src/implicit_cast.cpp

   1 // Copyright (c) 2003 Daniel Wallin and Arvid Norberg
   2
   3 // Permission is hereby granted, free of charge, to any person obtaining a
   4 // copy of this software and associated documentation files (the "Software"),
   5 // to deal in the Software without restriction, including without limitation
   6 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
   7 // and/or sell copies of the Software, and to permit persons to whom the
   8 // Software is furnished to do so, subject to the following conditions:
   9
  10 // The above copyright notice and this permission notice shall be included
  11 // in all copies or substantial portions of the Software.
  12
  13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
  14 // ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
  15 // TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
  16 // PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
  17 // SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
  18 // ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  19 // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
  21 // OR OTHER DEALINGS IN THE SOFTWARE.
  22
  23 extern "C"
  24 {
  25         #include "lua.h"
  26 }
  27
  28 #include <luabind/luabind.hpp>
  29 #include <luabind/detail/implicit_cast.hpp>
  30
  31 using namespace luabind::detail;
  32
  33         // returns -1 if there exists no implicit cast from the given class_rep
  34         // to T. If there exists an implicit cast to T, the number of steps times 2
  35         // is returned and pointer_offset is filled with the number of bytes
  36         // the pointer have to be offseted to perform the cast
  37         // the reason why we return the number of cast-steps times two, instead of
  38         // just the number of steps is to be consistent with the function matchers. They
  39         // have to give one matching-point extra to match const functions. There may be
  40         // two functions that match their parameters exactly, but there is one const
  41         // function and one non-const function, then (if the this-pointer is non-const)
  42         // both functions will match. To avoid amiguaties, the const version will get
  43         // one penalty point to make the match-selector select the non-const version. It
  44         // the this-pointer is const, there's no problem, since the non-const function
  45         // will not match at all.
  46 namespace luabind { namespace detail
  47 {
  48         int implicit_cast(const class_rep* crep,
  49                                                                 LUABIND_TYPE_INFO const& type_id,
  50                                                                  int& pointer_offset)
  51         {
  52                 int offset = 0;
  53                 if (LUABIND_TYPE_INFO_EQUAL(crep->type(), type_id)) return 0;
  54
  55                 for (std::vector<class_rep::base_info>::const_iterator
  56                                 i = crep->bases().begin(); i != crep->bases().end(); ++i)
  57                 {
  58                         int steps = implicit_cast(i->base, type_id, offset);
  59                         pointer_offset = offset + i->pointer_offset;
  60                         if (steps >= 0) return steps + 2;
  61                 }
  62                 return -1;
  63         }
  64 }}
  65