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package dotty.tools.dotc
package transform
import core._
import Types._
import Symbols._
import SymDenotations._
import Contexts._
import Flags._
import StdNames._
/** Methods that apply to user-defined value classes */
object ValueClasses {
def isDerivedValueClass(d: SymDenotation)(implicit ctx: Context) = {
!ctx.settings.XnoValueClasses.value &&
!d.isRefinementClass &&
d.isValueClass &&
(d.initial.symbol ne defn.AnyValClass) && // Compare the initial symbol because AnyVal does not exist after erasure
!d.isPrimitiveValueClass
}
def isMethodWithExtension(d: SymDenotation)(implicit ctx: Context) =
d.isRealMethod &&
isDerivedValueClass(d.owner) &&
!d.isConstructor &&
!d.is(SuperAccessor) &&
!d.is(Macro)
/** The member that of a derived value class that unboxes it. */
def valueClassUnbox(d: ClassDenotation)(implicit ctx: Context): Symbol =
// (info.decl(nme.unbox)).orElse(...) uncomment once we accept unbox methods
d.classInfo.decls
.find(d => d.isTerm && d.symbol.is(ParamAccessor))
.map(_.symbol)
.getOrElse(NoSymbol)
/** For a value class `d`, this returns the synthetic cast from the underlying type to
* ErasedValueType defined in the companion module. This method is added to the module
* and further described in [[ExtensionMethods]].
*/
def u2evt(d: ClassDenotation)(implicit ctx: Context): Symbol =
d.linkedClass.info.decl(nme.U2EVT).symbol
/** For a value class `d`, this returns the synthetic cast from ErasedValueType to the
* underlying type defined in the companion module. This method is added to the module
* and further described in [[ExtensionMethods]].
*/
def evt2u(d: ClassDenotation)(implicit ctx: Context): Symbol =
d.linkedClass.info.decl(nme.EVT2U).symbol
/** The unboxed type that underlies a derived value class */
def underlyingOfValueClass(d: ClassDenotation)(implicit ctx: Context): Type =
valueClassUnbox(d).info.resultType
/** Whether a value class wraps itself */
def isCyclic(cls: ClassSymbol)(implicit ctx: Context): Boolean = {
def recur(seen: Set[Symbol], clazz: ClassSymbol)(implicit ctx: Context): Boolean =
(seen contains clazz) || {
val unboxed = underlyingOfValueClass(clazz).typeSymbol
(isDerivedValueClass(unboxed)) && recur(seen + clazz, unboxed.asClass)
}
recur(Set[Symbol](), cls)
}
}
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