js/src/vm/PropertyKey.h

   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 #ifndef vm_PropertyKey_h
   8 #define vm_PropertyKey_h
   9
  10 #include "mozilla/HashFunctions.h"  // mozilla::HashGeneric
  11
  12 #include "NamespaceImports.h"  // js::PropertyKey
  13
  14 #include "js/HashTable.h"   // js::DefaultHasher
  15 #include "js/Id.h"          // JS::PropertyKey
  16 #include "vm/StringType.h"  // JSAtom::hash
  17 #include "vm/SymbolType.h"  // JS::Symbol::hash
  18
  19 namespace js {
  20
  21 static MOZ_ALWAYS_INLINE HashNumber HashPropertyKey(PropertyKey key) {
  22   // HashGeneric alone would work, but bits of atom and symbol addresses
  23   // could then be recovered from the hash code. See bug 1330769.
  24   if (MOZ_LIKELY(key.isAtom())) {
  25     return key.toAtom()->hash();
  26   }
  27   if (key.isSymbol()) {
  28     return key.toSymbol()->hash();
  29   }
  30   return mozilla::HashGeneric(key.asRawBits());
  31 }
  32
  33 // Like HashPropertyKey but optimized for callers that only use atom or symbol
  34 // keys.
  35 static MOZ_ALWAYS_INLINE HashNumber
  36 HashAtomOrSymbolPropertyKey(PropertyKey key) {
  37   if (MOZ_LIKELY(key.isAtom())) {
  38     return key.toAtom()->hash();
  39   }
  40   return key.toSymbol()->hash();
  41 }
  42
  43 }  // namespace js
  44
  45 namespace mozilla {
  46
  47 template <>
  48 struct DefaultHasher<JS::PropertyKey> {
  49   using Lookup = JS::PropertyKey;
  50   static HashNumber hash(JS::PropertyKey key) {
  51     return js::HashPropertyKey(key);
  52   }
  53   static bool match(JS::PropertyKey key1, JS::PropertyKey key2) {
  54     return key1 == key2;
  55   }
  56 };
  57
  58 }  // namespace mozilla
  59
  60 #endif /* vm_PropertyKey_h */