contexts.scala

来自「JAVA 语言的函数式编程扩展」· SCALA 代码 · 共 643 行 · 第 1/2 页

          enterElems(c.outer)
          enterLocalElems(c.scope.elems)
        }
      }
      enterElems(this)
      argContext
    }

    //todo: remove
    def makeConstructorSuffixContext = {
      val c = make(tree)
      c.inConstructorSuffix = true
      c
    }

    def error(pos: Position, err: Error) {
      val msg = err.getMessage()
      if (reportGeneralErrors)
        unit.error(pos, if (checking) "**** ERROR DURING INTERNAL CHECKING ****\n" + msg else msg)
      else
        throw err
    }

    def error(pos: Position, msg: String) {
      if (reportGeneralErrors)
        unit.error(pos, if (checking) "**** ERROR DURING INTERNAL CHECKING ****\n" + msg else msg)
      else
        throw new TypeError(pos, msg)
    }

    def warning(pos:  Position, msg: String) {
      if (reportGeneralErrors) unit.warning(pos, msg)
    }

    /**
     *  @param pos  ...
     *  @param pre  ...
     *  @param sym1 ...
     *  @param sym2 ...
     *  @param rest ...
     */
    def ambiguousError(pos: Position, pre: Type, sym1: Symbol,
                       sym2: Symbol, rest: String) {
      val msg =
        ("ambiguous reference to overloaded definition,\n" +
         "both " + sym1 + sym1.locationString + " of type " + pre.memberType(sym1) +
         "\nand  " + sym2 + sym2.locationString + " of type " + pre.memberType(sym2) +
         "\nmatch " + rest)
      if (reportAmbiguousErrors) {
        if (!pre.isErroneous && !sym1.isErroneous && !sym2.isErroneous)
          unit.error(pos, msg)
      } else throw new TypeError(pos, msg)
    }

    def outerContext(clazz: Symbol): Context = {
      var c = this
      while (c != NoContext && c.owner != clazz) c = c.outer.enclClass
      c
    }

    def isLocal(): Boolean = tree match {
      case Block(_,_) => true
      case PackageDef(_, _) => false
      case EmptyTree => false
      case _ => outer.isLocal()
    }

    def nextEnclosing(p: Context => Boolean): Context =
      if (this == NoContext || p(this)) this else outer.nextEnclosing(p)

    override def toString(): String = {
      if (this == NoContext) "NoContext"
      else owner.toString() + " @ " + tree.getClass() +
           " " + tree.toString() + ", scope = " + scope.hashCode() +
           " " + scope.toList + "\n:: " + outer.toString()
    }

    /** Return closest enclosing context that defines a superclass of `clazz', or a 
     *  companion module of a superclass of `clazz', or NoContext if none exists */
    def enclosingSuperClassContext(clazz: Symbol): Context = {
      var c = this.enclClass
      while (c != NoContext && 
             !clazz.isNonBottomSubClass(c.owner) &&
             !(c.owner.isModuleClass && clazz.isNonBottomSubClass(c.owner.linkedClassOfModule)))
        c = c.outer.enclClass
      c
    }

    /** Return closest enclosing context that defines a subclass of `clazz', or NoContext
     *  if none exists */
    def enclosingSubClassContext(clazz: Symbol): Context = {
      var c = this.enclClass
      while (c != NoContext && !c.owner.isNonBottomSubClass(clazz))
        c = c.outer.enclClass
      c
    }

    /** Is <code>sym</code> accessible as a member of tree `site' with type
     *  <code>pre</code> in current context?
     *
     *  @param sym         ...
     *  @param pre         ...
     *  @param superAccess ...
     *  @return            ...
     */
    def isAccessible(sym: Symbol, pre: Type, superAccess: Boolean): Boolean = {

      /** Are we inside definition of `owner'? */
      def accessWithin(owner: Symbol): Boolean = {
        var c = this
        while (c != NoContext && c.owner != owner) {
          if (false && inIDE) // XXX: we didn't get to update these syms.... 
            assert(c.owner.fullNameString != owner.fullNameString)
          if (c.outer eq null) assert(false, "accessWithin(" + owner + ") " + c);//debug
          if (c.outer.enclClass eq null) assert(false, "accessWithin(" + owner + ") " + c);//debug
          c = c.outer.enclClass
        }
        c != NoContext
      }

