This addresses a few long standing irritations ...

This addresses a few long standing irritations with jline, rewriting
chunks of it along the way. No longer does columnar output spill over
and double space everything if you're unlucky with the chosen widths.
Pagination works for a higher definition of work. Etc.

Also, for those who enjoy operating missile systems from their repls,
crash recovery now requests your permission before replaying the
session.

Closes #4194, no review.

8 files changed, 161 insertions, 42 deletions

diff --git a/src/compiler/scala/tools/nsc/interpreter/ConsoleReaderHelper.scala b/src/compiler/scala/tools/nsc/interpreter/ConsoleReaderHelper.scala
new file mode 100644
index 0000000000..d0d3349038
--- /dev/null
+++ b/src/compiler/scala/tools/nsc/interpreter/ConsoleReaderHelper.scala
@@ -0,0 +1,66 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2011 LAMP/EPFL
+ * @author Paul Phillips
+ */
+
+package scala.tools.nsc
+package interpreter
+
+import scala.tools.jline.console.{ ConsoleReader, CursorBuffer }
+import scala.tools.jline.console.completer.CompletionHandler
+import Completion._
+
+trait ConsoleReaderHelper extends ConsoleReader {
+  def currentLine = "" + getCursorBuffer.buffer
+  def currentPos  = getCursorBuffer.cursor
+  def terminal    = getTerminal()
+  def width       = terminal.getWidth()
+  def height      = terminal.getHeight()
+  def paginate    = isPaginationEnabled()
+  def paginate_=(value: Boolean) = setPaginationEnabled(value)
+
+  def goBack(num: Int): Unit
+  def readOneKey(prompt: String): Int
+  def eraseLine(): Unit
+
+  private val marginSize = 3
+  private def morePrompt = "--More--"
+  private def emulateMore(): Int = {
+    val key = readOneKey(morePrompt)
+    try key match {
+      case '\r' | '\n'  => 1
+      case 'q'          => -1
+      case _            => height - 1
+    }
+    finally {
+      eraseLine()
+      // TODO: still not quite managing to erase --More-- and get
+      // back to a scala prompt without another keypress.
+      if (key == 'q') {
+        putString(getPrompt())
+        redrawLine()
+        flush()
+      }
+    }
+  }
+
+  override def printColumns(items: JCollection[_ <: CharSequence]): Unit =
+    printColumns(items: List[String])
+
+  def printColumns(items: List[String]): Unit = {
+    val longest    = items map (_.length) max
+    var linesLeft  = if (isPaginationEnabled()) height - 1 else Int.MaxValue
+    val columnSize = longest + marginSize
+    val padded     = items map ("%-" + columnSize + "s" format _)
+
+    padded grouped (width / columnSize) foreach { xs =>
+      println(xs.mkString)
+      linesLeft -= 1
+      if (linesLeft <= 0) {
+        linesLeft = emulateMore()
+        if (linesLeft < 0)
+          return
+      }
+    }
+  }
+}
diff --git a/src/compiler/scala/tools/nsc/interpreter/ILoop.scala b/src/compiler/scala/tools/nsc/interpreter/ILoop.scala
index 90346c480f..38084af016 100644
--- a/src/compiler/scala/tools/nsc/interpreter/ILoop.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/ILoop.scala
@@ -249,13 +249,6 @@ class ILoop(in0: Option[BufferedReader], protected val out: PrintWriter)
     import global.Symbol
 
     def p(x: Any) = intp.reporter.printMessage("" + x)
-    def toDefString(sym: Symbol) = {
-      TypeStrings.quieter(
-        intp.afterTyper(sym.defString),
-        sym.owner.name + ".this.",
-        sym.owner.fullName + "."
-      )
-    }
 
