boost/intrusive/detail/parent_from_member.hpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga  2007-2008
   4 //
   5 // Distributed under the Boost Software License, Version 1.0.
   6 //    (See accompanying file LICENSE_1_0.txt or copy at
   7 //          http://www.boost.org/LICENSE_1_0.txt)
   8 //
   9 // See http://www.boost.org/libs/intrusive for documentation.
  10 //
  11 /////////////////////////////////////////////////////////////////////////////
  12 #ifndef BOOST_INTRUSIVE_PARENT_FROM_MEMBER_HPP
  13 #define BOOST_INTRUSIVE_PARENT_FROM_MEMBER_HPP
  14
  15 #include <boost/intrusive/detail/config_begin.hpp>
  16 #include <cstddef>
  17
  18 #if defined(BOOST_MSVC) || ((defined(_WIN32) || defined(__WIN32__) || defined(WIN32)) && defined(BOOST_INTEL))
  19
  20 #define BOOST_INTRUSIVE_MSVC_COMPLIANT_PTR_TO_MEMBER
  21 #include <boost/cstdint.hpp>
  22 #endif
  23
  24 namespace boost {
  25 namespace intrusive {
  26 namespace detail {
  27
  28 template<class Parent, class Member>
  29 inline std::ptrdiff_t offset_from_pointer_to_member(const Member Parent::* ptr_to_member)
  30 {
  31    //The implementation of a pointer to member is compiler dependent.
  32    #if defined(BOOST_INTRUSIVE_MSVC_COMPLIANT_PTR_TO_MEMBER)
  33    //msvc compliant compilers use their the first 32 bits as offset (even in 64 bit mode)
  34    return *(const boost::int32_t*)(void*)&ptr_to_member;
  35    //This works with gcc, msvc, ac++, ibmcpp
  36    #elif defined(__GNUC__)   || defined(__HP_aCC) || defined(BOOST_INTEL) || \
  37          defined(__IBMCPP__) || defined(__DECCXX)
  38    const Parent * const parent = 0;
  39    const char *const member = reinterpret_cast<const char*>(&(parent->*ptr_to_member));
  40    return std::ptrdiff_t(member - reinterpret_cast<const char*>(parent));
  41    #else
  42    //This is the traditional C-front approach: __MWERKS__, __DMC__, __SUNPRO_CC
  43    return (*(const std::ptrdiff_t*)(void*)&ptr_to_member) - 1;
  44    #endif
  45 }
  46
  47 template<class Parent, class Member>
  48 inline Parent *parent_from_member(Member *member, const Member Parent::* ptr_to_member)
  49 {
  50    return (Parent*)((char*)member -
  51       offset_from_pointer_to_member(ptr_to_member));
  52 }
  53
  54 template<class Parent, class Member>
  55 inline const Parent *parent_from_member(const Member *member, const Member Parent::* ptr_to_member)
  56 {
  57    return (const Parent*)((const char*)member -
  58       offset_from_pointer_to_member(ptr_to_member));
  59 }
  60
  61 }  //namespace detail {
  62 }  //namespace intrusive {
  63 }  //namespace boost {
  64
  65 #ifdef BOOST_INTRUSIVE_MSVC_COMPLIANT_PTR_TO_MEMBER
  66 #undef BOOST_INTRUSIVE_MSVC_COMPLIANT_PTR_TO_MEMBER
  67 #endif
  68
  69 #include <boost/intrusive/detail/config_end.hpp>
  70
  71 #endif   //#ifndef BOOST_INTRUSIVE_PARENT_FROM_MEMBER_HPP