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