-
Notifications
You must be signed in to change notification settings - Fork 2.1k
/
cast.h
2231 lines (1923 loc) · 92.1 KB
/
cast.h
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
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
pybind11/cast.h: Partial template specializations to cast between
C++ and Python types
Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.
*/
#pragma once
#include "pytypes.h"
#include "detail/typeid.h"
#include "detail/descr.h"
#include "detail/internals.h"
#include <array>
#include <limits>
#include <tuple>
#include <type_traits>
#if defined(PYBIND11_CPP17)
# if defined(__has_include)
# if __has_include(<string_view>)
# define PYBIND11_HAS_STRING_VIEW
# endif
# elif defined(_MSC_VER)
# define PYBIND11_HAS_STRING_VIEW
# endif
#endif
#ifdef PYBIND11_HAS_STRING_VIEW
#include <string_view>
#endif
#if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
# define PYBIND11_HAS_U8STRING
#endif
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
PYBIND11_NAMESPACE_BEGIN(detail)
/// A life support system for temporary objects created by `type_caster::load()`.
/// Adding a patient will keep it alive up until the enclosing function returns.
class loader_life_support {
public:
/// A new patient frame is created when a function is entered
loader_life_support() {
get_internals().loader_patient_stack.push_back(nullptr);
}
/// ... and destroyed after it returns
~loader_life_support() {
auto &stack = get_internals().loader_patient_stack;
if (stack.empty())
pybind11_fail("loader_life_support: internal error");
auto ptr = stack.back();
stack.pop_back();
Py_CLEAR(ptr);
// A heuristic to reduce the stack's capacity (e.g. after long recursive calls)
if (stack.capacity() > 16 && !stack.empty() && stack.capacity() / stack.size() > 2)
stack.shrink_to_fit();
}
/// This can only be used inside a pybind11-bound function, either by `argument_loader`
/// at argument preparation time or by `py::cast()` at execution time.
PYBIND11_NOINLINE static void add_patient(handle h) {
auto &stack = get_internals().loader_patient_stack;
if (stack.empty())
throw cast_error("When called outside a bound function, py::cast() cannot "
"do Python -> C++ conversions which require the creation "
"of temporary values");
auto &list_ptr = stack.back();
if (list_ptr == nullptr) {
list_ptr = PyList_New(1);
if (!list_ptr)
pybind11_fail("loader_life_support: error allocating list");
PyList_SET_ITEM(list_ptr, 0, h.inc_ref().ptr());
} else {
auto result = PyList_Append(list_ptr, h.ptr());
if (result == -1)
pybind11_fail("loader_life_support: error adding patient");
}
}
};
// Gets the cache entry for the given type, creating it if necessary. The return value is the pair
// returned by emplace, i.e. an iterator for the entry and a bool set to `true` if the entry was
// just created.
inline std::pair<decltype(internals::registered_types_py)::iterator, bool> all_type_info_get_cache(PyTypeObject *type);
// Populates a just-created cache entry.
PYBIND11_NOINLINE inline void all_type_info_populate(PyTypeObject *t, std::vector<type_info *> &bases) {
std::vector<PyTypeObject *> check;
for (handle parent : reinterpret_borrow<tuple>(t->tp_bases))
check.push_back((PyTypeObject *) parent.ptr());
auto const &type_dict = get_internals().registered_types_py;
for (size_t i = 0; i < check.size(); i++) {
auto type = check[i];
// Ignore Python2 old-style class super type:
if (!PyType_Check((PyObject *) type)) continue;
// Check `type` in the current set of registered python types:
auto it = type_dict.find(type);
if (it != type_dict.end()) {
// We found a cache entry for it, so it's either pybind-registered or has pre-computed
// pybind bases, but we have to make sure we haven't already seen the type(s) before: we
// want to follow Python/virtual C++ rules that there should only be one instance of a
// common base.
for (auto *tinfo : it->second) {
// NB: Could use a second set here, rather than doing a linear search, but since
// having a large number of immediate pybind11-registered types seems fairly
// unlikely, that probably isn't worthwhile.
bool found = false;
for (auto *known : bases) {
if (known == tinfo) { found = true; break; }
}
if (!found) bases.push_back(tinfo);
}
}
else if (type->tp_bases) {
// It's some python type, so keep follow its bases classes to look for one or more
// registered types
if (i + 1 == check.size()) {
// When we're at the end, we can pop off the current element to avoid growing
// `check` when adding just one base (which is typical--i.e. when there is no
// multiple inheritance)
check.pop_back();
i--;
}
for (handle parent : reinterpret_borrow<tuple>(type->tp_bases))
check.push_back((PyTypeObject *) parent.ptr());
}
}
}
/**
* Extracts vector of type_info pointers of pybind-registered roots of the given Python type. Will
* be just 1 pybind type for the Python type of a pybind-registered class, or for any Python-side
* derived class that uses single inheritance. Will contain as many types as required for a Python
* class that uses multiple inheritance to inherit (directly or indirectly) from multiple
* pybind-registered classes. Will be empty if neither the type nor any base classes are
* pybind-registered.
