Defined root context with imports

… and cleaned up and simplified other context-reated features.

9 files changed, 42 insertions, 37 deletions

diff --git a/src/dotty/tools/dotc/CompilationUnit.scala b/src/dotty/tools/dotc/CompilationUnit.scala
index 0c662116e..791e8899d 100644
--- a/src/dotty/tools/dotc/CompilationUnit.scala
+++ b/src/dotty/tools/dotc/CompilationUnit.scala
@@ -12,4 +12,6 @@ class CompilationUnit(val source: SourceFile) {
 
   var tpdTree: tpd.Tree = tpd.EmptyTree
 
+  def isJava = source.file.name.endsWith(".java")
+
 }
\ No newline at end of file
diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index 6f5e162ee..d285fef5a 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -5,20 +5,28 @@ import core._
 import Contexts._
 import Periods._
 import Symbols._
-import typer.{FrontEnd, Typer}
+import typer.{FrontEnd, Typer, Mode, ImportInfo}
 import reporting.ConsoleReporter
 
 class Compiler {
 
   def phases = List(new FrontEnd)
 
+  def rootImports(implicit ctx: Context) =
+    defn.JavaLangPackageVal :: defn.ScalaPackageVal :: defn.PredefModule :: Nil
+
   def rootContext(implicit ctx: Context): Context = {
     ctx.usePhases(phases)
-    ctx.fresh
+    val start = ctx.fresh
       .withPeriod(Period(ctx.runId + 1, FirstPhaseId))
+      .withRunInfo(new RunInfo)
       .withOwner(defn.RootClass)
       .withTyper(new Typer)
+      .withMode(Mode.None)
       .withTyperState(new MutableTyperState(ctx.typerState, new ConsoleReporter()(ctx)))
+    def addImport(ctx: Context, sym: Symbol) =
+      ctx.fresh.withImportInfo(ImportInfo.rootImport(sym)(ctx))
+    (start /: rootImports)(addImport)
   }
 
   def newRun(implicit ctx: Context): Run =
diff --git a/src/dotty/tools/dotc/ast/Trees.scala b/src/dotty/tools/dotc/ast/Trees.scala
index 9eeb28da4..8157c287d 100644
--- a/src/dotty/tools/dotc/ast/Trees.scala
+++ b/src/dotty/tools/dotc/ast/Trees.scala
@@ -805,12 +805,6 @@ object Trees {
       traverser.traverse(tree)
     }
 
-    // ----- Position handling -----------------------------------------
-
-    protected implicit def pos(implicit ctx: Context): Position = ctx.position
-
-    def defPos(sym: Symbol)(implicit ctx: Context) = ctx.position union sym.coord.toPosition
-
     // ----- Helper classes for copying, transforming, accumulating -----------------
 
     val cpy: TreeCopier
diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index 6c2670d5d..ed86849b9 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/src/dotty/tools/dotc/core/Contexts.scala
@@ -88,20 +88,10 @@ object Contexts {
     protected def typerState_=(typerState: TyperState) = _typerState = typerState
     def typerState: TyperState = _typerState
 
-    /** The current position */
-    private[this] var _position: Position = _
-    protected def position_=(position: Position) = _position = position
-    def position: Position = _position
-
     /** The current plain printer */
-    private[this] var _plainPrinter: Context => Printer = _
-    protected def plainPrinter_=(plainPrinter: Context => Printer) = _plainPrinter = plainPrinter
-    def plainPrinter: Context => Printer = _plainPrinter
-
-    /** The current refined printer */
-    private[this] var _refinedPrinter: Context => Printer = _
-    protected def refinedPrinter_=(refinedPrinter: Context => Printer) = _refinedPrinter = refinedPrinter
-    def refinedPrinter: Context => Printer = _refinedPrinter
+    private[this] var _printerFn: Context => Printer = _
+    protected def printerFn_=(printerFn: Context => Printer) = _printerFn = printerFn
+    def printerFn: Context => Printer = _printerFn
 
     /** The current owner symbol */
     private[this] var _owner: Symbol = _
@@ -162,7 +152,7 @@ object Contexts {
       _typeComparer
     }
 
