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Diffstat (limited to 'indexlib/thing.h')
| -rw-r--r-- | indexlib/thing.h | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/indexlib/thing.h b/indexlib/thing.h new file mode 100644 index 00000000..26afb07b --- /dev/null +++ b/indexlib/thing.h @@ -0,0 +1,168 @@ +#ifndef LPC_THING_H1103643194_INCLUDE_GUARD_ +#define LPC_THING_H1103643194_INCLUDE_GUARD_ + +/* This file is part of indexlib. + * Copyright (C) 2005 Luís Pedro Coelho <luis@luispedro.org> + * + * Indexlib is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License, version 2, as + * published by the Free Software Foundation and available as file + * GPL_V2 which is distributed along with indexlib. + * + * Indexlib 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 + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, + * MA 02110-1301, USA + * + * In addition, as a special exception, the copyright holders give + * permission to link the code of this program with any edition of + * the Qt library by Trolltech AS, Norway (or with modified versions + * of Qt that use the same license as Qt), and distribute linked + * combinations including the two. You must obey the GNU General + * Public License in all respects for all of the code used other than + * Qt. If you modify this file, you may extend this exception to + * your version of the file, but you are not obligated to do so. If + * you do not wish to do so, delete this exception statement from + * your version. + */ + + +#include <inttypes.h> +#include "bitio.h" +#include "pointer.h" + +/** + * \class thing + * + * This is perhaps one of the most important classes in the system. + * + * Ideally one would like to have something like: + * + * struct_on_disk X { + * int32_t a; + * int32_t b; + * }; + * + * X var; + * + * And var would be accessed in our exact format. Since I want to control the exact format + * to be able to use the same index even in different architechtures, it's not really possible. + * + * So we would do: + * + * START_THING( X, simple_accessor ) + * MEMBER( int32_t, a, 0 ) + * MEMBER( int32_t, b, 4 ) + * END_THING( X ) + * + * This base class provides the machinery for this. + */ +template <typename accessor> +struct thing : protected accessor { // this allow the emtpy base optimization + protected: + thing( uint32_t idx, const accessor& access = accessor() ): + accessor( access ), + idx_( idx ) + { + } + + unsigned char* base() { + return reinterpret_cast<unsigned char*>( accessor::rw_base( idx_ ) ); + } + const unsigned char* base() const { + return reinterpret_cast<const unsigned char*>( accessor::ronly_base( idx_ ) ); + } + public: + ~thing() { } + thing( const thing& other ): + accessor( static_cast<const accessor&>( other ) ), + idx_( other.idx_ ) + { + } + + thing& operator = ( const thing& other ) { + accessor::operator=( other ); + idx_ = other.idx_; + return *this; + } + protected: + uint32_t idx_; +}; + +template <void * ( *get_base )()> +struct simple_accessor { + public: + void* rw_base( unsigned idx ) const { + return reinterpret_cast<unsigned char*>( get_base() ) + idx; + } + const void* ronly_base( unsigned idx ) const { + return reinterpret_cast<const unsigned char*>( get_base() ) + idx; + } +}; + + +#define START_THING( name, base ) \ + class name : public base { \ + friend class pointer<name>; \ + protected: \ + name ( const base& b ) \ + :base( b ) \ + { \ + } \ + \ + name ( uint32_t i ) \ + :base( i ) \ + { \ + } \ + public: + +#define MEMBER( type, name, idx ) \ + type name() const { \ + const unsigned char* data = this->base() + idx; \ + return byte_io::read<type>( data ); \ + } \ + \ + void set_ ## name ( const type & n_ ## name ) { \ + unsigned char* data = this->base() + idx; \ + byte_io::write<type>( data, n_ ## name ); \ + } + +#define MY_BASE( idx ) \ + private: \ + unsigned char* my_base() { return base() + idx; } \ + const unsigned char* my_base() const { return base() + idx; } \ + + +#define END_THING( name ) \ + }; \ + \ + typedef ::pointer< name > name ## ptr; + +#define DO_POINTER_SPECS( name ) \ + namespace byte_io { \ + template<> \ + inline \ + pointer<name> read< pointer<name> >( const unsigned char* in ) \ + { \ + return pointer< name >::cast_from_uint32( read<uint32_t>( in ) ); \ + }\ + template<> \ + inline \ + void write< pointer<name> >( unsigned char* out, pointer<name> p ) { \ + write<uint32_t>( out, p.cast_to_uint32() ); \ + } \ + template<> \ + struct byte_lenght_struct< pointer <name> > { \ + static const unsigned value = byte_lenght_struct<uint32_t>::value; \ + }; \ + } // namespace + + + + +#endif /* LPC_THING_H1103643194_INCLUDE_GUARD_ */ |