Merge pull request #28 from scala/topic/cleanups

Collection of clean-ups

Author: phaller

src/main/scala/scala/async/internal/AnfTransform.scala

@@ -127,12 +127,12 @@ private[async] trait AnfTransform {
     private object trace {
       private var indent = -1
 
-      def indentString = "  " * indent
+      private def indentString = "  " * indent
 
       def apply[T](args: Any)(t: => T): T = {
         def prefix = mode.toString.toLowerCase
         indent += 1
-        def oneLine(s: Any) = s.toString.replaceAll( """\n""", "\\\\n").take(127)
+        def oneLine(s: Any) = s.toString.replaceAll("""\n""", "\\\\n").take(127)
         try {
           AsyncUtils.trace(s"${indentString}$prefix(${oneLine(args)})")
           val result = t
@@ -173,7 +173,7 @@ private[async] trait AnfTransform {
             stats :+ treeCopy.Typed(tree, expr1, tpt)
 
           case treeInfo.Applied(fun, targs, argss) if argss.nonEmpty =>
-            // we an assume that no await call appears in a by-name argument position,
+            // we can assume that no await call appears in a by-name argument position,
             // this has already been checked.
             val funStats :+ simpleFun = linearize.transformToList(fun)
             val (argStatss, argExprss): (List[List[List[Tree]]], List[List[Tree]]) =
@@ -221,14 +221,7 @@ private[async] trait AnfTransform {
             val condStats :+ condExpr = linearize.transformToList(cond)
             val thenBlock = linearize.transformToBlock(thenp)
             val elseBlock = linearize.transformToBlock(elsep)
-            // Typechecking with `condExpr` as the condition fails if the condition
-            // contains an await. `ifTree.setType(tree.tpe)` also fails; it seems
-            // we rely on this call to `typeCheck` descending into the branches.
-            // But, we can get away with typechecking a throwaway `If` tree with the
-            // original scrutinee and the new branches, and setting that type on
-            // the real `If` tree.
-            val iff = treeCopy.If(tree, condExpr, thenBlock, elseBlock)
-            condStats :+ iff
+            condStats :+ treeCopy.If(tree, condExpr, thenBlock, elseBlock)
 
           case Match(scrut, cases) =>
             val scrutStats :+ scrutExpr = linearize.transformToList(scrut)
@@ -248,9 +241,7 @@ private[async] trait AnfTransform {
                 val newBlock = treeCopy.Block(b, valDefs ++ stats1, expr1)
                 treeCopy.CaseDef(tree, pat, guard, newBlock)
             }
-            // Refer to comments the translation of `If` above.
-            val typedMatch = treeCopy.Match(tree, scrutExpr, caseDefs)
-            scrutStats :+ typedMatch
+            scrutStats :+ treeCopy.Match(tree, scrutExpr, caseDefs)
 
           case LabelDef(name, params, rhs) =>
             List(LabelDef(name, params, Block(linearize.transformToList(rhs), Literal(Constant(())))).setSymbol(tree.symbol))

src/main/scala/scala/async/internal/AsyncBase.scala

@@ -52,6 +52,7 @@ abstract class AsyncBase {
       execContext.tree.asInstanceOf[asyncMacro.global.Tree],
       fallbackEnabled)(implicitly[c.WeakTypeTag[T]].asInstanceOf[asyncMacro.global.WeakTypeTag[T]]).asInstanceOf[Tree]
 
+    // Mark range positions for synthetic code as transparent to allow some wiggle room for overlapping ranges
     for (t <- code)
       t.pos = t.pos.makeTransparent
 

src/main/scala/scala/async/internal/AsyncMacro.scala

@@ -6,7 +6,7 @@ import scala.tools.nsc.transform.TypingTransformers
 object AsyncMacro {
   def apply(c: reflect.macros.Context, futureSystem0: FutureSystem): AsyncMacro = {
     import language.reflectiveCalls
-    val powerContext = c.asInstanceOf[c.type {val universe: Global; val callsiteTyper: universe.analyzer.Typer}]
+    val powerContext = c.asInstanceOf[c.type { val universe: Global; val callsiteTyper: universe.analyzer.Typer }]
     new AsyncMacro {
       val global: powerContext.universe.type = powerContext.universe
       val callSiteTyper: global.analyzer.Typer = powerContext.callsiteTyper
@@ -26,7 +26,7 @@ private[async] trait AsyncMacro
   val callSiteTyper: global.analyzer.Typer
   val macroApplication: global.Tree
 
