path: root/src/dotty/tools/dotc/ast/TypedTrees.scala

package dotty.tools
package dotc
package ast

import core._
import util.Positions._, Types._, Contexts._, Constants._, Names._, Flags._
import SymDenotations._, Symbols._, StdNames._, Annotations._, Trees._
import CheckTrees._

object TypedTrees {

  object tpd extends Trees.Instance[Type] {

    def Modifiers(sym: Symbol)(implicit ctx: Context): Modifiers = Trees.Modifiers[Type](
      sym.flags & ModifierFlags,
      if (sym.privateWithin.exists) sym.privateWithin.asType.name else tpnme.EMPTY,
      sym.annotations map (_.tree))

    def Ident(tp: NamedType)(implicit ctx: Context): Ident =
      Trees.Ident(tp.name).withType(tp).checked

    def Select(pre: Tree, tp: NamedType)(implicit ctx: Context): Select =
      Trees.Select(pre, tp.name).withType(tp).checked

    def This(cls: ClassSymbol)(implicit ctx: Context): This =
      Trees.This(cls.name).withType(cls.thisType).checked

    def Super(qual: Tree, mix: TypeName)(implicit ctx: Context): Super = {
      val owntype =
        if (mix.isEmpty) ctx.glb(qual.tpe.parents)
        else {
          val mixParents = qual.tpe.parents filter (_.name == mix)
          check(mixParents.length == 1)
          mixParents.head
        }
      Trees.Super(qual, mix).withType(SuperType(qual.tpe, owntype)).checked
    }

    def Apply(fn: Tree, args: List[Tree])(implicit ctx: Context): Apply = {
      val owntype = fn.tpe.widen match {
        case fntpe @ MethodType(pnames, ptypes) =>
          check(sameLength(ptypes, args), s"${fn.show}: ${fntpe.show} to ${args.map(_.show).mkString(", ")}")
          fntpe.instantiate(args map (_.tpe))
        case _ =>
          check(false)
          ErrorType
      }
      Trees.Apply(fn, args).withType(owntype).checked
    }

    def TypeApply(fn: Tree, args: List[Tree])(implicit ctx: Context): TypeApply = {
      val owntype = fn.tpe.widen match {
        case fntpe @ PolyType(pnames) =>
          check(sameLength(pnames, args))
          fntpe.instantiate(args map (_.tpe))
        case _ =>
          check(false)
          ErrorType
      }
      Trees.TypeApply(fn, args).withType(owntype).checked
    }

    def Literal(const: Constant)(implicit ctx: Context): Literal =
      Trees.Literal(const).withType(const.tpe).checked

    def New(tp: Type)(implicit ctx: Context): New =
      Trees.New(TypeTree(tp)).withType(tp).checked

    def Pair(left: Tree, right: Tree)(implicit ctx: Context): Pair =
      Trees.Pair(left, right).withType(defn.PairType.appliedTo(left.tpe, right.tpe)).checked

    def Typed(expr: Tree, tpt: Tree)(implicit ctx: Context): Typed =
      Trees.Typed(expr, tpt).withType(tpt.tpe).checked

    def NamedArg(name: TermName, arg: Tree)(implicit ctx: Context) =
      Trees.NamedArg(name, arg).withType(arg.tpe).checked

    def Assign(lhs: Tree, rhs: Tree)(implicit ctx: Context): Assign =
      Trees.Assign(lhs, rhs).withType(defn.UnitType).checked

    def Block(stats: List[Tree], expr: Tree)(implicit ctx: Context): Block = {
      lazy val locals = localSyms(stats).toSet
      val blk = Trees.Block(stats, expr)
      def widen(tp: Type): Type = tp match {
        case tp: TermRef if locals contains tp.symbol =>
          widen(tp.info)
        case _ => tp
      }
      blk.withType(widen(expr.tpe))
    }

    def If(cond: Tree, thenp: Tree, elsep: Tree)(implicit ctx: Context): If =
      Trees.If(cond, thenp, elsep).withType(thenp.tpe | elsep.tpe).checked

    def Match(selector: Tree, cases: List[CaseDef])(implicit ctx: Context): Match =
      Trees.Match(selector, cases).withType(ctx.lub(cases map (_.body.tpe))).checked

    def CaseDef(pat: Tree, guard: Tree, body: Tree)(implicit ctx: Context): CaseDef =
      Trees.CaseDef(pat, guard, body).withType(body.tpe).checked

    def Return(expr: Tree, from: Ident)(implicit ctx: Context): Return =
      Trees.Return(expr, from).withType(defn.NothingType).checked

    def Try(block: Tree, handler: Tree, finalizer: Tree)(implicit ctx: Context): Try =
      Trees.Try(block, handler, finalizer).withType(block.tpe | handler.tpe).checked

