refactor out fresh name prefix extraction logic

1. refactor out FreshNameExtractor out of Quasiquotes cake into
   SymbolTable (can’t put it outside due to the fact that names are
   path-dependent)

2. add optional parameter to the fresh name creator to cover additional
   qq$ prefix needed for quasiquotes

3. add unit tests

5 files changed, 43 insertions, 26 deletions

diff --git a/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala b/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala
index 3901184c25..126c14ac81 100644
--- a/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala
+++ b/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala
@@ -55,9 +55,7 @@ trait Parsers { self: Quasiquotes =>
 
       def isHole(name: Name): Boolean = holeMap.contains(name)
 
-      override implicit def fresh: FreshNameCreator = new FreshNameCreator {
-        override def newName(prefix: String) = super.newName(nme.QUASIQUOTE_PREFIX + prefix)
-      }
+      override implicit def fresh: FreshNameCreator = new FreshNameCreator(nme.QUASIQUOTE_PREFIX)
 
       override val treeBuilder = new ParserTreeBuilder {
         override implicit def fresh: FreshNameCreator = parser.fresh
@@ -189,19 +187,5 @@ trait Parsers { self: Quasiquotes =>
     }
   }
 
-  // Extractor that matches names which were generated by call to
-  // freshTermName or freshTypeName within quasiquotes. Such names
-  // have qq$some$random$prefix$0 shape where qq$ part is added
-  // by modified fresh name creator in QuasiquoteParser.
-  object FreshName {
-    def unapply(name: Name): Option[String] =
-      name.toString.split("\\$").toSeq match {
-        case qq +: (middle :+ last)
-          if qq + "$" == nme.QUASIQUOTE_PREFIX
-          && Try(last.toInt).isSuccess && middle.nonEmpty =>
-          Some(middle.mkString("", "$", "$"))
-        case _ =>
-          None
-      }
-  }
+  object FreshName extends FreshNameExtractor(nme.QUASIQUOTE_PREFIX)
 }
\ No newline at end of file
diff --git a/src/reflect/scala/reflect/internal/FreshNames.scala b/src/reflect/scala/reflect/internal/FreshNames.scala
new file mode 100644
index 0000000000..ab9e488fa7
--- /dev/null
+++ b/src/reflect/scala/reflect/internal/FreshNames.scala
@@ -0,0 +1,35 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2013 LAMP/EPFL
+ */
+
+package scala
+package reflect
+package internal
+
+import scala.reflect.internal.util.FreshNameCreator
+
+trait FreshNames { self: SymbolTable =>
+  // default fresh name creator used to abstract over currentUnit.fresh and runtime fresh name creator
+  def currentFreshNameCreator: FreshNameCreator
+
+  // create fresh term/type name using implicit fresh name creator
+  def freshTermName(prefix: String = "x$")(implicit creator: FreshNameCreator): TermName = newTermName(creator.newName(prefix))
+  def freshTypeName(prefix: String)(implicit creator: FreshNameCreator): TypeName        = newTypeName(creator.newName(prefix))
+
+  // Extractor that matches names which were generated by some
+  // FreshNameCreator with known prefix. Extracts user-specified
+  // prefix that was used as a parameter to newName by stripping
+  // global creator prefix and unique number in the end of the name.
+  class FreshNameExtractor(creatorPrefix: String = "") {
+    // quote prefix so that it can be used with replaceFirst
+    // which expects regExp rather than simple string
+    val quotedCreatorPrefix = java.util.regex.Pattern.quote(creatorPrefix)
+
+    def unapply(name: Name): Option[String] = {
+      val sname = name.toString
+      // name should start with creatorPrefix and end with number
+      if (!sname.startsWith(creatorPrefix) || !sname.matches("^.*\\d*$")) None
+      else Some(NameTransformer.decode(sname.replaceFirst(quotedCreatorPrefix, "").replaceAll("\\d*$", "")))
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/reflect/scala/reflect/internal/SymbolTable.scala b/src/reflect/scala/reflect/internal/SymbolTable.scala
index 4998580a7d..c3f3e35fb3 100644
--- a/src/reflect/scala/reflect/internal/SymbolTable.scala
+++ b/src/reflect/scala/reflect/internal/SymbolTable.scala
@@ -42,6 +42,7 @@ abstract class SymbolTable extends macros.Universe
                               with BuildUtils
                               with PrivateWithin
                               with pickling.Translations
+                              with FreshNames
 {
 
   val gen = new TreeGen { val global: SymbolTable.this.type = SymbolTable.this }
@@ -398,11 +399,6 @@ abstract class SymbolTable extends macros.Universe
    * Adds the `sm` String interpolator to a [[scala.StringContext]].
    */
   implicit val StringContextStripMarginOps: StringContext => StringContextStripMarginOps = util.StringContextStripMarginOps
-
-  // fresh name creation
-  def currentFreshNameCreator: FreshNameCreator
-  def freshTermName(prefix: String = "x$")(implicit creator: FreshNameCreator): TermName = newTermName(creator.newName(prefix))
-  def freshTypeName(prefix: String)(implicit creator: FreshNameCreator): TypeName        = newTypeName(creator.newName(prefix))
 }
 
 object SymbolTableStats {
diff --git a/src/reflect/scala/reflect/internal/util/FreshNameCreator.scala b/src/reflect/scala/reflect/internal/util/FreshNameCreator.scala
index 3e54de8e1e..8442c1015f 100644
--- a/src/reflect/scala/reflect/internal/util/FreshNameCreator.scala
+++ b/src/reflect/scala/reflect/internal/util/FreshNameCreator.scala
@@ -11,7 +11,7 @@ import java.util.concurrent.atomic.AtomicLong
 import scala.collection.mutable
 import scala.reflect.NameTransformer
 
-class FreshNameCreator {
+class FreshNameCreator(creatorPrefix: String = "") {
   protected val counters = new ConcurrentHashMap[String, AtomicLong]()
 
   /**
@@ -21,7 +21,8 @@ class FreshNameCreator {
    */
   def newName(prefix: String): String = {
     val safePrefix = NameTransformer.encode(prefix)
-    counters.putIfAbsent(safePrefix, new AtomicLong(0));
-    safePrefix + counters.get(safePrefix).incrementAndGet();
+    counters.putIfAbsent(safePrefix, new AtomicLong(0))
+    val idx = counters.get(safePrefix).incrementAndGet()
+    s"$creatorPrefix$safePrefix$idx"
   }
 }
diff --git a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
index bce506ee0a..344f7682c1 100644
--- a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
+++ b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
@@ -51,6 +51,7 @@ trait JavaUniverseForce { self: runtime.JavaUniverse  =>
     // inaccessible: this.SimpleNameOrdering
     this.traceSymbols
     this.perRunCaches
+    this.FreshNameExtractor
     this.FixedMirrorTreeCreator
     this.FixedMirrorTypeCreator
     this.CompoundTypeTreeOriginalAttachment