*
* The value is cached for the lifetime of the Python type.
*/
inline const std::vector<detail::type_info *> &all_type_info(PyTypeObject *type) {
auto ins = all_type_info_get_cache(type);
if (ins.second)
// New cache entry: populate it
all_type_info_populate(type, ins.first->second);
return ins.first->second;
}
/**
* Gets a single pybind11 type info for a python type. Returns nullptr if neither the type nor any
* ancestors are pybind11-registered. Throws an exception if there are multiple bases--use
* `all_type_info` instead if you want to support multiple bases.
*/
PYBIND11_NOINLINE inline detail::type_info* get_type_info(PyTypeObject *type) {
auto &bases = all_type_info(type);
if (bases.empty())
return nullptr;
if (bases.size() > 1)
pybind11_fail("pybind11::detail::get_type_info: type has multiple pybind11-registered bases");
return bases.front();
}
inline detail::type_info *get_local_type_info(const std::type_index &tp) {
auto &locals = registered_local_types_cpp();
auto it = locals.find(tp);
if (it != locals.end())
return it->second;
return nullptr;
}
inline detail::type_info *get_global_type_info(const std::type_index &tp) {
auto &types = get_internals().registered_types_cpp;
auto it = types.find(tp);
if (it != types.end())
return it->second;
return nullptr;
}
/// Return the type info for a given C++ type; on lookup failure can either throw or return nullptr.
PYBIND11_NOINLINE inline detail::type_info *get_type_info(const std::type_index &tp,
bool throw_if_missing = false) {
if (auto ltype = get_local_type_info(tp))
return ltype;
if (auto gtype = get_global_type_info(tp))
return gtype;
if (throw_if_missing) {
std::string tname = tp.name();
detail::clean_type_id(tname);
pybind11_fail("pybind11::detail::get_type_info: unable to find type info for \"" + tname + "\"");
}
return nullptr;
}
PYBIND11_NOINLINE inline handle get_type_handle(const std::type_info &tp, bool throw_if_missing) {
detail::type_info *type_info = get_type_info(tp, throw_if_missing);
return handle(type_info ? ((PyObject *) type_info->type) : nullptr);
}
struct value_and_holder {
instance *inst = nullptr;
size_t index = 0u;
const detail::type_info *type = nullptr;
void **vh = nullptr;
// Main constructor for a found value/holder:
value_and_holder(instance *i, const detail::type_info *type, size_t vpos, size_t index) :
inst{i}, index{index}, type{type},
vh{inst->simple_layout ? inst->simple_value_holder : &inst->nonsimple.values_and_holders[vpos]}
{}
// Default constructor (used to signal a value-and-holder not found by get_value_and_holder())
value_and_holder() = default;
// Used for past-the-end iterator
value_and_holder(size_t index) : index{index} {}
template <typename V = void> V *&value_ptr() const {
return reinterpret_cast<V *&>(vh[0]);
}
// True if this `value_and_holder` has a non-null value pointer
explicit operator bool() const { return value_ptr(); }
template <typename H> H &holder() const {
return reinterpret_cast<H &>(vh[1]);
}
bool holder_constructed() const {
return inst->simple_layout
? inst->simple_holder_constructed
: inst->nonsimple.status[index] & instance::status_holder_constructed;
}
void set_holder_constructed(bool v = true) {
if (inst->simple_layout)
inst->simple_holder_constructed = v;
else if (v)
inst->nonsimple.status[index] |= instance::status_holder_constructed;
else
inst->nonsimple.status[index] &= (uint8_t) ~instance::status_holder_constructed;
}
bool instance_registered() const {
return inst->simple_layout
? inst->simple_instance_registered
: inst->nonsimple.status[index] & instance::status_instance_registered;
}
void set_instance_registered(bool v = true) {
if (inst->simple_layout)
inst->simple_instance_registered = v;
else if (v)
inst->nonsimple.status[index] |= instance::status_instance_registered;
else
inst->nonsimple.status[index] &= (uint8_t) ~instance::status_instance_registered;
}
};
// Container for accessing and iterating over an instance's values/holders
struct values_and_holders {
private:
instance *inst;
using type_vec = std::vector<detail::type_info *>;
const type_vec &tinfo;
public:
values_and_holders(instance *inst) : inst{inst}, tinfo(all_type_info(Py_TYPE(inst))) {}
struct iterator {
private:
instance *inst = nullptr;
