Implement quoted type patterns

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala

@@ -75,7 +75,9 @@ object PickledQuotes {
     unpickled match {
       case Block(aliases, tpt) =>
         // `@quoteTypeTag type` aliasses are not required after unpickling
-        tpt
+        // `@quoteTypeTag type` aliasses are not required after unpickling
+        val aliases1 = aliases.filter(!_.symbol.hasAnnotation(defn.InternalQuoted_QuoteTypeTagAnnot))
+        seq(aliases1, tpt)
       case tpt => tpt
     }
   }

compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala

@@ -346,14 +346,16 @@ trait QuotesAndSplices { self: Typer =>
 
     val splicePat = typed(untpd.Tuple(splices.map(x => untpd.TypedSplice(replaceBindingsInTree.transform(x)))).withSpan(quoted.span), patType)
 
+    val unapplySym = if (tree.quoted.isTerm) defn.InternalQuotedExpr_unapply else defn.InternalQuotedType_unapply
+    val quoteClass = if (tree.quoted.isTerm) defn.QuotedExprClass else defn.QuotedTypeClass
+    val quotedPattern =
+      if (tree.quoted.isTerm) ref(defn.InternalQuoted_exprQuote.termRef).appliedToType(defn.AnyType).appliedTo(shape).select(nme.apply).appliedTo(qctx)
+      else ref(defn.InternalQuoted_typeQuote.termRef).appliedToTypeTrees(shape :: Nil)
     UnApply(
-      fun = ref(defn.InternalQuotedExpr_unapply.termRef).appliedToTypeTrees(typeBindingsTuple :: TypeTree(patType) :: Nil),
-      implicits =
-          ref(defn.InternalQuoted_exprQuote.termRef).appliedToType(defn.AnyType).appliedTo(shape).select(nme.apply).appliedTo(qctx) ::
-          Literal(Constant(typeBindings.nonEmpty)) ::
-          qctx :: Nil,
+      fun = ref(unapplySym.termRef).appliedToTypeTrees(typeBindingsTuple :: TypeTree(patType) :: Nil),
+      implicits = quotedPattern :: Literal(Constant(typeBindings.nonEmpty)) :: qctx :: Nil,
       patterns = splicePat :: Nil,
-      proto = defn.QuotedExprClass.typeRef.appliedTo(replaceBindings(quoted1.tpe) & quotedPt))
+      proto = quoteClass.typeRef.appliedTo(replaceBindings(quoted1.tpe) & quotedPt))
   }
 
 }

tests/run-macros/quote-type-matcher-2.check

@@ -0,0 +1,4 @@
+%Int%
+%List[%Int%]%
+%Option[%Int%]%
+%%Int% => scala.Double%

tests/run-macros/quote-type-matcher-2/quoted_1.scala

@@ -0,0 +1,18 @@
+import scala.quoted._
+
+object Macros {
+
+  inline def lift[A]: String = ${ matchesExpr('[A]) }
+
+  private def matchesExpr(tp: Type[_]) given QuoteContext: Expr[String] = {
+    def lift(tp: Type[_]): String = tp match {
+      case '[Int] => "%Int%"
+      case '[List[$t]] => s"%List[${lift(t)}]%"
+      case '[Option[$t]] => s"%Option[${lift(t)}]%"
+      case '[Function1[$t, $u]] => s"%${lift(t)} => ${lift(u)}%"
+      case _ => tp.show
+    }
+    lift(tp).toExpr
+  }
+
+}

tests/run-macros/quote-type-matcher-2/quoted_2.scala

@@ -0,0 +1,16 @@
+
+import Macros._
+
+import scala.internal.Quoted._
+
+object Test {
+
+  def main(args: Array[String]): Unit = {
+
+    println(lift[Int])
+    println(lift[List[Int]])
+    println(lift[Option[Int]])
+    println(lift[Int => Double])
+
+  }
+}

tests/run-macros/quote-type-matcher.check

@@ -0,0 +1,20 @@
+Scrutinee: scala.Int
+Pattern: scala.Int
+Result: Some(List())
+
+Scrutinee: 1
+Pattern: scala.Int
+Result: Some(List())
+
+Scrutinee: scala.Int
+Pattern: 2
+Result: None
+
+Scrutinee: scala.collection.immutable.List[scala.Int]
+Pattern: scala.collection.immutable.List[scala.Int]
+Result: Some(List())
+
+Scrutinee: scala.collection.immutable.List[scala.Int]
+Pattern: scala.collection.immutable.List[scala.Double]
+Result: None
+

tests/run-macros/quote-type-matcher/quoted_1.scala

@@ -0,0 +1,29 @@
+import scala.quoted._
+import scala.quoted.matching._
+
+
+object Macros {
+
+  inline def matches[A, B]: Unit = ${ matchesExpr('[A], '[B]) }
+
+  private def matchesExpr[A, B](a: Type[A], b: Type[B]) given (qctx: QuoteContext): Expr[Unit] = {
+    import qctx.tasty.{Bind => _, _}
+
+    val res = scala.internal.quoted.Type.unapply[Tuple, Tuple](a)(b, true, qctx).map { tup =>
+      tup.toArray.toList.map {
+        case r: quoted.Type[_] =>
+          s"Type(${r.unseal.show})"
+        case r: Bind[_] =>
+          s"Bind(${r.name})"
+      }
+    }
+
+    '{
+      println("Scrutinee: " + ${a.unseal.show.toExpr})
+      println("Pattern: " + ${b.unseal.show.toExpr})
+      println("Result: " + ${res.toString.toExpr})
+      println()
+    }
+  }
+
+}

tests/run-macros/quote-type-matcher/quoted_2.scala

@@ -0,0 +1,19 @@
+
+import Macros._
+
+import scala.internal.Quoted._
+
+object Test {
+
+  def main(args: Array[String]): Unit = {
+
+    matches[Int, Int]
+    matches[1, Int]
+    matches[Int, 2]
+
+    matches[List[Int], List[Int]]
+    matches[List[Int], List[Double]]
+
+  }
+}
+