     // If an argument is given, only show a source with that
     // in its name somewhere.
@@ -300,7 +293,7 @@ class ILoop(in0: Option[BufferedReader], protected val out: PrintWriter)
             p("  /* " + members.size + ownerMessage + owner.fullName + " */")
 
             memberGroups foreach { group =>
-              group foreach (s => p("  " + toDefString(s)))
+              group foreach (s => p("  " + intp.symbolDefString(s)))
               p("")
             }
         }
@@ -392,6 +385,12 @@ class ILoop(in0: Option[BufferedReader], protected val out: PrintWriter)
     else powerCommands
   )
 
+  val replayQuestionMessage =
+    """|The repl compiler has crashed spectacularly. Shall I replay your
+       |session? I can re-run all lines except the last one.
+       |[y/n]
+    """.trim.stripMargin
+
   private val crashRecovery: PartialFunction[Throwable, Unit] = {
     case ex: Throwable =>
       if (settings.YrichExes.value) {
@@ -406,9 +405,19 @@ class ILoop(in0: Option[BufferedReader], protected val out: PrintWriter)
       else {
         out.println(util.stackTraceString(ex))
       }
-      out.println("Attempting session recovery...")
-
-      replay()
+      ex match {
+        case _: NoSuchMethodError | _: NoClassDefFoundError =>
+          out.println("Unrecoverable error.")
+          throw ex
+        case _  =>
+          out.print(replayQuestionMessage)
+          out.flush()
+          if (in.readAssumingNo("")) {
+            out.println("\nAttempting session recovery with replay.")
+            replay()
+          }
+          else out.println("\nAbandoning crashed session.")
+      }
   }
 
   /** The main read-eval-print loop for the repl.  It calls
diff --git a/src/compiler/scala/tools/nsc/interpreter/IMain.scala b/src/compiler/scala/tools/nsc/interpreter/IMain.scala
index c3cc0f9e03..33dcfa59e6 100644
--- a/src/compiler/scala/tools/nsc/interpreter/IMain.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/IMain.scala
@@ -83,6 +83,7 @@ class IMain(val settings: Settings, protected val out: PrintWriter) {
   /** reporter */
   lazy val reporter: ConsoleReporter = new IMain.ReplReporter(this)
   import reporter.{ printMessage, withoutTruncating }
+
   // not sure if we have some motivation to print directly to console
   private def echo(msg: String) { Console println msg }
 
@@ -1088,6 +1089,14 @@ class IMain(val settings: Settings, protected val out: PrintWriter) {
     finally isettings.unwrapStrings = saved
   }
 
+  def symbolDefString(sym: Symbol) = {
+    TypeStrings.quieter(
+      afterTyper(sym.defString),
+      sym.owner.name + ".this.",
+      sym.owner.fullName + "."
+    )
+  }
+
   def showCodeIfDebugging(code: String) {
     /** Secret bookcase entrance for repl debuggers: end the line
      *  with "// show" and see what's going on.
@@ -1110,6 +1119,14 @@ class IMain(val settings: Settings, protected val out: PrintWriter) {
 
 /** Utility methods for the Interpreter. */
 object IMain {
+  // The two name forms this is catching are the two sides of this assignment:
+  //
+  // $line3.$read.$iw.$iw.Bippy =
+  //   $line3.$read$$iw$$iw$Bippy@4a6a00ca
+  private def removeLineWrapper(s: String) = s.replaceAll("""\$line\d+[./]\$(read|eval|print)[$.]""", "")
+  private def removeIWPackages(s: String)  = s.replaceAll("""\$(iw|read|eval|print)[$.]""", "")
+  def stripString(s: String)               = removeIWPackages(removeLineWrapper(s))
+
   trait CodeAssembler[T] {
     def preamble: String
     def generate: T => String
@@ -1152,7 +1169,7 @@ object IMain {
     def isTruncating       = reporter.truncationOK
 
