87 lines
2.3 KiB
C++
87 lines
2.3 KiB
C++
/*
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Symbol(impl) - helpers for working with literal string IDs
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Copyright (C) Lumiera.org
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2009, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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* *****************************************************/
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/** @file symbol-impl.hpp
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** Collection of helpers for working with the lib::Symbol.
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**
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** @todo currently as of 9/09 this is more of a placeholder.
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** And maybe a location for collecting small bits of implementation,
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** which could be usable later for real Symbol and Literal datatypes.
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**
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** lib::Symbol
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** control::CommandRegistry for usage example of the hash function.
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**
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*/
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#include "lib/symbol.hpp"
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#include "include/limits.h"
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extern "C" {
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#include "lib/safeclib.h"
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}
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#include <boost/functional/hash.hpp>
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#include <cstddef>
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using std::size_t;
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using boost::hash_combine;
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namespace lib {
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const size_t STRING_MAX_RELEVANT = LUMIERA_IDSTRING_MAX_RELEVANT;
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/** equality on Symbol values is defined
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* based on the content, not the address. */
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bool
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operator== (Literal sy1, Literal sy2)
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{
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return !lumiera_strncmp (sy1,sy2, STRING_MAX_RELEVANT);
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}
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/** generating a hash value, e.g. for hashtables.
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This function is intended to be picked up by ADL,
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and should be usable both with \c std::tr1 and
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\c <boost/functional/hash.hpp> . It is implemented
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similar as the boost::hash specialisation for std::string */
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size_t hash_value (Literal sym)
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{
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size_t hash=0;
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if (sym)
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{
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const char *pos = sym;
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size_t maxpos = STRING_MAX_RELEVANT;
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for ( ; *pos && --maxpos; ++pos)
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hash_combine(hash, *pos);
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}
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return hash;
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}
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} // namespace lib
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