-
Notifications
You must be signed in to change notification settings - Fork 1.1k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
2 changed files
with
78 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,75 @@ | ||
import scala.annotation.{tailrec, unused} | ||
import scala.deriving.Mirror | ||
import scala.quoted.* | ||
|
||
trait TypeLength[A] { | ||
type Length <: Int | ||
def length: Length | ||
} | ||
object TypeLength extends TypeLengthLowPriority: | ||
type Aux[A, Length0 <: Int] = TypeLength[A] { | ||
type Length = Length0 | ||
} | ||
|
||
transparent inline given fromMirror[A](using m: Mirror.Of[A]): TypeLength[A] = | ||
${ macroImpl[A, m.MirroredElemTypes] } | ||
|
||
@tailrec | ||
private def typesOfTuple( | ||
using q: Quotes | ||
)(tpe: q.reflect.TypeRepr, acc: List[q.reflect.TypeRepr]): List[q.reflect.TypeRepr] = | ||
import q.reflect.* | ||
val cons = Symbol.classSymbol("scala.*:") | ||
tpe.widenTermRefByName.dealias match | ||
case AppliedType(fn, tpes) if defn.isTupleClass(fn.typeSymbol) => | ||
tpes.reverse_:::(acc) | ||
case AppliedType(tp, List(headType, tailType)) if tp.derivesFrom(cons) => | ||
typesOfTuple(tailType, headType :: acc) | ||
case tpe => | ||
if tpe.derivesFrom(Symbol.classSymbol("scala.EmptyTuple")) then acc.reverse | ||
else report.errorAndAbort(s"Unknown type encountered in tuple ${tpe.show}") | ||
|
||
def macroImpl[A: Type, T <: Tuple: scala.quoted.Type]( | ||
using q: scala.quoted.Quotes | ||
): scala.quoted.Expr[TypeLength[A]] = | ||
import q.reflect.* | ||
val l = typesOfTuple(TypeRepr.of[T], Nil).length | ||
ConstantType(IntConstant(l)).asType match | ||
case '[lt] => | ||
val le = Expr[Int](l).asExprOf[lt & Int] | ||
'{ | ||
val r: TypeLength.Aux[A, lt & Int] = new TypeLength[A] { | ||
type Length = lt & Int | ||
val length: Length = ${ le } | ||
} | ||
r | ||
} | ||
|
||
transparent inline given fromTuple[T <: Tuple]: TypeLength[T] = | ||
${ macroImpl[T, T] } | ||
|
||
trait TypeLengthLowPriority: | ||
self: TypeLength.type => | ||
given tupleFromMirrorAndLength[A, T <: Tuple]( | ||
using @unused m: Mirror.Of[A] { type MirroredElemTypes = T }, | ||
length: TypeLength[A] | ||
): TypeLength.Aux[T, length.Length] = length.asInstanceOf[TypeLength.Aux[T, length.Length]] | ||
|
||
trait HKDSumGeneric[A] | ||
object HKDSumGeneric: | ||
type NotZero[N <: Int] = N match | ||
case 0 => false | ||
case _ => true | ||
|
||
transparent inline given derived[A](using m: Mirror.SumOf[A], typeLength: TypeLength[A])( | ||
using NotZero[typeLength.Length] =:= true | ||
): HKDSumGeneric[A] = | ||
derivedImpl[A, m.MirroredElemTypes, m.MirroredLabel] // error | ||
|
||
def derivedImpl[A, ElemTypes <: Tuple, Label <: String]( | ||
using m: Mirror.SumOf[A] { | ||
type MirroredElemTypes = ElemTypes; type MirroredLabel = Label; | ||
}, | ||
typeLength: TypeLength[ElemTypes], | ||
nz: NotZero[typeLength.Length] =:= true | ||
): HKDSumGeneric[A] = ??? |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,3 @@ | ||
trait Foo { type Num <: Int } | ||
given derived[A](using foo: Foo): Any = derivedImpl(foo) // error | ||
def derivedImpl(foo: Foo)(using bar: foo.Num =:= Int): Any = ??? |