/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package typechecker
import scala.tools.nsc.symtab.Flags
import scala.collection.mutable
/** Duplicate trees and re-type check them, taking care to replace
* and create fresh symbols for new local definitions.
*
* @author Iulian Dragos
* @version 1.0
*/
abstract class Duplicators extends Analyzer {
import global._
import definitions._
/** Retype the given tree in the given context. Use this method when retyping
* a method in a different class. The typer will replace references to the this of
* the old class with the new class, and map symbols through the given 'env'. The
* environment is a map from type skolems to concrete types (see SpecializedTypes).
*/
def retyped(context: Context, tree: Tree, oldThis: Symbol, newThis: Symbol, env: scala.collection.Map[Symbol, Type]): Tree = {
if (oldThis ne newThis) {
oldClassOwner = oldThis
newClassOwner = newThis
} else resetClassOwners()
envSubstitution = new SubstSkolemsTypeMap(env.keysIterator.toList, env.valuesIterator.toList)
debuglog("retyped with env: " + env)
newBodyDuplicator(context).typed(tree)
}
protected def newBodyDuplicator(context: Context) = new BodyDuplicator(context)
/** Return the special typer for duplicate method bodies. */
override def newTyper(context: Context): Typer =
newBodyDuplicator(context)
private def resetClassOwners() {
oldClassOwner = null
newClassOwner = null
}
private var oldClassOwner: Symbol = _
private var newClassOwner: Symbol = _
private var envSubstitution: SubstTypeMap = _
private class SubstSkolemsTypeMap(from: List[Symbol], to: List[Type]) extends SubstTypeMap(from, to) {
protected override def matches(sym1: Symbol, sym2: Symbol) =
if (sym2.isTypeSkolem) sym2.deSkolemize eq sym1
else sym1 eq sym2
}
private val invalidSyms: mutable.Map[Symbol, Tree] = perRunCaches.newMap[Symbol, Tree]()
/** A typer that creates new symbols for all definitions in the given tree
* and updates references to them while re-typechecking. All types in the
* tree, except for TypeTrees, are erased prior to type checking. TypeTrees
* are fixed by substituting invalid symbols for the new ones.
*/
class BodyDuplicator(_context: Context) extends Typer(_context) {
class FixInvalidSyms extends TypeMap {
def apply(tpe: Type): Type = {
mapOver(tpe)
}
override def mapOver(tpe: Type): Type = tpe match {
case TypeRef(NoPrefix, sym, args) if sym.isTypeParameterOrSkolem =>
val sym1 = (
context.scope lookup sym.name orElse {
// try harder (look in outer scopes)
// with virtpatmat, this can happen when the sym is referenced in the scope of a LabelDef but
// is defined in the scope of an outer DefDef (e.g., in AbstractPartialFunction's andThen)
BodyDuplicator.super.silent(_ typedType Ident(sym.name)).fold(NoSymbol: Symbol)(_.symbol)
} filter (_ ne sym)
)
if (sym1.exists) {
debuglog(s"fixing $sym -> $sym1")
typeRef(NoPrefix, sym1, mapOverArgs(args, sym1.typeParams))
}
else super.mapOver(tpe)
case TypeRef(pre, sym, args) =>
val newsym = updateSym(sym)
if (newsym ne sym) {
debuglog("fixing " + sym + " -> " + newsym)
typeRef(mapOver(pre), newsym, mapOverArgs(args, newsym.typeParams))
} else
super.mapOver(tpe)
case SingleType(pre, sym) =>
val sym1 = updateSym(sym)
if (sym1 ne sym) {
debuglog("fixing " + sym + " -> " + sym1)
singleType(mapOver(pre), sym1)
} else
super.mapOver(tpe)
case ThisType(sym) =>
val sym1 = updateSym(sym)
if (sym1 ne sym) {
