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744 lines
26 KiB
C++
744 lines
26 KiB
C++
// Methods for type_info for -*- C++ -*- Run Time Type Identification.
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// Copyright (C) 1994, 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004
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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, 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, 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 functions 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 <bits/c++config.h>
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#include <cstddef>
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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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std::type_info::
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~type_info ()
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{ }
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std::bad_cast::~bad_cast() throw() { }
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std::bad_typeid::~bad_typeid() throw() { }
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#if !__GXX_MERGED_TYPEINFO_NAMES
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// We can't rely on common symbols being shared between shared objects.
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bool std::type_info::
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operator== (const std::type_info& arg) const
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{
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return (&arg == this) || (__builtin_strcmp (name (), arg.name ()) == 0);
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}
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#endif
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namespace std {
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// return true if this is a type_info for a pointer type
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bool type_info::
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__is_pointer_p () const
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{
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return false;
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}
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// return true if this is a type_info for a function type
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bool type_info::
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__is_function_p () const
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{
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return false;
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}
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// try and catch a thrown object.
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bool type_info::
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__do_catch (const type_info *thr_type, void **, unsigned) const
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{
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return *this == *thr_type;
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}
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// upcast from this type to the target. __class_type_info will override
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bool type_info::
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__do_upcast (const abi::__class_type_info *, void **) const
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{
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return false;
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}
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}
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namespace {
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using namespace std;
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using namespace abi;
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// Initial part of a vtable, this structure is used with offsetof, so we don't
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// have to keep alignments consistent manually.
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struct vtable_prefix
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{
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// Offset to most derived object.
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ptrdiff_t whole_object;
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// Additional padding if necessary.
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#ifdef _GLIBCXX_VTABLE_PADDING
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ptrdiff_t padding1;
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#endif
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// Pointer to most derived type_info.
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const __class_type_info *whole_type;
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// Additional padding if necessary.
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#ifdef _GLIBCXX_VTABLE_PADDING
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ptrdiff_t padding2;
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#endif
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// What a class's vptr points to.
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const void *origin;
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};
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template <typename T>
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inline const T *
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adjust_pointer (const void *base, ptrdiff_t offset)
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{
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return reinterpret_cast <const T *>
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(reinterpret_cast <const char *> (base) + offset);
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}
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// ADDR is a pointer to an object. Convert it to a pointer to a base,
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// using OFFSET. IS_VIRTUAL is true, if we are getting a virtual base.
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inline void const *
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convert_to_base (void const *addr, bool is_virtual, ptrdiff_t offset)
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{
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if (is_virtual)
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{
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const void *vtable = *static_cast <const void *const *> (addr);
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offset = *adjust_pointer<ptrdiff_t> (vtable, offset);
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}
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return adjust_pointer<void> (addr, offset);
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}
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// some predicate functions for __class_type_info::__sub_kind
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inline bool contained_p (__class_type_info::__sub_kind access_path)
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{
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return access_path >= __class_type_info::__contained_mask;
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}
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inline bool public_p (__class_type_info::__sub_kind access_path)
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{
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return access_path & __class_type_info::__contained_public_mask;
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}
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inline bool virtual_p (__class_type_info::__sub_kind access_path)
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{
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return (access_path & __class_type_info::__contained_virtual_mask);
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}
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inline bool contained_public_p (__class_type_info::__sub_kind access_path)
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{
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return ((access_path & __class_type_info::__contained_public)
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== __class_type_info::__contained_public);
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}
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inline bool contained_nonpublic_p (__class_type_info::__sub_kind access_path)
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{
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return ((access_path & __class_type_info::__contained_public)
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== __class_type_info::__contained_mask);
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}
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inline bool contained_nonvirtual_p (__class_type_info::__sub_kind access_path)
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{
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return ((access_path & (__class_type_info::__contained_mask
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| __class_type_info::__contained_virtual_mask))
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== __class_type_info::__contained_mask);
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}
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static const __class_type_info *const nonvirtual_base_type =
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static_cast <const __class_type_info *> (0) + 1;
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} // namespace
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namespace __cxxabiv1
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{
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__class_type_info::
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~__class_type_info ()
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{}
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__si_class_type_info::
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~__si_class_type_info ()
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{}
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__vmi_class_type_info::
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~__vmi_class_type_info ()
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{}
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// __upcast_result is used to hold information during traversal of a class
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// hierarchy when catch matching.
