package dotty.tools.dotc
package core
import Contexts._, Types._, Symbols._, Names._, Flags._, Scopes._
import SymDenotations._, Denotations.Denotation
import config.Printers._
import Decorators._
import StdNames._
import util.SimpleMap
import collection.mutable
import ast.tpd._
trait TypeOps { this: Context => // TODO: Make standalone object.
final def asSeenFrom(tp: Type, pre: Type, cls: Symbol): Type = {
val m = if (pre.isStable || ctx.isAfterTyper) null else new AsSeenFromMap(pre, cls)
asSeenFrom(tp, pre, cls, null)
}
final def asSeenFrom(tp: Type, pre: Type, cls: Symbol, theMap: AsSeenFromMap): Type = {
def toPrefix(pre: Type, cls: Symbol, thiscls: ClassSymbol): Type = /*>|>*/ ctx.conditionalTraceIndented(TypeOps.track, s"toPrefix($pre, $cls, $thiscls)") /*<|<*/ {
if ((pre eq NoType) || (pre eq NoPrefix) || (cls is PackageClass))
tp
else if (thiscls.derivesFrom(cls) && pre.baseTypeRef(thiscls).exists) {
if (!pre.isStable && theMap != null && theMap.currentVariance <= 0) {
theMap.unstable = true
}
pre match {
case SuperType(thispre, _) => thispre
case _ => pre
}
}
else if ((pre.termSymbol is Package) && !(thiscls is Package))
toPrefix(pre.select(nme.PACKAGE), cls, thiscls)
else
toPrefix(pre.baseTypeRef(cls).normalizedPrefix, cls.owner, thiscls)
}
/*>|>*/ ctx.conditionalTraceIndented(TypeOps.track, s"asSeen ${tp.show} from (${pre.show}, ${cls.show})", show = true) /*<|<*/ { // !!! DEBUG
tp match {
case tp: NamedType =>
val sym = tp.symbol
if (sym.isStatic) tp
else {
val pre1 = asSeenFrom(tp.prefix, pre, cls, theMap)
if (theMap != null && theMap.unstable) {
pre1.member(tp.name).info match {
case TypeAlias(alias) => return alias
case _ =>
}
}
tp.derivedSelect(pre1)
}
case tp: ThisType =>
toPrefix(pre, cls, tp.cls)
case _: BoundType | NoPrefix =>
tp
case tp: RefinedType =>
tp.derivedRefinedType(
asSeenFrom(tp.parent, pre, cls, theMap),
tp.refinedName,
asSeenFrom(tp.refinedInfo, pre, cls, theMap))
case tp: TypeAlias =>
tp.derivedTypeAlias(asSeenFrom(tp.alias, 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)
def currentVariance = variance
var unstable = false
}
/** Implementation of Types#simplified */
final def simplify(tp: Type, theMap: SimplifyMap): Type = tp match {
case tp: NamedType =>
if (tp.symbol.isStatic) tp
else tp.derivedSelect(simplify(tp.prefix, theMap)) match {
case tp1: NamedType if tp1.denotationIsCurrent =>
val tp2 = tp1.reduceProjection
//if (tp2 ne tp1) println(i"simplified $tp1 -> $tp2")
tp2
case tp1 => tp1
}
case tp: PolyParam =>
typerState.constraint.typeVarOfParam(tp) orElse tp
case _: ThisType | _: BoundType | NoPrefix =>
tp
case tp: RefinedType =>
tp.derivedRefinedType(simplify(tp.parent, theMap), tp.refinedName, simplify(tp.refinedInfo, theMap))
case tp: TypeAlias =>
tp.derivedTypeAlias(simplify(tp.alias, theMap))
case AndType(l, r) =>
simplify(l, theMap) & simplify(r, theMap)
case OrType(l, r) =>
simplify(l, theMap) | simplify(r, theMap)
case _ =>
(if (theMap != null) theMap else new SimplifyMap).mapOver(tp)
}
class SimplifyMap extends TypeMap {
def apply(tp: Type) = simplify(tp, this)
}
/** Approximate union type by intersection of its dominators.
* See Type#approximateUnion for an explanation.