    def Throw(expr: Tree)(implicit ctx: Context): Throw =
      Trees.Throw(expr).withType(defn.NothingType).checked

    def SeqLiteral(elemtpt: Tree, elems: List[Tree])(implicit ctx: Context): SeqLiteral =
      Trees.SeqLiteral(elemtpt, elems).withType(defn.RepeatedParamType.appliedTo(elemtpt.tpe)).checked

    def SeqLiteral(elems: List[Tree])(implicit ctx: Context): SeqLiteral =
      SeqLiteral(TypeTree(ctx.lub(elems map (_.tpe))), elems)

    def TypeTree(tp: Type, original: Tree = EmptyTree)(implicit ctx: Context): TypeTree =
      Trees.TypeTree(original).withType(tp).checked

    def SingletonTypeTree(ref: Tree)(implicit ctx: Context): SingletonTypeTree =
      Trees.SingletonTypeTree(ref).withType(ref.tpe).checked

    def SelectFromTypeTree(qualifier: Tree, tp: NamedType)(implicit ctx: Context): SelectFromTypeTree =
      Trees.SelectFromTypeTree(qualifier, tp.name).withType(tp).checked

    def AndTypeTree(left: Tree, right: Tree)(implicit ctx: Context): AndTypeTree =
      Trees.AndTypeTree(left, right).withType(left.tpe & right.tpe).checked

    def OrTypeTree(left: Tree, right: Tree)(implicit ctx: Context): OrTypeTree =
      Trees.OrTypeTree(left, right).withType(left.tpe | right.tpe).checked

    def RefinedTypeTree(tpt: Tree, refinements: List[DefTree])(implicit ctx: Context): RefinedTypeTree = {
      def refineType(tp: Type, refinement: Symbol): Type =
        RefinedType(tp, refinement.name, refinement.info)
      Trees.RefinedTypeTree(tpt, refinements)
        .withType((tpt.tpe /: (refinements map (_.symbol)))(refineType)).checked
    }

    def refineType(tp: Type, refinement: Symbol)(implicit ctx: Context): Type =
      RefinedType(tp, refinement.name, refinement.info)

    def AppliedTypeTree(tpt: Tree, args: List[Tree])(implicit ctx: Context): AppliedTypeTree =
      Trees.AppliedTypeTree(tpt, args).withType(tpt.tpe.appliedTo(args map (_.tpe))).checked

    def TypeBoundsTree(lo: Tree, hi: Tree)(implicit ctx: Context): TypeBoundsTree =
      Trees.TypeBoundsTree(lo, hi).withType(TypeBounds(lo.tpe, hi.tpe)).checked

    def Bind(sym: TermSymbol, body: Tree)(implicit ctx: Context): Bind =
      Trees.Bind(sym.name, body).withType(refType(sym)).checked

    def Alternative(trees: List[Tree])(implicit ctx: Context): Alternative =
      Trees.Alternative(trees).withType(ctx.lub(trees map (_.tpe))).checked

    def UnApply(fun: Tree, args: List[Tree])(implicit ctx: Context): UnApply = {
      val owntype = fun.tpe.widen match {
        case MethodType(_, paramType :: Nil) => paramType
        case _ => check(false); ErrorType
      }
      Trees.UnApply(fun, args).withType(owntype).checked
    }

    def ValDef(sym: TermSymbol, rhs: Tree = EmptyTree)(implicit ctx: Context): ValDef =
      Trees.ValDef(Modifiers(sym), sym.name, TypeTree(sym.info), rhs).withType(refType(sym)).checked

    def DefDef(sym: TermSymbol, rhs: Tree = EmptyTree)(implicit ctx: Context): DefDef = {

      val (tparams, mtp) = sym.info match {
        case tp: PolyType =>
          val tparams = ctx.newTypeParams(sym, tp.paramNames, EmptyFlags, tp.instantiateBounds)
          (tparams, tp.instantiate(tparams map (_.typeConstructor)))
        case tp => (Nil, tp)
      }

      def valueParamss(tp: Type): (List[List[TermSymbol]], Type) = tp match {
        case tp @ MethodType(paramNames, paramTypes) =>
          def valueParam(name: TermName, info: Type): TermSymbol =
            ctx.newSymbol(sym, name, TermParam, info)
          val params = (paramNames, paramTypes).zipped.map(valueParam)
          val (paramss, rtp) = valueParamss(tp.instantiate(params map (_.typeConstructor)))
          (params :: paramss, rtp)
        case tp => (Nil, tp)
      }
      val (vparamss, rtp) = valueParamss(mtp)

