Scala example source code file (Positions.scala)

This example Scala source code file (Positions.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

compiler, defaultposassigner, emptytree, global, noposition, nsc, posassigner, position, positioned, positions, tree, validatingposassigner

The Positions.scala Scala example source code

package scala.tools.nsc
package ast

trait Positions extends scala.reflect.internal.Positions {
  self: Global =>

  class ValidatingPosAssigner extends PosAssigner {
    var pos: Position = _
    override def traverse(t: Tree) {
      if (t eq EmptyTree) ()
      else if (t.pos == NoPosition) super.traverse(t setPos pos)
      else if (globalPhase.id <= currentRun.picklerPhase.id) {
        // When we prune due to encountering a position, traverse the
        // pruned children so we can warn about those lacking positions.
        t.children foreach { c =>
          if (!c.canHaveAttrs) ()
          else if (c.pos == NoPosition) {
            reporter.warning(t.pos, " Positioned tree has unpositioned child in phase " + globalPhase)
            inform("parent: " + treeSymStatus(t))
            inform(" child: " + treeSymStatus(c) + "\n")
          }
        }
      }
    }
  }

  override protected[this] lazy val posAssigner: PosAssigner =
    if (settings.Yrangepos && settings.debug || settings.Yposdebug) new ValidatingPosAssigner
    else new DefaultPosAssigner
}