debuglog("fixing " + sym + " -> " + sym1)
ThisType(sym1)
} else
super.mapOver(tpe)
case _ =>
super.mapOver(tpe)
}
}
/** Fix the given type by replacing invalid symbols with the new ones. */
def fixType(tpe: Type): Type = {
val tpe1 = envSubstitution(tpe)
val tpe2: Type = (new FixInvalidSyms)(tpe1)
val tpe3 = if (newClassOwner ne null) {
tpe2.asSeenFrom(newClassOwner.thisType, oldClassOwner)
} else tpe2
tpe3
}
/** Return the new symbol corresponding to `sym`. */
private def updateSym(sym: Symbol): Symbol =
if (invalidSyms.isDefinedAt(sym))
invalidSyms(sym).symbol
else
sym
private def invalidate(tree: Tree, owner: Symbol = NoSymbol) {
debuglog(s"attempting to invalidate symbol = ${tree.symbol}")
if ((tree.isDef || tree.isInstanceOf[Function]) && tree.symbol != NoSymbol) {
debuglog("invalid " + tree.symbol)
invalidSyms(tree.symbol) = tree
tree match {
case ldef @ LabelDef(name, params, rhs) =>
debuglog("LabelDef " + name + " sym.info: " + ldef.symbol.info)
invalidSyms(ldef.symbol) = ldef
// breakIf(true, this, ldef, context)
val newsym = ldef.symbol.cloneSymbol(context.owner)
newsym.setInfo(fixType(ldef.symbol.info))
ldef.symbol = newsym
debuglog("newsym: " + newsym + " info: " + newsym.info)
// don't retypecheck val members or local lazy vals -- you'll end up with duplicate symbols because
// entering a valdef results in synthesizing getters etc
// TODO: why retype check any valdefs?? I checked and the rhs is specialized just fine this way
// (and there are no args/type params/... to warrant full type checking?)
case vdef @ ValDef(mods, name, _, rhs) if mods.hasFlag(Flags.LAZY) || owner.isClass =>
debuglog(s"ValDef $name in $owner sym.info: ${vdef.symbol.info}")
invalidSyms(vdef.symbol) = vdef
val newowner = owner orElse context.owner
val newsym = vdef.symbol.cloneSymbol(newowner)
newsym.setInfo(fixType(vdef.symbol.info))
vdef.symbol = newsym
debuglog("newsym: " + newsym + " info: " + newsym.info + ", owner: " + newsym.owner + ", " + newsym.owner.isClass)
if (newsym.owner.isClass) newsym.owner.info.decls enter newsym
case DefDef(_, name, tparams, vparamss, _, rhs) =>
// invalidate parameters
invalidateAll(tparams ::: vparamss.flatten)
tree.symbol = NoSymbol
case Function(vparams, _) =>
// invalidate parameters
invalidateAll(vparams)
tree.symbol = NoSymbol
case _ =>
tree.symbol = NoSymbol
}
}
}
private def invalidateAll(stats: List[Tree], owner: Symbol = NoSymbol) {
stats.foreach(invalidate(_, owner))
}
/** Optionally cast this tree into some other type, if required.
* Unless overridden, just returns the tree.
*/
def castType(tree: Tree, pt: Type): Tree = tree
/** Special typer method for re-type checking trees. It expects a typed tree.
* Returns a typed tree that has fresh symbols for all definitions in the original tree.
*
* Each definition tree is visited and its symbol added to the invalidSyms map (except LabelDefs),
* then cleared (forcing the namer to create fresh symbols).
* All invalid symbols found in trees are cleared (except for LabelDefs), forcing the
* typechecker to look for fresh ones in the context.
*
* Type trees are typed by substituting old symbols for new ones (@see fixType).
*
* LabelDefs are not typable from trees alone, unless they have the type ()Unit. Therefore,
* their symbols are recreated ad-hoc and their types are fixed inline, instead of letting the
* namer/typer handle them, or Idents that refer to them.
