Merge pull request scala#10728 from som-snytt/issue/12894-repl-mutation

REPL handles assignment ops like Assign

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}
@@ -621,16 +621,14 @@ class IMain(val settings: Settings, parentClassLoaderOverride: Option[ClassLoade
   override lazy val power = new Power(this, new StdReplVals(this))(tagOfStdReplVals, classTag[StdReplVals])
 
   /** Here is where we:
-    *
-    *  1) Read some source code, and put it in the "read" object.
-    *  2) Evaluate the read object, and put the result in the "eval" object.
-    *  3) Create a String for human consumption, and put it in the "print" object.
-    *
-    *  Read! Eval! Print! Some of that not yet centralized here.
-    */
-  class ReadEvalPrint(val lineId: Int) {
-    def this() = this(freshLineId())
-
+   *
+   *  1) Read some source code, and put it in the "read" object.
+   *  2) Evaluate the read object, and put the result in the "eval" object.
+   *  3) Create a String for human consumption, and put it in the "print" object.
+   *
+   *  Read! Eval! Print! Some of that not yet centralized here.
+   */
+  class ReadEvalPrint(val lineId: Int = freshLineId()) {
     val packageName = sessionNames.packageName(lineId)
     val readName    = sessionNames.read
     val evalName    = sessionNames.eval
@@ -813,6 +811,7 @@ 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
@@ -823,7 +822,7 @@ class IMain(val settings: Settings, parentClassLoaderOverride: Option[ClassLoade
     }
 
     /** handlers for each tree in this request */
-    val handlers: List[MemberHandler] = trees map (memberHandlers chooseHandler _)
+    val handlers: List[MemberHandler] = trees.map(memberHandlers.chooseHandler(_))
     val definesValueClass = handlers.exists(_.definesValueClass)
 
     val isClassBased = IMain.this.isClassBased && !definesValueClass
@@ -967,7 +966,8 @@ class IMain(val settings: Settings, parentClassLoaderOverride: Option[ClassLoade
 
 
     /** Compile the object file.  Returns whether the compilation succeeded.
-      *  If all goes well, the "types" map is computed. */
+     *  If all goes well, the "types" map is computed.
+     */
     def compile: Boolean = {
 
       // compile the object containing the user's code

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

@@ -1,14 +1,14 @@
 
-scala> var x = 10
-var x: Int = 10
+scala> var x = 42
+var x: Int = 42
 
-scala> var y = 11
-var y: Int = 11
+scala> x = 17
+// mutated x
 
-scala> x = 12
+scala> x += 10
 // mutated x
 
-scala> y = 13
-// mutated y
+scala> x
+val res0: Int = 27
 
 scala> :quit

test/files/run/repl-assign.scala

@@ -1,10 +1,4 @@
-import scala.tools.partest.ReplTest
 
-object Test extends ReplTest {
-  def code = """
-var x = 10
-var y = 11
-x = 12
-y = 13
-  """
-}
+import scala.tools.partest.SessionTest
+
+object Test extends SessionTest

test/files/run/t8935-object.scala

@@ -1,31 +1,3 @@
 import scala.tools.partest.SessionTest
 
-import scala.tools.nsc.Settings
-
-object Test extends SessionTest {
-  /* future
-  override def transformSettings(s: Settings): Settings = {
-    //s.YreplWrap.value = "object"
-    s
-  }
-  */
-  override def session =
-"""
-scala> 41+1
-res0: Int = 42
-
-scala> $intp.valueOfTerm($intp.mostRecentVar)
-res1: Option[Any] = Some(42)
-
-scala> val i = 17 ; 64
-i: Int = 17
-res2: Int = 64
-
-scala> $intp.valueOfTerm($intp.mostRecentVar)
-res3: Option[Any] = Some(64)
-
-scala> $intp.valueOfTerm("i")
-res4: Option[Any] = Some(17)
-
-scala> :quit"""
-}
+object Test extends SessionTest