Merge pull request #6380 from dotty-staging/use-contextual-types-in-quote-matcher

Use contextual types in quote matcher

Author: nicolasstucki

library/src-3.x/scala/internal/quoted/Matcher.scala

@@ -33,17 +33,19 @@ object Matcher {
   def unapply[Tup <: Tuple](scrutineeExpr: Expr[_])(implicit patternExpr: Expr[_], reflection: Reflection): Option[Tup] = {
     import reflection.{Bind => BindPattern, _}
 
+    type Env = Set[(Symbol, Symbol)]
+
     // TODO improve performance
 
     /** Check that the trees match and return the contents from the pattern holes.
      *  Return None if the trees do not match otherwise return Some of a tuple containing all the contents in the holes.
      *
      * @param scrutinee The tree beeing matched
      * @param pattern The pattern tree that the scrutinee should match. Contains `patternHole` holes.
-     * @param env Set of tuples containing pairs of symbols (s, p) where s defines a symbol in `scrutinee` which corresponds to symbol p in `pattern`.
+     * @param `the[Env]` Set of tuples containing pairs of symbols (s, p) where s defines a symbol in `scrutinee` which corresponds to symbol p in `pattern`.
      * @return `None` if it did not match or `Some(tup: Tuple)` if it matched where `tup` contains the contents of the holes.
      */
-    def treeMatches(scrutinee: Tree, pattern: Tree)(implicit env: Set[(Symbol, Symbol)]): Option[Tuple] = {
+    def treeMatches(scrutinee: Tree, pattern: Tree) given Env: Option[Tuple] = {
 
       /** Check that both are `val` or both are `lazy val` or both are `var` **/
       def checkValFlags(): Boolean = {
@@ -101,7 +103,7 @@ object Matcher {
         case (Typed(expr1, tpt1), Typed(expr2, tpt2)) =>
           foldMatchings(treeMatches(expr1, expr2), treeMatches(tpt1, tpt2))
 
-        case (Ident(_), Ident(_)) if scrutinee.symbol == pattern.symbol || env((scrutinee.symbol, pattern.symbol)) =>
+        case (Ident(_), Ident(_)) if scrutinee.symbol == pattern.symbol || the[Env].apply((scrutinee.symbol, pattern.symbol)) =>
           Some(())
 
         case (Select(qual1, _), Select(qual2, _)) if scrutinee.symbol == pattern.symbol =>
@@ -160,8 +162,8 @@ object Matcher {
             if (hasBindAnnotation(pattern.symbol) || hasBindTypeAnnotation(tpt2)) bindingMatch(scrutinee.symbol)
             else Some(())
           val returnTptMatch = treeMatches(tpt1, tpt2)
-          val rhsEnv = env + (scrutinee.symbol -> pattern.symbol)
-          val rhsMatchings = treeOptMatches(rhs1, rhs2)(rhsEnv)
+          val rhsEnv = the[Env] + (scrutinee.symbol -> pattern.symbol)
+          val rhsMatchings = treeOptMatches(rhs1, rhs2) given rhsEnv
           foldMatchings(bindMatch, returnTptMatch, rhsMatchings)
 
         case (DefDef(_, typeParams1, paramss1, tpt1, Some(rhs1)), DefDef(_, typeParams2, paramss2, tpt2, Some(rhs2))) =>
@@ -174,10 +176,10 @@ object Matcher {
             else Some(())
           val tptMatch = treeMatches(tpt1, tpt2)
           val rhsEnv =
-            env + (scrutinee.symbol -> pattern.symbol) ++
+            the[Env] + (scrutinee.symbol -> pattern.symbol) ++
               typeParams1.zip(typeParams2).map((tparam1, tparam2) => tparam1.symbol -> tparam2.symbol) ++
               paramss1.flatten.zip(paramss2.flatten).map((param1, param2) => param1.symbol -> param2.symbol)
-          val rhsMatch = treeMatches(rhs1, rhs2)(rhsEnv)
+          val rhsMatch = treeMatches(rhs1, rhs2) given rhsEnv
 
           foldMatchings(bindMatch, typeParmasMatch, paramssMatch, tptMatch, rhsMatch)
 
@@ -227,19 +229,23 @@ object Matcher {
       }
     }
 
-    def treeOptMatches(scrutinee: Option[Tree], pattern: Option[Tree])(implicit env: Set[(Symbol, Symbol)]): Option[Tuple] = {
+    def treeOptMatches(scrutinee: Option[Tree], pattern: Option[Tree]) given Env: Option[Tuple] = {
       (scrutinee, pattern) match {
         case (Some(x), Some(y)) => treeMatches(x, y)
         case (None, None) => Some(())
         case _ => None
       }
     }
 
