From 69b9515d0e3161ea7573e819de155710e7e3997f Mon Sep 17 00:00:00 2001
From: Albert Meltzer <7529386+kitbellew@users.noreply.github.com>
Date: Wed, 26 Jan 2022 11:56:28 -0800
Subject: [PATCH] FormatOps: implement indentOperator.exemptScope

---
 .../org/scalafmt/config/IndentOperator.scala  |  8 ++++++-
 .../org/scalafmt/internal/FormatOps.scala     | 24 +++++++++++++++++--
 .../test/resources/test/IndentOperator.stat   | 12 +++++-----
 3 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala
index f9cead6006..56bdfcbd02 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala
@@ -53,7 +53,7 @@ case class IndentOperator(
       "Use indentOperator.exemptScope instead (true->topLevelOnly, false->all)",
       "3.4.0"
     )
-    topLevelOnly: Boolean = true,
+    private val topLevelOnly: Boolean = true,
     private val exemptScope: Option[IndentOperator.Exempt] = None,
     @annotation.ExtraName("include")
     includeRegex: String = ".*",
@@ -65,6 +65,12 @@ case class IndentOperator(
 
   def noindent(op: String): Boolean =
     excludeRegexp.matcher(op).find() || !includeRegexp.matcher(op).find()
+
+  lazy val getExemptScope: IndentOperator.Exempt =
+    exemptScope.getOrElse(
+      if (topLevelOnly) IndentOperator.Exempt.topLevel
+      else IndentOperator.Exempt.all
+    )
 }
 
 object IndentOperator {
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
index 5c3ad02c71..e88dfad769 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
@@ -3,6 +3,7 @@ package org.scalafmt.internal
 import org.scalafmt.Error.UnexpectedTree
 import org.scalafmt.config.{
   BinPack,
+  IndentOperator,
   Newlines,
   ScalafmtConfig,
   ScalafmtRunner,
@@ -583,8 +584,27 @@ class FormatOps(
         case t: Case => t.pat.eq(child) || t.body.eq(child)
         case _ => false
       }
-      val allowNoIndent =
-        !style.indentOperator.topLevelOnly || isTopLevel(getChild)
+      def isEnclosedAlone(child: Tree) = child.parent.exists {
+        case Case(`child`, _, _) => true
+        case Term.If(`child`, _, _) => true
+        case Term.While(`child`, _) => true
+        case Term.Block(List(`child`)) => true
+        case SplitCallIntoParts(_, Left(Seq(`child`))) => true
+        case fun: Term.FunctionTerm => isBlockFunction(fun)
+        case _ =>
+          tokens.getHeadOpt(child).exists { headFt =>
+            val last = tokens.getLast(child)
+            matchingOpt(headFt.left)
+              .contains(prevNonComment(last).left) ||
+            matchingOpt(prevNonComment(prev(headFt)).left)
+              .contains(nextNonComment(last).right)
+          }
+      }
+      val allowNoIndent = style.indentOperator.getExemptScope match {
+        case IndentOperator.Exempt.all => true
+        case IndentOperator.Exempt.topLevel => isTopLevel(getChild)
+        case IndentOperator.Exempt.enclosedAlone => isEnclosedAlone(getChild)
+      }
       def isInfixTopLevelMatch(op: String, noindent: Boolean): Boolean = {
         noindent == style.indentOperator.noindent(op) &&
         noindent == allowNoIndent
diff --git a/scalafmt-tests/src/test/resources/test/IndentOperator.stat b/scalafmt-tests/src/test/resources/test/IndentOperator.stat
index aac5b2bba6..c7b0c16338 100644
--- a/scalafmt-tests/src/test/resources/test/IndentOperator.stat
+++ b/scalafmt-tests/src/test/resources/test/IndentOperator.stat
@@ -2930,7 +2930,7 @@ object a {
     b
   } else
     a &&
-    b
+      b
 }
 <<< ONLY enclosedAloneOnly, while
 indentOperator.exemptScope = enclosedAlone
@@ -2964,7 +2964,7 @@ object a {
     b
   )
     a &&
-    b
+      b
 }
 <<< ONLY enclosedAloneOnly, apply
 indentOperator.exemptScope = enclosedAlone
@@ -2996,7 +2996,7 @@ object a {
 object a {
   foo(
     a &&
-      b
+    b
   )
   foo {
     a &&
@@ -3010,10 +3010,10 @@ object a {
   )
   foo(
     a &&
-      b
+    b
   )(
     a &&
-      b
+    b
   )
 }
 <<< ONLY enclosedAloneOnly, case
@@ -3032,7 +3032,7 @@ a match {
 a match {
   case foo =>
     a &&
-    b
+      b
   case bar => {
     a &&
     b