mirror of https://github.com/CGAL/cgal
150 lines
3.1 KiB
C++
150 lines
3.1 KiB
C++
// ======================================================================
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//
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// Copyright (c) 1999 The CGAL Consortium
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//
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// This software and related documentation is part of an INTERNAL release
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// of the Computational Geometry Algorithms Library (CGAL). It is not
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// intended for general use.
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//
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// ----------------------------------------------------------------------
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//
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// release :
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// release_date :
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//
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// file : Handle_for.h
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// package : Kernel_basic
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// revision : $Revision$
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// revision_date : $Date$
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// author(s) : Stefan Schirra
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//
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//
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// coordinator : MPI, Saarbruecken (<Stefan.Schirra@mpi-sb.mpg.de>)
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// ======================================================================
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#ifndef CGAL_HANDLE_FOR_H
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#define CGAL_HANDLE_FOR_H
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#include <CGAL/memory.h>
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namespace CGAL {
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template <class RefCounted, class Allocator> class Handle_for;
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class Object;
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class Ref_counted
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{
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public:
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Ref_counted() : count(1) {}
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Ref_counted(const Ref_counted&) : count(1) {}
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void add_reference() { ++count; }
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void remove_reference() { --count; }
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bool is_referenced() { return (count != 0); }
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bool is_shared() { return (count > 1); }
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friend class Object;
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protected:
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unsigned int count;
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};
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template <class RefCounted,
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class Allocator = CGAL_ALLOCATOR(RefCounted) >
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// RefCounted must provide
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// add_reference()
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// remove_reference()
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// bool is_referenced()
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// bool is_shared()
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// and initialize count to 1 in default and copy constructor
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class Handle_for
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{
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public:
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typedef RefCounted element_type;
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Handle_for(const RefCounted& rc)
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{
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ptr = allocator.allocate(1);
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allocator.construct(ptr, rc);
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}
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Handle_for()
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{
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ptr = allocator.allocate(1);
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}
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Handle_for( const Handle_for& h)
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{
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ptr = h.ptr;
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ptr->add_reference();
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}
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~Handle_for()
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{
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ptr->remove_reference();
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if ( !ptr->is_referenced() )
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{
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allocator.destroy( ptr);
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allocator.deallocate( ptr, 1);
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}
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}
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Handle_for&
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operator=( const Handle_for& h)
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{
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h.ptr->add_reference();
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ptr->remove_reference();
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if ( !ptr->is_referenced() )
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{
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allocator.destroy( ptr);
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allocator.deallocate( ptr, 1);
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}
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ptr = h.ptr;
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return *this;
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}
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void
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initialize_with( const RefCounted& rc)
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{
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allocator.construct(ptr, rc);
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}
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void
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copy_on_write()
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{
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if ( ptr->is_shared() )
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{
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RefCounted* tmp_ptr = allocator.allocate(1);
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allocator.construct( tmp_ptr, *ptr);
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ptr->remove_reference();
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ptr = tmp_ptr;
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}
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}
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bool
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identical( const Handle_for& h) const
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{ return ptr == h.ptr; }
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long int
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id() const
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{ return reinterpret_cast<long int>( &(*ptr)); }
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const typename Allocator::pointer
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Ptr() const
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{ return ptr; }
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protected:
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static Allocator allocator;
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typename Allocator::pointer ptr;
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};
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template <class RefCounted, class Allocator>
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Allocator Handle_for<RefCounted,Allocator>::allocator;
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} // namespace CGAL
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#endif // CGAL_HANDLE_FOR_H
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