-    def caseMatches(scrutinee: CaseDef, pattern: CaseDef)(implicit env: Set[(Symbol, Symbol)]): Option[Tuple] = {
+    def caseMatches(scrutinee: CaseDef, pattern: CaseDef) given Env: Option[Tuple] = {
       val (caseEnv, patternMatch) = patternMatches(scrutinee.pattern, pattern.pattern)
-      val guardMatch = treeOptMatches(scrutinee.guard, pattern.guard)(caseEnv)
-      val rhsMatch = treeMatches(scrutinee.rhs, pattern.rhs)(caseEnv)
-      foldMatchings(patternMatch, guardMatch, rhsMatch)
+
+      {
+        implied for Env = caseEnv
+        val guardMatch = treeOptMatches(scrutinee.guard, pattern.guard)
+        val rhsMatch = treeMatches(scrutinee.rhs, pattern.rhs)
+        foldMatchings(patternMatch, guardMatch, rhsMatch)
+      }
     }
 
     /** Check that the pattern trees match and return the contents from the pattern holes.
@@ -248,21 +254,21 @@ object Matcher {
      *
      * @param scrutinee The pattern tree beeing matched
      * @param pattern The pattern tree that the scrutinee should match. Contains `patternHole` holes.
-     * @param env Set of tuples containing pairs of symbols (s, p) where s defines a symbol in `scrutinee` which corresponds to symbol p in `pattern`.
+     * @param `the[Env]` Set of tuples containing pairs of symbols (s, p) where s defines a symbol in `scrutinee` which corresponds to symbol p in `pattern`.
      * @return The new environment containing the bindings defined in this pattern tuppled with
      *         `None` if it did not match or `Some(tup: Tuple)` if it matched where `tup` contains the contents of the holes.
      */
-    def patternMatches(scrutinee: Pattern, pattern: Pattern)(implicit env: Set[(Symbol, Symbol)]): (Set[(Symbol, Symbol)], Option[Tuple]) = (scrutinee, pattern) match {
+    def patternMatches(scrutinee: Pattern, pattern: Pattern) given Env: (Env, Option[Tuple]) = (scrutinee, pattern) match {
       case (Pattern.Value(v1), Pattern.Unapply(TypeApply(Select(patternHole @ Ident("patternHole"), "unapply"), List(tpt)), Nil, Nil))
           if patternHole.symbol.owner.fullName == "scala.runtime.quoted.Matcher$" =>
-        (env, Some(Tuple1(v1.seal)))
+        (the[Env], Some(Tuple1(v1.seal)))
 
       case (Pattern.Value(v1), Pattern.Value(v2)) =>
-        (env, treeMatches(v1, v2))
+        (the[Env], treeMatches(v1, v2))
 
       case (Pattern.Bind(name1, body1), Pattern.Bind(name2, body2)) =>
-        val bindEnv = env + (scrutinee.symbol -> pattern.symbol)
-        patternMatches(body1, body2)(bindEnv)
+        val bindEnv = the[Env] + (scrutinee.symbol -> pattern.symbol)
+        patternMatches(body1, body2) given bindEnv
 
       case (Pattern.Unapply(fun1, implicits1, patterns1), Pattern.Unapply(fun2, implicits2, patterns2)) =>
         val funMatch = treeMatches(fun1, fun2)
@@ -276,10 +282,10 @@ object Matcher {
         foldPatterns(patterns1, patterns2)
 
       case (Pattern.TypeTest(tpt1), Pattern.TypeTest(tpt2)) =>
-        (env, treeMatches(tpt1, tpt2))
+        (the[Env], treeMatches(tpt1, tpt2))
 
       case (Pattern.WildcardPattern(), Pattern.WildcardPattern()) =>
-        (env, Some(()))
+        (the[Env], Some(()))
 
       case _ =>
         if (debug)
@@ -299,18 +305,19 @@ object Matcher {
                |
                |
                |""".stripMargin)
-        (env, None)
+        (the[Env], None)
     }
 
-    def foldPatterns(patterns1: List[Pattern], patterns2: List[Pattern])(implicit env: Set[(Symbol, Symbol)]): (Set[(Symbol, Symbol)], Option[Tuple]) = {
-      if (patterns1.size != patterns2.size) (env, None)
-      else patterns1.zip(patterns2).foldLeft((env, Option[Tuple](()))) { (acc, x) =>
-        val (env, res) = patternMatches(x._1, x._2)(acc._1)
+    def foldPatterns(patterns1: List[Pattern], patterns2: List[Pattern]) given Env: (Env, Option[Tuple]) = {
+      if (patterns1.size != patterns2.size) (the[Env], None)
+      else patterns1.zip(patterns2).foldLeft((the[Env], Option[Tuple](()))) { (acc, x) =>
+        val (env, res) = patternMatches(x._1, x._2) given acc._1
         (env, foldMatchings(acc._2, res))
       }
     }
 
-    treeMatches(scrutineeExpr.unseal, patternExpr.unseal)(Set.empty).asInstanceOf[Option[Tup]]
+    implied for Env = Set.empty
+    treeMatches(scrutineeExpr.unseal, patternExpr.unseal).asInstanceOf[Option[Tup]]
   }
 
   /** Joins the mattchings into a single matching. If any matching is `None` the result is `None`.