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The Tor Browser
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PairHash.h (2089B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 /* Utilities for hashing pairs. */
      8 
      9 #ifndef mozilla_PairHash_h
     10 #define mozilla_PairHash_h
     11 
     12 #include "mozilla/CompactPair.h"
     13 #include "mozilla/HashFunctions.h"
     14 
     15 #include <utility>  // std::pair
     16 
     17 namespace mozilla {
     18 
     19 /**
     20 * The HashPair overloads below do just what you'd expect.
     21 *
     22 * These functions support hash of std::pair<T,U> and mozilla::CompactPair<T,u>
     23 * where type T and U both support AddToHash.
     24 */
     25 template <typename U, typename V>
     26 [[nodiscard]] inline HashNumber HashPair(const std::pair<U, V>& pair) {
     27  // Pair hash combines the hash of each member
     28  return HashGeneric(pair.first, pair.second);
     29 }
     30 
     31 template <typename U, typename V>
     32 [[nodiscard]] inline HashNumber HashCompactPair(const CompactPair<U, V>& pair) {
     33  // Pair hash combines the hash of each member
     34  return HashGeneric(pair.first(), pair.second());
     35 }
     36 
     37 /**
     38 * Hash policy for std::pair compatible with HashTable
     39 */
     40 template <typename T, typename U>
     41 struct PairHasher {
     42  using Key = std::pair<T, U>;
     43  using Lookup = Key;
     44 
     45  static HashNumber hash(const Lookup& aLookup) { return HashPair(aLookup); }
     46 
     47  static bool match(const Key& aKey, const Lookup& aLookup) {
     48    return aKey == aLookup;
     49  }
     50 
     51  static void rekey(Key& aKey, const Key& aNewKey) { aKey = aNewKey; }
     52 };
     53 
     54 /**
     55 * Hash policy for mozilla::CompactPair compatible with HashTable
     56 */
     57 template <typename T, typename U>
     58 struct CompactPairHasher {
     59  using Key = CompactPair<T, U>;
     60  using Lookup = Key;
     61 
     62  static HashNumber hash(const Lookup& aLookup) {
     63    return HashCompactPair(aLookup);
     64  }
     65 
     66  static bool match(const Key& aKey, const Lookup& aLookup) {
     67    return aKey == aLookup;
     68  }
     69 
     70  static void rekey(Key& aKey, const Key& aNewKey) { aKey = aNewKey; }
     71 };
     72 
     73 }  // namespace mozilla
     74 
     75 #endif /* mozilla_PairHash_h */