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struct __class_type_info::__upcast_result
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{
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const void *dst_ptr; // pointer to caught object
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__sub_kind part2dst; // path from current base to target
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int src_details; // hints about the source type hierarchy
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const __class_type_info *base_type; // where we found the target,
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// if in vbase the __class_type_info of vbase
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// if a non-virtual base then 1
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// else NULL
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__upcast_result (int d)
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:dst_ptr (NULL), part2dst (__unknown), src_details (d), base_type (NULL)
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{}
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};
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// __dyncast_result is used to hold information during traversal of a class
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// hierarchy when dynamic casting.
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struct __class_type_info::__dyncast_result
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{
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const void *dst_ptr; // pointer to target object or NULL
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__sub_kind whole2dst; // path from most derived object to target
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__sub_kind whole2src; // path from most derived object to sub object
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__sub_kind dst2src; // path from target to sub object
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int whole_details; // details of the whole class hierarchy
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__dyncast_result (int details_ = __vmi_class_type_info::__flags_unknown_mask)
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:dst_ptr (NULL), whole2dst (__unknown),
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whole2src (__unknown), dst2src (__unknown),
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whole_details (details_)
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{}
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protected:
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__dyncast_result(const __dyncast_result&);
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__dyncast_result&
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operator=(const __dyncast_result&);
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};
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bool __class_type_info::
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__do_catch (const type_info *thr_type,
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void **thr_obj,
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unsigned outer) const
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{
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if (*this == *thr_type)
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return true;
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if (outer >= 4)
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// Neither `A' nor `A *'.
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return false;
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return thr_type->__do_upcast (this, thr_obj);
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}
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bool __class_type_info::
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__do_upcast (const __class_type_info *dst_type,
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void **obj_ptr) const
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{
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__upcast_result result (__vmi_class_type_info::__flags_unknown_mask);
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__do_upcast (dst_type, *obj_ptr, result);
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if (!contained_public_p (result.part2dst))
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return false;
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*obj_ptr = const_cast <void *> (result.dst_ptr);
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return true;
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}
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inline __class_type_info::__sub_kind __class_type_info::
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__find_public_src (ptrdiff_t src2dst,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr) const
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{
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if (src2dst >= 0)
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return adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
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? __contained_public : __not_contained;
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if (src2dst == -2)
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return __not_contained;
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return __do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
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}
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__class_type_info::__sub_kind __class_type_info::
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__do_find_public_src (ptrdiff_t,
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const void *obj_ptr,
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const __class_type_info *,
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const void *src_ptr) const
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{
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if (src_ptr == obj_ptr)
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// Must be our type, as the pointers match.
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return __contained_public;
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return __not_contained;
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}
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__class_type_info::__sub_kind __si_class_type_info::
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__do_find_public_src (ptrdiff_t src2dst,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr) const
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{
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if (src_ptr == obj_ptr && *this == *src_type)
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return __contained_public;
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return __base_type->__do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
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}
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__class_type_info::__sub_kind __vmi_class_type_info::
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__do_find_public_src (ptrdiff_t src2dst,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr) const
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{
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if (obj_ptr == src_ptr && *this == *src_type)
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return __contained_public;
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for (std::size_t i = __base_count; i--;)
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{
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if (!__base_info[i].__is_public_p ())
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continue; // Not public, can't be here.
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const void *base = obj_ptr;
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ptrdiff_t offset = __base_info[i].__offset ();
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bool is_virtual = __base_info[i].__is_virtual_p ();
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if (is_virtual)
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{
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if (src2dst == -3)
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continue; // Not a virtual base, so can't be here.
