99 lines
3.6 KiB
C++
99 lines
3.6 KiB
C++
/*
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* This program source code file is part of KiCad, a free EDA CAD application.
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*
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* Copyright (C) 2012 SoftPLC Corporation, Dick Hollenbeck <dick@softplc.com>
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* Copyright (C) 2012-2020 KiCad Developers, see AUTHORS.TXT for contributors.
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*
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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
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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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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*
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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, you may find one here:
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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* or you may search the http://www.gnu.org website for the version 2 license,
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* or you may write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#ifndef HASHTABLES_H_
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#define HASHTABLES_H_
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#include <unordered_map>
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#include <wx/string.h>
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// First some utility classes and functions
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/// Equality test for "const char*" type used in very specialized KEYWORD_MAP below
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struct iequal_to
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{
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bool operator()( const char* x, const char* y ) const
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{
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return !strcmp( x, y );
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}
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};
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/// Very fast and efficient hash function for "const char*" type, used in specialized
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/// KEYWORD_MAP below.
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/// taken from: http://www.boost.org/doc/libs/1_53_0/libs/unordered/examples/fnv1.hpp
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struct fnv_1a
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{
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std::size_t operator()( const char* it ) const
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{
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std::size_t hash = 2166136261u;
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for( ; *it; ++it )
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{
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hash ^= (unsigned char) *it;
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hash *= 16777619;
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}
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return hash;
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}
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};
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#ifdef SWIG
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/// Declare a std::unordered_map and also the swig %template in unison
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#define DECL_HASH_FOR_SWIG( TypeName, KeyType, ValueType ) \
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namespace std \
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{ \
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% template( TypeName ) unordered_map<KeyType, ValueType>; \
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} \
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typedef std::unordered_map<KeyType, ValueType> TypeName;
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#else
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/// Declare a std::unordered_map but no swig %template
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#define DECL_HASH_FOR_SWIG( TypeName, KeyType, ValueType ) \
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typedef std::unordered_map<KeyType, ValueType> TypeName;
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#endif
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/**
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* A hashtable made of a const char* and an int.
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*
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* @note The use of this type outside very specific circumstances is foolish since there is
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* no storage provided for the actual C string itself.
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*
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* This type assumes use with type #KEYWORD that is created by CMake and that table creates
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* *constant* storage for C strings (and pointers to those C strings). Here we are only
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* interested in the C strings themselves and only the pointers are duplicated within the
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* hashtable. If the strings were not constant and fixed, this type would not work. Also
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* note that normally a hashtable (i.e. unordered_map) using a const char* key would simply
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* compare the 32 bit or 64 bit pointers themselves, rather than the C strings which they
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* are known to point to in this context. I force the latter behavior by supplying both
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* "hash" and "equality" overloads to the hashtable (unordered_map) template.
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*
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* @author Dick Hollenbeck
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*/
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typedef std::unordered_map< const char*, int, fnv_1a, iequal_to > KEYWORD_MAP;
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#endif // HASHTABLES_H_
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