126 lines
3.6 KiB
C++
126 lines
3.6 KiB
C++
// Methods for type_info for -*- C++ -*- Run Time Type Identification.
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// Copyright (C) 1994, 1996 Free Software Foundation
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// This file is part of GNU CC.
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// GNU CC is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// GNU CC is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with GNU CC; see the file COPYING. If not, write to
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// the Free Software Foundation, 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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// As a special exception, if you link this library with other files,
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// some of which are compiled with GCC, to produce an executable,
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// this library does not by itself cause the resulting executable
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// to be covered by the GNU General Public License.
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// This exception does not however invalidate any other reasons why
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// the executable file might be covered by the GNU General Public License.
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#include <stddef.h>
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#include "tinfo.h"
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#include "new" // for placement new
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// This file contains the minimal working set necessary to link with code
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// that uses virtual functions and -frtti but does not actually use RTTI
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// functionality.
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type_info::
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~type_info ()
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{ }
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extern "C" void
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__rtti_class (void *addr, const char *name,
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const __class_type_info::base_info *bl, size_t bn)
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{ new (addr) __class_type_info (name, bl, bn); }
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extern "C" void
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__rtti_si (void *addr, const char *n, const type_info *ti)
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{
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new (addr) __si_type_info
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(n, static_cast <const __user_type_info &> (*ti));
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}
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extern "C" void
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__rtti_user (void *addr, const char *name)
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{ new (addr) __user_type_info (name); }
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// dynamic_cast helper methods.
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// Returns a pointer to the desired sub-object or 0.
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void * __user_type_info::
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dcast (const type_info& to, int, void *addr, const type_info *, void *) const
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{ return (*this == to) ? addr : 0; }
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void * __si_type_info::
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dcast (const type_info& to, int require_public, void *addr,
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const type_info *sub, void *subptr) const
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{
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if (*this == to)
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return addr;
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return base.dcast (to, require_public, addr, sub, subptr);
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}
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void* __class_type_info::
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dcast (const type_info& desired, int is_public, void *objptr,
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const type_info *sub, void *subptr) const
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{
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if (*this == desired)
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return objptr;
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void *match_found = 0;
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for (int i = 0; i < n_bases; i++)
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{
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if (is_public && base_list[i].access != PUBLIC)
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continue;
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void *p = (char *)objptr + base_list[i].offset;
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if (base_list[i].is_virtual)
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p = *(void **)p;
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p = base_list[i].base->dcast (desired, is_public, p, sub, subptr);
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if (p)
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{
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if (match_found == 0)
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match_found = p;
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else if (match_found != p)
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{
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if (sub)
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{
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// Perhaps we're downcasting from *sub to desired; see if
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// subptr is a subobject of exactly one of {match_found,p}.
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const __user_type_info &d =
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static_cast <const __user_type_info &> (desired);
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void *os = d.dcast (*sub, 1, match_found);
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void *ns = d.dcast (*sub, 1, p);
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if (os == ns)
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/* ambiguous -- subptr is a virtual base */;
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else if (os == subptr)
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continue;
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else if (ns == subptr)
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{
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match_found = p;
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continue;
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}
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}
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// base found at two different pointers,
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// conversion is not unique
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return 0;
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}
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}
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}
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return match_found;
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}
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