1 // Copyright 2014 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_SPDY_HPACK_OUTPUT_STREAM_H_ 6 #define NET_SPDY_HPACK_OUTPUT_STREAM_H_ 7 8 #include <map> 9 #include <string> 10 11 #include "base/basictypes.h" 12 #include "base/macros.h" 13 #include "base/strings/string_piece.h" 14 #include "net/base/net_export.h" 15 #include "net/spdy/hpack_constants.h" 16 17 // All section references below are to 18 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-07 19 20 namespace net { 21 22 // An HpackOutputStream handles all the low-level details of encoding 23 // header fields. 24 class NET_EXPORT_PRIVATE HpackOutputStream { 25 public: 26 explicit HpackOutputStream(); 27 ~HpackOutputStream(); 28 29 // Appends the lower |bit_size| bits of |bits| to the internal buffer. 30 // 31 // |bit_size| must be > 0 and <= 8. |bits| must not have any bits 32 // set other than the lower |bit_size| bits. 33 void AppendBits(uint8 bits, size_t bit_size); 34 35 // Simply forwards to AppendBits(prefix.bits, prefix.bit-size). 36 void AppendPrefix(HpackPrefix prefix); 37 38 // Directly appends |buffer|. 39 void AppendBytes(base::StringPiece buffer); 40 41 // Appends the given integer using the representation described in 42 // 4.1.1. If the internal buffer ends on a byte boundary, the prefix 43 // length N is taken to be 8; otherwise, it is taken to be the 44 // number of bits to the next byte boundary. 45 // 46 // It is guaranteed that the internal buffer will end on a byte 47 // boundary after this function is called. 48 void AppendUint32(uint32 I); 49 50 // Swaps the interal buffer with |output|. 51 void TakeString(std::string* output); 52 53 private: 54 // The internal bit buffer. 55 std::string buffer_; 56 57 // If 0, the buffer ends on a byte boundary. If non-zero, the buffer 58 // ends on the most significant nth bit. Guaranteed to be < 8. 59 size_t bit_offset_; 60 61 DISALLOW_COPY_AND_ASSIGN(HpackOutputStream); 62 }; 63 64 } // namespace net 65 66 #endif // NET_SPDY_HPACK_OUTPUT_STREAM_H_ 67