54 lines
1.9 KiB
C++
54 lines
1.9 KiB
C++
/**
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* @file llhash.h
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* @brief Wrapper for a hash function.
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*
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* $LicenseInfo:firstyear=2004&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2010, Linden Research, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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#ifndef LL_LLHASH_H
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#define LL_LLHASH_H
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#include <boost/functional/hash.hpp>
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// Warning - an earlier template-based version of this routine did not do
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// the correct thing on Windows. Since this is only used to get
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// a string hash, it was converted to a regular routine and
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// unit tests added.
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inline size_t llhash( const char * value )
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{
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// boost::hash is defined for std::string and for char, but there's no
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// special overload for const char*. The lazy approach would be to
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// instantiate a std::string and take its hash, but that might be more
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// overhead than our callers want. Or we could use boost::hash_range() --
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// but that would require a preliminary pass over the value to determine
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// the end iterator. Instead, use boost::hash_combine() to hash individual
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// characters.
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std::size_t seed = 0;
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for ( ; *value; ++value)
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boost::hash_combine(seed, *value);
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return seed;
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}
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#endif
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