const type_vec *types = nullptr;
value_and_holder curr;
friend struct values_and_holders;
iterator(instance *inst, const type_vec *tinfo)
: inst{inst}, types{tinfo},
curr(inst /* instance */,
types->empty() ? nullptr : (*types)[0] /* type info */,
0, /* vpos: (non-simple types only): the first vptr comes first */
0 /* index */)
{}
// Past-the-end iterator:
iterator(size_t end) : curr(end) {}
public:
bool operator==(const iterator &other) const { return curr.index == other.curr.index; }
bool operator!=(const iterator &other) const { return curr.index != other.curr.index; }
iterator &operator++() {
if (!inst->simple_layout)
curr.vh += 1 + (*types)[curr.index]->holder_size_in_ptrs;
++curr.index;
curr.type = curr.index < types->size() ? (*types)[curr.index] : nullptr;
return *this;
}
value_and_holder &operator*() { return curr; }
value_and_holder *operator->() { return &curr; }
};
iterator begin() { return iterator(inst, &tinfo); }
iterator end() { return iterator(tinfo.size()); }
iterator find(const type_info *find_type) {
auto it = begin(), endit = end();
while (it != endit && it->type != find_type) ++it;
return it;
}
size_t size() { return tinfo.size(); }
};
/**
* Extracts C++ value and holder pointer references from an instance (which may contain multiple
* values/holders for python-side multiple inheritance) that match the given type. Throws an error
* if the given type (or ValueType, if omitted) is not a pybind11 base of the given instance. If
* `find_type` is omitted (or explicitly specified as nullptr) the first value/holder are returned,
* regardless of type (and the resulting .type will be nullptr).
*
* The returned object should be short-lived: in particular, it must not outlive the called-upon
* instance.
*/
PYBIND11_NOINLINE inline value_and_holder instance::get_value_and_holder(const type_info *find_type /*= nullptr default in common.h*/, bool throw_if_missing /*= true in common.h*/) {
// Optimize common case:
if (!find_type || Py_TYPE(this) == find_type->type)
return value_and_holder(this, find_type, 0, 0);
detail::values_and_holders vhs(this);
auto it = vhs.find(find_type);
if (it != vhs.end())
return *it;
if (!throw_if_missing)
return value_and_holder();
#if defined(NDEBUG)
pybind11_fail("pybind11::detail::instance::get_value_and_holder: "
"type is not a pybind11 base of the given instance "
"(compile in debug mode for type details)");
#else
pybind11_fail("pybind11::detail::instance::get_value_and_holder: `" +
get_fully_qualified_tp_name(find_type->type) + "' is not a pybind11 base of the given `" +
get_fully_qualified_tp_name(Py_TYPE(this)) + "' instance");
#endif
}
PYBIND11_NOINLINE inline void instance::allocate_layout() {
auto &tinfo = all_type_info(Py_TYPE(this));
const size_t n_types = tinfo.size();
if (n_types == 0)
pybind11_fail("instance allocation failed: new instance has no pybind11-registered base types");
simple_layout =
n_types == 1 && tinfo.front()->holder_size_in_ptrs <= instance_simple_holder_in_ptrs();
// Simple path: no python-side multiple inheritance, and a small-enough holder
if (simple_layout) {
simple_value_holder[0] = nullptr;
simple_holder_constructed = false;
simple_instance_registered = false;
}
else { // multiple base types or a too-large holder
// Allocate space to hold: [v1*][h1][v2*][h2]...[bb...] where [vN*] is a value pointer,
// [hN] is the (uninitialized) holder instance for value N, and [bb...] is a set of bool
// values that tracks whether each associated holder has been initialized. Each [block] is
// padded, if necessary, to an integer multiple of sizeof(void *).
size_t space = 0;
for (auto t : tinfo) {
space += 1; // value pointer
space += t->holder_size_in_ptrs; // holder instance
}
size_t flags_at = space;
space += size_in_ptrs(n_types); // status bytes (holder_constructed and instance_registered)
// Allocate space for flags, values, and holders, and initialize it to 0 (flags and values,
// in particular, need to be 0). Use Python's memory allocation functions: in Python 3.6
// they default to using pymalloc, which is designed to be efficient for small allocations
// like the one we're doing here; in earlier versions (and for larger allocations) they are
// just wrappers around malloc.
