WIP

Author: nicolasstucki

library/src/scala/quoted/Expr.scala

@@ -175,20 +175,39 @@ package quoted {
     }
 
     // TODO generalize for any function arity (see Expr.betaReduce)
-    def open[T, U, X](f: Expr[T => U])(content: (Expr[U], [t] => Expr[t] => Expr[T] => Expr[t]) => X)(given qctx: QuoteContext): X = {
+    def open[T1, R, X](f: Expr[T1 => R])(content: (Expr[R], [t] => Expr[t] => Expr[T1] => Expr[t]) => X)(given qctx: QuoteContext): X = {
       import qctx.tasty.{given, _}
-      f.unseal.etaExpand match
-        case Block(List(DefDef("$anonfun", Nil, List(List(param)), _, Some(body))), Closure(Ident("$anonfun"), None)) =>
-          val bodyExpr = body.seal.asInstanceOf[Expr[U]]
-          def bodyFn[V](e: Expr[V])(v: Expr[T]): Expr[V] = {
-            new TreeMap {
-              override def transformTerm(tree: Term)(given ctx: Context): Term =
-                super.transformTerm(tree) match
-                  case tree: Ident if tree.symbol == param.symbol => v.unseal
-                  case tree => tree
-            }.transformTerm(e.unseal).seal.asInstanceOf[Expr[V]]
-          }
-          content(bodyExpr, [t] => (e: Expr[t]) => (v: Expr[T]) => bodyFn[t](e)(v))
+      val (params, bodyExpr) = paramsAndBody(f)
+      content(bodyExpr, [t] => (e: Expr[t]) => (v: Expr[T1]) => bodyFn[t](e.unseal, params, List(v.unseal)).seal.asInstanceOf[Expr[t]])
+    }
+
+    def open[T1, T2, R, X](f: Expr[(T1, T2) => R])(content: (Expr[R], [t] => Expr[t] => (Expr[T1], Expr[T2]) => Expr[t]) => X)(given qctx: QuoteContext)(given DummyImplicit): X = {
+      import qctx.tasty.{given, _}
+      val (params, bodyExpr) = paramsAndBody(f)
+      content(bodyExpr, [t] => (e: Expr[t]) => (v1: Expr[T1], v2: Expr[T2]) => bodyFn[t](e.unseal, params, List(v1.unseal, v2.unseal)).seal.asInstanceOf[Expr[t]])
+    }
+
+    def open[T1, T2, T3, R, X](f: Expr[(T1, T2) => R])(content: (Expr[R], [t] => Expr[t] => (Expr[T1], Expr[T2], Expr[T3]) => Expr[t]) => X)(given qctx: QuoteContext)(given DummyImplicit, DummyImplicit): X = {
+      import qctx.tasty.{given, _}
+      val (params, bodyExpr) = paramsAndBody(f)
+      content(bodyExpr, [t] => (e: Expr[t]) => (v1: Expr[T1], v2: Expr[T2], v3: Expr[T3]) => bodyFn[t](e.unseal, params, List(v1.unseal, v2.unseal, v3.unseal)).seal.asInstanceOf[Expr[t]])
+    }
+
+    private def paramsAndBody[R](given qctx: QuoteContext)(f: Expr[Any]) = {
+      import qctx.tasty.{given, _}
+      val Block(List(DefDef("$anonfun", Nil, List(params), _, Some(body))), Closure(Ident("$anonfun"), None)) = f.unseal.etaExpand
+      (params, body.seal.asInstanceOf[Expr[R]])
+    }
+
+    private def bodyFn[t](given qctx: QuoteContext)(e: qctx.tasty.Term, params: List[qctx.tasty.ValDef], args: List[qctx.tasty.Term]): qctx.tasty.Term = {
+      import qctx.tasty.{given, _}
+      val map = params.map(_.symbol).zip(args).toMap
+      new TreeMap {
+        override def transformTerm(tree: Term)(given ctx: Context): Term =
+          super.transformTerm(tree) match
+            case tree: Ident => map.getOrElse(tree.symbol, tree)
+            case tree => tree
+      }.transformTerm(e)
     }
 
   }

tests/run-macros/quoted-pattern-open-expr/Macro_1.scala

@@ -7,5 +7,6 @@ private def testExpr(e: Expr[Int])(given QuoteContext): Expr[String] = {
     case '{ val y: Int = 4; $body } => Expr("Matched closed\n" + body.show)
     case '{ val y: Int = 4; ($body: Int => Int)(y) } => Expr("Matched open\n" + body.show)
     case '{ val y: Int => Int = x => x + 1; ($body: (Int => Int) => Int)(y) } => Expr("Matched open\n" + body.show)
+    case '{ def g(x: Int): Int = ($body: (Int => Int, Int) => Int)(g, x); 5 } => Expr("Matched open\n" + body.show)
   }
 }

tests/run-macros/quoted-pattern-open-expr/Test_2.scala

@@ -4,5 +4,9 @@ object Test {
     println(test { val x: Int = 4; 6: Int })
     println(test { val x: Int = 4; x * x })
     println(test { val f: Int => Int = x => x + 1; f(3) })
+    println(test { def g(x: Int): Int = x; 5 })
+    println(test { def g(x: Int): Int = g(4); 5 })
+    println(test { def g(x: Int): Int = g(x); 5 })
+
   }
 }