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      1 // Copyright 2013 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 NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_
      6 #define NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_
      7 
      8 #include <deque>
      9 #include <vector>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/memory/ref_counted.h"
     13 #include "base/memory/scoped_ptr.h"
     14 #include "net/base/net_export.h"
     15 
     16 extern "C" struct z_stream_s;
     17 
     18 namespace net {
     19 
     20 class IOBufferWithSize;
     21 
     22 class NET_EXPORT_PRIVATE WebSocketDeflater {
     23  public:
     24   enum ContextTakeOverMode {
     25     DO_NOT_TAKE_OVER_CONTEXT,
     26     TAKE_OVER_CONTEXT,
     27   };
     28 
     29   explicit WebSocketDeflater(ContextTakeOverMode mode);
     30   ~WebSocketDeflater();
     31 
     32   // Returns true if there is no error and false otherwise.
     33   // This function must be called exactly once before calling any of
     34   // following methods.
     35   // |window_bits| must be between 8 and 15 (both inclusive).
     36   bool Initialize(int window_bits);
     37 
     38   // Adds bytes to |stream_|.
     39   // Returns true if there is no error and false otherwise.
     40   bool AddBytes(const char* data, size_t size);
     41 
     42   // Flushes the current processing data.
     43   // Returns true if there is no error and false otherwise.
     44   bool Finish();
     45 
     46   // Pushes "\x00\x00\xff\xff" to the end of the buffer.
     47   void PushSyncMark();
     48 
     49   // Returns the current deflated output.
     50   // If the current output is larger than |size| bytes,
     51   // returns the first |size| bytes of the current output.
     52   // The returned bytes will be dropped from the current output and never be
     53   // returned thereafter.
     54   scoped_refptr<IOBufferWithSize> GetOutput(size_t size);
     55 
     56   // Returns the size of the current deflated output.
     57   size_t CurrentOutputSize() const { return buffer_.size(); }
     58 
     59  private:
     60   void ResetContext();
     61   int Deflate(int flush);
     62 
     63   scoped_ptr<z_stream_s> stream_;
     64   ContextTakeOverMode mode_;
     65   std::deque<char> buffer_;
     66   std::vector<char> fixed_buffer_;
     67   // true if bytes were added after last Finish().
     68   bool are_bytes_added_;
     69 
     70   DISALLOW_COPY_AND_ASSIGN(WebSocketDeflater);
     71 };
     72 
     73 }  // namespace net
     74 
     75 #endif  // NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_
     76