Improvements to repl completion.

(it was only behind an option to be super conservative) but it can be
disabled with -Yno-completion. Now all top level identifiers can be
completed upon, so if you define

  val dingdong = "abc"
  def dingwhoa = 5
then d.<tab> will complete up to "ding".

4 files changed, 29 insertions, 11 deletions

diff --git a/src/compiler/scala/tools/nsc/Interpreter.scala b/src/compiler/scala/tools/nsc/Interpreter.scala
index 78ac10b021..01071c1981 100644
--- a/src/compiler/scala/tools/nsc/Interpreter.scala
+++ b/src/compiler/scala/tools/nsc/Interpreter.scala
@@ -828,7 +828,6 @@ class Interpreter(val settings: Settings, out: PrintWriter) {
     }
 
     """** Power User mode enabled - BEEP BOOP      **
-      |** Launch scala with -Ycompletion for <tab> **
       |** New vals! Try interpreter.<tab>          **
       |** New defs! Try mkType("T", "String")      **
       |** New cmds! :help to discover them         **""".stripMargin
@@ -881,6 +880,12 @@ class Interpreter(val settings: Settings, out: PrintWriter) {
     res getOrElse Nil
   }
 
+  def unqualifiedIds(line: String): List[String] =
+    allBoundNames .
+      map(_.toString) .
+      filter(!isSynthVarName(_)) .
+      filter(_ startsWith line)
+
   // debugging
   private var debuggingOutput = false
   def DBG(s: String) = if (debuggingOutput) out println s else ()
diff --git a/src/compiler/scala/tools/nsc/InterpreterLoop.scala b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
index 52097e0ebf..944a978ec7 100644
--- a/src/compiler/scala/tools/nsc/InterpreterLoop.scala
+++ b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
@@ -207,7 +207,8 @@ class InterpreterLoop(in0: Option[BufferedReader], out: PrintWriter) {
      */
     val futLine = scala.concurrent.ops.future(readOneLine)
     bindSettings()
-    processLine(futLine())
+    if (!processLine(futLine()))
+      return out.println("Leaving already? That hurts, it really does.")
 
     // loops until false, then returns
     while (processLine(readOneLine)) { }
@@ -331,10 +332,10 @@ class InterpreterLoop(in0: Option[BufferedReader], out: PrintWriter) {
       case None       =>
         val emacsShell = System.getProperty("env.emacs", "") != ""
 
-        // tab completion off by default for now
+        // the interpeter is passed as an argument to expose tab completion info
         if (settings.Xnojline.value || emacsShell) new SimpleReader
-        else if (settings.completion.value) InteractiveReader.createDefault(interpreter)
-        else InteractiveReader.createDefault()
+        else if (settings.noCompletion.value) InteractiveReader.createDefault()
+        else InteractiveReader.createDefault(interpreter)
     }
 
     loadFiles(settings)
diff --git a/src/compiler/scala/tools/nsc/Settings.scala b/src/compiler/scala/tools/nsc/Settings.scala
index 6026186010..a05a6dd157 100644
--- a/src/compiler/scala/tools/nsc/Settings.scala
+++ b/src/compiler/scala/tools/nsc/Settings.scala
@@ -651,7 +651,7 @@ trait ScalacSettings
   val check         = PhasesSetting     ("-Ycheck", "Check the tree at the end of")
   val Xcloselim     = BooleanSetting    ("-Yclosure-elim", "Perform closure elimination")
   val Xcodebase     = StringSetting     ("-Ycodebase", "codebase", "Specify the URL containing the Scala libraries", "")
-  val completion    = BooleanSetting    ("-Ycompletion", "Enable tab-completion in the REPL")
+  val noCompletion  = BooleanSetting    ("-Yno-completion", "Disable tab-completion in the REPL")
   val Xdce          = BooleanSetting    ("-Ydead-code", "Perform dead code elimination")
   val debug         = BooleanSetting    ("-Ydebug", "Output debugging messages")
   val debugger      = BooleanSetting    ("-Ydebugger", "Enable interactive debugger")
diff --git a/src/compiler/scala/tools/nsc/interpreter/Completion.scala b/src/compiler/scala/tools/nsc/interpreter/Completion.scala
index 7e2c8a9f04..cf804f4669 100644
--- a/src/compiler/scala/tools/nsc/interpreter/Completion.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/Completion.scala
@@ -13,16 +13,28 @@ import jline._
 class Completion(val interpreter: Interpreter) extends Completor {
   import java.util.{ List => JList }
 
-  override def complete(buffer: String, cursor: Int, candidates: JList[_]): Int = {
-    if (buffer == null) return 0
+  override def complete(_buffer: String, cursor: Int, candidates: JList[_]): Int = {
+    val buffer = if (_buffer == null) "" else _buffer
     val clist = candidates.asInstanceOf[JList[String]]
     val lastDot = buffer.lastIndexOf('.')
     val (path, stub) =
       if (lastDot < 0) (buffer, "")
       else (buffer.substring(0, lastDot), buffer.substring(lastDot + 1))
 
-    val members = interpreter membersOfIdentifier path
-    members.filter(_ startsWith stub).foreach(x => clist add x)
-    buffer.length - stub.length
+    def completeMembers(needsDot: Boolean): Int = {
+      def withDot(s: String) = if (needsDot) "." + s else s
+      val members = interpreter membersOfIdentifier path
+      members.filter(_ startsWith stub).foreach(x => clist add withDot(x))
+      buffer.length - stub.length
+    }
+
+    // if there is no dot, complete on unqualified identifiers; otherwise, id's members
+    lazy val ids = interpreter unqualifiedIds path
+    if (lastDot >= 0) completeMembers(false)
+    else ids match {
+      case Nil                    => 0
+      case x :: Nil if x == path  => completeMembers(true)  // only one id matches, insert the dot
+      case xs                     => xs foreach (x => clist add x) ; 0
+    }
   }
 }