Source/JavaScriptCore/wtf/text/AtomicString.cpp - platform/external/webkit - Git at Google

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Patrick Gansterer <paroga@paroga.com>
  *
  * 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.
  *
  */

 #include "config.h"

 #include "AtomicString.h"

 #include "StringHash.h"
 #include <wtf/HashSet.h>
 #include <wtf/Threading.h>
 #include <wtf/WTFThreadData.h>
 #include <wtf/unicode/UTF8.h>

 namespace WTF {

 using namespace Unicode;

 COMPILE_ASSERT(sizeof(AtomicString) == sizeof(String), atomic_string_and_string_must_be_same_size);

 class AtomicStringTable {
 public:
     static AtomicStringTable* create()
     {
         AtomicStringTable* table = new AtomicStringTable;

         WTFThreadData& data = wtfThreadData();
         data.m_atomicStringTable = table;
         data.m_atomicStringTableDestructor = AtomicStringTable::destroy;

         return table;
     }

     HashSet<StringImpl*>& table()
     {
         return m_table;
     }

 private:
     static void destroy(AtomicStringTable* table)
     {
         HashSet<StringImpl*>::iterator end = table->m_table.end();
         for (HashSet<StringImpl*>::iterator iter = table->m_table.begin(); iter != end; ++iter)
             (*iter)->setIsAtomic(false);
         delete table;
     }

     HashSet<StringImpl*> m_table;
 };

 static inline HashSet<StringImpl*>& stringTable()
 {
     // Once possible we should make this non-lazy (constructed in WTFThreadData's constructor).
     AtomicStringTable* table = wtfThreadData().atomicStringTable();
     if (UNLIKELY(!table))
         table = AtomicStringTable::create();
     return table->table();
 }

 template<typename T, typename HashTranslator>
 static inline PassRefPtr<StringImpl> addToStringTable(const T& value)
 {
     pair<HashSet<StringImpl*>::iterator, bool> addResult = stringTable().add<T, HashTranslator>(value);

     // If the string is newly-translated, then we need to adopt it.
     // The boolean in the pair tells us if that is so.
     return addResult.second ? adoptRef(*addResult.first) : *addResult.first;
 }

 struct CStringTranslator {
     static unsigned hash(const char* c)
     {
         return StringHasher::computeHash(c);
     }

     static bool equal(StringImpl* r, const char* s)
     {
         int length = r->length();
         const UChar* d = r->characters();
         for (int i = 0; i != length; ++i) {
             unsigned char c = s[i];
             if (d[i] != c)
                 return false;
         }
         return !s[length];
     }

     static void translate(StringImpl*& location, const char* const& c, unsigned hash)
     {
         location = StringImpl::create(c).leakRef();
         location->setHash(hash);
         location->setIsAtomic(true);
     }
 };

 bool operator==(const AtomicString& a, const char* b)
 {
     StringImpl* impl = a.impl();
     if ((!impl || !impl->characters()) && !b)
         return true;
     if ((!impl || !impl->characters()) || !b)
         return false;
     return CStringTranslator::equal(impl, b);
 }

 PassRefPtr<StringImpl> AtomicString::add(const char* c)
 {
     if (!c)
         return 0;
     if (!*c)
         return StringImpl::empty();

     return addToStringTable<const char*, CStringTranslator>(c);
 }

 struct UCharBuffer {
     const UChar* s;
     unsigned length;
 };

 static inline bool equal(StringImpl* string, const UChar* characters, unsigned length)
 {
     if (string->length() != length)
         return false;

     // FIXME: perhaps we should have a more abstract macro that indicates when
     // going 4 bytes at a time is unsafe
 #if CPU(ARM) || CPU(SH4) || CPU(MIPS) || CPU(SPARC)
     const UChar* stringCharacters = string->characters();
     for (unsigned i = 0; i != length; ++i) {
         if (*stringCharacters++ != *characters++)
             return false;
     }
     return true;
 #else
     /* Do it 4-bytes-at-a-time on architectures where it's safe */

     const uint32_t* stringCharacters = reinterpret_cast<const uint32_t*>(string->characters());
     const uint32_t* bufferCharacters = reinterpret_cast<const uint32_t*>(characters);