      Trees.DefDef(
        Modifiers(sym), sym.name, tparams map TypeDef,
        vparamss map (_ map (ValDef(_))), TypeTree(rtp), rhs)
          .withType(refType(sym)).checked
    }

    def TypeDef(sym: TypeSymbol)(implicit ctx: Context): TypeDef =
      Trees.TypeDef(Modifiers(sym), sym.name, Nil, TypeTree(sym.info)) // !!! fill in typeParams
        .withType(refType(sym)).checked

    def ClassDef(cls: ClassSymbol, typeParams: List[TypeSymbol], constr: DefDef, body: List[Tree])(implicit ctx: Context): ClassDef = {
      val parents = cls.info.parents map (TypeTree(_))
      val selfType =
        if (cls.classInfo.optSelfType.exists) ValDef(ctx.newSelfSym(cls))
        else EmptyValDef
      def isOwnTypeParamAccessor(stat: Tree) =
        (stat.symbol is TypeParam) && stat.symbol.owner == cls
      val (tparamAccessors, rest) = body partition isOwnTypeParamAccessor
      val tparams =
        (typeParams map TypeDef) ++
          (tparamAccessors collect {
            case td: TypeDef if !(typeParams contains td.symbol) => td
          })
      val findLocalDummy = new FindLocalDummyAccumulator(cls)
      val localDummy = ((NoSymbol: Symbol) /: body)(findLocalDummy)
        .orElse(ctx.newLocalDummy(cls))
      val impl = Trees.Template(constr, parents, selfType, rest)
        .withType(refType(localDummy)).checked
      Trees.ClassDef(Modifiers(cls), cls.name, tparams, impl)
        .withType(refType(cls)).checked
    }

    def Import(expr: Tree, selectors: List[Trees.UntypedTree])(implicit ctx: Context): Import =
      Trees.Import(expr, selectors).withType(refType(ctx.newImportSymbol(SharedTree(expr)))).checked

    def PackageDef(pid: RefTree, stats: List[Tree])(implicit ctx: Context): PackageDef =
      Trees.PackageDef(pid, stats).withType(refType(pid.symbol)).checked

    def Annotated(annot: Tree, arg: Tree)(implicit ctx: Context): Annotated =
      Trees.Annotated(annot, arg).withType(AnnotatedType(Annotation(annot), arg.tpe)).checked

    val EmptyTree: Tree = Trees.EmptyTree[Type]

    val EmptyValDef: ValDef = Trees.EmptyValDef[Type]

    def SharedTree(tree: Tree): SharedTree =
      Trees.SharedTree(tree).withType(tree.tpe)

    def refType(sym: Symbol)(implicit ctx: Context): NamedType = NamedType.withSym(sym.owner.thisType, sym)

    // ------ Creating typed equivalents of trees that exist only in untyped form -------

    /** A tree representing the same reference as the given type */
    def ref(tp: NamedType)(implicit ctx: Context): NameTree =
      if (tp.symbol.isStatic) Ident(tp)
      else tp.prefix match {
        case pre: TermRef => Select(ref(pre), tp)
        case pre => SelectFromTypeTree(TypeTree(pre), tp)
      }  // no checks necessary

    def ref(sym: Symbol)(implicit ctx: Context): tpd.NameTree =
      ref(NamedType(sym.owner.thisType, sym.name).withDenot(sym))

    /** new C(args) */
    def New(tp: Type, args: List[Tree])(implicit ctx: Context): Apply =
      Apply(
        Select(
          New(tp),
          TermRef.withSym(tp.normalizedPrefix, tp.typeSymbol.primaryConstructor.asTerm)),
        args)

    /** An object def
     *
     *     object obs extends parents { decls }
     *
     *  gets expanded to
     *
     *     <module> lazy val obj = {
     *       class obj$ extends parents { this: obj.type => decls }
     *       new obj$
     *     }
     *
     *  What's interesting here is that the block is well typed
     *  (because class obj$ is hoistable), but the type of the `obj` val is
     *  not expressible. What needs to happen in general when
     *  inferring the type of a val from its RHS, is: if the type contains
     *  a class that has the val itself as owner, then that class
     *  is remapped to have the val's owner as owner. Remapping could be
     *  done by cloning the class with the new owner and substituting
     *  everywhere in the tree. We know that remapping is safe
     *  because the only way a local class can appear in the RHS of a val is
     *  by being hoisted outside of a block, and the necessary checks are
     *  done at this point already.
     *
     *  On the other hand, for method result type inference, if the type of
     *  the RHS of a method contains a class owned by the method, this would be
     *  an error.
     */
    def ModuleDef(sym: TermSymbol, body: List[Tree])(implicit ctx: Context): tpd.TempTrees = {
      val modcls = sym.moduleClass.asClass
      val constr = DefDef(modcls.primaryConstructor.asTerm, EmptyTree)
      val clsdef = ClassDef(modcls, Nil, constr, body)
      val valdef = ValDef(sym, New(modcls.typeConstructor))
      TempTrees(valdef :: clsdef :: Nil)
    }

