| /* |
| * Copyright (C) 2006, 2007, 2008, 2012, 2013 Apple Inc. All rights reserved |
| * Copyright (C) Research In Motion Limited 2009. 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 THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_TEXT_STRING_HASH_H_ |
| #define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_TEXT_STRING_HASH_H_ |
| |
| #include "third_party/blink/renderer/platform/wtf/allocator/allocator.h" |
| #include "third_party/blink/renderer/platform/wtf/hash_traits.h" |
| #include "third_party/blink/renderer/platform/wtf/text/atomic_string.h" |
| #include "third_party/blink/renderer/platform/wtf/text/string_hasher.h" |
| |
| namespace WTF { |
| |
| inline bool HashTraits<String>::IsEmptyValue(const String& value) { |
| return value.IsNull(); |
| } |
| |
| inline bool HashTraits<String>::IsDeletedValue(const String& value) { |
| return HashTraits<scoped_refptr<StringImpl>>::IsDeletedValue(value.impl_); |
| } |
| |
| inline void HashTraits<String>::ConstructDeletedValue(String& slot, |
| bool zero_value) { |
| HashTraits<scoped_refptr<StringImpl>>::ConstructDeletedValue(slot.impl_, |
| zero_value); |
| } |
| |
| // The hash() functions on StringHash and CaseFoldingHash do not support null |
| // strings. get(), contains(), and add() on HashMap<String,..., StringHash> |
| // cause a null-pointer dereference when passed null strings. |
| |
| // FIXME: We should really figure out a way to put the computeHash function |
| // that's currently a member function of StringImpl into this file so we can be |
| // a little closer to having all the nearly-identical hash functions in one |
| // place. |
| |
| struct StringHash { |
| STATIC_ONLY(StringHash); |
| static unsigned GetHash(StringImpl* key) { return key->GetHash(); } |
| static inline bool Equal(const StringImpl* a, const StringImpl* b) { |
| return EqualNonNull(a, b); |
| } |
| |
| static unsigned GetHash(const scoped_refptr<StringImpl>& key) { |
| return key->GetHash(); |
| } |
| static bool Equal(const scoped_refptr<StringImpl>& a, |
| const scoped_refptr<StringImpl>& b) { |
| return Equal(a.get(), b.get()); |
| } |
| |
| static unsigned GetHash(const String& key) { return key.Impl()->GetHash(); } |
| static bool Equal(const String& a, const String& b) { |
| return Equal(a.Impl(), b.Impl()); |
| } |
| |
| static const bool safe_to_compare_to_empty_or_deleted = false; |
| }; |
| |
| class CaseFoldingHash { |
| STATIC_ONLY(CaseFoldingHash); |
| |
| public: |
| static unsigned GetHash(const UChar* data, unsigned length) { |
| return StringHasher::ComputeHashAndMaskTop8Bits<UChar, FoldCase<UChar>>( |
| data, length); |
| } |
| |
| static unsigned GetHash(StringImpl* str) { |
| if (str->Is8Bit()) |
| return GetHash(str->Characters8(), str->length()); |
| return GetHash(str->Characters16(), str->length()); |
| } |
| |
| static unsigned GetHash(const LChar* data, unsigned length) { |
| return StringHasher::ComputeHashAndMaskTop8Bits<LChar, FoldCase<LChar>>( |
| data, length); |
| } |
| |
| static inline unsigned GetHash(const char* data, unsigned length) { |
| return CaseFoldingHash::GetHash(reinterpret_cast<const LChar*>(data), |
| length); |
| } |
| |
| static inline bool Equal(const StringImpl* a, const StringImpl* b) { |
| DCHECK(a); |
| DCHECK(b); |
| // Save one branch inside each StringView by derefing the StringImpl, |
| // and another branch inside the compare function by skipping the null |
| // checks. |
| return DeprecatedEqualIgnoringCaseAndNullity(*a, *b); |
| } |
| |
| static unsigned GetHash(const scoped_refptr<StringImpl>& key) { |
| return GetHash(key.get()); |
| } |
| |
| static bool Equal(const scoped_refptr<StringImpl>& a, |
| const scoped_refptr<StringImpl>& b) { |
| return Equal(a.get(), b.get()); |
| } |
| |
| static unsigned GetHash(const String& key) { return GetHash(key.Impl()); } |
| static unsigned GetHash(const AtomicString& key) { |
| return GetHash(key.Impl()); |
| } |
| static bool Equal(const String& a, const String& b) { |
| return Equal(a.Impl(), b.Impl()); |
| } |
| static bool Equal(const AtomicString& a, const AtomicString& b) { |
| return (a == b) || Equal(a.Impl(), b.Impl()); |
| } |
| |
| static const bool safe_to_compare_to_empty_or_deleted = false; |
| |
| private: |
| // Private so no one uses this in the belief that it will return the |
| // correctly-folded code point in all cases (see comment below). |
| template <typename T> |
| static inline UChar FoldCase(T ch) { |
| if (std::is_same<T, LChar>::value) |
| return StringImpl::kLatin1CaseFoldTable[ch]; |
| // It's possible for WTF::unicode::foldCase() to return a 32-bit value |
| // that's not representable as a UChar. However, since this is rare and |
| // deterministic, and the result of this is merely used for hashing, go |
| // ahead and clamp the value. |
| return static_cast<UChar>(WTF::unicode::FoldCase(ch)); |
| } |
| }; |
| |
| // This hash can be used in cases where the key is a hash of a string, but we |
| // don't want to store the string. It's not really specific to string hashing, |
| // but all our current uses of it are for strings. |
| struct AlreadyHashed : IntHash<unsigned> { |
| STATIC_ONLY(AlreadyHashed); |
| static unsigned GetHash(unsigned key) { return key; } |
| |
| // To use a hash value as a key for a hash table, we need to eliminate the |
| // "deleted" value, which is negative one. That could be done by changing |
| // the string hash function to never generate negative one, but this works |
| // and is still relatively efficient. |
| static unsigned AvoidDeletedValue(unsigned hash) { |
| DCHECK(hash); |
| unsigned new_hash = hash | (!(hash + 1) << 31); |
| DCHECK(new_hash); |
| DCHECK_NE(new_hash, 0xFFFFFFFF); |
| return new_hash; |
| } |
| }; |
| |
| } // namespace WTF |
| |
| using WTF::AlreadyHashed; |
| using WTF::CaseFoldingHash; |
| using WTF::StringHash; |
| |
| #endif |