     unsigned halfLength = length >> 1;
     for (unsigned i = 0; i != halfLength; ++i) {
         if (*stringCharacters++ != *bufferCharacters++)
             return false;
     }

     if (length & 1 &&  *reinterpret_cast<const uint16_t*>(stringCharacters) != *reinterpret_cast<const uint16_t*>(bufferCharacters))
         return false;

     return true;
 #endif
 }

 bool operator==(const AtomicString& string, const Vector<UChar>& vector)
 {
     return string.impl() && equal(string.impl(), vector.data(), vector.size());
 }

 struct UCharBufferTranslator {
     static unsigned hash(const UCharBuffer& buf)
     {
         return StringHasher::computeHash(buf.s, buf.length);
     }

     static bool equal(StringImpl* const& str, const UCharBuffer& buf)
     {
         return WTF::equal(str, buf.s, buf.length);
     }

     static void translate(StringImpl*& location, const UCharBuffer& buf, unsigned hash)
     {
         location = StringImpl::create(buf.s, buf.length).leakRef();
         location->setHash(hash);
         location->setIsAtomic(true);
     }
 };

 struct HashAndCharacters {
     unsigned hash;
     const UChar* characters;
     unsigned length;
 };

 struct HashAndCharactersTranslator {
     static unsigned hash(const HashAndCharacters& buffer)
     {
         ASSERT(buffer.hash == StringHasher::computeHash(buffer.characters, buffer.length));
         return buffer.hash;
     }

     static bool equal(StringImpl* const& string, const HashAndCharacters& buffer)
     {
         return WTF::equal(string, buffer.characters, buffer.length);
     }

     static void translate(StringImpl*& location, const HashAndCharacters& buffer, unsigned hash)
     {
         location = StringImpl::create(buffer.characters, buffer.length).leakRef();
         location->setHash(hash);
         location->setIsAtomic(true);
     }
 };

 struct HashAndUTF8Characters {
     unsigned hash;
     const char* characters;
     unsigned length;
     unsigned utf16Length;
 };

 struct HashAndUTF8CharactersTranslator {
     static unsigned hash(const HashAndUTF8Characters& buffer)
     {
         return buffer.hash;
     }

     static bool equal(StringImpl* const& string, const HashAndUTF8Characters& buffer)
     {
         if (buffer.utf16Length != string->length())
             return false;

         const UChar* stringCharacters = string->characters();

         // If buffer contains only ASCII characters UTF-8 and UTF16 length are the same.
         if (buffer.utf16Length != buffer.length)
             return equalUTF16WithUTF8(stringCharacters, stringCharacters + string->length(), buffer.characters, buffer.characters + buffer.length);

         for (unsigned i = 0; i < buffer.length; ++i) {
             ASSERT(isASCII(buffer.characters[i]));
             if (stringCharacters[i] != buffer.characters[i])
                 return false;
         }

         return true;
     }

     static void translate(StringImpl*& location, const HashAndUTF8Characters& buffer, unsigned hash)
     {
         UChar* target;
         location = StringImpl::createUninitialized(buffer.utf16Length, target).releaseRef();

         const char* source = buffer.characters;
         if (convertUTF8ToUTF16(&source, source + buffer.length, &target, target + buffer.utf16Length) != conversionOK)
             ASSERT_NOT_REACHED();

         location->setHash(hash);
         location->setIsAtomic(true);
     }
 };

 PassRefPtr<StringImpl> AtomicString::add(const UChar* s, unsigned length)
 {
     if (!s)
         return 0;

     if (!length)
         return StringImpl::empty();

     UCharBuffer buffer = { s, length };
     return addToStringTable<UCharBuffer, UCharBufferTranslator>(buffer);
 }

 PassRefPtr<StringImpl> AtomicString::add(const UChar* s, unsigned length, unsigned existingHash)
 {
     ASSERT(s);
     ASSERT(existingHash);

     if (!length)
         return StringImpl::empty();

     HashAndCharacters buffer = { existingHash, s, length };
     return addToStringTable<HashAndCharacters, HashAndCharactersTranslator>(buffer);
 }

 PassRefPtr<StringImpl> AtomicString::add(const UChar* s)
 {
     if (!s)
         return 0;

     int length = 0;
     while (s[length] != UChar(0))
         length++;

     if (!length)
         return StringImpl::empty();

