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package dotty.tools.dotc.core
import Types._, Contexts._, Symbols._
import collection.mutable
object SubTypers {
type Constraints = Map[PolyParam, TypeBounds]
object SubTyper {
private final val LogPendingSubTypesThreshold = 50
}
class SubTyper(_ctx: Context) extends DotClass {
import SubTyper._
implicit val ctx = _ctx
var constraints = ctx.constraints
private var pendingSubTypes: mutable.Set[(Type, Type)] = null
private var recCount = 0
def addConstraint(param: PolyParam, bounds: TypeBounds): Boolean = {
val newbounds = constraints(param) & bounds
constraints = constraints.updated(param, newbounds)
newbounds.lo <:< newbounds.hi
}
def isSubType(tp1: Type, tp2: Type): Boolean =
if (tp1 == NoType || tp2 == NoType) false
else if (tp1 eq tp2) true
else {
val cs = constraints
try {
recCount += 1
val result =
if (recCount < LogPendingSubTypesThreshold) firstTry(tp1, tp2)
else monitoredIsSubType(tp1, tp2)
recCount -= 1
if (!result) constraints = cs
result
} catch {
case ex: Throwable =>
recCount -= 1
constraints = cs
throw ex
}
}
def monitoredIsSubType(tp1: Type, tp2: Type) = {
if (pendingSubTypes == null)
pendingSubTypes = new mutable.HashSet[(Type, Type)]
val p = (tp1, tp2)
!pendingSubTypes(p) && {
try {
pendingSubTypes += p
firstTry(tp1, tp2)
} finally {
pendingSubTypes -= p
}
}
}
def firstTry(tp1: Type, tp2: Type): Boolean = tp2 match {
case tp2: TypeRef =>
tp1 match {
case tp1: TypeRef =>
val sym1 = tp1.symbol
val sym2 = tp2.symbol
val pre1 = tp1.prefix
val pre2 = tp2.prefix
(sym1 == sym2 && (
ctx.erasedTypes ||
sym1.owner.hasFlag(Flags.Package) ||
isSubType(pre1, pre2))
||
tp1.name == tp2.name &&
isSubType(pre1, pre2) &&
(sym2.isAbstractType || isSubType(pre2, pre1)) // ???
||
(sym2.isClass) && {
val base = tp1.baseType(sym2)
(base ne tp1) && isSubType(base, tp2)
}
||
thirdTryRef(tp1, tp2))
case _ =>
secondTry(tp1, tp2)
}
case WildcardType | ErrorType =>
true
case tp2: PolyParam if (constraints contains tp2) =>
addConstraint(tp2, TypeBounds(tp1, defn.AnyType))
case _ =>
secondTry(tp1, tp2)
}
def secondTry(tp1: Type, tp2: Type): Boolean = tp1 match {
case tp1: PolyParam if (constraints contains tp1) =>
addConstraint(tp1, TypeBounds(defn.NothingType, tp2))
case WildcardType | ErrorType =>
true
case _ =>
thirdTry(tp1, tp2)
}
def thirdTryRef(tp1: Type, tp2: TypeRef): Boolean = (
(tp2 == defn.SingletonType && tp1.isStable)
||
(!tp2.symbol.isClass && isSubType(tp1, tp2.info.bounds.lo))
||
fourthTry(tp1, tp2)
)
def thirdTry(tp1: Type, tp2: Type): Boolean = tp2 match {
case tp2: TypeRef =>
thirdTryRef(tp1, tp2)
case AppliedType(tycon, targs) =>
val clazz2 = tycon.typeSymbol
val base = tp1.baseType(clazz2)
base.exists && isSubArgs(base.typeArgs, tp2.typeArgs, clazz2.typeParams) ||
fourthTry(tp1, tp2)
case tp2: RefinedType =>
isSubType(tp1, tp2.parent) &&
((tp2.names, tp2.infos).zipped forall ((name, info) =>
isSubType(tp1.member(name).info, info)))
case AndType(tp21, tp22) =>
isSubType(tp1, tp21) && isSubType(tp1, tp22)
case OrType(tp21, tp22) =>
isSubType(tp1, tp21) || isSubType(tp1, tp22)
case tp2 @ MethodType(_, formals1) =>
tp1 match {
case tp1 @ MethodType(_, formals2) =>
tp1.signature == tp2.signature &&
matchingParams(formals1, formals2, tp1.isJava, tp2.isJava) &&
tp1.isImplicit == tp2.isImplicit &&
isSubType(tp1.resultType, tp2.resultType.subst(tp2, tp1))
