SI-7747 Support class based wrappers clean up

Simplified the code paths to just use one of two `Wrapper` types
for textual templating.

Simplified the class-based template to use the same `$iw` name
for the both the class and the wrapper value.  In addition,
the $read value is an object extending $read, instead of containing
an extra instance field, which keeps paths to values the same
for both templates.

Both styles trigger loading the value object by referencing the
value that immediately wraps the user code, although for the
class style, inner vals are eager and it would suffice to load
the enclosing `$read` object.

The proposed template included extra vals for values imported
from history, but this is not necessary since such an import
is always a stable path. (Or, counter-example to test is welcome.)

The test for t5148 is updated as a side effect. Probably internal
APIs don't make good test subjects.

Modify -Y option message.

1 files changed, 6 insertions, 26 deletions

diff --git a/src/repl/scala/tools/nsc/interpreter/Imports.scala b/src/repl/scala/tools/nsc/interpreter/Imports.scala
index c8f9a677b2..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.
@@ -130,23 +130,10 @@ trait Imports {
 
     // add code for a new object to hold some imports
     def addWrapper() {
-      if (classBasedWrappers) addClassBasedWrapper()
-      else addObjectBasedWrapper()
-    }
-
-    def addObjectBasedWrapper() {
-      val impname = nme.INTERPRETER_IMPORT_WRAPPER
-      code append "object %s {\n".format(impname)
-      trailingBraces append "}\n"
-      accessPath append ("." + impname)
-      currentImps.clear()
-    }
-
-    def addClassBasedWrapper() {
-      val impname = nme.INTERPRETER_IMPORT_WRAPPER
-      code append "class %sC extends Serializable {\n".format(impname)
-      trailingBraces append "}\nval " + impname + " = new " + impname + "C;\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()
     }
 
@@ -178,14 +165,7 @@ trait Imports {
           case x =>
             for (sym <- x.definedSymbols) {
               maybeWrap(sym.name)
-              if (classBasedWrappers) {
-                if (!code.toString.endsWith(".`" + sym.name + "`;\n")) {
-                  val valName = "$VAL" + req.lineRep.lineId
-                  code.append("val " + valName + " = " + req.lineRep.readPath + ".INSTANCE;\n")
-                  code.append("import " + valName + req.accessPath + ".`" + sym.name + "`;\n")
-                }
-              } else
-                code append s"import ${x.path}\n"
+              code append s"import ${x.path}\n"
               currentImps += sym.name
             }
         }