FormatTokensRewrite: keep each token's replacement

scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/FormatTokensRewrite.scala

@@ -133,7 +133,7 @@ class FormatTokensRewrite(
             if (formatOff) None
             else
               session.claimedRule match {
-                case x @ Some(rule) => if (applyRule(rule)) x else None
+                case Some(c) => if (applyRule(c.rule)) Some(c.rule) else None
                 case _ => applyRules
               }
           leftDelimIndex.prepend((ldelimIdx, ruleOpt))
@@ -147,7 +147,7 @@ class FormatTokensRewrite(
           val replacement = ruleOpt match {
             case Some(rule)
                 if !ft.meta.formatOff &&
-                  session.claimedRule.forall(_ eq rule) =>
+                  session.claimedRule.forall(_.rule eq rule) =>
               implicit val style = styleMap.at(ft.right)
               if (rule.enabled) rule.onRight(tokens(ldelimIdx), formatOff)
               else None
@@ -243,20 +243,26 @@ object FormatTokensRewrite {
 
   private[rewrite] class Session(rules: Seq[Rule]) {
     private implicit val implicitSession: Session = this
-    private val claimed = new mutable.HashMap[Int, Rule]()
+    private val claimed = new mutable.HashMap[Int, Claimant]()
     private[FormatTokensRewrite] val tokens =
       new mutable.ArrayBuffer[Replacement]()
 
-    def claimedRule(implicit ft: FormatToken): Option[Rule] =
-      claimed.get(ft.meta.idx)
+    @inline
+    def claimedRule(implicit ft: FormatToken): Option[Claimant] =
+      claimedRule(ft.meta.idx)
+
+    @inline
+    private[rewrite] def claimedRule(ftIdx: Int): Option[Claimant] =
+      claimed.get(ftIdx)
 
     private[FormatTokensRewrite] def applyRule(
         rule: Rule
     )(implicit ft: FormatToken, style: ScalafmtConfig): Boolean =
       rule.enabled && (rule.onToken match {
         case Some(repl) =>
-          claimed.getOrElseUpdate(ft.meta.idx, rule)
-          repl.claim.foreach { claimed.getOrElseUpdate(_, rule) }
+          val claimant = new Claimant(rule, repl)
+          claimed.getOrElseUpdate(ft.meta.idx, claimant)
+          repl.claim.foreach { claimed.getOrElseUpdate(_, claimant) }
           tokens.append(repl)
           true
         case _ => false
@@ -277,6 +283,11 @@ object FormatTokensRewrite {
       rules.find(tag.runtimeClass.isInstance)
   }
 
+  private[rewrite] class Claimant(
+      val rule: Rule,
+      val replacement: Replacement
+  )
+
   private[rewrite] class Replacement(
       val ft: FormatToken,
       val how: ReplacementType,

scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantParens.scala

@@ -91,7 +91,7 @@ class RedundantParens(ftoks: FormatTokens) extends FormatTokensRewrite.Rule {
       case _: Token.RightParen if (left.how eq ReplacementType.Remove) && {
             val maybeCommaFt = ftoks.prevNonComment(ft)
             !maybeCommaFt.left.is[Token.Comma] ||
-            session.claimedRule(ftoks.prev(maybeCommaFt)).isDefined
+            session.claimedRule(maybeCommaFt.meta.idx - 1).isDefined
           } /* check for trailing comma */ =>
         Some((left, removeToken))
       case _ => None

scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RewriteTrailingCommas.scala

@@ -46,8 +46,8 @@ private class RewriteTrailingCommas(ftoks: FormatTokens)
         case rp: Token.RightParen =>
           rightOwner.isAny[Member.SyntaxValuesClause, Member.Tuple] ||
           ftoks.matchingOpt(rp).exists { lp =>
-            val rule = session.claimedRule(ftoks.justBefore(lp))
-            rule.forall(_.isInstanceOf[RedundantParens])
+            val claimant = session.claimedRule(ftoks.justBefore(lp))
+            claimant.forall(_.rule.isInstanceOf[RedundantParens])
           }
 
         case _: Token.RightBracket =>