Debugger wire protocol: setting breakpoints

lib/json/json.dart

 // Copyright (c) 2011, 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.
 
 #library("json");
 
 // Pure Dart implementation of JSON protocol.
 
 /**
  * Utility class to parse JSON and serialize objects to JSON.
  */
 class JSON {
   /**
    * Parses [:json:] and build the corresponding object.
    */
   static parse(String json) {
     return _JsonParser.parse(json);
   }
 
   /**
+   * Checks validity of JSON source in [:str:] and returns its text
+   * length. Returns 0 if [:str:] does not begin with a valid JSON
+   * object.
+   */
+  static int length(String str) {
+    return _JsonParser.objectLength(str);
+  }
+
+  /**
    * Serializes [:object:] into JSON string.
    */
   static String stringify(Object object) {
     return JsonStringifier.stringify(object);
   }
 }
 
 //// Implementation ///////////////////////////////////////////////////////////
 
 // TODO(ajohnsen): Introduce when we have a common exception interface for json.
@@ skipping 58 matching lines @@
 
   static final String NULL_STRING = "null";
   static final String TRUE_STRING = "true";
   static final String FALSE_STRING = "false";
 
 
   static parse(String json) {
     return new _JsonParser._internal(json)._parseToplevel();
   }
 
+  static objectLength(String str) {
+    var p = new _JsonParser._internal(str);
+    try {
+      p._parseObject();

[Anton Muhin, 2012/05/15 15:17:56]

I am not sure it's valid implementation: _parseObject will unconditionally skip
first char as it's used under dispatch in _parseValue, so it will probably
accept something like [ 'foo': 1 }

[hausner, 2012/05/15 15:32:56]

Nice catch! Thank you for taking a look. I'll fix it in a separate checkin.

On 2012/05/15 15:17:56, antonmuhin wrote:

+      assert(p.position <= p.length);
+      return p.position;
+    } catch (var e) {
+      return 0;
+    }
+  }
+
   _JsonParser._internal(String json)
       : json = json,
         length = json.length {
     if (tokens !== null) return;
 
     // Use a list as jump-table, faster then switch and if.
     tokens = new List<int>(LAST_ASCII + 1);
     tokens[TAB] = WHITESPACE;
     tokens[NEW_LINE] = WHITESPACE;
     tokens[CARRIAGE_RETURN] = WHITESPACE;
@@ skipping 411 matching lines @@
         });
         _sb.add('}');
         _seen.removeLast();
         return;
 
       default:
         throw const JsonUnsupportedObjectType();
     }
   }
 }