      /** Is `clazz' a subclass of an enclosing class? */
      def isSubClassOfEnclosing(clazz: Symbol): Boolean =
        enclosingSuperClassContext(clazz) != NoContext

      def isSubThisType(pre: Type, clazz: Symbol): Boolean = pre match {
        case ThisType(pclazz) => pclazz isNonBottomSubClass clazz
        case _ => false
      }

      (pre == NoPrefix) || {
        val ab = sym.accessBoundary(sym.owner)
        ((ab.isTerm || ab == definitions.RootClass)
         ||
         (accessWithin(ab) || accessWithin(ab.linkedClassOfClass)) &&
         (!sym.hasFlag(LOCAL) || 
          (sym hasFlag PROTECTED) && isSubThisType(pre, sym.owner) ||
          pre =:= sym.owner.thisType)
         ||
         (sym hasFlag PROTECTED) &&
         (superAccess ||
          (pre.widen.typeSymbol.isNonBottomSubClass(sym.owner) && 
           (isSubClassOfEnclosing(pre.widen.typeSymbol) || phase.erasedTypes))))
        // note: phase.erasedTypes disables last test, because fater addinterfaces
        // implementation classes are not in the superclass chain. If we enable the
        // test, bug780 fails.
      }
    }

    def pushTypeBounds(sym: Symbol) {
      savedTypeBounds = (sym, sym.info) :: savedTypeBounds
    }

    def restoreTypeBounds(tp: Type): Type = {
      var current = tp
      for ((sym, info) <- savedTypeBounds) {
        if (settings.debug.value) log("resetting " + sym + " to " + info);
        sym.info match {
          case TypeBounds(lo, hi) if (hi <:< lo && lo <:< hi) => 
            current = current.instantiateTypeParams(List(sym), List(lo))
//@M TODO: when higher-kinded types are inferred, probably need a case PolyType(_, TypeBounds(...)) if ... =>            
          case _ =>
        }
        sym.setInfo(info)
      }
      savedTypeBounds = List()
      current
    }

    private var implicitsCache: List[List[ImplicitInfo]] = null
    private var implicitsRunId = NoRunId
    
    def resetCache : Unit = {
      implicitsRunId = NoRunId
      implicitsCache = null
      if (outer != null && outer != this) outer.resetCache
    }
    private def collectImplicits(syms: List[Symbol], pre: Type): List[ImplicitInfo] =
      for (sym <- syms if sym.hasFlag(IMPLICIT) && isAccessible(sym, pre, false))
      yield new ImplicitInfo(sym.name, pre, sym)

    private def collectImplicitImports(imp: ImportInfo): List[ImplicitInfo] = {
      val pre = imp.qual.tpe
      def collect(sels: List[(Name, Name)]): List[ImplicitInfo] = sels match {
        case List() => List()
        case List((nme.WILDCARD, _)) => collectImplicits(pre.implicitMembers, pre)
        case (from, to) :: sels1 => 
          var impls = collect(sels1) filter (info => info.name != from)
          if (to != nme.WILDCARD) {
            val sym = imp.importedSymbol(to)
            if (sym.hasFlag(IMPLICIT)) impls = new ImplicitInfo(to, pre, sym) :: impls
          }
          impls
      }
      if (settings.debug.value)
        log("collect implicit imports " + imp + "=" + collect(imp.tree.selectors))//debug
      collect(imp.tree.selectors)
    }

