WIP exploring places where we can avoid Name.toString

src/compiler/scala/tools/nsc/ast/parser/Parsers.scala

@@ -338,13 +338,14 @@ self =>
 
     /** Are we inside the Scala package? Set for files that start with package scala
      */
-    private var inScalaPackage = false
-    private var currentPackage = ""
+    private var packageStack: List[Tree] = Nil
     def resetPackage(): Unit = {
-      inScalaPackage = false
-      currentPackage = ""
+      packageStack = Nil
+    }
+    private def inScalaRootPackage = packageStack match {
+      case Ident(nme.scala_) :: Nil => true
+      case _ => false
     }
-    private def inScalaRootPackage = inScalaPackage && currentPackage == "scala"
 
     def parseStartRule: () => Tree
 
@@ -1294,14 +1295,10 @@ self =>
     }
     /** Calls `qualId()` and manages some package state. */
     private def pkgQualId() = {
-      if (in.token == IDENTIFIER && in.name.encode == nme.scala_)
-        inScalaPackage = true
-
       val pkg = qualId()
       newLineOptWhenFollowedBy(LBRACE)
 
-      if (currentPackage == "") currentPackage = pkg.toString
-      else currentPackage = currentPackage + "." + pkg
+      packageStack ::= pkg
 
       pkg
     }
@@ -3351,6 +3348,8 @@ self =>
           } else {
             in.flushDoc
             val pkg = pkgQualId()
+            val saved = packageStack
+            packageStack ::= pkg
 
             if (in.token == EOF) {
               ts += makePackaging(start, pkg, List())
@@ -3362,6 +3361,7 @@ self =>
               acceptStatSepOpt()
               ts ++= topStatSeq()
             }
+            packageStack = saved
           }
         } else {
           ts ++= topStatSeq()

src/library/scala/reflect/NameTransformer.scala

@@ -67,23 +67,35 @@ object NameTransformer {
    *  @return     the string with all recognized opchars replaced with their encoding
    */
   def encode(name: String): String = {
-    var buf: StringBuilder = null
+    encode(name: CharSequence) match {
+      case s: String => s
+      case sb: java.lang.StringBuilder => sb.toString
+    }
+  }
+
+  /** Replace operator symbols by corresponding `\$opname`.
+   *
+   *  @param name the text to encode
+   *  @return     the text with all recognized opchars replaced with their encoding
+   */
+  def encode(name: CharSequence): CharSequence /* String | java.lang.StringBuilder */ = {
+    var buf: java.lang.StringBuilder = null
     val len = name.length()
     var i = 0
     while (i < len) {
       val c = name charAt i
       if (c < nops && (op2code(c.toInt) ne null)) {
         if (buf eq null) {
-          buf = new StringBuilder()
-          buf.append(name.substring(0, i))
+          buf = new java.lang.StringBuilder()
+          buf.append(name.subSequence(0, i))
         }
         buf.append(op2code(c.toInt))
       /* Handle glyphs that are not valid Java/JVM identifiers */
       }
       else if (!Character.isJavaIdentifierPart(c)) {
         if (buf eq null) {
-          buf = new StringBuilder()
-          buf.append(name.substring(0, i))
+          buf = new java.lang.StringBuilder()
+          buf.append(name.subSequence(0, i))
         }
         buf.append("$u%04X".format(c.toInt))
       }
@@ -92,7 +104,7 @@ object NameTransformer {
       }
       i += 1
     }
-    if (buf eq null) name else buf.toString()
+    if (buf eq null) name else buf
   }
 
   /** Replace `\$opname` by corresponding operator symbol.

src/reflect/scala/reflect/internal/Names.scala

@@ -446,9 +446,8 @@ trait Names extends api.Names {
 
     /** Replace operator symbols by corresponding \$op_name. */
     def encode: ThisNameType = {
-      val str = toString
-      val res = NameTransformer.encode(str)
-      if (res == str) thisName else newName(res)
+      val res = NameTransformer.encode(this)
+      if (res eq this) thisName else newName(res.toString)
     }
 
     /** Replace \$op_name by corresponding operator symbol. */
@@ -521,12 +520,18 @@ trait Names extends api.Names {
   /** TermName_S and TypeName_S have fields containing the string version of the name.
    *  TermName_R and TypeName_R recreate it each time toString is called.
    */
-  private final class TermName_S(index0: Int, len0: Int, next0: TermName, override val toString: String) extends TermName(index0, len0, next0) {
-    protected def createCompanionName(next: TypeName): TypeName = new TypeName_S(index, len, next, toString)
+  private final class TermName_S(index0: Int, len0: Int, next0: TermName, cachedString: String) extends TermName(index0, len0, next0) {
+    protected def createCompanionName(next: TypeName): TypeName = new TypeName_S(index, len, next, cachedString)
     override def newName(str: String): TermName = newTermNameCached(str)
+    override def toString: String = {
+      cachedString
+    }
   }
-  private final class TypeName_S(index0: Int, len0: Int, next0: TypeName, override val toString: String) extends TypeName(index0, len0, next0) {
+  private final class TypeName_S(index0: Int, len0: Int, next0: TypeName, cachedString: String) extends TypeName(index0, len0, next0) {
     override def newName(str: String): TypeName = newTypeNameCached(str)
+    override def toString: String = {
+      cachedString
+    }
   }
 
   private final class TermName_R(index0: Int, len0: Int, next0: TermName) extends TermName(index0, len0, next0) {