*/
def approximateUnion(tp: Type): Type = {
/** a faster version of cs1 intersect cs2 */
def intersect(cs1: List[ClassSymbol], cs2: List[ClassSymbol]): List[ClassSymbol] = {
val cs2AsSet = new util.HashSet[ClassSymbol](100)
cs2.foreach(cs2AsSet.addEntry)
cs1.filter(cs2AsSet.contains)
}
/** The minimal set of classes in `cs` which derive all other classes in `cs` */
def dominators(cs: List[ClassSymbol], accu: List[ClassSymbol]): List[ClassSymbol] = (cs: @unchecked) match {
case c :: rest =>
val accu1 = if (accu exists (_ derivesFrom c)) accu else c :: accu
if (cs == c.baseClasses) accu1 else dominators(rest, accu1)
}
if (ctx.featureEnabled(defn.LanguageModuleClass, nme.keepUnions)) tp
else tp match {
case tp: OrType =>
val commonBaseClasses = tp.mapReduceOr(_.baseClasses)(intersect)
val doms = dominators(commonBaseClasses, Nil)
doms.map(tp.baseTypeWithArgs).reduceLeft(AndType.apply)
case tp @ AndType(tp1, tp2) =>
tp derived_& (approximateUnion(tp1), approximateUnion(tp2))
case tp: RefinedType =>
tp.derivedRefinedType(approximateUnion(tp.parent), tp.refinedName, tp.refinedInfo)
case _ =>
tp
}
}
/** A type is volatile if its DNF contains an alternative of the form
* {P1, ..., Pn}, {N1, ..., Nk}, where the Pi are parent typerefs and the
* Nj are refinement names, and one the 4 following conditions is met:
*
* 1. At least two of the parents Pi are abstract types.
* 2. One of the parents Pi is an abstract type, and one other type Pj,
* j != i has an abstract member which has the same name as an
* abstract member of the whole type.
* 3. One of the parents Pi is an abstract type, and one of the refinement
* names Nj refers to an abstract member of the whole type.
* 4. One of the parents Pi is an an alias type with a volatile alias
* or an abstract type with a volatile upper bound.
*
* Lazy values are not allowed to have volatile type, as otherwise
* unsoundness can result.
*/
final def isVolatile(tp: Type): Boolean = {
/** Pre-filter to avoid expensive DNF computation
* If needsChecking returns false it is guaranteed that
* DNF does not contain intersections, or abstract types with upper
* bounds that themselves need checking.
*/
def needsChecking(tp: Type, isPart: Boolean): Boolean = tp match {
case tp: TypeRef =>
tp.info match {
case TypeAlias(alias) =>
needsChecking(alias, isPart)
case TypeBounds(lo, hi) =>
isPart || tp.controlled(isVolatile(hi))
case _ => false
}
case tp: RefinedType =>
needsChecking(tp.parent, true)
case tp: TypeProxy =>
needsChecking(tp.underlying, isPart)
case tp: AndType =>
true
case tp: OrType =>
isPart || needsChecking(tp.tp1, isPart) && needsChecking(tp.tp2, isPart)
case _ =>
false
}
needsChecking(tp, false) && {
DNF(tp) forall { case (parents, refinedNames) =>
val absParents = parents filter (_.symbol is Deferred)
absParents.nonEmpty && {
absParents.lengthCompare(2) >= 0 || {
val ap = absParents.head
((parents exists (p =>
(p ne ap)
|| p.memberNames(abstractTypeNameFilter, tp).nonEmpty
|| p.memberNames(abstractTermNameFilter, tp).nonEmpty))
|| (refinedNames & tp.memberNames(abstractTypeNameFilter, tp)).nonEmpty
|| (refinedNames & tp.memberNames(abstractTermNameFilter, tp)).nonEmpty
|| isVolatile(ap))
}
}
}
}
}
/** The disjunctive normal form of this type.
* This collects a set of alternatives, each alternative consisting
* of a set of typerefs and a set of refinement names. Both sets are represented
* as lists, to obtain a deterministic order. Collected are
* all type refs reachable by following aliases and type proxies, and
* collecting the elements of conjunctions (&) and disjunctions (|).
* The set of refinement names in each alternative
* are the set of names in refinement types encountered during the collection.
