Implement 'print', 'up', 'down', and 'frame' commands in the Observatory debugger.

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.
+// 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) {
-  var args = line.split(' ').where((arg) {
-      return arg != ' ' && arg != '';
-    }).toList();
+  line = line.trimLeft();
+  var args = [];
+  var codes = line.codeUnits;
+
+  int pos = 0;
+  while (pos < line.length) {
+    int startPos = pos;
+
+    // Advance to end of word.
+    for (; pos < line.length && line[pos] != ' '; pos++);
+
+    // Advance to end of spaces.
+    for (; pos < line.length && line[pos] == ' '; pos++);
+
+    args.add(line.substring(startPos, pos));
+  }
   return args;
 }
 
 // Concatenates the first 'count' args.
 String _concatArgs(List<String> args, int count) {
   if (count == 0) {
     return '';
   }
-  return '${args.sublist(0, count).join(" ")} ';
+  return '${args.sublist(0, count).join('')}';
 }
 
 // Shared functionality for RootCommand and Command.
 abstract class _CommandBase {
   _CommandBase(List<Command> children) {
     assert(children != null);
     _children.addAll(children);
     for (var child in _children) {
       child._parent = this;
     }
   }
 
   // A command may optionally have sub-commands.
   List<Command> _children = [];
 
   _CommandBase _parent;
   int get _depth => (_parent == null ? 0 : _parent._depth + 1);
 
   // Override in subclasses to provide command-specific argument completion.
   //
   // Given a list of arguments to this command, provide a list of
   // possible completions for those arguments.
   Future<List<String>> complete(List<String> args) => new Future.value([]);
 
   // Override in subclasses to provide command-specific execution.
   Future run(List<String> args);
 
   // Returns a list of local subcommands which match the args.
-  List<Command> _matchLocal(String arg, bool preferExact) {
+  List<Command> _matchLocal(String argWithSpace, bool preferExact) {
     var matches = new List<Command>();
+    var arg = argWithSpace.trimRight();
     for (var child in _children) {
       if (child.name.startsWith(arg)) {
         if (preferExact && ((child.name == arg) || (child.alias == arg))) {
           return [child];
         }
         matches.add(child);
       }
     }
     return matches;
   }
@@ skipping 165 matching lines @@
     if (_parent is RootCommand) {
       return name;
     } else {
       Command parent = _parent;
       return '${parent.fullName} $name';
     }
   }
 
   toString() => 'Command(${name})';
 }