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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author
*/
package scala.tools.nsc
package transform
/**
* An InfoTransform contains a compiler phase that transforms trees and symbol infos -- making sure they stay consistent.
* The symbol info is transformed assuming it is consistent right before this phase.
* The info transformation is triggered by Symbol::rawInfo, which caches the results in the symbol's type history.
* This way sym.info (during an enteringPhase(p)) can look up what the symbol's info should look like at the beginning of phase p.
* (If the transformed info had not been stored yet, rawInfo will compute the info by composing the info-transformers
* of the most recent phase before p, up to the transformer of the phase right before p.)
*
* Concretely, enteringPhase(p) { sym.info } yields the info *before* phase p has transformed it. Imagine you're a phase and it all makes sense.
*/
trait InfoTransform extends Transform {
import global.{Symbol, Type, InfoTransformer, infoTransformers}
def transformInfo(sym: Symbol, tpe: Type): Type
override def newPhase(prev: scala.tools.nsc.Phase): StdPhase =
new Phase(prev)
protected def changesBaseClasses = true
protected def keepsTypeParams = true
class Phase(prev: scala.tools.nsc.Phase) extends super.Phase(prev) {
override val keepsTypeParams = InfoTransform.this.keepsTypeParams
if (infoTransformers.nextFrom(id).pid != id) {
// this phase is not yet in the infoTransformers
val infoTransformer = new InfoTransformer {
val pid = id
val changesBaseClasses = InfoTransform.this.changesBaseClasses
def transform(sym: Symbol, tpe: Type): Type = transformInfo(sym, tpe)
}
infoTransformers insert infoTransformer
}
}
}
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