     def stripImpl(str: String): String = {
-      val cleaned = removeIWPackages(removeLineWrapper(str))
+      val cleaned = stripString(str)
       var ctrlChars = 0
       cleaned map { ch =>
         if (ch.isControl && !ch.isWhitespace) {
@@ -1163,13 +1180,6 @@ object IMain {
         else ch
       }
     }
-
-    // The two name forms this is catching are the two sides of this assignment:
-    //
-    // $line3.$read.$iw.$iw.Bippy =
-    //   $line3.$read$$iw$$iw$Bippy@4a6a00ca
-    private def removeLineWrapper(s: String) = s.replaceAll("""\$line\d+[./]\$(read|eval|print)[$.]""", "")
-    private def removeIWPackages(s: String) = s.replaceAll("""\$(iw|read|eval|print)[$.]""", "")
   }
 
   class ReplReporter(intp: IMain) extends ConsoleReporter(intp.settings, null, new ReplStrippingWriter(intp)) {
diff --git a/src/compiler/scala/tools/nsc/interpreter/InteractiveReader.scala b/src/compiler/scala/tools/nsc/interpreter/InteractiveReader.scala
index 782fd52ab2..1430cbe55c 100644
--- a/src/compiler/scala/tools/nsc/interpreter/InteractiveReader.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/InteractiveReader.scala
@@ -17,16 +17,25 @@ import Properties.isMac
 trait InteractiveReader {
   val interactive: Boolean
 
+  def init(): Unit
+  def reset(): Unit
+
   def history: History
   def completion: Completion
   def keyBindings: List[KeyBinding]
+  def eraseLine(): Unit
+  def redrawLine(): Unit
+  def currentLine: String
 
-  def init(): Unit
-  def reset(): Unit
+  def readYesOrNo(prompt: String) = readOneKey(prompt) match {
+    case 'y'  => true
+    case 'n'  => false
+  }
+  def readAssumingNo(prompt: String)  = try readYesOrNo(prompt) catch { case _: MatchError  => false }
+  def readAssumingYes(prompt: String) = try readYesOrNo(prompt) catch { case _: MatchError  => true }
 
   protected def readOneLine(prompt: String): String
-  def redrawLine(): Unit
-  def currentLine: String
+  protected def readOneKey(prompt: String): Int
 
   def readLine(prompt: String): String =
     // hack necessary for OSX jvm suspension because read calls are not restarted after SIGTSTP
diff --git a/src/compiler/scala/tools/nsc/interpreter/JLineReader.scala b/src/compiler/scala/tools/nsc/interpreter/JLineReader.scala
index 9ca10b9e6b..d9260427b3 100644
--- a/src/compiler/scala/tools/nsc/interpreter/JLineReader.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/JLineReader.scala
@@ -35,33 +35,41 @@ class JLineReader(val completion: Completion) extends InteractiveReader {
     }
   }
 
-  def argCompletor: ArgumentCompleter = {
-    val c = new ArgumentCompleter(new JLineDelimiter, scalaToJline(completion.completer()))
-    c setStrict false
-    c
-  }
+  class JLineConsoleReader extends ConsoleReader with ConsoleReaderHelper {
+    // working around protected/trait/java insufficiencies.
+    def goBack(num: Int): Unit = back(num)
+    def readOneKey(prompt: String) = {
+      this.print(prompt)
+      this.flush()
+      this.readVirtualKey()
+    }
+    def eraseLine() = consoleReader.resetPromptLine("", "", 0)
+    def redrawLineAndFlush(): Unit = { flush() ; drawLine() ; flush() }
 
-  val consoleReader = {
-    val r = new ConsoleReader()
-    r setBellEnabled false
+    this setBellEnabled false
     if (history ne NoHistory)
-      r setHistory history
+      this setHistory history
 
     if (completion ne NoCompletion) {
-      r addCompleter argCompletor
-      r setAutoprintThreshold 400 // max completion candidates without warning
-    }
+      val argCompletor: ArgumentCompleter =
+        new ArgumentCompleter(new JLineDelimiter, scalaToJline(completion.completer()))
+      argCompletor setStrict false
 
-    r
+      this addCompleter argCompletor
+      this setAutoprintThreshold 400 // max completion candidates without warning
+    }
   }
 
