net/spdy/hpack_entry.h

   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_ENTRY_H_
   6 #define NET_SPDY_HPACK_ENTRY_H_
   7
   8 #include <cstddef>
   9 #include <set>
  10 #include <string>
  11
  12 #include "base/basictypes.h"
  13 #include "base/macros.h"
  14 #include "base/strings/string_piece.h"
  15 #include "net/base/net_export.h"
  16
  17 // All section references below are to
  18 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08
  19
  20 namespace net {
  21
  22 // A structure for an entry in the static table (3.3.1)
  23 // and the header table (3.3.2).
  24 class NET_EXPORT_PRIVATE HpackEntry {
  25  public:
  26   // The constant amount added to name().size() and value().size() to
  27   // get the size of an HpackEntry as defined in 5.1.
  28   static const size_t kSizeOverhead;
  29
  30   // Creates an entry. Preconditions:
  31   // - |is_static| captures whether this entry is a member of the static
  32   //   or dynamic header table.
  33   // - |insertion_index| is this entry's index in the total set of entries ever
  34   //   inserted into the header table (including static entries).
  35   //
  36   // The combination of |is_static| and |insertion_index| allows an
  37   // HpackEntryTable to determine the index of an HpackEntry in O(1) time.
  38   HpackEntry(base::StringPiece name,
  39              base::StringPiece value,
  40              bool is_static,
  41              size_t insertion_index);
  42
  43   // Create a 'lookup' entry (only) suitable for querying a HpackEntrySet. The
  44   // instance InsertionIndex() always returns 0 and IsLookup() returns true.
  45   HpackEntry(base::StringPiece name, base::StringPiece value);
  46
  47   // Creates an entry with empty name and value. Only defined so that
  48   // entries can be stored in STL containers.
  49   HpackEntry();
  50
  51   ~HpackEntry();
  52
  53   const std::string& name() const { return name_; }
  54   const std::string& value() const { return value_; }
  55
  56   // Returns whether this entry is a member of the static (as opposed to
  57   // dynamic) table.
  58   bool IsStatic() const { return type_ == STATIC; }
  59
  60   // Returns whether this entry is a lookup-only entry.
  61   bool IsLookup() const { return type_ == LOOKUP; }
  62
  63   // Used to compute the entry's index in the header table.
  64   size_t InsertionIndex() const { return insertion_index_; }
  65
  66   // Returns the size of an entry as defined in 5.1.
  67   static size_t Size(base::StringPiece name, base::StringPiece value);
  68   size_t Size() const;
  69
  70   std::string GetDebugString() const;
  71
  72  private:
  73   enum EntryType {
  74     LOOKUP,
  75     DYNAMIC,
  76     STATIC,
  77   };
  78
  79   // TODO(jgraettinger): Reduce copies, possibly via SpdyPinnableBufferPiece.
  80   std::string name_;
  81   std::string value_;
  82
  83   // The entry's index in the total set of entries ever inserted into the header
  84   // table.
  85   size_t insertion_index_;
  86
  87   EntryType type_;
  88 };
  89
  90 }  // namespace net
  91
  92 #endif  // NET_SPDY_HPACK_ENTRY_H_