Converted Observatory debugger elements

runtime/observatory/lib/src/cli/command.dart

 // Copyright (c) 2015, the Dart 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 file.
 
 part of cli;
 
 // Splits a line into a list of string args.  Each arg retains any
 // trailing whitespace so that we can reconstruct the original command
 // line from the pieces.
 List<String> _splitLine(String line) {
@@ skipping 97 matching lines @@
         }
         var prefix = _concatArgs(args, _depth);
         return completions.map((str) => '${prefix}${str}').toList();
       });
   }
 
 }
 
 // The root of a tree of commands.
 class RootCommand extends _CommandBase {
-  RootCommand(List<Command> children) : super(children);
+  RootCommand(List<Command> children, [List<String> history])
+     : this._(children, history ?? ['']);
+
+   RootCommand._(List<Command> children, List<String> history)
+      : history = history,
+        historyPos = history.length - 1,
+      super(children);
 
   // Provides a list of possible completions for a line of text.
   Future<List<String>> completeCommand(String line) {
     var args = _splitLine(line);
     bool showAll = line.endsWith(' ') || args.isEmpty;
     if (showAll) {
       // Adding an empty string to the end causes us to match all
       // subcommands of the last command.
       args.add('');
     }
@@ skipping 55 matching lines @@
     if (args.isEmpty) {
       // Adding an empty string to the end causes us to match all
       // subcommands of the last command.
       args.add('');
     }
     return _match(args, preferExact);
   }
 
   // Command line history always contains one slot to hold the current
   // line, so we start off with one entry.
-  List<String> history = [''];
-  int historyPos = 0;
+  List<String> history;
+  int historyPos;
 
   String historyPrev(String line) {
     if (historyPos == 0) {
       return line;
     }
     history[historyPos] = line;
     historyPos--;
     return history[historyPos];
   }
 
@@ skipping 34 matching lines @@
     if (_parent is RootCommand) {
       return name;
     } else {
       Command parent = _parent;
       return '${parent.fullName} $name';
     }
   }
 
   toString() => 'Command(${name})';
 }