501 lines
18 KiB
C++
501 lines
18 KiB
C++
//////////////////////////////////////////////////////////////////////////////
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//
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// (C) Copyright Ion Gaztanaga 2005-2009. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/interprocess for documentation.
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//
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//////////////////////////////////////////////////////////////////////////////
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#ifndef BOOST_OFFSET_PTR_HPP
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#define BOOST_OFFSET_PTR_HPP
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#if (defined _MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif
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#include <boost/interprocess/detail/config_begin.hpp>
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#include <boost/interprocess/detail/workaround.hpp>
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#include <boost/interprocess/interprocess_fwd.hpp>
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#include <boost/interprocess/detail/utilities.hpp>
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#include <boost/interprocess/detail/cast_tags.hpp>
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#include <boost/interprocess/detail/mpl.hpp>
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#include <boost/pointer_cast.hpp>
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#include <boost/pointer_to_other.hpp>
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#include <boost/assert.hpp>
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#include <ostream>
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#include <istream>
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#include <iterator>
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#include <boost/aligned_storage.hpp>
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#include <boost/type_traits/alignment_of.hpp>
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//!\file
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//!Describes a smart pointer that stores the offset between this pointer and
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//!target pointee, called offset_ptr.
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namespace boost {
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//Predeclarations
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template <class T>
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struct has_trivial_constructor;
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template <class T>
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struct has_trivial_destructor;
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namespace interprocess {
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//!A smart pointer that stores the offset between between the pointer and the
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//!the object it points. This allows offset allows special properties, since
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//!the pointer is independent from the address address of the pointee, if the
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//!pointer and the pointee are still separated by the same offset. This feature
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//!converts offset_ptr in a smart pointer that can be placed in shared memory and
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//!memory mapped files mapped in different addresses in every process.
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template <class PointedType, class DifferenceType, class OffsetType, std::size_t OffsetAlignment>
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class offset_ptr
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{
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/// @cond
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typedef offset_ptr<PointedType, DifferenceType, OffsetType, OffsetAlignment> self_t;
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void unspecified_bool_type_func() const {}
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typedef void (self_t::*unspecified_bool_type)() const;
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//Note: using the address of a local variable to point to another address
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//is not standard conforming and this can be optimized-away by the compiler.
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//Non-inlining is a method to remain illegal and correct
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#if defined(_MSC_VER) && (_MSC_VER >= 1400)
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__declspec(noinline) //this workaround is needed for msvc-8.0 and msvc-9.0
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#elif defined (__GNUC__)//this workaround is needed for GCC
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__attribute__((noinline))
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#endif
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void set_offset(const PointedType *ptr)
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{
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#if defined (__GNUC__)
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//asm(""); //Prevents the function to be optimized-away (provokes an special "side-effect")
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#endif
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//offset == 1 && ptr != 0 is not legal for this pointer
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if(!ptr){
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internal.m_offset = 1;
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}
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else{
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internal.m_offset = (OffsetType)((const char*)ptr - (const char*)(this));
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BOOST_ASSERT(internal.m_offset != 1);
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}
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}
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#if defined(_MSC_VER) && (_MSC_VER >= 1400)
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__declspec(noinline)
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#elif defined (__GNUC__)
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__attribute__((noinline))
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#endif
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PointedType * get_pointer() const
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{
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#if defined (__GNUC__)
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//asm(""); //Prevents the function to be optimized-away (provokes an special "side-effect")
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#endif
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return static_cast<PointedType *>(
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static_cast<void*>(
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(internal.m_offset == 1) ?
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0 :
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(const_cast<char*>(reinterpret_cast<const char*>(this)) + internal.m_offset)
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)
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);
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}
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void inc_offset(DifferenceType bytes)
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{ internal.m_offset += bytes; }
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void dec_offset(DifferenceType bytes)
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{ internal.m_offset -= bytes; }
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union internal_type{
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OffsetType m_offset; //Distance between this object and pointed address
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typename ::boost::aligned_storage
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< sizeof(OffsetType)
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, (OffsetAlignment == offset_type_alignment) ?
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::boost::alignment_of<OffsetType>::value : OffsetAlignment
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>::type alignment_helper;
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} internal;
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/// @endcond
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public:
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typedef PointedType * pointer;
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typedef typename ipcdetail::
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add_reference<PointedType>::type reference;
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typedef PointedType value_type;
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typedef DifferenceType difference_type;
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typedef std::random_access_iterator_tag iterator_category;
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typedef OffsetType offset_type;
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public: //Public Functions
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//!Constructor from raw pointer (allows "0" pointer conversion).
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//!Never throws.
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offset_ptr(pointer ptr = 0) { this->set_offset(ptr); }
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//!Constructor from other pointer.
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//!Never throws.
