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Diffstat (limited to 'indexlib/pointer.h')
| -rw-r--r-- | indexlib/pointer.h | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/indexlib/pointer.h b/indexlib/pointer.h new file mode 100644 index 000000000..0699be192 --- /dev/null +++ b/indexlib/pointer.h @@ -0,0 +1,107 @@ +#ifndef LPC_POINTER_H1103643194_INCLUDE_GUARD_ +#define LPC_POINTER_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 <iostream> +#include "boost-compat/static_assert.hpp" +#ifdef HAVE_BOOST +#include <boost/type_traits.hpp> +#endif + +/** + * \class pointer + * + * Works with \ref thing in providing disk translucency (not transparency, but half-way there). + * + * This is a pointer like object which is really an index into a memory block which must be deferenced + * every time it is accessed. The main advantage of this is that it allows the pointer to remain valid even + * if the base memory block changes place. + * + * Actually, implementation-wise, thing does all this already and this is mainly an adapter. + */ +template <typename Thing > +struct pointer: private Thing { + private: + typedef Thing base_type; + + pointer( uint32_t i ) + :base_type( i ) + { + } + public: + pointer() + :base_type( 0 ) + { + } + typedef Thing value_type; + template <typename D> + pointer( const pointer<D>& other ) + :base_type( other.cast_to_uint32() ) + { + typedef D derived_type; + BOOST_STATIC_ASSERT( (boost::is_convertible<derived_type, value_type>::value ) ); + } + uint32_t cast_to_uint32() const { + return this->idx_; + } + static pointer cast_from_uint32( uint32_t d ) { + return d; + } + value_type& operator* () const { + return const_cast<value_type&>( static_cast<const value_type&>( *this ) ); + } + value_type* operator -> () const { + return const_cast<value_type*>( static_cast<const value_type*>( this ) ); + } + bool operator!() const { + return !this->idx_; + } + + operator const volatile void*() const { + return this->idx_ ? this : 0; + } + void* raw_pointer() { return base_type::base(); } + private: +}; + + + +template <typename T> +std::ostream& operator << ( std::ostream& out, const pointer<T>& p ) { + return out << p.cast_to_uint32(); +} + + + +#endif /* LPC_POINTER_H1103643194_INCLUDE_GUARD_ */ |