+  val consoleReader: JLineConsoleReader = new JLineConsoleReader()
+
   def currentLine: String = consoleReader.getCursorBuffer.buffer.toString
-  def redrawLine() = {
-    consoleReader.flush()
-    consoleReader.drawLine()
-    consoleReader.flush()
+  def redrawLine() = consoleReader.redrawLineAndFlush()
+  def eraseLine() = {
+    while (consoleReader.delete()) { }
+    // consoleReader.eraseLine()
   }
   def readOneLine(prompt: String) = consoleReader readLine prompt
+  def readOneKey(prompt: String)  = consoleReader readOneKey prompt
 }
 
 object JLineReader {
diff --git a/src/compiler/scala/tools/nsc/interpreter/SimpleReader.scala b/src/compiler/scala/tools/nsc/interpreter/SimpleReader.scala
index d8181e1793..5249f89dfb 100644
--- a/src/compiler/scala/tools/nsc/interpreter/SimpleReader.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/SimpleReader.scala
@@ -22,6 +22,7 @@ extends InteractiveReader
 
   def init() = ()
   def reset() = ()
+  def eraseLine() = ()
   def redrawLine() = ()
   def currentLine = ""
   def readOneLine(prompt: String): String = {
@@ -31,6 +32,7 @@ extends InteractiveReader
     }
     in.readLine()
   }
+  def readOneKey(prompt: String)  = sys.error("No char-based input in SimpleReader")
 }
 
 object SimpleReader {
diff --git a/src/compiler/scala/tools/nsc/interpreter/package.scala b/src/compiler/scala/tools/nsc/interpreter/package.scala
index 42826e9c6d..e2e6cb6651 100644
--- a/src/compiler/scala/tools/nsc/interpreter/package.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/package.scala
@@ -23,7 +23,9 @@ package scala.tools.nsc
  *  IMain contains { global: Global }
  */
 package object interpreter {
-  type JClass = java.lang.Class[_]
+  type JClass         = java.lang.Class[_]
+  type JList[T]       = java.util.List[T]
+  type JCollection[T] = java.util.Collection[T]
 
   private[nsc] val DebugProperty = "scala.repl.debug"
   private[nsc] val TraceProperty = "scala.repl.trace"
@@ -31,6 +33,10 @@ package object interpreter {
   private[nsc] var isReplDebug   = sys.props contains DebugProperty // Also set by -Yrepl-debug
 
   private[nsc] implicit def enrichClass[T](clazz: Class[T]) = new RichClass[T](clazz)
+  private[interpreter] implicit def javaCharSeqCollectionToScala(xs: JCollection[_ <: CharSequence]): List[String] = {
+    import collection.JavaConverters._
+    xs.asScala.toList map ("" + _)
+  }
 
   /** Debug output */
   private[nsc] def repldbg(msg: String) = if (isReplDebug) Console println msg
@@ -43,6 +49,16 @@ package object interpreter {
     x
   }
 
+  // Longest common prefix
+  def longestCommonPrefix(xs: List[String]): String = {
+    if (xs.isEmpty || xs.contains("")) ""
+    else xs.head.head match {
+      case ch =>
+        if (xs.tail forall (_.head == ch)) "" + ch + longestCommonPrefix(xs map (_.tail))
+        else ""
+    }
+  }
+
   private[nsc] def words(s: String) = s.trim split "\\s+" toList
   private[nsc] def isQuoted(s: String) =
     (s.length >= 2) && (s.head == s.last) && ("\"'" contains s.head)
diff --git a/src/compiler/scala/tools/nsc/interpreter/session/package.scala b/src/compiler/scala/tools/nsc/interpreter/session/package.scala
index e6ff2c3e03..8fbba2f05e 100644
--- a/src/compiler/scala/tools/nsc/interpreter/session/package.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/session/package.scala
@@ -12,7 +12,6 @@ package interpreter
 package object session {
   type JIterator[T]       = java.util.Iterator[T]
   type JListIterator[T]   = java.util.ListIterator[T]
-  type JList[T]           = java.util.List[T]
 
   type JEntry             = scala.tools.jline.console.history.History.Entry
   type JHistory           = scala.tools.jline.console.history.History