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package dotty.tools.dotc.core
import Contexts._, Types._, Symbols._, Names._, Flags._, Scopes._
trait TypeOps { this: Context =>
def newSkolemSingleton(underlying: Type) = TermRef(NoPrefix, newSkolem(underlying))
final def asSeenFrom(tp: Type, pre: Type, cls: Symbol, theMap: AsSeenFromMap): Type = {
def toPrefix(pre: Type, cls: Symbol, thiscls: ClassSymbol): Type =
if ((pre eq NoType) || (pre eq NoPrefix) || (cls is PackageClass))
tp
else if (thiscls.isNonBottomSubClass(cls) && pre.baseType(thiscls).exists)
pre match {
case SuperType(thispre, _) => thispre
case _ => pre
}
else
toPrefix(pre.baseType(cls).normalizedPrefix, cls.owner, thiscls)
tp match {
case tp: NamedType =>
val sym = tp.symbol
if (sym.isStatic) tp
else {
val tp1 = tp.derivedNamedType(asSeenFrom(tp.prefix, pre, cls, theMap))
// short-circuit instantiated type parameters
if ((tp1 ne tp) && (sym is (TypeParam, butNot = Deferred))) tp1.dealias
else tp1
}
case ThisType(thiscls) =>
toPrefix(pre, cls, thiscls)
case _: BoundType | NoPrefix =>
tp
case tp: RefinedType =>
tp.derivedRefinedType(
asSeenFrom(tp.parent, pre, cls, theMap),
tp.refinedName,
asSeenFrom(tp.refinedInfo, pre, cls, theMap))
case _ =>
(if (theMap != null) theMap else new AsSeenFromMap(pre, cls))
.mapOver(tp)
}
}
class AsSeenFromMap(pre: Type, cls: Symbol) extends TypeMap {
def apply(tp: Type) = asSeenFrom(tp, pre, cls, this)
}
final def isVolatile(tp: Type): Boolean = {
/** Pre-filter to avoid expensive DNF computation */
def needsChecking(tp: Type, isPart: Boolean): Boolean = tp match {
case tp: TypeRef =>
tp.info match {
case TypeBounds(lo, hi) =>
if (lo eq hi) needsChecking(hi, isPart)
else isPart || tp.controlled(isVolatile(hi))
case _ => false
}
case tp: RefinedType =>
needsChecking(tp.parent, true)
case tp: TypeProxy =>
needsChecking(tp.underlying, isPart)
case AndType(l, r) =>
needsChecking(l, true) || needsChecking(r, true)
case OrType(l, r) =>
isPart || needsChecking(l, isPart) && needsChecking(r, isPart)
case _ =>
false
}
needsChecking(tp, false) && {
tp.DNF forall { case (parents, refinedNames) =>
val absParents = parents filter (_.symbol is Deferred)
absParents.size >= 2 || {
val ap = absParents.head
(parents exists (p =>
(p ne ap) || p.abstractMemberNames(tp).nonEmpty)) ||
(refinedNames & tp.abstractMemberNames()).nonEmpty ||
isVolatile(ap)
}
}
}
}
final def glb(tp1: Type, tp2: Type): Type =
if (tp1 eq tp2) tp1
else tp2 match { // normalize to disjunctive normal form if possible.
case OrType(tp21, tp22) =>
tp1 & tp21 | tp1 & tp22
case _ =>
tp1 match {
case OrType(tp11, tp12) =>
tp11 & tp2 | tp12 & tp2
case _ =>
val t1 = mergeIfSub(tp1, tp2)
if (t1.exists) t1
else {
val t2 = mergeIfSub(tp2, tp1)
if (t2.exists) t2
else AndType(tp1, tp2)
}
}
}
final def glb(tps: List[Type]): Type =
(defn.AnyType /: tps)(glb)
def lub(tp1: Type, tp2: Type): Type =
if (tp1 eq tp2) tp1
else {
val t1 = mergeIfSuper(tp1, tp2)
if (t1.exists) t1
else {
val t2 = mergeIfSuper(tp2, tp1)
if (t2.exists) t2
else OrType(tp1, tp2)
}
}
final def lub(tps: List[Type]): Type =
(defn.NothingType /: tps)(lub)
/** Merge `t1` into `tp2` if t1 is a subtype of some &-summand of tp2.
*/
private def mergeIfSub(tp1: Type, tp2: Type)(implicit ctx: Context): Type =
if (tp1 <:< tp2)
if (tp2 <:< tp1) tp2 else tp1 // keep existing type if possible
else tp2 match {
case tp2 @ AndType(tp21, tp22) =>
val lower1 = mergeIfSub(tp1, tp21)
if (lower1 eq tp21) tp2
else if (lower1.exists) lower1 & tp22
else {
val lower2 = mergeIfSub(tp1, tp22)
if (lower2 eq tp22) tp2
else if (lower2.exists) tp21 & lower2
else NoType
}
case _ =>
NoType
}
/** Merge `tp1` into `tp2` if tp1 is a supertype of some |-summand of tp2.
*/
private def mergeIfSuper(tp1: Type, tp2: Type)(implicit ctx: Context): Type =
if (tp2 <:< tp1)
if (tp1 <:< tp2) tp2 else tp1 // keep existing type if possible
else tp2 match {
case tp2 @ OrType(tp21, tp22) =>
val higher1 = mergeIfSuper(tp1, tp21)
if (higher1 eq tp21) tp2
else if (higher1.exists) higher1 | tp22
else {
val higher2 = mergeIfSuper(tp1, tp22)
if (higher2 eq tp22) tp2
else if (higher2.exists) tp21 | higher2
else NoType
}
case _ =>
NoType
}
/** Normalize a list of parent types of class `cls` that may contain refinements
* to a list of typerefs, by converting all refinements to member
* definitions in scope `decls`. Can add members to `decls` as a side-effect.
*/
def normalizeToRefs(parents: List[Type], cls: ClassSymbol, decls: MutableScope): List[TypeRef] = {
var refinements = Map[TypeName, Type]()
var formals = Map[TypeName, Symbol]()
def normalizeToRef(tp: Type): TypeRef = tp match {
case tp @ RefinedType(tp1, name: TypeName) =>
refinements = refinements.updated(name,
refinements get name match {
case Some(info) => info & tp.refinedInfo
case none => tp.refinedInfo
})
formals = formals.updated(name, tp1.typeParamNamed(name))
normalizeToRef(tp1)
case tp: TypeRef =>
tp
case _ =>
throw new TypeError(s"unexpected parent type: $tp")
}
val parentRefs = parents map normalizeToRef
for ((name, tpe) <- refinements) decls.enter {
val formal = formals(name)
val bounds = tpe //.toRHS(formal)
ctx.newSymbol(cls, name, formal.flags & RetainedTypeArgFlags, bounds)
}
parentRefs
}
}
|
