Don't quit debugger when the program terminates, only after `quit`.

pkg/dartino_compiler/lib/cli_debugger.dart

 // Copyright (c) 2015, the Dartino project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE.md file.
 
 import "dart:async";
 
 import "dart:convert" show
     UTF8;
 
 import "dart:io" show
@@ skipping 59 matching lines @@
   final bool echo;
   final Uri base;
   final Sink<List<int>> stdout;
 
   bool printForTesting = false;
 
   bool get colorsDisabled => printForTesting;
   bool verbose = true;
 
   String previousLine = '';
+  bool quitDebugger = false;
 
   int processPagingCount = 10;
   int processPagingCurrent = 0;
 
   CommandLineDebugger(
       this.vmContext, this.stream, this.base, this.stdout, {bool echo: false})
     : echo = echo,
       printForTesting = echo;
 
   void printPrompt() => writeStdout('> ');
@@ skipping 289 matching lines @@
         }
         if (variable == null) {
           writeStdoutLine('### no such variable: $variableName');
         } else {
           writeStdoutLine(vmContext.remoteObjectToString(variable));
         }
         break;
       case 'q':
       case 'quit':
         await vmContext.terminate();
+        quitDebugger = true;
         break;
       case 'r':
       case 'run':
         if (checkNotLoaded("use 'restart' to run again")) {
           await handleProcessStopResponse(await vmContext.startRunning());
         }
         break;
       case 'step':
       case 's':
         if (checkRunning('cannot step to next expression')) {
@@ skipping 38 matching lines @@
           default:
             writeStdoutLine('### invalid flag $toggle');
             break;
         }
         break;
       default:
         writeStdoutLine('### unknown command: $command');
         break;
     }
     previousLine = line;
-    if (!vmContext.terminated) printPrompt();
   }
 
   bool toggleVerbose() => verbose = !verbose;
 
   // This method is used to deal with the stopped process command responses
   // that can be returned when sending the Dartino VM a command request.
   Future handleProcessStopResponse(
       VmCommand response) async {
     String output = await processStopResponseToString(
         vmContext,
@@ skipping 33 matching lines @@
     if (vmContext.running) {
       String prefix = '### process already running';
       writeStdoutLine(postfix != null ? '$prefix, $postfix' : prefix);
     }
     return !vmContext.running;
   }
 
   Future<int> run(SessionState state, {Uri snapshotLocation}) async {
     await vmContext.initialize(state, snapshotLocation: snapshotLocation);
     writeStdoutLine(BANNER);
-    printPrompt();
     StreamIterator streamIterator = new StreamIterator(stream);
-    while (await streamIterator.moveNext()) {
+
+    Future<bool> getNext() async {
+      printPrompt();
+      return await streamIterator.moveNext();
+    }
+
+    while (!quitDebugger && await getNext()) {
       try {
         await handleLine(streamIterator);
       } catch (e, s) {
         Future cancel = streamIterator.cancel()?.catchError((_) {});
         if (!vmContext.terminated) {
           await vmContext.terminate().catchError((_) {});
         }
         await cancel;
         return new Future.error(e, s);
       }
-      if (vmContext.terminated) {
-        await streamIterator.cancel();
-      }
     }
-    if (!vmContext.terminated) await vmContext.terminate();
+    if (!vmContext.terminated) {
+      await vmContext.terminate();
+    }
     return vmContext.interactiveExitCode;
   }
 
   // Prompt the user to select among a set of choices.
   // Returns a set of indexes that are the chosen indexes from the input set.
   // If the size of choices is less then two, then the result is that the full
   // input set is selected without prompting the user. Otherwise the user is
   // interactively prompted to choose a selection.
   Future<Iterable<int>> select(
       StreamIterator stream,
@@ skipping 104 matching lines @@
       return '';
     } else if (response is ProcessTerminated) {
       return '### process terminated\n';
 
     } else if (response is ConnectionError) {
       return '### lost connection to the virtual machine\n';
     }
     return '';
   }
 }