Merge pull request #3123 from som-snytt/issue/7747-scrapcodes-fix

SI-7747 Support class based wrappers in REPL

3 files changed, 60 insertions, 17 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index b8ca4adc14..7568c789fb 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -174,6 +174,7 @@ trait ScalaSettings extends AbsScalaSettings
   val Yreifycopypaste = BooleanSetting    ("-Yreify-copypaste", "Dump the reified trees in copypasteable representation.")
   val Ymacronoexpand  = BooleanSetting    ("-Ymacro-no-expand", "Don't expand macros. Might be useful for scaladoc and presentation compiler, but will crash anything which uses macros and gets past typer.")
   val Yreplsync       = BooleanSetting    ("-Yrepl-sync", "Do not use asynchronous code for repl startup")
+  val Yreplclassbased = BooleanSetting    ("-Yrepl-class-based", "Use classes to wrap REPL snippets instead of objects")
   val Yreploutdir     = StringSetting     ("-Yrepl-outdir", "path", "Write repl-generated classfiles to given output directory (use \"\" to generate a temporary dir)" , "")
   val YmethodInfer    = BooleanSetting    ("-Yinfer-argument-types", "Infer types for arguments of overriden methods.")
   val etaExpandKeepsStar = BooleanSetting ("-Yeta-expand-keeps-star", "Eta-expand varargs methods to T* rather than Seq[T].  This is a temporary option to ease transition.").withDeprecationMessage(removalIn212)
diff --git a/src/repl/scala/tools/nsc/interpreter/IMain.scala b/src/repl/scala/tools/nsc/interpreter/IMain.scala
index e4a3416152..0d55423247 100644
--- a/src/repl/scala/tools/nsc/interpreter/IMain.scala
+++ b/src/repl/scala/tools/nsc/interpreter/IMain.scala
@@ -272,6 +272,7 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
       case s                                 => s
     } mkString "."
   )
+  def readRootPath(readPath: String) = getModuleIfDefined(readPath)
 
   abstract class PhaseDependentOps {
     def shift[T](op: => T): T
@@ -700,7 +701,7 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
    *
    *  Read! Eval! Print! Some of that not yet centralized here.
    */
-  class ReadEvalPrint(lineId: Int) {
+  class ReadEvalPrint(val lineId: Int) {
     def this() = this(freshLineId())
 
     val packageName = sessionNames.line + lineId
@@ -777,7 +778,7 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
       * following accessPath into the outer one.
       */
     def resolvePathToSymbol(accessPath: String): Symbol = {
-      val readRoot  = getModuleIfDefined(readPath)   // the outermost wrapper
+      val readRoot = readRootPath(readPath) // the outermost wrapper
       (accessPath split '.').foldLeft(readRoot: Symbol) {
         case (sym, "")    => sym
         case (sym, name)  => exitingTyper(termMember(sym, name))
@@ -848,30 +849,69 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
     /** Code to import bound names from previous lines - accessPath is code to
       * append to objectName to access anything bound by request.
       */
-    val ComputedImports(importsPreamble, importsTrailer, accessPath) =
-      exitingTyper(importsCode(referencedNames.toSet))
+    lazy val ComputedImports(importsPreamble, importsTrailer, accessPath) =
+      exitingTyper(importsCode(referencedNames.toSet, ObjectSourceCode))
 
     /** the line of code to compute */
     def toCompute = line
 
-    def fullPath(vname: String) = s"${lineRep.readPath}$accessPath.`$vname`"
+    /** The path of the value that contains the user code. */
+    def fullAccessPath = s"${lineRep.readPath}$accessPath"
+
+    /** The path of the given member of the wrapping instance. */
+    def fullPath(vname: String) = s"$fullAccessPath.`$vname`"
 