    def implicitss: List[List[ImplicitInfo]] = {
      val nextOuter = 
        if (owner.isConstructor) {
          if (outer.tree.isInstanceOf[Template]) outer.outer.outer
          else outer.outer
        } else outer
        // can we can do something smarter to bring back the implicit cache?
      if (implicitsRunId != currentRunId) {
        implicitsRunId = currentRunId
        implicitsCache = List()
        val newImplicits: List[ImplicitInfo] =
          if (owner != nextOuter.owner && owner.isClass && !owner.isPackageClass) {
            if (!owner.isInitialized) return nextOuter.implicitss
            if (settings.debug.value)
              log("collect member implicits " + owner + ", implicit members = " +
                  owner.thisType.implicitMembers)//debug
            collectImplicits(owner.thisType.implicitMembers, owner.thisType)
          } else if (scope != nextOuter.scope && !owner.isPackageClass) {
            if (settings.debug.value)
              log("collect local implicits " + scope.toList)//debug
            collectImplicits(scope.toList, NoPrefix)
          } else if (imports != nextOuter.imports) {
            assert(imports.tail == nextOuter.imports)
            collectImplicitImports(imports.head)
          } else List()
        implicitsCache = if (newImplicits.isEmpty) nextOuter.implicitss
                         else newImplicits :: nextOuter.implicitss
      }
      implicitsCache
    }
    override def hashCode = {
      var hc = 0
      implicit def b2i(b : Boolean) = if (b) 1 else 0
      // assum enclClass/enclMethod/outer are all interned already.
      hc += tree.hashCodeStructure
      def f(txt : Context) = if (txt eq this) 0 else System.identityHashCode(txt)
      hc += f(enclClass)
      hc += f(enclMethod)
      hc += f(outer)
      hc += owner.hashCode
      hc += scope.hashCode
      hc += variance.hashCode
      hc += _undetparams.hashCode
      hc += depth
      hc += imports.hashCode
      hc += prefix.hashCode
      hc += inConstructorSuffix
      hc += checking
      hc += retyping
      hc += savedTypeBounds.hashCode
      hc += (if (unit eq null) 0 else unit.hashCode)
      hc
    }
    
  }
  class ImportInfo(val tree: Import, val depth: Int) {
    /** The prefix expression */
    def qual: Tree = tree.symbol.info match {
      case ImportType(expr) => expr
      case _ => throw new FatalError("symbol " + tree.symbol + " has bad type: " + tree.symbol.info);//debug
    }

    /** Is name imported explicitly, not via wildcard? */
    def isExplicitImport(name: Name): Boolean =
      tree.selectors exists (_._2 == name.toTermName)

    /** The symbol with name <code>name</code> imported from import clause
     *  <code>tree</code>.
     */
    def importedSymbol(name: Name): Symbol = {
      var result: Symbol = NoSymbol
      var renamed = false
      var selectors = tree.selectors
      while (selectors != Nil && result == NoSymbol) {
        if (selectors.head._1 != nme.WILDCARD)
          notifyImport(name, qual.tpe, selectors.head._1, selectors.head._2)

        if (selectors.head._2 == name.toTermName)
          result = qual.tpe.member(
            if (name.isTypeName) selectors.head._1.toTypeName else selectors.head._1)
        else if (selectors.head._1 == name.toTermName)
          renamed = true
        else if (selectors.head._1 == nme.WILDCARD && !renamed)
          result = qual.tpe.member(name)
        selectors = selectors.tail
      }
      result
    }

    override def toString() = tree.toString()
    
    override def hashCode = tree.hashCodeStructure + depth
    override def equals(that : Any) = that match {
      case that : ImportInfo =>
        depth == that.depth && (tree equalsStructure that.tree)
      case _ => false
    }
  }

  class ImplicitInfo(val name: Name, val pre: Type, val sym: Symbol) {
    private var tpeCache: Type = null
    def tpe: Type = {
      if (tpeCache eq null) tpeCache = pre.memberType(sym)
      tpeCache
    }
    override def toString = "ImplicitInfo(" + name + "," + pre + "," + sym + ")"
  }

  val NoImplicitInfo = new ImplicitInfo(null, null, null)

  case class ImportType(expr: Tree) extends Type {
    override def equals(that : Any) = that match {
    case ImportType(expr) =>
      if (inIDE) this.expr equalsStructure expr
      else this.expr == expr
    case _ => false
    }
    override def hashCode = if (inIDE) expr.hashCodeStructure else expr.hashCode
  }
  protected def intern(txt : Context) = txt
  
}