chrome/browser/web_resource/json_asynchronous_unpacker.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_WEB_RESOURCE_JSON_ASYNCHRONOUS_UNPACKER_H_
   6 #define CHROME_BROWSER_WEB_RESOURCE_JSON_ASYNCHRONOUS_UNPACKER_H_
   7
   8 #include <string>
   9
  10 #include "base/values.h"
  11
  12 // A delegate interface for users of JSONAsynchronousUnpacker.
  13 class JSONAsynchronousUnpackerDelegate {
  14  public:
  15   virtual ~JSONAsynchronousUnpackerDelegate() {}
  16
  17   // This will be called when the response is parsed properly. |parsed_json|
  18   // contains the decoded information.
  19   virtual void OnUnpackFinished(const base::DictionaryValue& parsed_json) = 0;
  20
  21   // This will be called if there is an error while parsing the data.
  22   virtual void OnUnpackError(const std::string& error_message) = 0;
  23 };
  24
  25 // This class coordinates a web resource unpack and parse task which is run
  26 // asynchronously.  Results are sent back to the delegate via one of its
  27 // OnUnpack<xxx> methods.
  28 class JSONAsynchronousUnpacker {
  29  public:
  30   // Creates a WebResourceServiceUnpacker appropriate for the platform. The
  31   // delegate must be kept around until one of the delegate methods is called.
  32   // In case the delegate is no longer valid, ClearDelegate() must be called.
  33   static JSONAsynchronousUnpacker*
  34       Create(JSONAsynchronousUnpackerDelegate* delegate);
  35
  36   virtual ~JSONAsynchronousUnpacker() {}
  37
  38   // Start the decoding. The concrete implementation should delete itself after
  39   // calling the delegate method.
  40   virtual void Start(const std::string& json_data) = 0;
  41
  42   // If the delegate is going away it needs to inform the unpacker about it.
  43   void ClearDelegate() {
  44     delegate_ = NULL;
  45   };
  46
  47  protected:
  48   explicit JSONAsynchronousUnpacker(JSONAsynchronousUnpackerDelegate* delegate)
  49       : delegate_(delegate) {
  50   }
  51
  52   JSONAsynchronousUnpackerDelegate* delegate_;
  53 };
  54
  55 #endif  // CHROME_BROWSER_WEB_RESOURCE_JSON_ASYNCHRONOUS_UNPACKER_H_