78 lines
3.3 KiB
C++
78 lines
3.3 KiB
C++
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// Copyright (C) 1994, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2007
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// Free Software Foundation
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//
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// This file is part of GCC.
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//
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// GCC 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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// GCC 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 GCC; see the file COPYING. If not, write to
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// the Free Software Foundation, 51 Franklin Street, Fifth Floor,
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// Boston, MA 02110-1301, USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline enums from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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#include "tinfo.h"
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namespace __cxxabiv1 {
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// this is the external interface to the dynamic cast machinery
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extern "C" void *
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__dynamic_cast (const void *src_ptr, // object started from
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const __class_type_info *src_type, // type of the starting object
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const __class_type_info *dst_type, // desired target type
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ptrdiff_t src2dst) // how src and dst are related
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{
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const void *vtable = *static_cast <const void *const *> (src_ptr);
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const vtable_prefix *prefix =
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adjust_pointer <vtable_prefix> (vtable,
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-offsetof (vtable_prefix, origin));
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const void *whole_ptr =
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adjust_pointer <void> (src_ptr, prefix->whole_object);
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const __class_type_info *whole_type = prefix->whole_type;
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__class_type_info::__dyncast_result result;
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whole_type->__do_dyncast (src2dst, __class_type_info::__contained_public,
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dst_type, whole_ptr, src_type, src_ptr, result);
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if (!result.dst_ptr)
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return NULL;
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if (contained_public_p (result.dst2src))
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// Src is known to be a public base of dst.
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return const_cast <void *> (result.dst_ptr);
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if (contained_public_p (__class_type_info::__sub_kind (result.whole2src & result.whole2dst)))
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// Both src and dst are known to be public bases of whole. Found a valid
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// cross cast.
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return const_cast <void *> (result.dst_ptr);
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if (contained_nonvirtual_p (result.whole2src))
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// Src is known to be a non-public nonvirtual base of whole, and not a
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// base of dst. Found an invalid cross cast, which cannot also be a down
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// cast
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return NULL;
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if (result.dst2src == __class_type_info::__unknown)
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result.dst2src = dst_type->__find_public_src (src2dst, result.dst_ptr,
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src_type, src_ptr);
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if (contained_public_p (result.dst2src))
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// Found a valid down cast
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return const_cast <void *> (result.dst_ptr);
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// Must be an invalid down cast, or the cross cast wasn't bettered
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return NULL;
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}
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}
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