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template <class T>
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offset_ptr(T *ptr)
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{ pointer p (ptr); (void)p; this->set_offset(p); }
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//!Constructor from other offset_ptr
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//!Never throws.
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offset_ptr(const offset_ptr& ptr)
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{ this->set_offset(ptr.get()); }
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//!Constructor from other offset_ptr. If pointers of pointee types are
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//!convertible, offset_ptrs will be convertibles. Never throws.
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template<class T2, class P2, class O2, std::size_t A2>
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offset_ptr(const offset_ptr<T2, P2, O2, A2> &ptr)
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{ pointer p(ptr.get()); (void)p; this->set_offset(p); }
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//!Emulates static_cast operator.
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//!Never throws.
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template<class T2, class P2, class O2, std::size_t A2>
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offset_ptr(const offset_ptr<T2, P2, O2, A2> & r, ipcdetail::static_cast_tag)
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{ this->set_offset(static_cast<PointedType*>(r.get())); }
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//!Emulates const_cast operator.
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//!Never throws.
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template<class T2, class P2, class O2, std::size_t A2>
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offset_ptr(const offset_ptr<T2, P2, O2, A2> & r, ipcdetail::const_cast_tag)
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{ this->set_offset(const_cast<PointedType*>(r.get())); }
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//!Emulates dynamic_cast operator.
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//!Never throws.
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template<class T2, class P2, class O2, std::size_t A2>
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offset_ptr(const offset_ptr<T2, P2, O2, A2> & r, ipcdetail::dynamic_cast_tag)
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{ this->set_offset(dynamic_cast<PointedType*>(r.get())); }
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//!Emulates reinterpret_cast operator.
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//!Never throws.
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template<class T2, class P2, class O2, std::size_t A2>
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offset_ptr(const offset_ptr<T2, P2, O2, A2> & r, ipcdetail::reinterpret_cast_tag)
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{ this->set_offset(reinterpret_cast<PointedType*>(r.get())); }
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//!Obtains raw pointer from offset.
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//!Never throws.
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pointer get()const
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{ return this->get_pointer(); }
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offset_type get_offset() const
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{ return internal.m_offset; }
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//!Pointer-like -> operator. It can return 0 pointer.
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//!Never throws.
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pointer operator->() const
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{ return this->get(); }
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//!Dereferencing operator, if it is a null offset_ptr behavior
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//! is undefined. Never throws.
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reference operator* () const
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{
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pointer p = this->get();
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reference r = *p;
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return r;
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}
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//!Indexing operator.
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//!Never throws.
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template<class T>
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reference operator[](T idx) const
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{ return this->get()[idx]; }
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//!Assignment from pointer (saves extra conversion).
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//!Never throws.
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offset_ptr& operator= (pointer from)
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{ this->set_offset(from); return *this; }
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//!Assignment from other offset_ptr.
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//!Never throws.
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offset_ptr& operator= (const offset_ptr & pt)
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{ pointer p(pt.get()); (void)p; this->set_offset(p); return *this; }
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//!Assignment from related offset_ptr. If pointers of pointee types
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//! are assignable, offset_ptrs will be assignable. Never throws.
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template<class T2, class P2, class O2, std::size_t A2>
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offset_ptr& operator= (const offset_ptr<T2, P2, O2, A2> & pt)
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{ pointer p(pt.get()); this->set_offset(p); return *this; }
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//!offset_ptr + difference_type.
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//!Never throws.
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template<class T>
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offset_ptr operator+ (T offset) const
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{ return offset_ptr(this->get()+offset); }
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//!offset_ptr - difference_type.
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//!Never throws.
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template<class T>
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offset_ptr operator- (T offset) const
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{ return offset_ptr(this->get()-offset); }
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//!offset_ptr += difference_type.
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//!Never throws.
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template<class T>
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offset_ptr &operator+= (T offset)
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{ this->inc_offset(offset * sizeof (PointedType)); return *this; }
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//!offset_ptr -= difference_type.
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//!Never throws.
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template<class T>
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offset_ptr &operator-= (T offset)
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{ this->dec_offset(offset * sizeof (PointedType)); return *this; }
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//!++offset_ptr.
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//!Never throws.
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offset_ptr& operator++ (void)
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{ this->inc_offset(sizeof (PointedType)); return *this; }
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//!offset_ptr++.
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//!Never throws.
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offset_ptr operator++ (int)
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{ offset_ptr temp(*this); ++*this; return temp; }
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//!--offset_ptr.
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//!Never throws.
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offset_ptr& operator-- (void)
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{ this->dec_offset(sizeof (PointedType)); return *this; }
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//!offset_ptr--.
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//!Never throws.
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offset_ptr operator-- (int)
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{ offset_ptr temp(*this); --*this; return temp; }
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//!safe bool conversion operator.
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//!Never throws.
