@@ -425,7 +425,7 @@ class Typer extends Namer with Applications with Implicits with Inferencing with
         typed(cpy.Block(tree, clsDef :: Nil, New(Ident(x), Nil)), pt)
       case _ =>
 	      val tpt1 = typedType(tree.tpt)
-        tpd.typedNew(cpy.New(tree, tpt1))
+        assignType(cpy.New(tree, tpt1))
         // todo in a later phase: checkInstantiatable(cls, tpt1.pos)
     }
   }