*/
override def typed(tree: Tree, mode: Mode, pt: Type): Tree = {
debuglog("typing " + tree + ": " + tree.tpe + ", " + tree.getClass)
val origtreesym = tree.symbol
if (tree.hasSymbolField && tree.symbol != NoSymbol
&& !tree.symbol.isLabel // labels cannot be retyped by the type checker as LabelDef has no ValDef/return type trees
&& invalidSyms.isDefinedAt(tree.symbol)) {
debuglog("removed symbol " + tree.symbol)
tree.symbol = NoSymbol
}
tree match {
case ttree @ TypeTree() =>
// log("fixing tpe: " + tree.tpe + " with sym: " + tree.tpe.typeSymbol)
ttree modifyType fixType
case Block(stats, res) =>
debuglog("invalidating block")
invalidateAll(stats)
invalidate(res)
super.typed(tree.clearType(), mode, pt)
case ClassDef(_, _, _, tmpl @ Template(parents, _, stats)) =>
// log("invalidating classdef " + tree)
tmpl.symbol = tree.symbol.newLocalDummy(tree.pos)
invalidateAll(stats, tree.symbol)
super.typed(tree.clearType(), mode, pt)
case ddef @ DefDef(_, _, _, _, tpt, rhs) =>
ddef.tpt modifyType fixType
val result = super.typed(ddef.clearType(), mode, pt)
// TODO this is a hack, we really need a cleaner way to transport symbol attachments to duplicated methods
// bodies in specialized subclasses.
if (ddef.hasAttachment[DelambdafyTarget.type])
result.symbol.updateAttachment(DelambdafyTarget)
result
case vdef @ ValDef(mods, name, tpt, rhs) =>
// log("vdef fixing tpe: " + tree.tpe + " with sym: " + tree.tpe.typeSymbol + " and " + invalidSyms)
//if (mods.hasFlag(Flags.LAZY)) vdef.symbol.resetFlag(Flags.MUTABLE) // Martin to Iulian: lazy vars can now appear because they are no longer boxed; Please check that deleting this statement is OK.
vdef.tpt modifyType fixType
super.typed(vdef.clearType(), mode, pt)
case ldef @ LabelDef(name, params, rhs) =>
// log("label def: " + ldef)
// in case the rhs contains any definitions -- TODO: is this necessary?
invalidate(rhs)
ldef.clearType()
// is this LabelDef generated by tailcalls?
val isTailLabel = (ldef.params.length >= 1) && (ldef.params.head.name == nme.THIS)
// the typer does not create the symbols for a LabelDef's params, so unless they were created before we need
// to do it manually here -- but for the tailcalls-generated labels, ValDefs are created before the LabelDef,
// so we just need to change the tree to point to the updated symbols
def newParam(p: Tree): Ident =
if (isTailLabel)
Ident(updateSym(p.symbol))
else {
val newsym = p.symbol.cloneSymbol //(context.owner) // TODO owner?
Ident(newsym.setInfo(fixType(p.symbol.info)))
}
val params1 = params map newParam
val rhs1 = (new TreeSubstituter(params map (_.symbol), params1) transform rhs) // TODO: duplicate?
super.typed(treeCopy.LabelDef(tree, name, params1, rhs1.clearType()), mode, pt)
case Bind(name, _) =>
// log("bind: " + tree)
invalidate(tree)
super.typed(tree.clearType(), mode, pt)
case Ident(_) if tree.symbol.isLabel =>
debuglog("Ident to labeldef " + tree + " switched to ")
tree.symbol = updateSym(tree.symbol)
super.typed(tree.clearType(), mode, pt)
case Ident(_) if (origtreesym ne null) && origtreesym.isLazy =>
debuglog("Ident to a lazy val " + tree + ", " + tree.symbol + " updated to " + origtreesym)
tree.symbol = updateSym(origtreesym)
super.typed(tree.clearType(), mode, pt)
case Select(th @ This(_), sel) if (oldClassOwner ne null) && (th.symbol == oldClassOwner) =>
// We use the symbol name instead of the tree name because the symbol
// may have been name mangled, rendering the tree name obsolete.
