Allow rewritings under constructs that could not be rewritten

Author: odersky

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -581,11 +581,6 @@ object Parsers {
      */
     var possibleColonOffset: Int = -1
 
-    /** A list of pending patches, to be issued if we can rewrite all enclosing braces to
-     *  indentation regions.
-     */
-    var pendingPatches: List[() => Unit] = Nil
-
     def testChar(idx: Int, p: Char => Boolean): Boolean = {
       val txt = source.content
       idx < txt.length && p(txt(idx))
@@ -607,10 +602,7 @@ object Parsers {
     /** Parse indentation region `body` and rewrite it to be in braces instead */
     def indentedToBraces[T](body: => T): T = {
       val enclRegion = in.currentRegion.enclosing
-      def indentWidth = enclRegion match {
-        case Indented(w, _, _, _) => w
-        case _ => IndentWidth.Zero
-      }
+      def indentWidth = enclRegion.indentWidth
       val followsColon = testChar(in.lastOffset - 1, ':')
       val startOpening =
         if (followsColon)
@@ -706,7 +698,6 @@ object Parsers {
       val colonRequired = possibleColonOffset == in.lastOffset
       val (startOpening, endOpening) = startingElimRegion(colonRequired)
       val isOutermost = in.currentRegion.isOutermost
-      val savedPending = pendingPatches
       def allBraces(r: Region): Boolean = r match {
         case r: InBraces => allBraces(r.enclosing)
         case _ => r.isOutermost
@@ -728,17 +719,9 @@ object Parsers {
           else if (testChar(startOpening - 1, Chars.isOperatorPart(_))) " :"
           else ":"
         val (startClosing, endClosing) = closingElimRegion()
-        val applyPatch = () => {
-          patch(source, Span(startOpening, endOpening), openingPatchStr)
-          patch(source, Span(startClosing, endClosing), "")
-        }
-        pendingPatches = applyPatch :: pendingPatches
-        if (isOutermost) {
-          pendingPatches.reverse.foreach(_())
-          pendingPatches = Nil
-        }
+        patch(source, Span(startOpening, endOpening), openingPatchStr)
+        patch(source, Span(startClosing, endClosing), "")
       }
-      else pendingPatches = savedPending // can't rewrite, cancel all nested patches.
       t
     }
 
@@ -1175,7 +1158,7 @@ object Parsers {
     }
 
     def indentRegion[T](tag: EndMarkerTag)(op: => T): T = {
-      val iw = in.currentIndentWidth
+      val iw = in.currentRegion.indentWidth
       val t = op
       in.consumeEndMarker(tag, iw)
       t
@@ -3370,9 +3353,8 @@ object Parsers {
         case _ => false
       }
 
-      def givenArgs(t: Tree): Tree = {
+      def givenArgs(t: Tree): Tree =
         if (in.token == GIVEN) givenArgs(applyGiven(t, prefixExpr)) else t
-      }
 
       if (in.token == LPAREN)
         inParens {

compiler/src/dotty/tools/dotc/parsing/Scanners.scala

@@ -307,11 +307,6 @@ object Scanners {
      */
     var currentRegion: Region = Outermost
 
-    def currentIndentWidth: IndentWidth = currentRegion match {
-      case r: Indented => r.width
-      case _ => IndentWidth.Zero
-    }
-
     /** The end marker that was skipped last */
     val endMarkers = new mutable.ListBuffer[EndMarker]
 
@@ -416,7 +411,7 @@ object Scanners {
      *  value at the end of the endMarkers queue.
      */
     private def handleEndMarkers(width: IndentWidth): Unit = {
-      if (next.token == IDENTIFIER && next.name == nme.end && width == currentIndentWidth) {
+      if (next.token == IDENTIFIER && next.name == nme.end && width == currentRegion.indentWidth) {
         val lookahead = lookaheadScanner
         lookahead.nextToken() // skip the `end`
 
@@ -589,15 +584,14 @@ object Scanners {
         insert(if (pastBlankLine) NEWLINES else NEWLINE, lineOffset)
       else if (indentIsSignificant) {
         if (nextWidth < lastWidth
-            || nextWidth == lastWidth && (indentPrefix == MATCH || indentPrefix == CATCH) && token != CASE) {
+            || nextWidth == lastWidth && (indentPrefix == MATCH || indentPrefix == CATCH) && token != CASE)
           currentRegion match {
             case r: Indented if !r.isOutermost && !isLeadingInfixOperator() =>
               currentRegion = r.enclosing
               insert(OUTDENT, offset)
               handleEndMarkers(nextWidth)
             case _ =>
           }
-        }
         else if (lastWidth < nextWidth ||
                  lastWidth == nextWidth && (lastToken == MATCH || lastToken == CATCH) && token == CASE) {
           if (canStartIndentTokens.contains(lastToken)) {
@@ -1369,16 +1363,21 @@ object Scanners {
     def outer: Region | Null
     def isOutermost = outer == null
     def enclosing: Region = outer.asInstanceOf[Region]
+    def indentWidth = IndentWidth.Zero
   }
-  case class InParens(prefix: Token, outer: Region) extends Region
-  case class InBraces(var width: IndentWidth | Null, outer: Region) extends Region
   case class InString(multiLine: Boolean, outer: Region) extends Region
+  case class InParens(prefix: Token, outer: Region) extends Region
+  case class InBraces(var width: IndentWidth | Null, outer: Region) extends Region {
+    override def indentWidth = width
+  }
 
   /** A class describing an indentation region.
    *  @param width   The principal indendation width
    *  @param others  Other indendation widths > width of lines in the same region
    */
-  case class Indented(width: IndentWidth, others: Set[IndentWidth], prefix: Token, outer: Region | Null) extends Region
+  case class Indented(width: IndentWidth, others: Set[IndentWidth], prefix: Token, outer: Region | Null) extends Region {
+    override def indentWidth = width
+  }
 
   val Outermost = Indented(IndentWidth.Zero, Set(), EMPTY, null)