| /* |
| * Copyright (C) 2006, 2007 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 |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Library General Public License for more details. |
| * |
| * You should have received a copy of the GNU Library General Public License |
| * along with this library; see the file COPYING.LIB. If not, write to |
| * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| * |
| */ |
| |
| #ifndef StringHash_h |
| #define StringHash_h |
| |
| #include "AtomicStringImpl.h" |
| #include "PlatformString.h" |
| #include <wtf/HashTraits.h> |
| #include <wtf/unicode/Unicode.h> |
| |
| namespace WebCore { |
| |
| struct StringHash { |
| static unsigned hash(StringImpl* key) { return key->hash(); } |
| static bool equal(StringImpl* a, StringImpl* b) |
| { |
| if (a == b) |
| return true; |
| if (!a || !b) |
| return false; |
| |
| unsigned aLength = a->length(); |
| unsigned bLength = b->length(); |
| if (aLength != bLength) |
| return false; |
| |
| const uint32_t* aChars = reinterpret_cast<const uint32_t*>(a->characters()); |
| const uint32_t* bChars = reinterpret_cast<const uint32_t*>(b->characters()); |
| |
| unsigned halfLength = aLength >> 1; |
| for (unsigned i = 0; i != halfLength; ++i) |
| if (*aChars++ != *bChars++) |
| return false; |
| |
| if (aLength & 1 && *reinterpret_cast<const uint16_t*>(aChars) != *reinterpret_cast<const uint16_t*>(bChars)) |
| return false; |
| |
| return true; |
| } |
| |
| static unsigned hash(const RefPtr<StringImpl>& key) { return key->hash(); } |
| static bool equal(const RefPtr<StringImpl>& a, const RefPtr<StringImpl>& b) |
| { |
| return equal(a.get(), b.get()); |
| } |
| |
| static unsigned hash(const String& key) { return key.impl()->hash(); } |
| static bool equal(const String& a, const String& b) |
| { |
| return equal(a.impl(), b.impl()); |
| } |
| |
| static const bool safeToCompareToEmptyOrDeleted = false; |
| }; |
| |
| class CaseFoldingHash { |
| private: |
| // Golden ratio - arbitrary start value to avoid mapping all 0's to all 0's |
| static const unsigned PHI = 0x9e3779b9U; |
| public: |
| // Paul Hsieh's SuperFastHash |
| // http://www.azillionmonkeys.com/qed/hash.html |
| static unsigned hash(StringImpl* str) |
| { |
| unsigned l = str->length(); |
| const UChar* s = str->characters(); |
| uint32_t hash = PHI; |
| uint32_t tmp; |
| |
| int rem = l & 1; |
| l >>= 1; |
| |
| // Main loop |
| for (; l > 0; l--) { |
| hash += WTF::Unicode::foldCase(s[0]); |
| tmp = (WTF::Unicode::foldCase(s[1]) << 11) ^ hash; |
| hash = (hash << 16) ^ tmp; |
| s += 2; |
| hash += hash >> 11; |
| } |
| |
| // Handle end case |
| if (rem) { |
| hash += WTF::Unicode::foldCase(s[0]); |
| hash ^= hash << 11; |
| hash += hash >> 17; |
| } |
| |
| // Force "avalanching" of final 127 bits |
| hash ^= hash << 3; |
| hash += hash >> 5; |
| hash ^= hash << 2; |
| hash += hash >> 15; |
| hash ^= hash << 10; |
| |
| // this avoids ever returning a hash code of 0, since that is used to |
| // signal "hash not computed yet", using a value that is likely to be |
| // effectively the same as 0 when the low bits are masked |
| if (hash == 0) |
| hash = 0x80000000; |
| |
| return hash; |
| } |
| |
| static unsigned hash(const char* str, unsigned length) |
| { |
| // This hash is designed to work on 16-bit chunks at a time. But since the normal case |
| // (above) is to hash UTF-16 characters, we just treat the 8-bit chars as if they |
| // were 16-bit chunks, which will give matching results. |
| |
| unsigned l = length; |