*/
final def DNF(tp: Type): List[(List[TypeRef], Set[Name])] = ctx.traceIndented(s"DNF($this)", checks) {
tp.dealias match {
case tp: TypeRef =>
(tp :: Nil, Set[Name]()) :: Nil
case RefinedType(parent, name) =>
for ((ps, rs) <- DNF(parent)) yield (ps, rs + name)
case tp: TypeProxy =>
DNF(tp.underlying)
case AndType(l, r) =>
for ((lps, lrs) <- DNF(l); (rps, rrs) <- DNF(r))
yield (lps | rps, lrs | rrs)
case OrType(l, r) =>
DNF(l) | DNF(r)
case tp =>
TypeOps.emptyDNF
}
}
private def enterArgBinding(formal: Symbol, info: Type, cls: ClassSymbol, decls: Scope) = {
val lazyInfo = new LazyType { // needed so we do not force `formal`.
def complete(denot: SymDenotation)(implicit ctx: Context): Unit = {
denot setFlag formal.flags & RetainedTypeArgFlags
denot.info = info
}
}
val typeArgFlag = if (formal is Local) TypeArgument else EmptyFlags
val sym = ctx.newSymbol(
cls, formal.name,
formal.flagsUNSAFE & RetainedTypeArgFlags | typeArgFlag | Override,
lazyInfo,
coord = cls.coord)
cls.enter(sym, decls)
}
/** If `tpe` is of the form `p.x` where `p` refers to a package
* but `x` is not owned by a package, expand it to
*
* p.package.x
*/
def makePackageObjPrefixExplicit(tpe: NamedType): Type = {
def tryInsert(pkgClass: SymDenotation): Type = pkgClass match {
case pkgCls: PackageClassDenotation if !(tpe.symbol.maybeOwner is Package) =>
tpe.derivedSelect(pkgCls.packageObj.valRef)
case _ =>
tpe
}
tpe.prefix match {
case pre: ThisType if pre.cls is Package => tryInsert(pre.cls)
case pre: TermRef if pre.symbol is Package => tryInsert(pre.symbol.moduleClass)
case _ => tpe
}
}
/** If we have member definitions
*
* type argSym v= from
* type from v= to
*
* where the variances of both alias are the same, then enter a new definition
*
* type argSym v= to
*
* unless a definition for `argSym` already exists in the current scope.
*/
def forwardRef(argSym: Symbol, from: Symbol, to: TypeBounds, cls: ClassSymbol, decls: Scope) =
argSym.info match {
case info @ TypeBounds(lo2 @ TypeRef(_: ThisType, name), hi2) =>
if (name == from.name &&
(lo2 eq hi2) &&
info.variance == to.variance &&
!decls.lookup(argSym.name).exists) {
// println(s"short-circuit ${argSym.name} was: ${argSym.info}, now: $to")
enterArgBinding(argSym, to, cls, decls)
}
case _ =>
}
/** Normalize a list of parent types of class `cls` that may contain refinements
* to a list of typerefs referring to classes, by converting all refinements to member
* definitions in scope `decls`. Can add members to `decls` as a side-effect.
*/
def normalizeToClassRefs(parents: List[Type], cls: ClassSymbol, decls: Scope): List[TypeRef] = {
/** If we just entered the type argument binding
*
* type From = To
*
* and there is a type argument binding in a parent in `prefs` of the form
*
* type X = From
*
* then also add the binding
*
* type X = To
*
* to the current scope, provided (1) variances of both aliases are the same, and
* (2) X is not yet defined in current scope. This "short-circuiting" prevents
* long chains of aliases which would have to be traversed in type comparers.
