1 files changed, 53 insertions, 0 deletions
diff --git a/src/repl/scala/tools/nsc/interpreter/CompletionAware.scala b/src/repl/scala/tools/nsc/interpreter/CompletionAware.scala
new file mode 100644
index 0000000000..3dd5d93390
--- /dev/null
+++ b/src/repl/scala/tools/nsc/interpreter/CompletionAware.scala
@@ -0,0 +1,53 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2013 LAMP/EPFL
+ * @author Paul Phillips
+ */
+
+package scala.tools.nsc
+package interpreter
+
+/** An interface for objects which are aware of tab completion and
+ *  will supply their own candidates and resolve their own paths.
+ */
+trait CompletionAware {
+  /** The complete list of unqualified Strings to which this
+   *  object will complete.
+   */
+  def completions(verbosity: Int): List[String]
+
+  /** The next completor in the chain.
+   */
+  def follow(id: String): Option[CompletionAware] = None
+
+  /** A list of useful information regarding a specific uniquely
+   *  identified completion.  This is specifically written for the
+   *  following situation, but should be useful elsewhere too:
+   *
+   *    x.y.z.methodName<tab>
+   *
+   *  If "methodName" is among z's completions, and verbosity > 0
+   *  indicating tab has been pressed twice consecutively, then we
+   *  call alternativesFor and show a list of overloaded method
+   *  signatures.
+   */
+  def alternativesFor(id: String): List[String] = Nil
+
+  /** Given string 'buf', return a list of all the strings
+   *  to which it can complete.  This may involve delegating
+   *  to other CompletionAware objects.
+   */
+  def completionsFor(parsed: Parsed): List[String] = {
+    import parsed.{ buffer, verbosity }
+    val comps = completions(verbosity) filter (_ startsWith buffer)
+    val exact = comps contains buffer
+
+    val results =
+      if (parsed.isEmpty) comps
+      else if (parsed.isUnqualified && !parsed.isLastDelimiter)
+        if (verbosity > 0 && exact) alternativesFor(buffer)
+        else comps
+      else follow(parsed.bufferHead) map (_ completionsFor parsed.bufferTail) getOrElse Nil
+
+    results.sorted
+  }
+}