@@ -799,7 +799,7 @@ object IfBodyHelpers {
799799 final case class MatchTuple (
800800 scrutinee : Term ,
801801 arity : Int ,
802- fields : List [Int -> Var ]
802+ fields : List [Str -> Var ]
803803 ) extends Condition
804804 final case class BooleanTest (test : Term ) extends Condition
805805 }
@@ -904,7 +904,8 @@ object IfBodyHelpers {
904904abstract class MutCaseOf {
905905 def merge
906906 (branch : Ls [IfBodyHelpers .Condition ] -> Term )
907- (implicit raise : Diagnostic => Unit , allowDuplicate : Boolean = false ): Unit
907+ (implicit raise : Diagnostic => Unit ): Unit
908+ def mergeDefault (default : Term ): Unit
908909 def toTerm : Term
909910}
910911
@@ -1008,11 +1009,10 @@ object MutCaseOf {
10081009
10091010 // A short-hand for pattern matchings with only true and false branches.
10101011 final case class IfThenElse (condition : Term , var whenTrue : MutCaseOf , var whenFalse : MutCaseOf ) extends MutCaseOf {
1011- override def merge (branch : Ls [Condition ] -> Term )(implicit raise : Diagnostic => Unit , allowDuplicate : Bool ): Unit =
1012+ override def merge (branch : Ls [Condition ] -> Term )(implicit raise : Diagnostic => Unit ): Unit =
10121013 branch match {
10131014 case Nil -> term =>
10141015 whenFalse match {
1015- case Consequent (_) if allowDuplicate => ()
10161016 case Consequent (_) =>
10171017 raise(WarningReport (Message .fromStr(" duplicated else branch" -> N :: Nil ))
10181018 case MissingCase => whenFalse = Consequent (term)
@@ -1035,14 +1035,23 @@ object MutCaseOf {
10351035 case _ => whenFalse.merge(branch)
10361036 }
10371037 }
1038+
1039+ override def mergeDefault (default : Term ): Unit = {
1040+ whenTrue.mergeDefault(default)
1041+ whenFalse match {
1042+ case MissingCase => whenFalse = Consequent (default)
1043+ case _ => whenFalse.mergeDefault(default)
1044+ }
1045+ }
1046+
10381047 override def toTerm : Term = {
10391048 val falseBranch = Wildcard (whenFalse.toTerm)
10401049 val trueBranch = Case (Var (" true"
10411050 CaseOf (condition, trueBranch)
10421051 }
10431052 }
10441053 final case class Match (scrutinee : Term , val branches : Buffer [Branch ]) extends MutCaseOf {
1045- override def merge (branch : Ls [Condition ] -> Term )(implicit raise : Diagnostic => Unit , allowDuplicate : Bool ): Unit = {
1054+ override def merge (branch : Ls [Condition ] -> Term )(implicit raise : Diagnostic => Unit ): Unit = {
10461055 branch match {
10471056 case (Condition .MatchClass (scrutinee2, className, fields) :: tail) -> term if scrutinee2 === scrutinee =>
10481057 branches.find(_.matches(className)) match {
@@ -1054,25 +1063,16 @@ object MutCaseOf {
10541063 branch.consequent.merge(tail -> term)
10551064 }
10561065 case (Condition .MatchTuple (scrutinee2, arity, fields) :: tail) -> term if scrutinee2 === scrutinee =>
1057- val tupleClassName = Var (s " Tuple# $arity" )
1058- val indexFields = fields.map { case (index, alias) => index.toString -> alias }
1066+ val tupleClassName = Var (s " Tuple# $arity" ) // TODO: Find a name known by Typer.
10591067 branches.find(_.matches(tupleClassName)) match {
10601068 case N =>
1061- branches += Branch (S (tupleClassName -> Buffer .from(indexFields )), buildBranch(tail, term))
1069+ branches += Branch (S (tupleClassName -> Buffer .from(fields )), buildBranch(tail, term))
10621070 case S (branch) =>
1063- branch.addFields(indexFields )
1071+ branch.addFields(fields )
10641072 branch.consequent.merge(tail -> term)
10651073 }
10661074 // A wild card case. We should propagate wildcard to every default positions.
1067- case Nil -> term =>
1068- var hasWildcard = false
1069- branches.foreach {
1070- case Branch (_, _ : Consequent | MissingCase ) => ()
1071- case Branch (patternFields, consequent) =>
1072- consequent.merge(branch)(implicitly, true )
1073- hasWildcard &&= patternFields.isEmpty
1074- }
1075- if (! hasWildcard) branches += Branch (N , Consequent (term))
1075+ case Nil -> term => mergeDefault(term)
10761076 case conditions -> term =>
10771077 // Locate the wildcard case.
10781078 branches.find(_.isWildcard) match {
@@ -1083,6 +1083,19 @@ object MutCaseOf {
10831083 }
10841084 }
10851085 }
1086+
1087+ override def mergeDefault (default : Term ): Unit = {
1088+ var hasWildcard = false
1089+ branches.foreach {
1090+ case Branch (_, _ : Consequent | MissingCase ) => ()
1091+ case Branch (patternFields, consequent) =>
1092+ consequent.mergeDefault(default)
1093+ hasWildcard &&= patternFields.isEmpty
1094+ }
1095+ // If this match doesn't have a default case, we make one.
1096+ if (! hasWildcard) branches += Branch (N , Consequent (default))
1097+ }
1098+
10861099 override def toTerm : Term = {
10871100 def rec (xs : Ls [Branch ]): CaseBranches =
10881101 xs match {
@@ -1098,16 +1111,18 @@ object MutCaseOf {
10981111 }
10991112 }
11001113 final case class Consequent (term : Term ) extends MutCaseOf {
1101- override def merge
1102- (branch : Ls [Condition ] -> Term )
1103- (implicit raise : Diagnostic => Unit , allowDuplicate : Bool ): Unit =
1114+ override def merge (branch : Ls [Condition ] -> Term )(implicit raise : Diagnostic => Unit ): Unit =
11041115 raise(WarningReport (Message .fromStr(" duplicated branch" -> N :: Nil ))
1116+
1117+ override def mergeDefault (default : Term ): Unit = ()
1118+
11051119 override def toTerm : Term = term
11061120 }
11071121 final case object MissingCase extends MutCaseOf {
1108- override def merge
1109- (branch : Ls [Condition ] -> Term )
1110- (implicit raise : Diagnostic => Unit , allowDuplicate : Bool ): Unit = ???
1122+ override def merge (branch : Ls [Condition ] -> Term )(implicit raise : Diagnostic => Unit ): Unit = ???
1123+
1124+ override def mergeDefault (default : Term ): Unit = ()
1125+
11111126 override def toTerm : Term =
11121127 throw new IfDesugaringException (" missing a default branch"
11131128 }
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