content/browser/speech/chunked_byte_buffer.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 CONTENT_BROWSER_SPEECH_CHUNKED_BYTE_BUFFER_H_
   6 #define CONTENT_BROWSER_SPEECH_CHUNKED_BYTE_BUFFER_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/memory/scoped_vector.h"
  14 #include "content/common/content_export.h"
  15
  16 namespace content {
  17
  18 // Models a chunk-oriented byte buffer. The term chunk is herein defined as an
  19 // arbitrary sequence of bytes that is preceeded by N header bytes, indicating
  20 // its size. Data may be appended to the buffer with no particular respect of
  21 // chunks boundaries. However, chunks can be extracted (FIFO) only when their
  22 // content (according to their header) is fully available in the buffer.
  23 // The current implementation support only 4 byte Big Endian headers.
  24 // Empty chunks (i.e. the sequence 00 00 00 00) are NOT allowed.
  25 //
  26 // E.g. 00 00 00 04 xx xx xx xx 00 00 00 02 yy yy 00 00 00 04 zz zz zz zz
  27 //      [----- CHUNK 1 -------] [--- CHUNK 2 ---] [------ CHUNK 3 ------]
  28 class CONTENT_EXPORT ChunkedByteBuffer {
  29  public:
  30   ChunkedByteBuffer();
  31   ~ChunkedByteBuffer();
  32
  33   // Appends |length| bytes starting from |start| to the buffer.
  34   void Append(const uint8* start, size_t length);
  35
  36   // Appends bytes contained in the |string| to the buffer.
  37   void Append(const std::string& string);
  38
  39   // Checks whether one or more complete chunks are available in the buffer.
  40   bool HasChunks() const;
  41
  42   // If enough data is available, reads and removes the first complete chunk
  43   // from the buffer. Returns a NULL pointer if no complete chunk is available.
  44   scoped_ptr< std::vector<uint8> > PopChunk();
  45
  46   // Clears all the content of the buffer.
  47   void Clear();
  48
  49   // Returns the number of raw bytes (including headers) present.
  50   size_t GetTotalLength() const { return total_bytes_stored_; }
  51
  52  private:
  53   struct Chunk {
  54     Chunk();
  55     ~Chunk();
  56
  57     std::vector<uint8> header;
  58     scoped_ptr< std::vector<uint8> > content;
  59     size_t ExpectedContentLength() const;
  60
  61    private:
  62     DISALLOW_COPY_AND_ASSIGN(Chunk);
  63   };
  64
  65   ScopedVector<Chunk> chunks_;
  66   scoped_ptr<Chunk> partial_chunk_;
  67   size_t total_bytes_stored_;
  68
  69   DISALLOW_COPY_AND_ASSIGN(ChunkedByteBuffer);
  70 };
  71
  72
  73 }  // namespace content
  74
  75 #endif  // CONTENT_BROWSER_SPEECH_CHUNKED_BYTE_BUFFER_H_