SI-9206 Local refactor to save eyesight

We talk about bit rot but not about how dust accumulates on
code that hasn't been swept since the last time the furniture
was moved around.

Author: som-snytt

src/repl/scala/tools/nsc/interpreter/ILoop.scala

@@ -783,8 +783,16 @@ class ILoop(in0: Option[BufferedReader], protected val out: JPrintWriter)
       echo("\n// Detected repl transcript paste: ctrl-D to finish.\n")
       apply(Iterator(start) ++ readWhile(!isPromptOnly(_)))
     }
+
+    def unapply(line: String): Boolean = isPrompted(line)
+  }
+
+  private object invocation {
+    def unapply(line: String): Boolean = Completion.looksLikeInvocation(line)
   }
 
+  private val lineComment = """\s*//.*""".r   // all comment
+
   /** Interpret expressions starting with the first line.
     * Read lines until a complete compilation unit is available
     * or until a syntax error has been seen.  If a full unit is
@@ -795,53 +803,42 @@ class ILoop(in0: Option[BufferedReader], protected val out: JPrintWriter)
     // signal completion non-completion input has been received
     in.completion.resetVerbosity()
 
-    def reallyInterpret = {
-      val reallyResult = intp.interpret(code)
-      (reallyResult, reallyResult match {
-        case IR.Error       => None
-        case IR.Success     => Some(code)
-        case IR.Incomplete  =>
-          if (in.interactive && code.endsWith("\n\n")) {
-            echo("You typed two blank lines.  Starting a new command.")
+    def reallyInterpret = intp.interpret(code) match {
+      case IR.Error      => None
+      case IR.Success    => Some(code)
+      case IR.Incomplete if in.interactive && code.endsWith("\n\n") =>
+        echo("You typed two blank lines.  Starting a new command.")
+        None
+      case IR.Incomplete =>
+        in.readLine(paste.ContinueString) match {
+          case null =>
+            // we know compilation is going to fail since we're at EOF and the
+            // parser thinks the input is still incomplete, but since this is
+            // a file being read non-interactively we want to fail.  So we send
+            // it straight to the compiler for the nice error message.
+            intp.compileString(code)
             None
-          }
-          else in.readLine(paste.ContinueString) match {
-            case null =>
-              // we know compilation is going to fail since we're at EOF and the
-              // parser thinks the input is still incomplete, but since this is
-              // a file being read non-interactively we want to fail.  So we send
-              // it straight to the compiler for the nice error message.
-              intp.compileString(code)
-              None
-
-            case line => interpretStartingWith(code + "\n" + line)
-          }
-      })
+
+          case line => interpretStartingWith(code + "\n" + line)
+        }
     }
 
-    /** Here we place ourselves between the user and the interpreter and examine
-     *  the input they are ostensibly submitting.  We intervene in several cases:
+    /* Here we place ourselves between the user and the interpreter and examine
+     * the input they are ostensibly submitting.  We intervene in several cases:
      *
-     *  1) If the line starts with "scala> " it is assumed to be an interpreter paste.
-     *  2) If the line starts with "." (but not ".." or "./") it is treated as an invocation
-     *     on the previous result.
-     *  3) If the Completion object's execute returns Some(_), we inject that value
-     *     and avoid the interpreter, as it's likely not valid scala code.
+     * 1) If the line starts with "scala> " it is assumed to be an interpreter paste.
+     * 2) If the line starts with "." (but not ".." or "./") it is treated as an invocation
+     *    on the previous result.
+     * 3) If the Completion object's execute returns Some(_), we inject that value
+     *    and avoid the interpreter, as it's likely not valid scala code.
      */
-    if (code == "") None
-    else if (!paste.running && paste.isPrompted(code)) {
-      paste.transcript(code)
-      None
-    }
-    else if (Completion.looksLikeInvocation(code) && intp.mostRecentVar != "") {
-      interpretStartingWith(intp.mostRecentVar + code)
+    code match {
+      case ""                                       => None
+      case lineComment()                            => None                 // line comment, do nothing
+      case paste() if !paste.running                => paste.transcript(code) ; None
+      case invocation() if intp.mostRecentVar != "" => interpretStartingWith(intp.mostRecentVar + code)
+      case _                                        => reallyInterpret
     }
-    else if (code.trim startsWith "//") {
-      // line comment, do nothing
-      None
-    }
-    else
-      reallyInterpret._2
   }
 
   // runs :load `file` on any files passed via -i

src/repl/scala/tools/nsc/interpreter/Pasted.scala

@@ -85,7 +85,7 @@ abstract class Pasted {
       case _ => code
     }
 
-    def run() {
+    def run(): Unit = {
       println("// Replaying %d commands from transcript.\n" format cmds.size)
       cmds foreach { cmd =>
         print(ActualPromptString)