Scala example source code file (TypingTransformers.scala)

This example Scala source code file (TypingTransformers.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

a, compilationunit, compiler, emptytree, global, nsc, packagedef, symbol, template, tree, typingtransformer, typingtransformers

The TypingTransformers.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author Martin Odersky
 */

package scala.tools.nsc
package transform

/** A base class for transforms.
 *  A transform contains a compiler phase which applies a tree transformer.
 */
trait TypingTransformers {

  val global: Global
  import global._

  abstract class TypingTransformer(unit: CompilationUnit) extends Transformer {
    var localTyper: analyzer.Typer =
      if (phase.erasedTypes)
        erasure.newTyper(erasure.rootContext(unit, EmptyTree, erasedTypes = true)).asInstanceOf[analyzer.Typer]
      else
        analyzer.newTyper(analyzer.rootContext(unit, EmptyTree, true))
    protected var curTree: Tree = _

    override final def atOwner[A](owner: Symbol)(trans: => A): A = atOwner(curTree, owner)(trans)

    def atOwner[A](tree: Tree, owner: Symbol)(trans: => A): A = {
      val savedLocalTyper = localTyper
      localTyper = localTyper.atOwner(tree, if (owner.isModule) owner.moduleClass else owner)
      val result = super.atOwner(owner)(trans)
      localTyper = savedLocalTyper
      result
    }

    override def transform(tree: Tree): Tree = {
      curTree = tree
      tree match {
        case Template(_, _, _) =>
          // enter template into context chain
          atOwner(currentOwner) { super.transform(tree) }
        case PackageDef(_, _) =>
          atOwner(tree.symbol) { super.transform(tree) }
        case _ =>
          super.transform(tree)
      }
    }
  }
}