WebCore/platform/StringHash.h - WebKit - Git at Google

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * 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., 59 Temple Place - Suite 330,
  * Boston, MA 02111-1307, USA.
  *
  */

 #ifndef StringHash_h
 #define StringHash_h

 #include "AtomicStringImpl.h"
 #include "PlatformString.h"
 #include <wtf/HashTraits.h>
 #include <wtf/unicode/Unicode.h>

 namespace WTF {

     template<typename T> struct StrHash;

     template<> struct StrHash<WebCore::StringImpl*> {
         static unsigned hash(const WebCore::StringImpl* key) { return key->hash(); }
         static bool equal(const WebCore::StringImpl* a, const WebCore::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;
         }
     };

     template<> struct StrHash<WebCore::AtomicStringImpl*> : public StrHash<WebCore::StringImpl*> { };

     template<> struct StrHash<RefPtr<WebCore::StringImpl> > {
         static unsigned hash(const RefPtr<WebCore::StringImpl>& key) { return key->hash(); }
         static bool equal(const RefPtr<WebCore::StringImpl>& a, const RefPtr<WebCore::StringImpl>& b)
         {
             return StrHash<WebCore::StringImpl*>::equal(a.get(), b.get());
         }
     };

     template<> struct StrHash<WebCore::String> {
         static unsigned hash(const WebCore::String& key) { return key.impl()->hash(); }
         static bool equal(const WebCore::String& a, const WebCore::String& b)
         {
             return StrHash<WebCore::StringImpl*>::equal(a.impl(), b.impl());
         }
     };

     template<typename T> struct CaseInsensitiveHash;

     template<> class CaseInsensitiveHash<WebCore::StringImpl*> {
     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(const WebCore::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(const WebCore::StringImpl* a, const WebCore::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;
         }
     };

     template<> struct CaseInsensitiveHash<WebCore::AtomicStringImpl*> : public CaseInsensitiveHash<WebCore::StringImpl*> { };

     template<> struct CaseInsensitiveHash<RefPtr<WebCore::StringImpl> > {
         static unsigned hash(const RefPtr<WebCore::StringImpl>& key)
         {
             return CaseInsensitiveHash<WebCore::StringImpl*>::hash(key.get());
         }

         static bool equal(const RefPtr<WebCore::StringImpl>& a, const RefPtr<WebCore::StringImpl>& b)
         {
             return CaseInsensitiveHash<WebCore::StringImpl*>::equal(a.get(), b.get());
         }
     };

     template<> struct CaseInsensitiveHash<WebCore::String> {
         static unsigned hash(const WebCore::String& key)
         {
             return CaseInsensitiveHash<WebCore::StringImpl*>::hash(key.impl());
         }
         static bool equal(const WebCore::String& a, const WebCore::String& b)
         {
             return CaseInsensitiveHash<WebCore::StringImpl*>::equal(a.impl(), b.impl());
         }
     };

     // 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<StrHash<RefPtr<WebCore::StringImpl> >, HashTraits<RefPtr<WebCore::StringImpl> > > {
         typedef StrHash<WebCore::StringImpl*> Hash;
         typedef HashTraits<WebCore::StringImpl*> Traits;
     };
     template<> struct HashKeyStorageTraits<StrHash<WebCore::String>, HashTraits<WebCore::String> > {
         typedef StrHash<WebCore::StringImpl*> Hash;
         typedef HashTraits<WebCore::StringImpl*> Traits;
     };

     template<> struct HashKeyStorageTraits<CaseInsensitiveHash<RefPtr<WebCore::StringImpl> >, HashTraits<RefPtr<WebCore::StringImpl> > > {
         typedef CaseInsensitiveHash<WebCore::StringImpl*> Hash;
         typedef HashTraits<WebCore::StringImpl*> Traits;
     };
     template<> struct HashKeyStorageTraits<CaseInsensitiveHash<WebCore::String>, HashTraits<WebCore::String> > {
         typedef CaseInsensitiveHash<WebCore::StringImpl*> Hash;
         typedef HashTraits<WebCore::StringImpl*> Traits;
     };

 }

 using WTF::CaseInsensitiveHash;