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}
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base = convert_to_base (base, is_virtual, offset);
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__sub_kind base_kind = __base_info[i].__base_type->__do_find_public_src
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(src2dst, base, src_type, src_ptr);
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if (contained_p (base_kind))
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{
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if (is_virtual)
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base_kind = __sub_kind (base_kind | __contained_virtual_mask);
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return base_kind;
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}
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}
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return __not_contained;
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}
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bool __class_type_info::
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__do_dyncast (ptrdiff_t,
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__sub_kind access_path,
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const __class_type_info *dst_type,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr,
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__dyncast_result &__restrict result) const
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{
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if (obj_ptr == src_ptr && *this == *src_type)
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{
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// The src object we started from. Indicate how we are accessible from
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// the most derived object.
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result.whole2src = access_path;
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return false;
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}
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if (*this == *dst_type)
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{
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result.dst_ptr = obj_ptr;
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result.whole2dst = access_path;
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result.dst2src = __not_contained;
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return false;
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}
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return false;
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}
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bool __si_class_type_info::
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__do_dyncast (ptrdiff_t src2dst,
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__sub_kind access_path,
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const __class_type_info *dst_type,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr,
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__dyncast_result &__restrict result) const
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{
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if (*this == *dst_type)
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{
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result.dst_ptr = obj_ptr;
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result.whole2dst = access_path;
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if (src2dst >= 0)
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result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
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? __contained_public : __not_contained;
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else if (src2dst == -2)
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result.dst2src = __not_contained;
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return false;
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}
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if (obj_ptr == src_ptr && *this == *src_type)
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{
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// The src object we started from. Indicate how we are accessible from
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// the most derived object.
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result.whole2src = access_path;
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return false;
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}
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return __base_type->__do_dyncast (src2dst, access_path, dst_type, obj_ptr,
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src_type, src_ptr, result);
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}
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// This is a big hairy function. Although the run-time behaviour of
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// dynamic_cast is simple to describe, it gives rise to some non-obvious
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// behaviour. We also desire to determine as early as possible any definite
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// answer we can get. Because it is unknown what the run-time ratio of
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// succeeding to failing dynamic casts is, we do not know in which direction
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// to bias any optimizations. To that end we make no particular effort towards
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// early fail answers or early success answers. Instead we try to minimize
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// work by filling in things lazily (when we know we need the information),
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// and opportunisticly take early success or failure results.
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bool __vmi_class_type_info::
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__do_dyncast (ptrdiff_t src2dst,
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__sub_kind access_path,
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const __class_type_info *dst_type,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr,
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__dyncast_result &__restrict result) const
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{
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if (result.whole_details & __flags_unknown_mask)
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result.whole_details = __flags;
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if (obj_ptr == src_ptr && *this == *src_type)
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{
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// The src object we started from. Indicate how we are accessible from
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// the most derived object.
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result.whole2src = access_path;
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return false;
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}
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if (*this == *dst_type)
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{
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result.dst_ptr = obj_ptr;
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result.whole2dst = access_path;
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if (src2dst >= 0)
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result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
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? __contained_public : __not_contained;
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else if (src2dst == -2)
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result.dst2src = __not_contained;
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return false;
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}
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bool result_ambig = false;
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for (std::size_t i = __base_count; i--;)
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{
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__dyncast_result result2 (result.whole_details);
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void const *base = obj_ptr;
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__sub_kind base_access = access_path;
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ptrdiff_t offset = __base_info[i].__offset ();
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bool is_virtual = __base_info[i].__is_virtual_p ();
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if (is_virtual)
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base_access = __sub_kind (base_access | __contained_virtual_mask);
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base = convert_to_base (base, is_virtual, offset);
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if (!__base_info[i].__is_public_p ())
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{
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if (src2dst == -2 &&
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!(result.whole_details
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& (__non_diamond_repeat_mask | __diamond_shaped_mask)))
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// The hierarchy has no duplicate bases (which might ambiguate
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// things) and where we started is not a public base of what we
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// want (so it cannot be a downcast). There is nothing of interest
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// hiding in a non-public base.
