Modifications in prepation of parsing.

1 files changed, 12 insertions, 2 deletions

diff --git a/src/dotty/tools/dotc/util/Positions.scala b/src/dotty/tools/dotc/util/Positions.scala
index 2ab6c1920..056af00d1 100644
--- a/src/dotty/tools/dotc/util/Positions.scala
+++ b/src/dotty/tools/dotc/util/Positions.scala
@@ -11,12 +11,12 @@ package util
 object Positions {
 
   private val StartEndBits = 26
-  private val StartEndMask = (1 << StartEndBits) - 1
+  private val StartEndMask: Long = (1L << StartEndBits) - 1
   private val PointOffsetLimit = 1L << (64 - StartEndBits * 2)
 
   class Position(val coords: Long) extends AnyVal {
-    def point: Int = start + (coords >>> (StartEndBits * 2)).toInt
     def start: Int = (coords & StartEndMask).toInt
+    def point: Int = start + (coords >>> (StartEndBits * 2)).toInt
     def end: Int = ((coords >>> StartEndBits) & StartEndMask).toInt
 
     /** The union of two positions. Tries to keep the point offset of
@@ -59,6 +59,16 @@ object Positions {
 
   val NoPosition = new Position(-1L)
 
+  case class PositionPrefix(val coords: Long) extends AnyVal {
+    def start: Int = (coords & StartEndMask).toInt
+    def point: Int = start + (coords >>> StartEndBits).toInt
+    def toPosition(end: Int) = Position(start, end, point - start max 0)
+  }
+
+  def PositionPrefix(start: Int, pointOffset: Int = 0): PositionPrefix =
+    new PositionPrefix(
+      (start & StartEndMask).toLong | pointOffset.toLong << StartEndBits)
+
   case class SourcePosition(source: SourceFile, pos: Position) {
     def point: Int = pos.point
     def start: Int = pos.start