 #endif
	/*
	* Copyright (C) 2006 Apple Computer, Inc.
	*
	* 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., 59 Temple Place - Suite 330,
	* Boston, MA 02111-1307, USA.
	*
	*/

	#ifndef StringHash_h
	#define StringHash_h

	#include "AtomicStringImpl.h"
	#include "PlatformString.h"
	#include <wtf/HashTraits.h>
	#include <wtf/unicode/Unicode.h>

	namespace WTF {

	template<typename T> struct StrHash;

	template<> struct StrHash<WebCore::StringImpl*> {
	static unsigned hash(const WebCore::StringImpl* key) { return key->hash(); }
	static bool equal(const WebCore::StringImpl* a, const WebCore::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;
	}
	};

	template<> struct StrHash<WebCore::AtomicStringImpl> : public StrHash<WebCore::StringImpl> { };

	template<> struct StrHash<RefPtr<WebCore::StringImpl> > {
	static unsigned hash(const RefPtr<WebCore::StringImpl>& key) { return key->hash(); }
	static bool equal(const RefPtr<WebCore::StringImpl>& a, const RefPtr<WebCore::StringImpl>& b)
	{
	return StrHash<WebCore::StringImpl*>::equal(a.get(), b.get());
	}
	};

	template<> struct StrHash<WebCore::String> {
	static unsigned hash(const WebCore::String& key) { return key.impl()->hash(); }
	static bool equal(const WebCore::String& a, const WebCore::String& b)
	{
	return StrHash<WebCore::StringImpl*>::equal(a.impl(), b.impl());
	}
	};

	template<typename T> struct CaseInsensitiveHash;

	template<> class CaseInsensitiveHash<WebCore::StringImpl*> {
	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(const WebCore::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(const WebCore::StringImpl* a, const WebCore::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;
	}
	};

	template<> struct CaseInsensitiveHash<WebCore::AtomicStringImpl> : public CaseInsensitiveHash<WebCore::StringImpl> { };

	template<> struct CaseInsensitiveHash<RefPtr<WebCore::StringImpl> > {
	static unsigned hash(const RefPtr<WebCore::StringImpl>& key)
	{
	return CaseInsensitiveHash<WebCore::StringImpl*>::hash(key.get());
	}

	static bool equal(const RefPtr<WebCore::StringImpl>& a, const RefPtr<WebCore::StringImpl>& b)
	{
	return CaseInsensitiveHash<WebCore::StringImpl*>::equal(a.get(), b.get());
	}
	};

	template<> struct CaseInsensitiveHash<WebCore::String> {
	static unsigned hash(const WebCore::String& key)
	{
	return CaseInsensitiveHash<WebCore::StringImpl*>::hash(key.impl());
	}
	static bool equal(const WebCore::String& a, const WebCore::String& b)
	{
	return CaseInsensitiveHash<WebCore::StringImpl*>::equal(a.impl(), b.impl());
	}
	};

	// 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<StrHash<RefPtr<WebCore::StringImpl> >, HashTraits<RefPtr<WebCore::StringImpl> > > {
	typedef StrHash<WebCore::StringImpl*> Hash;
	typedef HashTraits<WebCore::StringImpl*> Traits;
	};
	template<> struct HashKeyStorageTraits<StrHash<WebCore::String>, HashTraits<WebCore::String> > {
	typedef StrHash<WebCore::StringImpl*> Hash;
	typedef HashTraits<WebCore::StringImpl*> Traits;
	};

	template<> struct HashKeyStorageTraits<CaseInsensitiveHash<RefPtr<WebCore::StringImpl> >, HashTraits<RefPtr<WebCore::StringImpl> > > {
	typedef CaseInsensitiveHash<WebCore::StringImpl*> Hash;
	typedef HashTraits<WebCore::StringImpl*> Traits;
	};
	template<> struct HashKeyStorageTraits<CaseInsensitiveHash<WebCore::String>, HashTraits<WebCore::String> > {
	typedef CaseInsensitiveHash<WebCore::StringImpl*> Hash;
	typedef HashTraits<WebCore::StringImpl*> Traits;
	};

	}

	using WTF::CaseInsensitiveHash;

	#endif