*/
def forwardRefs(from: Symbol, to: Type, prefs: List[TypeRef]) = to match {
case to @ TypeBounds(lo1, hi1) if lo1 eq hi1 =>
for (pref <- prefs)
for (argSym <- pref.decls)
if (argSym is TypeArgument)
forwardRef(argSym, from, to, cls, decls)
case _ =>
}
// println(s"normalizing $parents of $cls in ${cls.owner}") // !!! DEBUG
var refinements: SimpleMap[TypeName, Type] = SimpleMap.Empty
var formals: SimpleMap[TypeName, Symbol] = SimpleMap.Empty
def normalizeToRef(tp: Type): TypeRef = tp.dealias match {
case tp: TypeRef =>
tp
case tp @ RefinedType(tp1, name: TypeName) =>
val prevInfo = refinements(name)
refinements = refinements.updated(name,
if (prevInfo == null) tp.refinedInfo else prevInfo & tp.refinedInfo)
formals = formals.updated(name, tp1.typeParamNamed(name))
normalizeToRef(tp1)
case ErrorType =>
defn.AnyClass.typeRef
case AnnotatedType(_, tpe) =>
normalizeToRef(tpe)
case _ =>
throw new TypeError(s"unexpected parent type: $tp")
}
val parentRefs = parents map normalizeToRef
refinements foreachBinding { (name, refinedInfo) =>
assert(decls.lookup(name) == NoSymbol, // DEBUG
s"redefinition of ${decls.lookup(name).debugString} in ${cls.showLocated}")
enterArgBinding(formals(name), refinedInfo, cls, decls)
}
// These two loops cannot be fused because second loop assumes that
// all arguments have been entered in `decls`.
refinements foreachBinding { (name, refinedInfo) =>
forwardRefs(formals(name), refinedInfo, parentRefs)
}
parentRefs
}
/** An argument bounds violation is a triple consisting of
* - the argument tree
* - a string "upper" or "lower" indicating which bound is violated
* - the violated bound
*/
type BoundsViolation = (Tree, String, Type)
/** The list of violations where arguments are not within bounds.
* @param args The arguments
* @param boundss The list of type bounds
* @param instantiate A function that maps a bound type and the list of argument types to a resulting type.
* Needed to handle bounds that refer to other bounds.
*/
def boundsViolations(args: List[Tree], boundss: List[TypeBounds], instantiate: (Type, List[Type]) => Type)(implicit ctx: Context): List[BoundsViolation] = {
val argTypes = args.tpes
val violations = new mutable.ListBuffer[BoundsViolation]
for ((arg, bounds) <- args zip boundss) {
def checkOverlapsBounds(lo: Type, hi: Type): Unit = {
//println(i"instantiating ${bounds.hi} with $argTypes")
//println(i" = ${instantiate(bounds.hi, argTypes)}")
val hiBound = instantiate(bounds.hi, argTypes.mapConserve(_.bounds.hi))
val loBound = instantiate(bounds.lo, argTypes.mapConserve(_.bounds.lo))
// Note that argTypes can contain a TypeBounds type for arguments that are
// not fully determined. In that case we need to check against the hi bound of the argument.
if (!(lo <:< hiBound)) violations += ((arg, "upper", hiBound))
if (!(loBound <:< hi)) violations += ((arg, "lower", bounds.lo))
}
arg.tpe match {
case TypeBounds(lo, hi) => checkOverlapsBounds(lo, hi)
case tp => checkOverlapsBounds(tp, tp)
}
}
violations.toList
}
/** Is `feature` enabled in class `owner`?
* This is the case if one of the following two alternatives holds:
*
* 1. The feature is imported by a named import
*
* import owner.feature
*
* (the feature may be bunched with others, or renamed, but wildcard imports
* don't count).
*
* 2. The feature is enabled by a compiler option
*
* - language:<prefix>feature
*
* where <prefix> is the full name of the owner followed by a "." minus
* the prefix "dotty.language.".
*/
def featureEnabled(owner: ClassSymbol, feature: TermName): Boolean = {
def toPrefix(sym: Symbol): String =
if (sym eq defn.LanguageModuleClass) "" else toPrefix(sym.owner) + sym.name + "."
def featureName = toPrefix(owner) + feature
def hasImport(implicit ctx: Context): Boolean = (
ctx.importInfo != null
&& ( (ctx.importInfo.site.widen.typeSymbol eq owner)
&& ctx.importInfo.originals.contains(feature)
||
{ var c = ctx.outer
while (c.importInfo eq ctx.importInfo) c = c.outer
hasImport(c)
}))
def hasOption = ctx.base.settings.language.value exists (s => s == featureName || s == "_")
hasImport || hasOption
}
/** Is auto-tupling enabled? */
def canAutoTuple =
!featureEnabled(defn.LanguageModuleClass, nme.noAutoTupling)
}
object TypeOps {
val emptyDNF = (Nil, Set[Name]()) :: Nil
var track = false // !!!DEBUG
}