     UCharBuffer buffer = { s, length };
     return addToStringTable<UCharBuffer, UCharBufferTranslator>(buffer);
 }

 PassRefPtr<StringImpl> AtomicString::addSlowCase(StringImpl* r)
 {
     if (!r || r->isAtomic())
         return r;

     if (!r->length())
         return StringImpl::empty();

     StringImpl* result = *stringTable().add(r).first;
     if (result == r)
         r->setIsAtomic(true);
     return result;
 }

 AtomicStringImpl* AtomicString::find(const UChar* s, unsigned length, unsigned existingHash)
 {
     ASSERT(s);
     ASSERT(existingHash);

     if (!length)
         return static_cast<AtomicStringImpl*>(StringImpl::empty());

     HashAndCharacters buffer = { existingHash, s, length };
     HashSet<StringImpl*>::iterator iterator = stringTable().find<HashAndCharacters, HashAndCharactersTranslator>(buffer);
     if (iterator == stringTable().end())
         return 0;
     return static_cast<AtomicStringImpl*>(*iterator);
 }

 void AtomicString::remove(StringImpl* r)
 {
     stringTable().remove(r);
 }

 AtomicString AtomicString::lower() const
 {
     // Note: This is a hot function in the Dromaeo benchmark.
     StringImpl* impl = this->impl();
     if (UNLIKELY(!impl))
         return *this;
     RefPtr<StringImpl> newImpl = impl->lower();
     if (LIKELY(newImpl == impl))
         return *this;
     return AtomicString(newImpl);
 }

 AtomicString AtomicString::fromUTF8Internal(const char* charactersStart, const char* charactersEnd)
 {
     HashAndUTF8Characters buffer;
     buffer.characters = charactersStart;
     buffer.hash = calculateStringHashAndLengthFromUTF8(charactersStart, charactersEnd, buffer.length, buffer.utf16Length);

     if (!buffer.hash)
         return nullAtom;

     AtomicString atomicString;
     atomicString.m_string = addToStringTable<HashAndUTF8Characters, HashAndUTF8CharactersTranslator>(buffer);
     return atomicString;
 }

 } // namespace WTF
	/*
	* Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
	* Copyright (C) 2010 Patrick Gansterer <paroga@paroga.com>
	*
	* 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.
	*
	*/

	#include "config.h"

	#include "AtomicString.h"

	#include "StringHash.h"
	#include <wtf/HashSet.h>
	#include <wtf/Threading.h>
	#include <wtf/WTFThreadData.h>
	#include <wtf/unicode/UTF8.h>

	namespace WTF {

	using namespace Unicode;

	COMPILE_ASSERT(sizeof(AtomicString) == sizeof(String), atomic_string_and_string_must_be_same_size);

	class AtomicStringTable {
	public:
	static AtomicStringTable* create()
	{
	AtomicStringTable* table = new AtomicStringTable;

	WTFThreadData& data = wtfThreadData();
	data.m_atomicStringTable = table;
	data.m_atomicStringTableDestructor = AtomicStringTable::destroy;

	return table;
	}

	HashSet<StringImpl*>& table()
	{
	return m_table;
	}

	private:
	static void destroy(AtomicStringTable* table)
	{
	HashSet<StringImpl*>::iterator end = table->m_table.end();
	for (HashSet<StringImpl*>::iterator iter = table->m_table.begin(); iter != end; ++iter)
	(*iter)->setIsAtomic(false);
	delete table;
	}

	HashSet<StringImpl*> m_table;
	};

	static inline HashSet<StringImpl*>& stringTable()
	{
	// Once possible we should make this non-lazy (constructed in WTFThreadData's constructor).
	AtomicStringTable* table = wtfThreadData().atomicStringTable();
	if (UNLIKELY(!table))
	table = AtomicStringTable::create();
	return table->table();
	}

	template<typename T, typename HashTranslator>
	static inline PassRefPtr<StringImpl> addToStringTable(const T& value)
	{
	pair<HashSet<StringImpl*>::iterator, bool> addResult = stringTable().add<T, HashTranslator>(value);