-    /** The new implicit references that are introduces by this scope */
+    /** The new implicit references that are introduced by this scope */
     private var implicitsCache: ContextualImplicits = null
     def implicits: ContextualImplicits = {
       if (implicitsCache == null )
@@ -255,8 +245,7 @@ object Contexts {
           .withMode(mode)
           // typerState and its constraint is not preserved in condensed
           // reporter is always ThrowingReporter
-          .withPlainPrinter(plainPrinter)
-          .withRefinedPrinter(refinedPrinter)
+          .withPrinterFn(printerFn)
           .withOwner(owner)
           .withSettings(sstate)
           // tree is not preserved in condensed
@@ -301,9 +290,7 @@ object Contexts {
     override def withMode(mode: Mode): this.type = { this.mode = mode; this }
     def withTyperState(typerState: TyperState): this.type = { this.typerState = typerState; this }
     def withNewTyperState: this.type = withTyperState(typerState.fresh)
-    def withPosition(position: Position): this.type = { this.position = position; this }
-    def withPlainPrinter(printer: Context => Printer): this.type = { this.plainPrinter = printer; this }
-    def withRefinedPrinter(printer: Context => Printer): this.type = { this.refinedPrinter = printer; this }
+    def withPrinterFn(printer: Context => Printer): this.type = { this.printerFn = printer; this }
     def withOwner(owner: Symbol): this.type = { this.owner = owner; this }
     def withSettings(sstate: SettingsState): this.type = { this.sstate = sstate; this }
     def withCompilationUnit(compilationUnit: CompilationUnit): this.type = { this.compilationUnit = compilationUnit; this }
@@ -334,9 +321,7 @@ object Contexts {
     period = InitialPeriod
     mode = Mode.None
     typerState = new TyperState(new ConsoleReporter()(this))
-    position = NoPosition
-    plainPrinter = new PlainPrinter(_)
-    refinedPrinter = new RefinedPrinter(_)
+    printerFn = new RefinedPrinter(_)
     owner = NoSymbol
     sstate = settings.defaultState
     tree = untpd.EmptyTree
diff --git a/src/dotty/tools/dotc/printing/PlainPrinter.scala b/src/dotty/tools/dotc/printing/PlainPrinter.scala
index ee3526d1b..fe67f5b89 100644
--- a/src/dotty/tools/dotc/printing/PlainPrinter.scala
+++ b/src/dotty/tools/dotc/printing/PlainPrinter.scala
@@ -354,5 +354,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
         tree.fallbackToText(this)
     }
   }.close // todo: override in refined printer
+
+  def plain = this
 }
 
diff --git a/src/dotty/tools/dotc/printing/Printer.scala b/src/dotty/tools/dotc/printing/Printer.scala
index 6944c4ae2..af87302e4 100644
--- a/src/dotty/tools/dotc/printing/Printer.scala
+++ b/src/dotty/tools/dotc/printing/Printer.scala
@@ -87,5 +87,8 @@ abstract class Printer {
 
   /** Textual representation of tree */
   def toText[T >: Untyped](tree: Tree[T]): Text
+
+  /** A plain printer without any embellishments */
+  def plain: Printer
 }
 
diff --git a/src/dotty/tools/dotc/printing/Printers.scala b/src/dotty/tools/dotc/printing/Printers.scala
index ba1cf83bb..7107ccb78 100644
--- a/src/dotty/tools/dotc/printing/Printers.scala
+++ b/src/dotty/tools/dotc/printing/Printers.scala
@@ -5,11 +5,10 @@ import core.Contexts.Context
 
 trait Printers { this: Context =>
 
-  /** A creation method for printers, depending on debug option */
-  def printerFn = if (this.debug) plainPrinter else refinedPrinter
-
-  /** A function creatung a printer */
-  def printer = printerFn(this)
-
+  /** A function creating a printer */
+  def printer = {
+    val pr = printerFn(this)
+    if (this.debug) pr.plain else pr
+  }
 }
 
diff --git a/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index 87441f7b7..fe6711e7f 100644
--- a/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -394,4 +394,6 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
   }
 
   override def toText(denot: Denotation): Text = toText(denot.symbol)
+
+  override def plain = new PlainPrinter(_ctx)
 }
diff --git a/src/dotty/tools/dotc/typer/ImportInfo.scala b/src/dotty/tools/dotc/typer/ImportInfo.scala
index 50455e97f..1b8cd115d 100644
--- a/src/dotty/tools/dotc/typer/ImportInfo.scala
+++ b/src/dotty/tools/dotc/typer/ImportInfo.scala
@@ -2,12 +2,22 @@ package dotty.tools
 package dotc
 package typer
 
-import ast.untpd
+import ast.{tpd, untpd}
 import ast.Trees._
 import core._
 import util.SimpleMap
 import Symbols._, Names._, Denotations._, Types._, Contexts._, StdNames._, Flags._
 
+object ImportInfo {
+  /** The import info for a root import from given symbol `sym` */
+  def rootImport(sym: Symbol)(implicit ctx: Context) = {
+    val expr = tpd.Ident(sym.symTermRef)
+    val selectors = untpd.Ident(nme.WILDCARD) :: Nil
+    val imp = tpd.Import(expr, selectors)
+    new ImportInfo(imp.symbol, selectors, rootImport = true)
+  }
+}
+
 /** Info relating to an import clause
  *  @param   sym        The import symbol defined by the clause
  *  @param   selectors  The selector clauses