forked from mirrors/gecko-dev
43091e2839
The simplistic shift-based hashing function creates a lot of collisions for pointers pointing to arrays as it doesn't do a great job at distributing the data randomly based on the input bytes.
49 lines
1.3 KiB
C++
49 lines
1.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* Definitions for nsPtrHashKey<T> and nsVoidPtrHashKey. */
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#ifndef nsPointerHashKeys_h
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#define nsPointerHashKeys_h
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#include "nscore.h"
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#include "mozilla/Attributes.h"
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#include "mozilla/HashFunctions.h"
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/**
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* hashkey wrapper using T* KeyType
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*
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* @see nsTHashtable::EntryType for specification
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*/
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template<class T>
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class nsPtrHashKey : public PLDHashEntryHdr
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{
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public:
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typedef T* KeyType;
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typedef const T* KeyTypePointer;
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explicit nsPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {}
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nsPtrHashKey(const nsPtrHashKey<T>& aToCopy) : mKey(aToCopy.mKey) {}
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~nsPtrHashKey() {}
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KeyType GetKey() const { return mKey; }
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bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; }
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static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
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static PLDHashNumber HashKey(KeyTypePointer aKey)
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{
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return mozilla::HashGeneric(aKey);
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}
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enum { ALLOW_MEMMOVE = true };
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protected:
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T* MOZ_NON_OWNING_REF mKey;
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};
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typedef nsPtrHashKey<const void> nsVoidPtrHashKey;
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#endif // nsPointerHashKeys_h
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