implicit_cast.cpp

来自「这是整套横扫千军3D版游戏的源码」· C++ 代码 · 共 63 行

// Copyright (c) 2003 Daniel Wallin and Arvid Norberg

// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
// ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.

#include <luabind/lua_include.hpp>

#include <luabind/luabind.hpp>
#include <luabind/detail/implicit_cast.hpp>

namespace luabind { namespace detail {

    // returns -1 if there exists no implicit cast from the given class_rep
    // to T. If there exists an implicit cast to T, the number of steps times
    // 2 is returned and pointer_offset is filled with the number of bytes 
    // the pointer have to be offseted to perform the cast the reason why we
    // return the number of cast-steps times two, instead of just the number 
    // of steps is to be consistent with the function matchers. They have to 
    // give one matching-point extra to match const functions. There may be
    // two functions that match their parameters exactly, but there is one 
    // const function and one non-const function, then (if the this-pointer
    // is non-const) both functions will match. To avoid amiguaties, the const
    // version will get one penalty point to make the match-selector select
    // the non-const version. If the this-pointer is const, there's no 
    // problem, since the non-const function will not match at all.
    
    int implicit_cast(
        class_rep const* crep
      , LUABIND_TYPE_INFO const& type_id
      , int& pointer_offset)
    {
        int offset = 0;
        if (LUABIND_TYPE_INFO_EQUAL(crep->type(), type_id)) return 0;

        for (std::vector<class_rep::base_info>::const_iterator i = 
            crep->bases().begin(); i != crep->bases().end(); ++i)
        {
            int steps = implicit_cast(i->base, type_id, offset);
            pointer_offset = offset + i->pointer_offset;
            if (steps >= 0) return steps + 2;
        }
        return -1;
    }
}}