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Add documentation on Repeated and RepeatedParamClass (#18792)
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Close #18784
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smarter authored Nov 8, 2023
2 parents dc0b43c + 9d57680 commit cee2610
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30 changes: 29 additions & 1 deletion library/src/scala/quoted/Quotes.scala
Original file line number Diff line number Diff line change
Expand Up @@ -1622,7 +1622,30 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
end extension
end ReturnMethods

/** Tree representing a variable argument list in the source code */
/** Tree representing a variable argument list in the source code.
*
* This tree is used to encode varargs terms. The Repeated encapsulates
* the sequence of the elements but needs to be wrapped in a
* `scala.<repeated>[T]` (see `defn.RepeatedParamClass`). For example the
* arguments `1, 2` of `List.apply(1, 2)` can be represented as follows:
*
*
* ```scala
* //{
* import scala.quoted._
* def inQuotes(using Quotes) = {
* val q: Quotes = summon[Quotes]
* import q.reflect._
* //}
* val intArgs = List(Literal(Constant(1)), Literal(Constant(2)))
* Typed(
* Repeated(intArgs, TypeTree.of[Int]),
* Inferred(defn.RepeatedParamClass.typeRef.appliedTo(TypeRepr.of[Int]))
* //{
* }
* //}
* ```
*/
type Repeated <: Term

/** `TypeTest` that allows testing at runtime in a pattern match if a `Tree` is a `Repeated` */
Expand All @@ -1633,8 +1656,11 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>

/** Methods of the module object `val Repeated` */
trait RepeatedModule { this: Repeated.type =>
/** Create a literal sequence of elements */
def apply(elems: List[Term], tpt: TypeTree): Repeated
/** Copy a literal sequence of elements */
def copy(original: Tree)(elems: List[Term], tpt: TypeTree): Repeated
/** Matches a literal sequence of elements */
def unapply(x: Repeated): (List[Term], TypeTree)
}

Expand Down Expand Up @@ -4314,6 +4340,8 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>

/** A dummy class symbol that is used to indicate repeated parameters
* compiled by the Scala compiler.
*
* @see Repeated
*/
def RepeatedParamClass: Symbol

Expand Down
20 changes: 20 additions & 0 deletions tests/pos/i18784/Macro_1.scala
Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
import scala.quoted.*

object Macro {
inline def repeated = ${Macro.repeatedImpl}
def repeatedImpl(using Quotes):Expr[List[Int]] = {
import quotes.reflect.*
val args = List(Expr(1), Expr(2))
val listObjectTerm = '{ List }.asTerm
Apply(
TypeApply(
Select.unique(listObjectTerm, "apply"),
List(TypeTree.of[Int])
),
List(
Typed(
Repeated(args.map(_.asTerm), TypeTree.of[Int]),
Inferred(defn.RepeatedParamClass.typeRef.appliedTo(TypeRepr.of[Int]))))
).asExprOf[List[Int]]
}
}
2 changes: 2 additions & 0 deletions tests/pos/i18784/Test_2.scala
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
def Test: Unit =
Macro.repeated

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