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/**
* @file llstringtable.h
* @brief The LLStringTable class provides a _fast_ method for finding
* unique copies of strings.
*
* $LicenseInfo:firstyear=2001&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#ifndef LL_STRING_TABLE_H
#define LL_STRING_TABLE_H
#include "lldefs.h"
#include "llformat.h"
#include "llstl.h"
#include <list>
#include <set>
#if LL_WINDOWS
# if (_MSC_VER >= 1300 && _MSC_VER < 1400)
# define STRING_TABLE_HASH_MAP 1
# endif
#else
//# define STRING_TABLE_HASH_MAP 1
#endif
#if STRING_TABLE_HASH_MAP
# if LL_WINDOWS
# include <hash_map>
# else
# include <ext/hash_map>
# endif
#endif
const U32 MAX_STRINGS_LENGTH = 256;
class LL_COMMON_API LLStringTableEntry
{
public:
LLStringTableEntry(const char *str);
~LLStringTableEntry();
void incCount() { mCount++; }
BOOL decCount() { return --mCount; }
char *mString;
S32 mCount;
};
class LL_COMMON_API LLStringTable
{
public:
LLStringTable(int tablesize);
~LLStringTable();
char *checkString(const char *str);
char *checkString(const std::string& str);
LLStringTableEntry *checkStringEntry(const char *str);
LLStringTableEntry *checkStringEntry(const std::string& str);
char *addString(const char *str);
char *addString(const std::string& str);
LLStringTableEntry *addStringEntry(const char *str);
LLStringTableEntry *addStringEntry(const std::string& str);
void removeString(const char *str);
S32 mMaxEntries;
S32 mUniqueEntries;
#if STRING_TABLE_HASH_MAP
#if LL_WINDOWS
typedef std::hash_multimap<U32, LLStringTableEntry *> string_hash_t;
#else
typedef __gnu_cxx::hash_multimap<U32, LLStringTableEntry *> string_hash_t;
#endif
string_hash_t mStringHash;
#else
typedef std::list<LLStringTableEntry *> string_list_t;
typedef string_list_t * string_list_ptr_t;
string_list_ptr_t *mStringList;
#endif
};
extern LL_COMMON_API LLStringTable gStringTable;
//============================================================================
// This class is designed to be used locally,
// e.g. as a member of an LLXmlTree
// Strings can be inserted only, then quickly looked up
typedef const std::string* LLStdStringHandle;
class LL_COMMON_API LLStdStringTable
{
public:
LLStdStringTable(S32 tablesize = 0)
{
if (tablesize == 0)
{
tablesize = 256; // default
}
// Make sure tablesize is power of 2
for (S32 i = 31; i>0; i--)
{
if (tablesize & (1<<i))
{
if (tablesize >= (3<<(i-1)))
tablesize = (1<<(i+1));
else
tablesize = (1<<i);
break;
}
}
mTableSize = tablesize;
mStringList = new string_set_t[tablesize];
}
~LLStdStringTable()
{
cleanup();
delete[] mStringList;
}
void cleanup()
{
// remove strings
for (S32 i = 0; i<mTableSize; i++)
{
string_set_t& stringset = mStringList[i];
for (string_set_t::iterator iter = stringset.begin(); iter != stringset.end(); iter++)
{
delete *iter;
}
stringset.clear();
}
}
LLStdStringHandle lookup(const std::string& s)
{
U32 hashval = makehash(s);
return lookup(hashval, s);
}
LLStdStringHandle checkString(const std::string& s)
{
U32 hashval = makehash(s);
return lookup(hashval, s);
}
LLStdStringHandle insert(const std::string& s)
{
U32 hashval = makehash(s);
LLStdStringHandle result = lookup(hashval, s);
if (result == NULL)
{
result = new std::string(s);
mStringList[hashval].insert(result);
}
return result;
}
LLStdStringHandle addString(const std::string& s)
{
return insert(s);
}
private:
U32 makehash(const std::string& s)
{
S32 len = (S32)s.size();
const char* c = s.c_str();
U32 hashval = 0;
for (S32 i=0; i<len; i++)
{
hashval = ((hashval<<5) + hashval) + *c++;
}
return hashval & (mTableSize-1);
}
LLStdStringHandle lookup(U32 hashval, const std::string& s)
{
string_set_t& stringset = mStringList[hashval];
LLStdStringHandle handle = &s;
string_set_t::iterator iter = stringset.find(handle); // compares actual strings
if (iter != stringset.end())
{
return *iter;
}
else
{
return NULL;
}
}
private:
S32 mTableSize;
typedef std::set<LLStdStringHandle, compare_pointer_contents<std::string> > string_set_t;
string_set_t* mStringList; // [mTableSize]
};
#endif
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