| const char* s = str; |
| uint32_t hash = PHI; |
| uint32_t tmp; |
| |
| int rem = l & 1; |
| l >>= 1; |
| |
| // Main loop |
| for (; l > 0; l--) { |
| hash += WTF::Unicode::foldCase(s[0]); |
| tmp = (WTF::Unicode::foldCase(s[1]) << 11) ^ hash; |
| hash = (hash << 16) ^ tmp; |
| s += 2; |
| hash += hash >> 11; |
| } |
| |
| // Handle end case |
| if (rem) { |
| hash += WTF::Unicode::foldCase(s[0]); |
| hash ^= hash << 11; |
| hash += hash >> 17; |
| } |
| |
| // Force "avalanching" of final 127 bits |
| hash ^= hash << 3; |
| hash += hash >> 5; |
| hash ^= hash << 2; |
| hash += hash >> 15; |
| hash ^= hash << 10; |
| |
| // this avoids ever returning a hash code of 0, since that is used to |
| // signal "hash not computed yet", using a value that is likely to be |
| // effectively the same as 0 when the low bits are masked |
| if (hash == 0) |
| hash = 0x80000000; |
| |
| return hash; |
| } |
| |
| static bool equal(StringImpl* a, StringImpl* b) |
| { |
| if (a == b) |
| return true; |
| if (!a || !b) |
| return false; |
| unsigned length = a->length(); |
| if (length != b->length()) |
| return false; |
| return WTF::Unicode::umemcasecmp(a->characters(), b->characters(), length) == 0; |
| } |
| |
| static unsigned hash(const RefPtr<StringImpl>& key) |
| { |
| return hash(key.get()); |
| } |
| |
| static bool equal(const RefPtr<StringImpl>& a, const RefPtr<StringImpl>& b) |
| { |
| return equal(a.get(), b.get()); |
| } |
| |
| static unsigned hash(const String& key) |
| { |
| return hash(key.impl()); |
| } |
| static bool equal(const String& a, const String& b) |
| { |
| return equal(a.impl(), b.impl()); |
| } |
| |
| static const bool safeToCompareToEmptyOrDeleted = false; |
| }; |
| |
| } |
| |
| namespace WTF { |
| |
| // store WebCore::String as StringImpl* |
| |
| template<> struct HashTraits<WebCore::String> : GenericHashTraits<WebCore::String> { |
| typedef HashTraits<WebCore::StringImpl*>::StorageTraits StorageTraits; |
| typedef StorageTraits::TraitType StorageType; |
| static const bool emptyValueIsZero = true; |
| static const bool needsRef = true; |
| |
| typedef union { |
| WebCore::StringImpl* m_p; |
| StorageType m_s; |
| } UnionType; |
| |
| static void ref(const StorageType& s) { ref(reinterpret_cast<const UnionType*>(&s)->m_p); } |
| static void deref(const StorageType& s) { deref(reinterpret_cast<const UnionType*>(&s)->m_p); } |
| |
| static void ref(const WebCore::StringImpl* str) { if (str) const_cast<WebCore::StringImpl*>(str)->ref(); } |
| static void deref(const WebCore::StringImpl* str) { if (str) const_cast<WebCore::StringImpl*>(str)->deref(); } |
| }; |
| |
| // share code between StringImpl*, RefPtr<StringImpl>, and String |
| |
| template<> struct HashKeyStorageTraits<WebCore::StringHash, HashTraits<RefPtr<WebCore::StringImpl> > > { |
| typedef WebCore::StringHash Hash; |
| typedef HashTraits<WebCore::StringImpl*> Traits; |
| }; |
| template<> struct HashKeyStorageTraits<WebCore::StringHash, HashTraits<WebCore::String> > { |
| typedef WebCore::StringHash Hash; |
| typedef HashTraits<WebCore::StringImpl*> Traits; |
| }; |
| |
| template<> struct HashKeyStorageTraits<WebCore::CaseFoldingHash, HashTraits<RefPtr<WebCore::StringImpl> > > { |
| typedef WebCore::CaseFoldingHash Hash; |
| typedef HashTraits<WebCore::StringImpl*> Traits; |
| }; |
| template<> struct HashKeyStorageTraits<WebCore::CaseFoldingHash, HashTraits<WebCore::String> > { |
| typedef WebCore::CaseFoldingHash Hash; |
| typedef HashTraits<WebCore::StringImpl*> Traits; |
| }; |
| |
| } |
| |
| #endif |
