1 files changed, 118 insertions, 0 deletions
diff --git a/src/repl/scala/tools/nsc/interpreter/PresentationCompilerCompleter.scala b/src/repl/scala/tools/nsc/interpreter/PresentationCompilerCompleter.scala
new file mode 100644
index 0000000000..ee901db1a0
--- /dev/null
+++ b/src/repl/scala/tools/nsc/interpreter/PresentationCompilerCompleter.scala
@@ -0,0 +1,118 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2013 LAMP/EPFL
+ * @author Martin Odersky
+ */
+package scala.tools.nsc.interpreter
+
+import scala.reflect.internal.Flags
+import scala.reflect.internal.util.StringOps
+import scala.tools.nsc.interpreter.Completion.{ScalaCompleter, Candidates}
+import scala.util.control.NonFatal
+
+class PresentationCompilerCompleter(intp: IMain) extends Completion with ScalaCompleter {
+  import PresentationCompilerCompleter._
+  import intp.{PresentationCompileResult => Result}
+
+  private type Handler = Result => Candidates
+
+  private var lastRequest = NoRequest
+  private var tabCount = 0
+  private var lastCommonPrefixCompletion: Option[String] = None
+
+  def resetVerbosity(): Unit = { tabCount = 0 ; lastRequest = NoRequest }
+  def completer(): ScalaCompleter = this
+
+  // A convenience for testing
+  def complete(before: String, after: String = ""): Candidates = complete(before + after, before.length)
+  override def complete(buf: String, cursor: Int): Candidates = {
+    val request = Request(buf, cursor)
+    if (request == lastRequest)
+      tabCount += 1
+    else {
+      tabCount = 0
+      lastRequest = request
+    }
+
+    // secret handshakes
+    val slashPrint  = """.*// *print *""".r
+    val slashTypeAt = """.*// *typeAt *(\d+) *(\d+) *""".r
+    val Cursor = IMain.DummyCursorFragment
+
+    def print(result: Result) = {
+      val offset = result.preambleLength
+      val pos1 = result.unit.source.position(offset).withEnd(offset + buf.length)
+      import result.compiler._
+      val tree = new Locator(pos1) locateIn result.unit.body match {
+        case Template(_, _, constructor :: (rest :+ last)) => if (rest.isEmpty) last else Block(rest, last)
+        case t => t
+      }
+      val printed = showCode(tree) + " // : " + tree.tpe.safeToString
+      Candidates(cursor, "" :: printed :: Nil)
+    }
+    def typeAt(result: Result, start: Int, end: Int) = {
+      val tpString = result.compiler.exitingTyper(result.typedTreeAt(buf, start, end).tpe.toString)
+      Candidates(cursor, "" :: tpString :: Nil)
+    }
+    def candidates(result: Result): Candidates = {
+      import result.compiler.CompletionResult._, result.compiler.{Symbol, NoSymbol, Type, Member, NoType, Name}
+      def defStringCandidates(qualTpe: Type, matching: List[Member], name: Name): Candidates = {
+        val defStrings = for {
+          member <- matching
+          if member.symNameDropLocal == name
+          sym <- member.sym.alternatives
+          sugared = sym.sugaredSymbolOrSelf
+        } yield {
+            val tp = qualTpe match {
+              case NoType => member.tpe
+              case _ => qualTpe memberType sym
+            }
+            sugared.defStringSeenAs(tp)
+          }
+        Candidates(cursor, "" :: defStrings.distinct)
+      }
+      val found = result.completionsAt(cursor) match {
+        case NoResults => Completion.NoCandidates
+        case r => val matching = r.matchingResults()
+          val tabAfterCommonPrefixCompletion = lastCommonPrefixCompletion.contains(buf.substring(0, cursor)) && matching.exists(_.symNameDropLocal == r.name)
+          val doubleTab = tabCount > 0 && matching.forall(_.symNameDropLocal == r.name)
+          if (tabAfterCommonPrefixCompletion || doubleTab) defStringCandidates(r.qualifierType, matching, r.name)
+          else {
+            if (matching.nonEmpty && matching.forall(_.symNameDropLocal == r.name))
+              Completion.NoCandidates // don't offer completion if the only option has been fully typed already
+            else {
+              // regular completion
+              val memberCompletions: List[String] = matching.map(_.symNameDropLocal.decoded).distinct
+              Candidates(cursor + r.positionDelta, memberCompletions)
+            }
+          }
+      }
+      lastCommonPrefixCompletion =
+        if (found != Completion.NoCandidates && buf.length >= found.cursor)
+          Some(buf.substring(0, found.cursor) + StringOps.longestCommonPrefix(found.candidates))
+        else
+          None
+      found
+    }
+    val buf1 = buf.patch(cursor, Cursor, 0)
+    try {
+      intp.presentationCompile(buf1) match {
+        case Left(_) => Completion.NoCandidates
+        case Right(result) => try {
+          buf match {
+            case slashPrint() if cursor == buf.length => print(result)
+            case slashTypeAt(start, end) if cursor == buf.length => typeAt(result, start.toInt, end.toInt)
+            case _ => candidates(result)
+          }
+        } finally result.cleanup()
+      }
+    } catch {
+      case NonFatal(e) =>
+        if (isReplDebug) e.printStackTrace()
+        Completion.NoCandidates
+    }
+  }
+}
+object PresentationCompilerCompleter {
+  private case class Request(line: String, cursor: Int)
+  private val NoRequest = Request("", -1)
+}