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operator unspecified_bool_type() const
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{ return this->get()? &self_t::unspecified_bool_type_func : 0; }
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//!Not operator. Not needed in theory, but improves portability.
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//!Never throws
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bool operator! () const
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{ return this->get() == 0; }
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/*
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friend void swap (offset_ptr &pt, offset_ptr &pt2)
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{
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value_type *ptr = pt.get();
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pt = pt2;
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pt2 = ptr;
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}
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*/
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};
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//!offset_ptr<T1, P1, O1, A1> == offset_ptr<T2, P2, O2, A2>.
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//!Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline bool operator== (const offset_ptr<T1, P1, O1, A1> &pt1,
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const offset_ptr<T2, P2, O2, A2> &pt2)
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{ return pt1.get() == pt2.get(); }
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//!offset_ptr<T1, P1, O1, A1> != offset_ptr<T2, P2, O2, A2>.
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//!Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline bool operator!= (const offset_ptr<T1, P1, O1, A1> &pt1,
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const offset_ptr<T2, P2, O2, A2> &pt2)
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{ return pt1.get() != pt2.get(); }
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//!offset_ptr<T1, P1, O1, A1> < offset_ptr<T2, P2, O2, A2>.
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//!Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline bool operator< (const offset_ptr<T1, P1, O1, A1> &pt1,
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const offset_ptr<T2, P2, O2, A2> &pt2)
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{ return pt1.get() < pt2.get(); }
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//!offset_ptr<T1, P1, O1, A1> <= offset_ptr<T2, P2, O2, A2>.
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//!Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline bool operator<= (const offset_ptr<T1, P1, O1, A1> &pt1,
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const offset_ptr<T2, P2, O2, A2> &pt2)
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{ return pt1.get() <= pt2.get(); }
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//!offset_ptr<T1, P1, O1, A1> > offset_ptr<T2, P2, O2, A2>.
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//!Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline bool operator> (const offset_ptr<T1, P1, O1, A1> &pt1,
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const offset_ptr<T2, P2, O2, A2> &pt2)
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{ return pt1.get() > pt2.get(); }
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//!offset_ptr<T1, P1, O1, A1> >= offset_ptr<T2, P2, O2, A2>.
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//!Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline bool operator>= (const offset_ptr<T1, P1, O1, A1> &pt1,
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const offset_ptr<T2, P2, O2, A2> &pt2)
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{ return pt1.get() >= pt2.get(); }
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//!operator<<
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//!for offset ptr
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template<class E, class T, class W, class X, class Y, std::size_t Z>
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inline std::basic_ostream<E, T> & operator<<
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(std::basic_ostream<E, T> & os, offset_ptr<W, X, Y, Z> const & p)
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{ return os << p.get_offset(); }
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//!operator>>
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//!for offset ptr
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template<class E, class T, class W, class X, class Y, std::size_t Z>
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inline std::basic_istream<E, T> & operator>>
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(std::basic_istream<E, T> & is, offset_ptr<W, X, Y, Z> & p)
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{ return is >> p.get_offset(); }
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//!difference_type + offset_ptr
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//!operation
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template<class T, class P, class O, std::size_t A, class D>
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inline offset_ptr<T, P, O, A> operator+(D diff, const offset_ptr<T, P, O, A>& right)
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{ return right + diff; }
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//!offset_ptr - offset_ptr
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//!operation
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline typename offset_ptr<T1, P1, O1, A1>::difference_type operator-
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(const offset_ptr<T1, P1, O1, A1> &pt, const offset_ptr<T2, P2, O2, A2> &pt2)
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{ return typename offset_ptr<T1, P1, O1, A1>::difference_type(pt.get()- pt2.get()); }
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//!swap specialization
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//!for offset_ptr
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template<class T, class P, class O, std::size_t A>
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inline void swap (boost::interprocess::offset_ptr<T, P, O, A> &pt,
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boost::interprocess::offset_ptr<T, P, O, A> &pt2)
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{
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typename offset_ptr<T, P, O, A>::value_type *ptr = pt.get();
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pt = pt2;
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pt2 = ptr;
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}
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//!Simulation of static_cast between pointers. Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline boost::interprocess::offset_ptr<T1, P1, O1, A1>
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static_pointer_cast(const boost::interprocess::offset_ptr<T2, P2, O2, A2> & r)
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{
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return boost::interprocess::offset_ptr<T1, P1, O1, A1>
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(r, boost::interprocess::ipcdetail::static_cast_tag());
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}
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//!Simulation of const_cast between pointers. Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline boost::interprocess::offset_ptr<T1, P1, O1, A1>
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const_pointer_cast(const boost::interprocess::offset_ptr<T2, P2, O2, A2> & r)
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{
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return boost::interprocess::offset_ptr<T1, P1, O1, A1>
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(r, boost::interprocess::ipcdetail::const_cast_tag());
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}
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//!Simulation of dynamic_cast between pointers. Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline boost::interprocess::offset_ptr<T1, P1, O1, A1>
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dynamic_pointer_cast(const boost::interprocess::offset_ptr<T2, P2, O2, A2> & r)
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{
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return boost::interprocess::offset_ptr<T1, P1, O1, A1>
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(r, boost::interprocess::ipcdetail::dynamic_cast_tag());
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}
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//!Simulation of reinterpret_cast between pointers. Never throws.