// ...but you can't just do a Select on a name because if the symbol is
// overloaded, you will crash in the backend.
val memberByName = newClassOwner.thisType.member(tree.symbol.name)
def nameSelection = Select(This(newClassOwner), tree.symbol.name)
val newTree = (
if (memberByName.isOverloaded) {
// Find the types of the overload alternatives as seen in the new class,
// and filter the list down to those which match the old type (after
// fixing the old type so it is seen as if from the new class.)
val typeInNewClass = fixType(oldClassOwner.info memberType tree.symbol)
val alts = memberByName.alternatives
val memberTypes = alts map (newClassOwner.info memberType _)
val memberString = memberByName.defString
alts zip memberTypes filter (_._2 =:= typeInNewClass) match {
case ((alt, tpe)) :: Nil =>
log(s"Arrested overloaded type in Duplicators, narrowing to ${alt.defStringSeenAs(tpe)}\n Overload was: $memberString")
Select(This(newClassOwner), alt)
case xs =>
alts filter (alt => (alt.paramss corresponds tree.symbol.paramss)(_.size == _.size)) match {
case alt :: Nil =>
log(s"Resorted to parameter list arity to disambiguate to $alt\n Overload was: $memberString")
Select(This(newClassOwner), alt)
case _ =>
log(s"Could not disambiguate $memberTypes. Attempting name-based selection, but we may crash later.")
nameSelection
}
}
}
else nameSelection
)
super.typed(atPos(tree.pos)(newTree), mode, pt)
case This(_) if (oldClassOwner ne null) && (tree.symbol == oldClassOwner) =>
// val tree1 = Typed(This(newClassOwner), TypeTree(fixType(tree.tpe.widen)))
// log("selection on this: " + tree)
val tree1 = This(newClassOwner)
// log("tree1: " + tree1)
debuglog("mapped " + tree + " to " + tree1)
super.typedPos(tree.pos, mode, pt)(tree1)
case This(_) =>
debuglog("selection on this, plain: " + tree)
tree.symbol = updateSym(tree.symbol)
val ntree = castType(tree, pt)
val tree1 = super.typed(ntree, mode, pt)
// log("plain this typed to: " + tree1)
tree1
/* no longer needed, because Super now contains a This(...)
case Super(qual, mix) if (oldClassOwner ne null) && (tree.symbol == oldClassOwner) =>
val tree1 = Super(qual, mix)
log("changed " + tree + " to " + tree1)
super.typed(atPos(tree.pos)(tree1))
*/
case Match(scrut, cases) =>
val scrut1 = typedByValueExpr(scrut)
val scrutTpe = scrut1.tpe.widen
val cases1 = {
if (scrutTpe.isFinalType) cases filter {
case CaseDef(Bind(_, pat @ Typed(_, tpt)), EmptyTree, body) =>
// the typed pattern is not incompatible with the scrutinee type
scrutTpe matchesPattern fixType(tpt.tpe)
case CaseDef(Typed(_, tpt), EmptyTree, body) =>
// the typed pattern is not incompatible with the scrutinee type
scrutTpe matchesPattern fixType(tpt.tpe)
case _ => true
}
// Without this, AnyRef specializations crash on patterns like
// case _: Boolean => ...
// Not at all sure this is safe.
else if (scrutTpe <:< AnyRefTpe)
cases filterNot (_.pat.tpe <:< AnyValTpe)
else
cases
}
super.typed(atPos(tree.pos)(Match(scrut, cases1)), mode, pt)
case EmptyTree =>
// no need to do anything, in particular, don't set the type to null, EmptyTree.tpe_= asserts
tree
case _ =>
debuglog("Duplicators default case: " + tree.summaryString)
debuglog(" ---> " + tree)
if (tree.hasSymbolField && tree.symbol.safeOwner == AnyClass)
tree.symbol = NoSymbol // maybe we can find a more specific member in a subclass of Any (see AnyVal members, like ==)
val ntree = castType(tree, pt)
super.typed(ntree, mode, pt)
}
}
}
}