case _ =>
false
}
case tp2: PolyType =>
tp1 match {
case tp1: PolyType =>
tp1.signature == tp2.signature &&
(tp1.paramBounds corresponds tp2.paramBounds)(
(b1, b2) => b1 =:= b2.subst(tp2, tp1)) &&
isSubType(tp1.resultType, tp2.resultType.subst(tp2, tp1))
case _ =>
false
}
case tp2 @ ExprType(restpe1) =>
tp1 match {
case tp1 @ ExprType(restpe2) =>
isSubType(restpe1, restpe2)
case _ =>
false
}
case TypeBounds(lo2, hi2) =>
tp1 match {
case TypeBounds(lo1, hi1) =>
isSubType(lo2, lo1) && isSubType(hi1, hi2)
case tp1: ClassInfo =>
val tt = tp1.typeTemplate
lo2 <:< tt && tt <:< hi2
case _ =>
false
}
case _ =>
fourthTry(tp1, tp2)
}
def fourthTry(tp1: Type, tp2: Type): Boolean = tp1 match {
case tp1: TypeRef =>
((tp1 eq defn.NothingType)
||
(tp1 eq defn.NullType) && tp2.typeSymbol.containsNull
||
(!tp1.symbol.isClass && isSubType(tp1.info.bounds.hi, tp2)))
case RefinedType(parent, _) =>
isSubType(parent, tp2)
case AndType(tp11, tp12) =>
isSubType(tp11, tp2) || isSubType(tp12, tp2)
case OrType(tp11, tp12) =>
isSubType(tp11, tp2) && isSubType(tp12, tp2)
case tp1: SingletonType =>
isSubType(tp1.underlying, tp2)
case _ =>
false
}
def isSubArgs(tps1: List[Type], tps2: List[Type], tparams: List[TypeSymbol]): Boolean = tparams match {
case tparam :: tparams1 =>
val variance = tparam.variance
val t1 = tps1.head
val t2 = tps2.head
(variance > 0 || isSubType(t2, t1)) &&
(variance < 0 || isSubType(t1, t2)) &&
isSubArgs(tps1.tail, tps2.tail, tparams1)
case _ =>
assert(tps1.isEmpty && tps2.isEmpty)
true
}
/** A function implementing `tp1` matches `tp2`. */
final def matchesType(tp1: Type, tp2: Type, alwaysMatchSimple: Boolean): Boolean = tp1 match {
case tp1: MethodType =>
tp2 match {
case tp2: MethodType =>
tp1.isImplicit == tp2.isImplicit &&
matchingParams(tp1.paramTypes, tp2.paramTypes, tp1.isJava, tp2.isJava) &&
matchesType(tp1.resultType, tp2.resultType.subst(tp2, tp1), alwaysMatchSimple)
case tp2: ExprType =>
tp1.paramNames.isEmpty &&
matchesType(tp1.resultType, tp2.resultType, alwaysMatchSimple)
case _ =>
false
}
case tp1: ExprType =>
tp2 match {
case tp2: MethodType =>
tp2.paramNames.isEmpty &&
matchesType(tp1.resultType, tp2.resultType, alwaysMatchSimple)
case tp2: ExprType =>
matchesType(tp1.resultType, tp2.resultType, alwaysMatchSimple)
case _ =>
matchesType(tp1.resultType, tp2, alwaysMatchSimple)
}
case tp1: PolyType =>
tp2 match {
case tp2: PolyType =>
sameLength(tp1.paramNames, tp2.paramNames) &&
matchesType(tp1.resultType, tp2.resultType.subst(tp2, tp1), alwaysMatchSimple)
case _ =>
false
}
case _ =>
tp2 match {
case _: MethodType | _: PolyType =>
false
case _ =>
alwaysMatchSimple || isSameType(tp1, tp2)
}
}
/** Are `syms1` and `syms2` parameter lists with pairwise equivalent types? */
private def matchingParams(formals1: List[Type], formals2: List[Type], isJava1: Boolean, isJava2: Boolean): Boolean = formals1 match {
case Nil =>
formals2.isEmpty
case formal1 :: rest1 =>
formals2 match {
case Nil =>
false
case formal2 :: rest2 =>
(formal1 =:= formal2 ||
isJava1 && formal2 == defn.ObjectType && formal1 == defn.AnyType ||
isJava2 && formal1 == defn.ObjectType && formal2 == defn.AnyType) &&
matchingParams(rest1, rest2, isJava1, isJava2)
}
}
def isSameType(tp1: Type, tp2: Type): Boolean =
if (tp1 == NoType || tp2 == NoType) false
else if (tp1 eq tp2) true
else isSubType(tp1, tp2) && isSubType(tp2, tp1)
}
}
|