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continue;
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base_access = __sub_kind (base_access & ~__contained_public_mask);
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}
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bool result2_ambig
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= __base_info[i].__base_type->__do_dyncast (src2dst, base_access,
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dst_type, base,
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src_type, src_ptr, result2);
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result.whole2src = __sub_kind (result.whole2src | result2.whole2src);
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if (result2.dst2src == __contained_public
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|| result2.dst2src == __contained_ambig)
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{
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result.dst_ptr = result2.dst_ptr;
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result.whole2dst = result2.whole2dst;
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result.dst2src = result2.dst2src;
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// Found a downcast which can't be bettered or an ambiguous downcast
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// which can't be disambiguated
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return result2_ambig;
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}
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if (!result_ambig && !result.dst_ptr)
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{
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// Not found anything yet.
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result.dst_ptr = result2.dst_ptr;
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result.whole2dst = result2.whole2dst;
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result_ambig = result2_ambig;
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if (result.dst_ptr && result.whole2src != __unknown
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&& !(__flags & __non_diamond_repeat_mask))
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// Found dst and src and we don't have repeated bases.
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return result_ambig;
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}
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else if (result.dst_ptr && result.dst_ptr == result2.dst_ptr)
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{
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// Found at same address, must be via virtual. Pick the most
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// accessible path.
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result.whole2dst =
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__sub_kind (result.whole2dst | result2.whole2dst);
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}
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else if ((result.dst_ptr != 0 & result2.dst_ptr != 0)
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|| (result.dst_ptr != 0 & result2_ambig)
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|| (result2.dst_ptr != 0 & result_ambig))
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{
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// Found two different DST_TYPE bases, or a valid one and a set of
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// ambiguous ones, must disambiguate. See whether SRC_PTR is
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// contained publicly within one of the non-ambiguous choices. If it
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// is in only one, then that's the choice. If it is in both, then
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// we're ambiguous and fail. If it is in neither, we're ambiguous,
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// but don't yet fail as we might later find a third base which does
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|
// contain SRC_PTR.
|
|
|
|
__sub_kind new_sub_kind = result2.dst2src;
|
|
__sub_kind old_sub_kind = result.dst2src;
|
|
|
|
if (contained_p (result.whole2src)
|
|
&& (!virtual_p (result.whole2src)
|
|
|| !(result.whole_details & __diamond_shaped_mask)))
|
|
{
|
|
// We already found SRC_PTR as a base of most derived, and
|
|
// either it was non-virtual, or the whole hierarchy is
|
|
// not-diamond shaped. Therefore if it is in either choice, it
|
|
// can only be in one of them, and we will already know.
|
|
if (old_sub_kind == __unknown)
|
|
old_sub_kind = __not_contained;
|
|
if (new_sub_kind == __unknown)
|
|
new_sub_kind = __not_contained;
|
|
}
|
|
else
|
|
{
|
|
if (old_sub_kind >= __not_contained)
|
|
;// already calculated
|
|
else if (contained_p (new_sub_kind)
|
|
&& (!virtual_p (new_sub_kind)
|
|
|| !(__flags & __diamond_shaped_mask)))
|
|
// Already found inside the other choice, and it was
|
|
// non-virtual or we are not diamond shaped.
|
|
old_sub_kind = __not_contained;
|
|
else
|
|
old_sub_kind = dst_type->__find_public_src
|
|
(src2dst, result.dst_ptr, src_type, src_ptr);
|
|
|
|
if (new_sub_kind >= __not_contained)
|
|
;// already calculated
|
|
else if (contained_p (old_sub_kind)
|
|
&& (!virtual_p (old_sub_kind)
|
|
|| !(__flags & __diamond_shaped_mask)))
|
|
// Already found inside the other choice, and it was
|
|
// non-virtual or we are not diamond shaped.
|
|
new_sub_kind = __not_contained;
|
|
else
|
|
new_sub_kind = dst_type->__find_public_src
|
|
(src2dst, result2.dst_ptr, src_type, src_ptr);
|
|
}
|
|
|
|
// Neither sub_kind can be contained_ambig -- we bail out early
|
|
// when we find those.
