1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
/**
* Implementation of array assignment support routines.
*
* Copyright: Copyright Digital Mars 2004 - 2010.
* License: $(HTTP www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
* Authors: Walter Bright, Sean Kelly
* Source: $(DRUNTIMESRC rt/_cast_.d)
*/
/* Copyright Digital Mars 2004 - 2010.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
module rt.cast_;
debug(cast_) import core.stdc.stdio : printf;
extern (C):
@nogc:
nothrow:
pure:
// Needed because ClassInfo.opEquals(Object) does a dynamic cast,
// but we are trying to implement dynamic cast.
extern (D) private bool areClassInfosEqual(scope const ClassInfo a, scope const ClassInfo b) @safe
{
// same class if signatures match, works with potential duplicates across binaries
if (a is b)
return true;
// new fast way
if (a.m_flags & TypeInfo_Class.ClassFlags.hasNameSig)
return a.nameSig[0] == b.nameSig[0]
&& a.nameSig[1] == b.nameSig[1]
&& a.nameSig[2] == b.nameSig[2]
&& a.nameSig[3] == b.nameSig[3];
// old slow way for temporary binary compatibility
return a.name == b.name;
}
/******************************************
* Given a pointer:
* If it is an Object, return that Object.
* If it is an interface, return the Object implementing the interface.
* If it is null, return null.
* Else, undefined crash
*/
Object _d_toObject(return scope void* p)
{
if (!p)
return null;
Object o = cast(Object) p;
ClassInfo oc = typeid(o);
Interface* pi = **cast(Interface***) p;
/* Interface.offset lines up with ClassInfo.name.ptr,
* so we rely on pointers never being less than 64K,
* and Objects never being greater.
*/
if (pi.offset < 0x10000)
{
debug(cast_) printf("\tpi.offset = %zd\n", pi.offset);
return cast(Object)(p - pi.offset);
}
return o;
}
/*************************************
* Attempts to cast interface Object o to class c.
* Returns o if successful, null if not.
*/
void* _d_interface_cast(void* p, ClassInfo c)
{
debug(cast_) printf("_d_interface_cast(p = %p, c = '%.*s')\n", p, cast(int) c.name.length, c.name.ptr);
if (!p)
return null;
Interface* pi = **cast(Interface***) p;
debug(cast_) printf("\tpi.offset = %zd\n", pi.offset);
Object o2 = cast(Object)(p - pi.offset);
void* res = null;
size_t offset = 0;
if (o2 && _d_isbaseof2(typeid(o2), c, offset))
{
debug(cast_) printf("\toffset = %zd\n", offset);
res = cast(void*) o2 + offset;
}
debug(cast_) printf("\tresult = %p\n", res);
return res;
}
/*****
* Dynamic cast from a class object `o` to class or interface `c`, where `c` is a subtype of `o`.
* Params:
* o = instance of class
* c = a subclass of o
* Returns:
* null if o is null or c is not a subclass of o. Otherwise, return o.
*/
void* _d_dynamic_cast(Object o, ClassInfo c)
{
debug(cast_) printf("_d_dynamic_cast(o = %p, c = '%.*s')\n", o, cast(int) c.name.length, c.name.ptr);
void* res = null;
size_t offset = 0;
if (o && _d_isbaseof2(typeid(o), c, offset))
{
debug(cast_) printf("\toffset = %zd\n", offset);
res = cast(void*) o + offset;
}
debug(cast_) printf("\tresult = %p\n", res);
return res;
}
/*****
* Dynamic cast from a class object o to class c, where c is a subclass of o.
* Params:
* o = instance of class
* c = a subclass of o
* Returns:
* null if o is null or c is not a subclass of o. Otherwise, return o.
*/
void* _d_class_cast(Object o, ClassInfo c)
{
debug(cast_) printf("_d_cast_cast(o = %p, c = '%.*s')\n", o, cast(int) c.name.length, c.name.ptr);
if (!o)
return null;
ClassInfo oc = typeid(o);
int delta = oc.depth;
if (delta && c.depth)
{
delta -= c.depth;
if (delta < 0)
return null;
while (delta--)
oc = oc.base;
if (areClassInfosEqual(oc, c))
return cast(void*)o;
return null;
}
// no depth data - support the old way
do
{
if (areClassInfosEqual(oc, c))
return cast(void*)o;
oc = oc.base;
} while (oc);
return null;
}
/**
* Dynamic cast `o` to final class `c` only one level down
* Params:
* o = object that is instance of a class
* c = class to cast it to
* Returns:
* o if it succeeds, null if it fails
*/
void* _d_paint_cast(Object o, ClassInfo c)
{
/* If o is really an instance of c, just do a paint
*/
auto p = o && cast(void*)(areClassInfosEqual(typeid(o), c)) ? o : null;
debug assert(cast(void*)p is cast(void*)_d_dynamic_cast(o, c));
return cast(void*)p;
}
int _d_isbaseof2(scope ClassInfo oc, scope const ClassInfo c, scope ref size_t offset) @safe
{
if (areClassInfosEqual(oc, c))
return true;
do
{
if (oc.base && areClassInfosEqual(oc.base, c))
return true;
// Bugzilla 2013: Use depth-first search to calculate offset
// from the derived (oc) to the base (c).
foreach (iface; oc.interfaces)
{
if (areClassInfosEqual(iface.classinfo, c) || _d_isbaseof2(iface.classinfo, c, offset))
{
offset += iface.offset;
return true;
}
}
oc = oc.base;
} while (oc);
return false;
}
int _d_isbaseof(scope ClassInfo oc, scope const ClassInfo c) @safe
{
size_t offset = 0;
return _d_isbaseof2(oc, c, offset);
}
|