	// If the string is newly-translated, then we need to adopt it.
	// The boolean in the pair tells us if that is so.
	return addResult.second ? adoptRef(addResult.first) : addResult.first;
	}

	struct CStringTranslator {
	static unsigned hash(const char* c)
	{
	return StringHasher::computeHash(c);
	}

	static bool equal(StringImpl* r, const char* s)
	{
	int length = r->length();
	const UChar* d = r->characters();
	for (int i = 0; i != length; ++i) {
	unsigned char c = s[i];
	if (d[i] != c)
	return false;
	}
	return !s[length];
	}

	static void translate(StringImpl& location, const char const& c, unsigned hash)
	{
	location = StringImpl::create(c).leakRef();
	location->setHash(hash);
	location->setIsAtomic(true);
	}
	};

	bool operator==(const AtomicString& a, const char* b)
	{
	StringImpl* impl = a.impl();
	if ((!impl \|\| !impl->characters()) && !b)
	return true;
	if ((!impl \|\| !impl->characters()) \|\| !b)
	return false;
	return CStringTranslator::equal(impl, b);
	}

	PassRefPtr<StringImpl> AtomicString::add(const char* c)
	{
	if (!c)
	return 0;
	if (!*c)
	return StringImpl::empty();

	return addToStringTable<const char*, CStringTranslator>(c);
	}

	struct UCharBuffer {
	const UChar* s;
	unsigned length;
	};

	static inline bool equal(StringImpl* string, const UChar* characters, unsigned length)
	{
	if (string->length() != length)
	return false;

	// FIXME: perhaps we should have a more abstract macro that indicates when
	// going 4 bytes at a time is unsafe
	#if CPU(ARM) \|\| CPU(SH4) \|\| CPU(MIPS) \|\| CPU(SPARC)
	const UChar* stringCharacters = string->characters();
	for (unsigned i = 0; i != length; ++i) {
	if (stringCharacters++ != characters++)
	return false;
	}
	return true;
	#else
	/* Do it 4-bytes-at-a-time on architectures where it's safe */

	const uint32_t* stringCharacters = reinterpret_cast<const uint32_t*>(string->characters());
	const uint32_t* bufferCharacters = reinterpret_cast<const uint32_t*>(characters);

	unsigned halfLength = length >> 1;
	for (unsigned i = 0; i != halfLength; ++i) {
	if (stringCharacters++ != bufferCharacters++)
	return false;
	}

	if (length & 1 && reinterpret_cast<const uint16_t>(stringCharacters) != reinterpret_cast<const uint16_t>(bufferCharacters))
	return false;

	return true;
	#endif
	}

	bool operator==(const AtomicString& string, const Vector<UChar>& vector)
	{
	return string.impl() && equal(string.impl(), vector.data(), vector.size());
	}

	struct UCharBufferTranslator {
	static unsigned hash(const UCharBuffer& buf)
	{
	return StringHasher::computeHash(buf.s, buf.length);
	}

	static bool equal(StringImpl* const& str, const UCharBuffer& buf)
	{
	return WTF::equal(str, buf.s, buf.length);
	}

	static void translate(StringImpl*& location, const UCharBuffer& buf, unsigned hash)
	{
	location = StringImpl::create(buf.s, buf.length).leakRef();
	location->setHash(hash);
	location->setIsAtomic(true);
	}
	};

	struct HashAndCharacters {
	unsigned hash;
	const UChar* characters;
	unsigned length;
	};

	struct HashAndCharactersTranslator {
	static unsigned hash(const HashAndCharacters& buffer)
	{
	ASSERT(buffer.hash == StringHasher::computeHash(buffer.characters, buffer.length));
	return buffer.hash;
	}

	static bool equal(StringImpl* const& string, const HashAndCharacters& buffer)
	{
	return WTF::equal(string, buffer.characters, buffer.length);
	}

	static void translate(StringImpl*& location, const HashAndCharacters& buffer, unsigned hash)
	{
	location = StringImpl::create(buffer.characters, buffer.length).leakRef();
	location->setHash(hash);
	location->setIsAtomic(true);
	}
	};

	struct HashAndUTF8Characters {
	unsigned hash;
	const char* characters;
	unsigned length;
	unsigned utf16Length;
	};

	struct HashAndUTF8CharactersTranslator {
	static unsigned hash(const HashAndUTF8Characters& buffer)
	{
	return buffer.hash;
	}

	static bool equal(StringImpl* const& string, const HashAndUTF8Characters& buffer)
	{
	if (buffer.utf16Length != string->length())
	return false;

	const UChar* stringCharacters = string->characters();