    /** A function def
     *
     *    vparams => expr
     *
     *  gets expanded to
     *
     *    { def $anonfun(vparams) = expr; $anonfun: pt }
     *
     *  where pt is the target type of the expression (FunctionN) unless
     *  otherwise specified.
     */
    def Function(meth: TermSymbol, body: Tree, target: Type = NoType)(implicit ctx: Context): Block = {
      val funtpe =
        if (target.exists) target
        else meth.info match {
          case mt @ MethodType(_, formals) =>
            assert(!mt.isDependent)
            defn.FunctionType(formals, mt.resultType)
        }
      Block(
        DefDef(meth, body) :: Nil,
        Typed(Ident(TermRef.withSym(NoPrefix, meth)), TypeTree(funtpe)))
    }

    private class FindLocalDummyAccumulator(cls: ClassSymbol)(implicit ctx: Context) extends TreeAccumulator[Symbol] {
      def apply(sym: Symbol, tree: Tree) =
        if (sym.exists) sym
        else if (tree.isDef) {
          val owner = tree.symbol.owner
          if (owner.isLocalDummy && owner.owner == cls) owner
          else if (owner == cls) foldOver(sym, tree)
          else sym
        } else foldOver(sym, tree)
    }
  }

  implicit class TreeOps[ThisTree <: tpd.Tree](val tree: ThisTree) extends AnyVal {

    def isValue(implicit ctx: Context): Boolean =
      tree.isTerm && tree.tpe.widen.isValueType

    def isValueOrPattern(implicit ctx: Context) =
      tree.isValue || tree.isPattern

    def isValueType: Boolean =
      tree.isType && tree.tpe.isValueType

    def isInstantiation: Boolean = tree match {
      case Apply(Select(New(_), nme.CONSTRUCTOR), _) => true
      case _ => false
    }

    def checked(implicit ctx: Context): ThisTree = {
      if (ctx.settings.YcheckTypedTrees.value) checkType(tree)
      tree
    }

    def shallowFold[T](z: T)(op: (T, tpd.Tree) => T) =
      new ShallowFolder(op).apply(z, tree)

    def deepFold[T](z: T)(op: (T, tpd.Tree) => T) =
      new DeepFolder(op).apply(z, tree)

    def subst(from: List[Symbol], to: List[Symbol])(implicit ctx: Context): ThisTree =
      new TreeMapper(typeMap = new ctx.SubstSymMap(from, to)).apply(tree)

    def changeOwner(from: Symbol, to: Symbol)(implicit ctx: Context): ThisTree =
      new TreeMapper(ownerMap = (sym => if (sym == from) to else sym)).apply(tree)
  }

  class TreeMapper(val typeMap: TypeMap = IdentityTypeMap, val ownerMap: Symbol => Symbol = identity)(implicit ctx: Context) extends TreeTransformer[Type] {
    override def transform(tree: tpd.Tree): tpd.Tree = {
      val tree1 =
        if (tree.isEmpty) tree
        else tree.withType(typeMap(tree.tpe))
      val tree2 = tree1 match {
        case bind: tpd.Bind =>
          val sym = bind.symbol
          val newOwner = ownerMap(sym.owner)
          val newInfo = typeMap(sym.info)
          if ((newOwner ne sym.owner) || (newInfo ne sym.info))
            bind.withType(tpd.refType(sym.copy(owner = newOwner, info = newInfo)))
          else
            tree1
        case _ =>
          tree1
      }
      super.transform(tree2)
    }
    override def transform(trees: List[tpd.Tree]) = {
      val locals = localSyms(trees)
      val mapped = ctx.mapSymbols(locals, typeMap, ownerMap)
      if (locals eq mapped) super.transform(trees)
      else withSubstitution(locals, mapped).transform(trees)
     }

    def apply[ThisTree <: tpd.Tree](tree: ThisTree): ThisTree = transform(tree).asInstanceOf[ThisTree]

    def apply(annot: Annotation): Annotation = {
      val tree1 = apply(annot.tree)
      if (tree1 eq annot.tree) annot else ConcreteAnnotation(tree1)
    }

    /** The current tree map composed with a substitution [from -> to] */
    def withSubstitution(from: List[Symbol], to: List[Symbol]) =
      new TreeMapper(
        typeMap andThen ((tp: Type) => tp.substSym(from, to)),
        ownerMap andThen (from zip to).toMap)
  }

  // ensure that constructors are fully applied?
  // ensure that normal methods are fully applied?

  def localSyms(stats: List[tpd.Tree])(implicit ctx: Context): List[Symbol] =
    for (stat <- stats if (stat.isDef)) yield stat.symbol
}