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      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 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     32   // In case the delegate is no longer valid, ClearDelegate() must be called.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_
     56