	// If buffer contains only ASCII characters UTF-8 and UTF16 length are the same.
	if (buffer.utf16Length != buffer.length)
	return equalUTF16WithUTF8(stringCharacters, stringCharacters + string->length(), buffer.characters, buffer.characters + buffer.length);

	for (unsigned i = 0; i < buffer.length; ++i) {
	ASSERT(isASCII(buffer.characters[i]));
	if (stringCharacters[i] != buffer.characters[i])
	return false;
	}

	return true;
	}

	static void translate(StringImpl*& location, const HashAndUTF8Characters& buffer, unsigned hash)
	{
	UChar* target;
	location = StringImpl::createUninitialized(buffer.utf16Length, target).releaseRef();

	const char* source = buffer.characters;
	if (convertUTF8ToUTF16(&source, source + buffer.length, &target, target + buffer.utf16Length) != conversionOK)
	ASSERT_NOT_REACHED();

	location->setHash(hash);
	location->setIsAtomic(true);
	}
	};

	PassRefPtr<StringImpl> AtomicString::add(const UChar* s, unsigned length)
	{
	if (!s)
	return 0;

	if (!length)
	return StringImpl::empty();

	UCharBuffer buffer = { s, length };
	return addToStringTable<UCharBuffer, UCharBufferTranslator>(buffer);
	}

	PassRefPtr<StringImpl> AtomicString::add(const UChar* s, unsigned length, unsigned existingHash)
	{
	ASSERT(s);
	ASSERT(existingHash);

	if (!length)
	return StringImpl::empty();

	HashAndCharacters buffer = { existingHash, s, length };
	return addToStringTable<HashAndCharacters, HashAndCharactersTranslator>(buffer);
	}

	PassRefPtr<StringImpl> AtomicString::add(const UChar* s)
	{
	if (!s)
	return 0;

	int length = 0;
	while (s[length] != UChar(0))
	length++;

	if (!length)
	return StringImpl::empty();

	UCharBuffer buffer = { s, length };
	return addToStringTable<UCharBuffer, UCharBufferTranslator>(buffer);
	}

	PassRefPtr<StringImpl> AtomicString::addSlowCase(StringImpl* r)
	{
	if (!r \|\| r->isAtomic())
	return r;

	if (!r->length())
	return StringImpl::empty();

	StringImpl* result = *stringTable().add(r).first;
	if (result == r)
	r->setIsAtomic(true);
	return result;
	}

	AtomicStringImpl* AtomicString::find(const UChar* s, unsigned length, unsigned existingHash)
	{
	ASSERT(s);
	ASSERT(existingHash);

	if (!length)
	return static_cast<AtomicStringImpl*>(StringImpl::empty());

	HashAndCharacters buffer = { existingHash, s, length };
	HashSet<StringImpl*>::iterator iterator = stringTable().find<HashAndCharacters, HashAndCharactersTranslator>(buffer);
	if (iterator == stringTable().end())
	return 0;
	return static_cast<AtomicStringImpl>(iterator);
	}

	void AtomicString::remove(StringImpl* r)
	{
	stringTable().remove(r);
	}

	AtomicString AtomicString::lower() const
	{
	// Note: This is a hot function in the Dromaeo benchmark.
	StringImpl* impl = this->impl();
	if (UNLIKELY(!impl))
	return *this;
	RefPtr<StringImpl> newImpl = impl->lower();
	if (LIKELY(newImpl == impl))
	return *this;
	return AtomicString(newImpl);
	}

	AtomicString AtomicString::fromUTF8Internal(const char* charactersStart, const char* charactersEnd)
	{
	HashAndUTF8Characters buffer;
	buffer.characters = charactersStart;
	buffer.hash = calculateStringHashAndLengthFromUTF8(charactersStart, charactersEnd, buffer.length, buffer.utf16Length);

	if (!buffer.hash)
	return nullAtom;

	AtomicString atomicString;
	atomicString.m_string = addToStringTable<HashAndUTF8Characters, HashAndUTF8CharactersTranslator>(buffer);
	return atomicString;
	}

	} // namespace WTF