-  def macroPos = macroApplication.pos.makeTransparent
+  lazy val macroPos = macroApplication.pos.makeTransparent
   def atMacroPos(t: global.Tree) = global.atPos(macroPos)(t)
 
 }

src/main/scala/scala/async/internal/ExprBuilder.scala

@@ -9,7 +9,6 @@ import collection.mutable
 import language.existentials
 import scala.reflect.api.Universe
 import scala.reflect.api
-import scala.Some
 
 trait ExprBuilder {
   builder: AsyncMacro =>
@@ -290,7 +289,8 @@ trait ExprBuilder {
   case class SymLookup(stateMachineClass: Symbol, applyTrParam: Symbol) {
     def stateMachineMember(name: TermName): Symbol =
       stateMachineClass.info.member(name)
-    def memberRef(name: TermName) = gen.mkAttributedRef(stateMachineMember(name))
+    def memberRef(name: TermName): Tree =
+      gen.mkAttributedRef(stateMachineMember(name))
   }
 
   def buildAsyncBlock(block: Block, symLookup: SymLookup): AsyncBlock = {
@@ -324,17 +324,17 @@ trait ExprBuilder {
 
       /**
        * def resume(): Unit = {
-       * try {
-       * state match {
-       * case 0 => {
-       * f11 = exprReturningFuture
-       * f11.onComplete(onCompleteHandler)(context)
-       * }
-       * ...
-       * }
-       * } catch {
-       * case NonFatal(t) => result.failure(t)
-       * }
+       *   try {
+       *     state match {
+       *       case 0 => {
+       *         f11 = exprReturningFuture
+       *         f11.onComplete(onCompleteHandler)(context)
+       *       }
+       *       ...
+       *     }
+       *   } catch {
+       *     case NonFatal(t) => result.failure(t)
+       *   }
        * }
        */
       def resumeFunTree[T]: DefDef =
@@ -352,16 +352,17 @@ trait ExprBuilder {
                 }), literalUnit))), EmptyTree))
 
       /**
-       * // assumes tr: Try[Any] is in scope.
-       * //
+       * assumes tr: Try[Any] is in scope.
+       *
        * state match {
-       * case 0 => {
-       * x11 = tr.get.asInstanceOf[Double];
-       * state = 1;
-       * resume()
+       *   case 0 =>
+       *     x11 = tr.get.asInstanceOf[Double]
+       *     state = 1
+       *     resume()
        * }
        */
-      def onCompleteHandler[T: WeakTypeTag]: Tree = Match(symLookup.memberRef(name.state), initStates.flatMap(_.mkOnCompleteHandler[T]).toList)
+      def onCompleteHandler[T: WeakTypeTag]: Tree =
+        Match(symLookup.memberRef(name.state), initStates.flatMap(_.mkOnCompleteHandler[T]).toList)
     }
   }
 

src/main/scala/scala/async/internal/FutureSystem.scala

@@ -4,8 +4,6 @@
 package scala.async.internal
 
 import scala.language.higherKinds
-
-import scala.reflect.macros.Context
 import scala.reflect.internal.SymbolTable
 
 /**
@@ -54,7 +52,7 @@ trait FutureSystem {
     def spawn(tree: Tree, execContext: Tree): Tree =
       future(Expr[Unit](tree))(Expr[ExecContext](execContext)).tree
 
-    // TODO Why is this needed?
+    // This is only needed in `AsyncBaseWithCPSFallback` and should be removed once CPS fall-back support is dropped.
     def castTo[A: WeakTypeTag](future: Expr[Fut[Any]]): Expr[Fut[A]]
   }
 

src/test/scala/scala/async/TreeInterrogation.scala

@@ -72,7 +72,6 @@ object TreeInterrogation extends App {
     import scala.async.Async._
     val tree = tb.parse(
       """ import _root_.scala.async.internal.AsyncId.{async, await}
-        | import reflect.runtime.universe._
         | async {
         |   implicit def view(a: Int): String = ""
         |   await(0).length