| ///////////////////////////////////////////////////////////////////////////// |
| // |
| // (C) Copyright Ion Gaztanaga 2007-2013 |
| // |
| // Distributed under the Boost Software License, Version 1.0. |
| // (See accompanying file LICENSE_1_0.txt or copy at |
| // http://www.boost.org/LICENSE_1_0.txt) |
| // |
| // See http://www.boost.org/libs/intrusive for documentation. |
| // |
| ///////////////////////////////////////////////////////////////////////////// |
| #ifndef BOOST_INTRUSIVE_DETAIL_PARENT_FROM_MEMBER_HPP |
| #define BOOST_INTRUSIVE_DETAIL_PARENT_FROM_MEMBER_HPP |
| |
| #ifndef BOOST_CONFIG_HPP |
| # include <boost/config.hpp> |
| #endif |
| |
| #if defined(BOOST_HAS_PRAGMA_ONCE) |
| # pragma once |
| #endif |
| |
| #include <boost/intrusive/detail/config_begin.hpp> |
| #include <cstddef> |
| |
| #if defined(BOOST_MSVC) || ((defined(_WIN32) || defined(__WIN32__) || defined(WIN32)) && defined(BOOST_INTEL)) |
| #define BOOST_INTRUSIVE_MSVC_ABI_PTR_TO_MEMBER |
| #include <boost/static_assert.hpp> |
| #endif |
| |
| namespace boost { |
| namespace intrusive { |
| namespace detail { |
| |
| template<class Parent, class Member> |
| inline std::ptrdiff_t offset_from_pointer_to_member(const Member Parent::* ptr_to_member) |
| { |
| //The implementation of a pointer to member is compiler dependent. |
| #if defined(BOOST_INTRUSIVE_MSVC_ABI_PTR_TO_MEMBER) |
| |
| //MSVC compliant compilers use their the first 32 bits as offset (even in 64 bit mode) |
| union caster_union |
| { |
| const Member Parent::* ptr_to_member; |
| int offset; |
| } caster; |
| |
| //MSVC ABI can use up to 3 int32 to represent pointer to member data |
| //with virtual base classes, in those cases there is no simple to |
| //obtain the address of the parent. So static assert to avoid runtime errors |
| BOOST_STATIC_ASSERT( sizeof(caster) == sizeof(int) ); |
| |
| caster.ptr_to_member = ptr_to_member; |
| return std::ptrdiff_t(caster.offset); |
| //Additional info on MSVC behaviour for the future. For 2/3 int ptr-to-member |
| //types dereference seems to be: |
| // |
| // vboffset = [compile_time_offset if 2-int ptr2memb] / |
| // [ptr2memb.i32[2] if 3-int ptr2memb]. |
| // vbtable = *(this + vboffset); |
| // adj = vbtable[ptr2memb.i32[1]]; |
| // var = adj + (this + vboffset) + ptr2memb.i32[0]; |
| // |
| //To reverse the operation we need to |
| // - obtain vboffset (in 2-int ptr2memb implementation only) |
| // - Go to Parent's vbtable and obtain adjustment at index ptr2memb.i32[1] |
| // - parent = member - adj - vboffset - ptr2memb.i32[0] |
| // |
| //Even accessing to RTTI we might not be able to obtain this information |
| //so anyone who thinks it's possible, please send a patch. |
| |
| //This works with gcc, msvc, ac++, ibmcpp |
| #elif defined(__GNUC__) || defined(__HP_aCC) || defined(BOOST_INTEL) || \ |
| defined(__IBMCPP__) || defined(__DECCXX) |
| const Parent * const parent = 0; |
| const char *const member = static_cast<const char*>(static_cast<const void*>(&(parent->*ptr_to_member))); |
| return std::ptrdiff_t(member - static_cast<const char*>(static_cast<const void*>(parent))); |
| #else |
| //This is the traditional C-front approach: __MWERKS__, __DMC__, __SUNPRO_CC |
| union caster_union |
| { |
| const Member Parent::* ptr_to_member; |
| std::ptrdiff_t offset; |
| } caster; |
| caster.ptr_to_member = ptr_to_member; |
| return caster.offset - 1; |
| #endif |
| } |
| |
| template<class Parent, class Member> |
| inline Parent *parent_from_member(Member *member, const Member Parent::* ptr_to_member) |
| { |
| return static_cast<Parent*> |
| ( |
| static_cast<void*> |
| ( |
| static_cast<char*>(static_cast<void*>(member)) - offset_from_pointer_to_member(ptr_to_member) |
| ) |
| ); |
| } |
| |
| template<class Parent, class Member> |
| inline const Parent *parent_from_member(const Member *member, const Member Parent::* ptr_to_member) |
| { |
| return static_cast<const Parent*> |
| ( |
| static_cast<const void*> |
| ( |
| static_cast<const char*>(static_cast<const void*>(member)) - offset_from_pointer_to_member(ptr_to_member) |
| ) |
| ); |
| } |
| |
| } //namespace detail { |
| } //namespace intrusive { |
| } //namespace boost { |
| |
| #ifdef BOOST_INTRUSIVE_MSVC_ABI_PTR_TO_MEMBER |
| #undef BOOST_INTRUSIVE_MSVC_ABI_PTR_TO_MEMBER |
| #endif |
| |
| #include <boost/intrusive/detail/config_end.hpp> |
| |
| #endif //#ifndef BOOST_INTRUSIVE_DETAIL_PARENT_FROM_MEMBER_HPP |