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108 lines
3.3 KiB
108 lines
3.3 KiB
#ifndef LPC_POINTER_H1103643194_INCLUDE_GUARD_
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#define LPC_POINTER_H1103643194_INCLUDE_GUARD_
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/* This file is part of indexlib.
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* Copyright (C) 2005 Luís Pedro Coelho <luis@luispedro.org>
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*
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* Indexlib is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation and available as file
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* GPL_V2 which is distributed along with indexlib.
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*
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* Indexlib is distributed in the hope that it will be useful, but
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* 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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* 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, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA
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*
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* In addition, as a special exception, the copyright holders give
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* permission to link the code of this program with any edition of
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* the Qt library by Trolltech AS, Norway (or with modified versions
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* of Qt that use the same license as Qt), and distribute linked
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* combinations including the two. You must obey the GNU General
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* Public License in all respects for all of the code used other than
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* Qt. If you modify this file, you may extend this exception to
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* your version of the file, but you are not obligated to do so. If
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* you do not wish to do so, delete this exception statement from
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* your version.
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*/
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#include <inttypes.h>
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#include <iostream>
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#include "boost-compat/static_assert.hpp"
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#ifdef HAVE_BOOST
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#include <boost/type_traits.hpp>
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#endif
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/**
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* \class pointer
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*
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* Works with \ref thing in providing disk translucency (not transparency, but half-way there).
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*
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* This is a pointer like object which is really an index into a memory block which must be deferenced
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* every time it is accessed. The main advantage of this is that it allows the pointer to remain valid even
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* if the base memory block changes place.
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*
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* Actually, implementation-wise, thing does all this already and this is mainly an adapter.
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*/
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template <typename Thing >
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struct pointer: private Thing {
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private:
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typedef Thing base_type;
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pointer( uint32_t i )
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:base_type( i )
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{
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}
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public:
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pointer()
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:base_type( 0 )
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{
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}
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typedef Thing value_type;
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template <typename D>
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pointer( const pointer<D>& other )
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:base_type( other.cast_to_uint32() )
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{
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typedef D derived_type;
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BOOST_STATIC_ASSERT( (boost::is_convertible<derived_type, value_type>::value ) );
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}
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uint32_t cast_to_uint32() const {
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return this->idx_;
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}
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static pointer cast_from_uint32( uint32_t d ) {
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return d;
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}
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value_type& operator* () const {
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return const_cast<value_type&>( static_cast<const value_type&>( *this ) );
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}
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value_type* operator -> () const {
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return const_cast<value_type*>( static_cast<const value_type*>( this ) );
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}
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bool operator!() const {
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return !this->idx_;
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}
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operator const volatile void*() const {
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return this->idx_ ? this : 0;
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}
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void* raw_pointer() { return base_type::base(); }
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private:
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};
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template <typename T>
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std::ostream& operator << ( std::ostream& out, const pointer<T>& p ) {
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return out << p.cast_to_uint32();
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}
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#endif /* LPC_POINTER_H1103643194_INCLUDE_GUARD_ */
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