     /** generate the source code for the object that computes this request */
-    private object ObjectSourceCode extends IMain.CodeAssembler[MemberHandler] {
+    abstract class Wrapper extends IMain.CodeAssembler[MemberHandler] {
       def path = originalPath("$intp")
       def envLines = {
         if (!isReplPower) Nil // power mode only for now
         else List("def %s = %s".format("$line", tquoted(originalLine)), "def %s = Nil".format("$trees"))
       }
-
-      val preamble = """
-        |object %s {
+      def preamble = s"""
+        |$preambleHeader
         |%s%s%s
-      """.stripMargin.format(lineRep.readName, envLines.map("  " + _ + ";\n").mkString, importsPreamble, indentCode(toCompute))
-      val postamble = importsTrailer + "\n}"
+      """.stripMargin.format(lineRep.readName, envLines.map("  " + _ + ";\n").mkString,
+        importsPreamble, indentCode(toCompute))
+
       val generate = (m: MemberHandler) => m extraCodeToEvaluate Request.this
+
+      /** A format string with %s for $read, specifying the wrapper definition. */
+      def preambleHeader: String
+
+      /** Like preambleHeader for an import wrapper. */
+      def prewrap: String = preambleHeader + "\n"
+
+      /** Like postamble for an import wrapper. */
+      def postwrap: String
+    }
+
+    private class ObjectBasedWrapper extends Wrapper {
+      def preambleHeader = "object %s {"
+
+      def postamble = importsTrailer + "\n}"
+
+      def postwrap = "}\n"
     }
 
+    private class ClassBasedWrapper extends Wrapper {
+      def preambleHeader = "class %s extends Serializable {"
+
+      /** Adds an object that instantiates the outer wrapping class. */
+      def postamble  = s"""$importsTrailer
+                          |}
+                          |object ${lineRep.readName} extends ${lineRep.readName}
+                          |""".stripMargin
+
+      import nme.{ INTERPRETER_IMPORT_WRAPPER => iw }
+
+      /** Adds a val that instantiates the wrapping class. */
+      def postwrap = s"}\nval $iw = new $iw\n"
+    }
+
+    private lazy val ObjectSourceCode: Wrapper =
+      if (settings.Yreplclassbased) new ClassBasedWrapper else new ObjectBasedWrapper
+
     private object ResultObjectSourceCode extends IMain.CodeAssembler[MemberHandler] {
       /** We only want to generate this code when the result
        *  is a value which can be referred to as-is.
@@ -890,7 +930,7 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
       |    (""
       """.stripMargin.format(
         lineRep.evalName, evalResult, lineRep.printName,
-        executionWrapper, lineRep.readName + accessPath
+        executionWrapper, fullAccessPath
       )
 
       val postamble = """
diff --git a/src/repl/scala/tools/nsc/interpreter/Imports.scala b/src/repl/scala/tools/nsc/interpreter/Imports.scala
index ff7bfd432c..5244858a62 100644
--- a/src/repl/scala/tools/nsc/interpreter/Imports.scala
+++ b/src/repl/scala/tools/nsc/interpreter/Imports.scala
@@ -92,7 +92,7 @@ trait Imports {
    * last one imported is actually usable.
    */
   case class ComputedImports(prepend: String, append: String, access: String)
-  protected def importsCode(wanted: Set[Name]): ComputedImports = {
+  protected def importsCode(wanted: Set[Name], wrapper: Request#Wrapper): ComputedImports = {
     /** Narrow down the list of requests from which imports
      *  should be taken.  Removes requests which cannot contribute
      *  useful imports for the specified set of wanted names.
@@ -130,13 +130,15 @@ trait Imports {
 
     // add code for a new object to hold some imports
     def addWrapper() {
-      val impname = nme.INTERPRETER_IMPORT_WRAPPER
-      code append "object %s {\n".format(impname)
-      trailingBraces append "}\n"
-      accessPath append ("." + impname)
+      import nme.{ INTERPRETER_IMPORT_WRAPPER => iw }
+      code append (wrapper.prewrap format iw)
+      trailingBraces append wrapper.postwrap
+      accessPath append s".$iw"
       currentImps.clear()
     }
+
     def maybeWrap(names: Name*) = if (names exists currentImps) addWrapper()
+
     def wrapBeforeAndAfter[T](op: => T): T = {
       addWrapper()
       try op finally addWrapper()