|
|
if (contained_p (__sub_kind (new_sub_kind ^ old_sub_kind)))
|
|
{
|
|
// Only on one choice, not ambiguous.
|
|
if (contained_p (new_sub_kind))
|
|
{
|
|
// Only in new.
|
|
result.dst_ptr = result2.dst_ptr;
|
|
result.whole2dst = result2.whole2dst;
|
|
result_ambig = false;
|
|
old_sub_kind = new_sub_kind;
|
|
}
|
|
result.dst2src = old_sub_kind;
|
|
if (public_p (result.dst2src))
|
|
return false; // Can't be an ambiguating downcast for later discovery.
|
|
if (!virtual_p (result.dst2src))
|
|
return false; // Found non-virtually can't be bettered
|
|
}
|
|
else if (contained_p (__sub_kind (new_sub_kind & old_sub_kind)))
|
|
{
|
|
// In both.
|
|
result.dst_ptr = NULL;
|
|
result.dst2src = __contained_ambig;
|
|
return true; // Fail.
|
|
}
|
|
else
|
|
{
|
|
// In neither publicly, ambiguous for the moment, but keep
|
|
// looking. It is possible that it was private in one or
|
|
// both and therefore we should fail, but that's just tough.
|
|
result.dst_ptr = NULL;
|
|
result.dst2src = __not_contained;
|
|
result_ambig = true;
|
|
}
|
|
}
|
|
|
|
if (result.whole2src == __contained_private)
|
|
// We found SRC_PTR as a private non-virtual base, therefore all
|
|
// cross casts will fail. We have already found a down cast, if
|
|
// there is one.
|
|
return result_ambig;
|
|
}
|
|
|
|
return result_ambig;
|
|
}
|
|
|
|
bool __class_type_info::
|
|
__do_upcast (const __class_type_info *dst, const void *obj,
|
|
__upcast_result &__restrict result) const
|
|
{
|
|
if (*this == *dst)
|
|
{
|
|
result.dst_ptr = obj;
|
|
result.base_type = nonvirtual_base_type;
|
|
result.part2dst = __contained_public;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool __si_class_type_info::
|
|
__do_upcast (const __class_type_info *dst, const void *obj_ptr,
|
|
__upcast_result &__restrict result) const
|
|
{
|
|
if (__class_type_info::__do_upcast (dst, obj_ptr, result))
|
|
return true;
|
|
|
|
return __base_type->__do_upcast (dst, obj_ptr, result);
|
|
}
|
|
|
|
bool __vmi_class_type_info::
|
|
__do_upcast (const __class_type_info *dst, const void *obj_ptr,
|
|
__upcast_result &__restrict result) const
|
|
{
|
|
if (__class_type_info::__do_upcast (dst, obj_ptr, result))
|
|
return true;
|
|
|
|
int src_details = result.src_details;
|
|
if (src_details & __flags_unknown_mask)
|
|
src_details = __flags;
|
|
|
|
for (std::size_t i = __base_count; i--;)
|
|
{
|
|
__upcast_result result2 (src_details);
|
|
const void *base = obj_ptr;
|
|
ptrdiff_t offset = __base_info[i].__offset ();
|
|
bool is_virtual = __base_info[i].__is_virtual_p ();
|
|
bool is_public = __base_info[i].__is_public_p ();
|
|
|
|
if (!is_public && !(src_details & __non_diamond_repeat_mask))
|
|
// original cannot have an ambiguous base, so skip private bases
|
|
continue;
|
|
|
|
if (base)
|
|
base = convert_to_base (base, is_virtual, offset);
|
|
|
|
if (__base_info[i].__base_type->__do_upcast (dst, base, result2))
|
|
{
|
|
if (result2.base_type == nonvirtual_base_type && is_virtual)
|
|
result2.base_type = __base_info[i].__base_type;
|
|
if (contained_p (result2.part2dst) && !is_public)
|
|
result2.part2dst = __sub_kind (result2.part2dst & ~__contained_public_mask);
|
|
|
|
if (!result.base_type)
|
|
{
|
|
result = result2;
|
|
if (!contained_p (result.part2dst))
|
|
return true; // found ambiguously
|
|
|
|
if (result.part2dst & __contained_public_mask)
|
|
{
|
|
if (!(__flags & __non_diamond_repeat_mask))
|
|
return true; // cannot have an ambiguous other base
|
|
}
|
|
else
|
|
{
|
|
if (!virtual_p (result.part2dst))
|
|
return true; // cannot have another path
|
|
if (!(__flags & __diamond_shaped_mask))
|
|
return true; // cannot have a more accessible path
|
|
}
|
|
}
|
|
else if (result.dst_ptr != result2.dst_ptr)
|
|
{
|
|
// Found an ambiguity.
