Handle assignment ops

Author: Som Snytt

src/repl/scala/tools/nsc/interpreter/IMain.scala

@@ -19,9 +19,9 @@ import java.net.URL
 import scala.collection.mutable, mutable.ListBuffer
 import scala.language.implicitConversions
 import scala.reflect.{ClassTag, classTag}
+import scala.reflect.internal.{FatalError, Flags, MissingRequirementError, NoPhase, Precedence}
 import scala.reflect.internal.util.ScalaClassLoader.URLClassLoader
 import scala.reflect.internal.util.{AbstractFileClassLoader, BatchSourceFile, ListOfNil, Position, ReplBatchSourceFile, SourceFile}
-import scala.reflect.internal.{FatalError, Flags, MissingRequirementError, NoPhase}
 import scala.reflect.runtime.{universe => ru}
 import scala.tools.nsc.{Global, Settings}
 import scala.tools.nsc.interpreter.Results.{Error, Incomplete, Result, Success}
@@ -813,6 +813,7 @@ class IMain(val settings: Settings, parentClassLoaderOverride: Option[ClassLoade
       case init :+ tree =>
         def loop(scrut: Tree): Tree = scrut match {
           case _: Assign                => tree
+          case Apply(Select(_, op), _) if Precedence(op.decoded).level == 0 => tree
           case _: RefTree | _: TermTree => storeInVal(tree)
           case Annotated(_, arg)        => loop(arg)
           case _                        => tree

src/repl/scala/tools/nsc/interpreter/MemberHandlers.scala

@@ -15,6 +15,7 @@ package scala.tools.nsc.interpreter
 import scala.language.implicitConversions
 
 import scala.collection.mutable
+import scala.reflect.internal.Precedence
 
 trait MemberHandlers {
   val intp: IMain
@@ -77,7 +78,9 @@ trait MemberHandlers {
     case member: ModuleDef                     => new ModuleHandler(member)
     case member: ClassDef                      => new ClassHandler(member)
     case member: TypeDef                       => new TypeAliasHandler(member)
-    case member: Assign                        => new AssignHandler(member)
+    case member: Assign                        => AssignHandler(member)
+    case member @ Apply(Select(_, op), _)
+    if Precedence(op.decoded).level == 0       => AssignHandler(member)
     case member: Import                        => new ImportHandler(member.duplicate) // duplicate because the same tree will be type checked (which loses info)
     case DocDef(_, documented)                 => chooseHandler(documented)
     case member                                => new GenericHandler(member)
@@ -175,9 +178,16 @@ trait MemberHandlers {
     def notification(req: Request) = s"def ${req.defTypeOf(name)}"
   }
 
-  class AssignHandler(member: Assign) extends MemberHandler(member) {
+  class AssignHandler private (member: Tree, lhs: Tree) extends MemberHandler(member) {
     override def resultExtractionCode(req: Request) =
-      codegenln(s"// mutated ${member.lhs}")
+      codegenln(s"// mutated $lhs")
+  }
+  object AssignHandler {
+    def apply(member: Assign) = new AssignHandler(member, member.lhs)
+    def apply(member: Apply) = member match {
+      case Apply(Select(qual, op), _) if Precedence(op.decoded).level == 0 => new AssignHandler(member, qual)
+      case _ => new GenericHandler(member)
+    }
   }
 
   class ModuleHandler(module: ModuleDef) extends MemberDefHandler(module) {

test/files/run/repl-assign.check

@@ -11,4 +11,7 @@ scala> x = 12
 scala> y = 13
 // mutated y
 
+scala> x += 30
+// mutated x
+
 scala> :quit

test/files/run/repl-assign.scala

@@ -6,5 +6,6 @@ var x = 10
 var y = 11
 x = 12
 y = 13
+x += 30
   """
 }