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template<class T1, class P1, class O1, std::size_t A1, class T2, class P2, class O2, std::size_t A2>
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inline boost::interprocess::offset_ptr<T1, P1, O1, A1>
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reinterpret_pointer_cast(const boost::interprocess::offset_ptr<T2, P2, O2, A2> & r)
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{
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return boost::interprocess::offset_ptr<T1, P1, O1, A1>
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(r, boost::interprocess::ipcdetail::reinterpret_cast_tag());
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}
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} //namespace interprocess {
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/// @cond
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//!has_trivial_constructor<> == true_type specialization for optimizations
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template <class T, class P, class O, std::size_t A>
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struct has_trivial_constructor< boost::interprocess::offset_ptr<T, P, O, A> >
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{
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enum { value = true };
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};
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///has_trivial_destructor<> == true_type specialization for optimizations
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template <class T, class P, class O, std::size_t A>
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struct has_trivial_destructor< boost::interprocess::offset_ptr<T, P, O, A> >
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{
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enum { value = true };
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};
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//#if !defined(_MSC_VER) || (_MSC_VER >= 1400)
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namespace interprocess {
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//#endif
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//!get_pointer() enables boost::mem_fn to recognize offset_ptr.
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//!Never throws.
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template <class T, class P, class O, std::size_t A>
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inline T * get_pointer(boost::interprocess::offset_ptr<T, P, O, A> const & p)
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{ return p.get(); }
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//#if !defined(_MSC_VER) || (_MSC_VER >= 1400)
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} //namespace interprocess
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//#endif
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/// @endcond
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} //namespace boost {
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/// @cond
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namespace boost{
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//This is to support embedding a bit in the pointer
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//for intrusive containers, saving space
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namespace intrusive {
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//Predeclaration to avoid including header
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template<class VoidPointer, std::size_t N>
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struct max_pointer_plus_bits;
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template<std::size_t OffsetAlignment, class P, class O, std::size_t A>
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struct max_pointer_plus_bits<boost::interprocess::offset_ptr<void, P, O, A>, OffsetAlignment>
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{
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//The offset ptr can embed one bit less than the alignment since it
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//uses offset == 1 to store the null pointer.
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static const std::size_t value = ::boost::interprocess::ipcdetail::ls_zeros<OffsetAlignment>::value - 1;
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};
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//Predeclaration
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template<class Pointer, std::size_t NumBits>
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struct pointer_plus_bits;
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template<class T, class P, class O, std::size_t A, std::size_t NumBits>
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struct pointer_plus_bits<boost::interprocess::offset_ptr<T, P, O, A>, NumBits>
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{
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typedef boost::interprocess::offset_ptr<T, P, O, A> pointer;
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//Bits are stored in the lower bits of the pointer except the LSB,
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//because this bit is used to represent the null pointer.
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static const std::size_t Mask = ((std::size_t(1) << NumBits)-1)<<1u;
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static pointer get_pointer(const pointer &n)
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{ return reinterpret_cast<T*>(std::size_t(n.get()) & ~std::size_t(Mask)); }
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static void set_pointer(pointer &n, pointer p)
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{
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std::size_t pint = std::size_t(p.get());
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BOOST_ASSERT(0 == (std::size_t(pint) & Mask));
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n = reinterpret_cast<T*>(pint | (std::size_t(n.get()) & std::size_t(Mask)));
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}
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static std::size_t get_bits(const pointer &n)
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{ return(std::size_t(n.get()) & std::size_t(Mask)) >> 1u; }
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static void set_bits(pointer &n, std::size_t b)
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{
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BOOST_ASSERT(b < (std::size_t(1) << NumBits));
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n = reinterpret_cast<T*>(std::size_t(get_pointer(n).get()) | (b << 1u));
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}
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};
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} //namespace intrusive
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template<class T, class T2, class T3, std::size_t A, class U>
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struct pointer_to_other< ::boost::interprocess::offset_ptr<T, T2, T3, A>, U >
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{
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typedef ::boost::interprocess::offset_ptr<U, T2, T3, A> type;
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};
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} //namespace boost{
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/// @endcond
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#include <boost/interprocess/detail/config_end.hpp>
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#endif //#ifndef BOOST_OFFSET_PTR_HPP
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