|
|
result.dst_ptr = NULL;
|
|
result.part2dst = __contained_ambig;
|
|
return true;
|
|
}
|
|
else if (result.dst_ptr)
|
|
{
|
|
// Ok, found real object via a virtual path.
|
|
result.part2dst
|
|
= __sub_kind (result.part2dst | result2.part2dst);
|
|
}
|
|
else
|
|
{
|
|
// Dealing with a null pointer, need to check vbase
|
|
// containing each of the two choices.
|
|
if (result2.base_type == nonvirtual_base_type
|
|
|| result.base_type == nonvirtual_base_type
|
|
|| !(*result2.base_type == *result.base_type))
|
|
{
|
|
// Already ambiguous, not virtual or via different virtuals.
|
|
// Cannot match.
|
|
result.part2dst = __contained_ambig;
|
|
return true;
|
|
}
|
|
result.part2dst
|
|
= __sub_kind (result.part2dst | result2.part2dst);
|
|
}
|
|
}
|
|
}
|
|
return result.part2dst != __unknown;
|
|
}
|
|
|
|
// this is the external interface to the dynamic cast machinery
|
|
extern "C" void *
|
|
__dynamic_cast (const void *src_ptr, // object started from
|
|
const __class_type_info *src_type, // type of the starting object
|
|
const __class_type_info *dst_type, // desired target type
|
|
ptrdiff_t src2dst) // how src and dst are related
|
|
{
|
|
const void *vtable = *static_cast <const void *const *> (src_ptr);
|
|
const vtable_prefix *prefix =
|
|
adjust_pointer <vtable_prefix> (vtable,
|
|
-offsetof (vtable_prefix, origin));
|
|
const void *whole_ptr =
|
|
adjust_pointer <void> (src_ptr, prefix->whole_object);
|
|
const __class_type_info *whole_type = prefix->whole_type;
|
|
__class_type_info::__dyncast_result result;
|
|
|
|
whole_type->__do_dyncast (src2dst, __class_type_info::__contained_public,
|
|
dst_type, whole_ptr, src_type, src_ptr, result);
|
|
if (!result.dst_ptr)
|
|
return NULL;
|
|
if (contained_public_p (result.dst2src))
|
|
// Src is known to be a public base of dst.
|
|
return const_cast <void *> (result.dst_ptr);
|
|
if (contained_public_p (__class_type_info::__sub_kind (result.whole2src & result.whole2dst)))
|
|
// Both src and dst are known to be public bases of whole. Found a valid
|
|
// cross cast.
|
|
return const_cast <void *> (result.dst_ptr);
|
|
if (contained_nonvirtual_p (result.whole2src))
|
|
// Src is known to be a non-public nonvirtual base of whole, and not a
|
|
// base of dst. Found an invalid cross cast, which cannot also be a down
|
|
// cast
|
|
return NULL;
|
|
if (result.dst2src == __class_type_info::__unknown)
|
|
result.dst2src = dst_type->__find_public_src (src2dst, result.dst_ptr,
|
|
src_type, src_ptr);
|
|
if (contained_public_p (result.dst2src))
|
|
// Found a valid down cast
|
|
return const_cast <void *> (result.dst_ptr);
|
|
// Must be an invalid down cast, or the cross cast wasn't bettered
|
|
return NULL;
|
|
}
|
|
|
|
} // namespace __cxxabiv1
|