Implement BroadcastChannel

third_party/WebKit/Source/wtf/HashTraits.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 227 matching lines @@
 template <typename FirstTraitsArg, typename SecondTraitsArg>
 struct PairHashTraits : GenericHashTraits<std::pair<typename FirstTraitsArg::TraitType, typename SecondTraitsArg::TraitType>> {
     typedef FirstTraitsArg FirstTraits;
     typedef SecondTraitsArg SecondTraits;
     typedef std::pair<typename FirstTraits::TraitType, typename SecondTraits::TraitType> TraitType;
     typedef std::pair<typename FirstTraits::EmptyValueType, typename SecondTraits::EmptyValueType> EmptyValueType;
 
     static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
     static EmptyValueType emptyValue() { return std::make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue()); }
 
+    static const bool hasIsEmptyValueFunction = FirstTraits::hasIsEmptyValueFunction || SecondTraits::hasIsEmptyValueFunction;

[haraken, 2016/06/02 04:23:41]

Would you elaborate why you need this change? Is this an existing bug of
WTF::HashMap?

[Marijn Kruisselbrink, 2016/06/02 18:33:30]

Yes, I'd say this is an existing bug of the std::pair HashTraits. It was
possible to have a HashMap<RefPtr<SecurityOrigin>, T>, and it was possible to
have a HashMap<std::pair<T, U>, V>, but the last one only if both T and U don't
use a custom isEmptyValue function. With this change it becomes possible to use
types with isEmptyValue functions inside std::pair in HashMap and friends as
well.

[haraken, 2016/06/03 05:33:03]

Would you make the change in a separate CL?

[Marijn Kruisselbrink, 2016/06/03 20:37:04]

Split off into https://codereview.chromium.org/2042453002

+    static bool isEmptyValue(const TraitType& value) { return isHashTraitsEmptyValue<FirstTraits>(value.first) && isHashTraitsEmptyValue<SecondTraits>(value.second); }
+
     static const unsigned minimumTableSize = FirstTraits::minimumTableSize;
 
     static void constructDeletedValue(TraitType& slot, bool zeroValue)
     {
         FirstTraits::constructDeletedValue(slot.first, zeroValue);
         // For GC collections the memory for the backing is zeroed when it is
         // allocated, and the constructors may take advantage of that,
         // especially if a GC occurs during insertion of an entry into the
         // table. This slot is being marked deleted, but If the slot is reused
         // at a later point, the same assumptions around memory zeroing must
@@ skipping 84 matching lines @@
 struct TraceInCollectionTrait;
 
 } // namespace WTF
 
 using WTF::HashTraits;
 using WTF::PairHashTraits;
 using WTF::NullableHashTraits;
 using WTF::SimpleClassHashTraits;
 
 #endif // WTF_HashTraits_h