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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package transform
/** A sample transform.
*/
abstract class SampleTransform extends Transform {
// inherits abstract value `global` and class `Phase` from Transform
import global._ // the global environment
import typer.typed // method to type trees
/** the following two members override abstract members in Transform */
val phaseName: String = "sample-phase"
protected def newTransformer(unit: CompilationUnit): Transformer =
new SampleTransformer(unit)
class SampleTransformer(unit: CompilationUnit) extends Transformer {
override def transform(tree: Tree): Tree = {
val tree1 = super.transform(tree); // transformers always maintain `currentOwner`.
tree1 match {
case Block(List(), expr) => // a simple optimization
expr
case Block(defs, sup @ Super(qual, mix)) => // A hypothetical transformation, which replaces
// {super} by {super.sample}
treeCopy.Block( // `copy` is the usual lazy tree copier
tree1, defs,
typed( // `typed` assigns types to its tree argument
atPos(tree1.pos)( // `atPos` fills in position of its tree argument
Select( // The `Select` factory method is defined in class `Trees`
sup,
currentOwner.newValue( // creates a new term symbol owned by `currentOwner`
newTermName("sample"), // The standard term name creator
tree1.pos)))))
case _ =>
tree1
}
}
}
}
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