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/*
* Copyright 2010-2011 PathScale, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "typeinfo.h"
#include <stdio.h>
using namespace ABI_NAMESPACE;
/**
* Vtable header.
*/
struct vtable_header
{
/** Offset of the leaf object. */
ptrdiff_t leaf_offset;
/** Type of the object. */
const __class_type_info *type;
};
/**
* Simple macro that does pointer arithmetic in bytes but returns a value of
* the same type as the original.
*/
#define ADD_TO_PTR(x, off) (__typeof__(x))(((char*)x) + off)
bool __class_type_info::can_cast_to(const struct __class_type_info *other) const
{
return this == other;
}
void *__class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
{
if (this == other)
{
return obj;
}
return 0;
}
bool __si_class_type_info::can_cast_to(const struct __class_type_info *other) const
{
return this == other || __base_type->can_cast_to(other);
}
void *__si_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
{
if (this == other)
{
return obj;
}
return __base_type->cast_to(obj, other);
}
bool __vmi_class_type_info::can_cast_to(const struct __class_type_info *other) const
{
if (this == other)
{
return true;
}
for (unsigned int i=0 ; i<__base_count ; i++)
{
const __base_class_type_info *info = &__base_info[i];
if(info->isPublic() && info->__base_type->can_cast_to(other))
{
return true;
}
}
return false;
}
void *__vmi_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
{
if (this == other)
{
return obj;
}
for (unsigned int i=0 ; i<__base_count ; i++)
{
const __base_class_type_info *info = &__base_info[i];
ptrdiff_t offset = info->offset();
// If this is a virtual superclass, the offset is stored in the
// object's vtable at the offset requested; 2.9.5.6.c:
//
// 'For a non-virtual base, this is the offset in the object of the
// base subobject. For a virtual base, this is the offset in the
// virtual table of the virtual base offset for the virtual base
// referenced (negative).'
if (info->isVirtual())
{
// Object's vtable
ptrdiff_t *off = *(ptrdiff_t**)obj;
// Offset location in vtable
off = ADD_TO_PTR(off, offset);
offset = *off;
}
void *cast = ADD_TO_PTR(obj, offset);
if (info->__base_type == other)
{
return cast;
}
if ((cast = info->__base_type->cast_to(cast, other)))
{
return cast;
}
}
return 0;
}
/**
* ABI function used to implement the dynamic_cast<> operator. Some cases of
* this operator are implemented entirely in the compiler (e.g. to void*).
* This function implements the dynamic casts of the form dynamic_cast<T>(v).
* This will be translated to a call to this function with the value v as the
* first argument. The type id of the static type of v is the second argument
* and the type id of the destination type (T) is the third argument.
*
* The third argument is a hint about the compiler's guess at the correct
* pointer offset. If this value is negative, then -1 indicates no hint, -2
* that src is not a public base of dst, and -3 that src is a multiple public
* base type but never a virtual base type
*/
extern "C" void* __dynamic_cast(const void *sub,
const __class_type_info *src,
const __class_type_info *dst,
ptrdiff_t src2dst_offset)
{
char *vtable_location = *(char**)sub;
const vtable_header *header =
(const vtable_header*)(vtable_location - sizeof(vtable_header));
void *leaf = ADD_TO_PTR((void*)sub, header->leaf_offset);
return header->type->cast_to(leaf, dst);
}
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