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 QUICHE_SPDY_CORE_HPACK_HPACK_ENTRY_H_ 6 #define QUICHE_SPDY_CORE_HPACK_HPACK_ENTRY_H_ 7 8 #include <cstddef> 9 #include <string> 10 #include <utility> 11 12 #include "absl/strings/string_view.h" 13 #include "quiche/common/platform/api/quiche_export.h" 14 15 // All section references below are to 16 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08 17 18 namespace spdy { 19 20 // The constant amount added to name().size() and value().size() to 21 // get the size of an HpackEntry as defined in 5.1. 22 inline constexpr size_t kHpackEntrySizeOverhead = 32; 23 24 // A structure for looking up entries in the static and dynamic tables. 25 struct QUICHE_EXPORT HpackLookupEntry { 26 absl::string_view name; 27 absl::string_view value; 28 29 bool operator==(const HpackLookupEntry& other) const { 30 return name == other.name && value == other.value; 31 } 32 33 // Abseil hashing framework extension according to absl/hash/hash.h: 34 template <typename H> AbslHashValueHpackLookupEntry35 friend H AbslHashValue(H h, const HpackLookupEntry& entry) { 36 return H::combine(std::move(h), entry.name, entry.value); 37 } 38 }; 39 40 // A structure for an entry in the static table (3.3.1) 41 // and the header table (3.3.2). 42 class QUICHE_EXPORT HpackEntry { 43 public: 44 HpackEntry(std::string name, std::string value); 45 46 // Make HpackEntry non-copyable to make sure it is always moved. 47 HpackEntry(const HpackEntry&) = delete; 48 HpackEntry& operator=(const HpackEntry&) = delete; 49 50 HpackEntry(HpackEntry&&) = default; 51 HpackEntry& operator=(HpackEntry&&) = default; 52 53 // Getters for std::string members traditionally return const std::string&. 54 // However, HpackHeaderTable uses string_view as keys in the maps 55 // static_name_index_ and dynamic_name_index_. If HpackEntry::name() returned 56 // const std::string&, then 57 // dynamic_name_index_.insert(std::make_pair(entry.name(), index)); 58 // would silently create a dangling reference: make_pair infers type from the 59 // return type of entry.name() and silently creates a temporary string copy. 60 // Insert creates a string_view that points to this copy, which then 61 // immediately goes out of scope and gets destroyed. While this is quite easy 62 // to avoid, for example, by explicitly specifying type as a template 63 // parameter to make_pair, returning string_view here is less error-prone. name()64 absl::string_view name() const { return name_; } value()65 absl::string_view value() const { return value_; } 66 67 // Returns the size of an entry as defined in 5.1. 68 static size_t Size(absl::string_view name, absl::string_view value); 69 size_t Size() const; 70 71 std::string GetDebugString() const; 72 73 private: 74 std::string name_; 75 std::string value_; 76 }; 77 78 } // namespace spdy 79 80 #endif // QUICHE_SPDY_CORE_HPACK_HPACK_ENTRY_H_ 81