#if PY_VERSION_HEX >= 0x03050000
nonsimple.values_and_holders = (void **) PyMem_Calloc(space, sizeof(void *));
if (!nonsimple.values_and_holders) throw std::bad_alloc();
#else
nonsimple.values_and_holders = (void **) PyMem_New(void *, space);
if (!nonsimple.values_and_holders) throw std::bad_alloc();
std::memset(nonsimple.values_and_holders, 0, space * sizeof(void *));
#endif
nonsimple.status = reinterpret_cast<uint8_t *>(&nonsimple.values_and_holders[flags_at]);
}
owned = true;
}
PYBIND11_NOINLINE inline void instance::deallocate_layout() {
if (!simple_layout)
PyMem_Free(nonsimple.values_and_holders);
}
PYBIND11_NOINLINE inline bool isinstance_generic(handle obj, const std::type_info &tp) {
handle type = detail::get_type_handle(tp, false);
if (!type)
return false;
return isinstance(obj, type);
}
PYBIND11_NOINLINE inline std::string error_string() {
if (!PyErr_Occurred()) {
PyErr_SetString(PyExc_RuntimeError, "Unknown internal error occurred");
return "Unknown internal error occurred";
}
error_scope scope; // Preserve error state
std::string errorString;
if (scope.type) {
errorString += handle(scope.type).attr("__name__").cast<std::string>();
errorString += ": ";
}
if (scope.value)
errorString += (std::string) str(scope.value);
PyErr_NormalizeException(&scope.type, &scope.value, &scope.trace);
#if PY_MAJOR_VERSION >= 3
if (scope.trace != nullptr)
PyException_SetTraceback(scope.value, scope.trace);
#endif
#if !defined(PYPY_VERSION)
if (scope.trace) {
auto *trace = (PyTracebackObject *) scope.trace;
/* Get the deepest trace possible */
while (trace->tb_next)
trace = trace->tb_next;
PyFrameObject *frame = trace->tb_frame;
errorString += "\n\nAt:\n";
while (frame) {
int lineno = PyFrame_GetLineNumber(frame);
errorString +=
" " + handle(frame->f_code->co_filename).cast<std::string>() +
"(" + std::to_string(lineno) + "): " +
handle(frame->f_code->co_name).cast<std::string>() + "\n";
frame = frame->f_back;
}
}
#endif
return errorString;
}
PYBIND11_NOINLINE inline handle get_object_handle(const void *ptr, const detail::type_info *type ) {
auto &instances = get_internals().registered_instances;
auto range = instances.equal_range(ptr);
for (auto it = range.first; it != range.second; ++it) {
for (const auto &vh : values_and_holders(it->second)) {
if (vh.type == type)
return handle((PyObject *) it->second);
}
}
return handle();
}
inline PyThreadState *get_thread_state_unchecked() {
#if defined(PYPY_VERSION)
return PyThreadState_GET();
#elif PY_VERSION_HEX < 0x03000000
return _PyThreadState_Current;
#elif PY_VERSION_HEX < 0x03050000
return (PyThreadState*) _Py_atomic_load_relaxed(&_PyThreadState_Current);
#elif PY_VERSION_HEX < 0x03050200
return (PyThreadState*) _PyThreadState_Current.value;
#else
return _PyThreadState_UncheckedGet();
#endif
}
// Forward declarations
inline void keep_alive_impl(handle nurse, handle patient);
inline PyObject *make_new_instance(PyTypeObject *type);
class type_caster_generic {
public:
PYBIND11_NOINLINE type_caster_generic(const std::type_info &type_info)
: typeinfo(get_type_info(type_info)), cpptype(&type_info) { }
type_caster_generic(const type_info *typeinfo)
: typeinfo(typeinfo), cpptype(typeinfo ? typeinfo->cpptype : nullptr) { }
bool load(handle src, bool convert) {
return load_impl<type_caster_generic>(src, convert);
}
PYBIND11_NOINLINE static handle cast(const void *_src, return_value_policy policy, handle parent,
const detail::type_info *tinfo,
void *(*copy_constructor)(const void *),
void *(*move_constructor)(const void *),
const void *existing_holder = nullptr) {
if (!tinfo) // no type info: error will be set already
return handle();
void *src = const_cast<void *>(_src);
if (src == nullptr)
return none().release();
auto it_instances = get_internals().registered_instances.equal_range(src);
for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
for (auto instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype))
return handle((PyObject *) it_i->second).inc_ref();
}
}
auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type));
auto wrapper = reinterpret_cast<instance *>(inst.ptr());
wrapper->owned = false;
void *&valueptr = values_and_holders(wrapper).begin()->value_ptr();
switch (policy) {
case return_value_policy::automatic:
case return_value_policy::take_ownership:
valueptr = src;
wrapper->owned = true;
break;
case return_value_policy::automatic_reference:
case return_value_policy::reference:
valueptr = src;
wrapper->owned = false;
break;
case return_value_policy::copy:
if (copy_constructor)
valueptr = copy_constructor(src);
else {
#if defined(NDEBUG)
throw cast_error("return_value_policy = copy, but type is "
"non-copyable! (compile in debug mode for details)");
#else
std::string type_name(tinfo->cpptype->name());
detail::clean_type_id(type_name);
throw cast_error("return_value_policy = copy, but type " +
type_name + " is non-copyable!");
#endif
}
wrapper->owned = true;
break;
case return_value_policy::move:
if (move_constructor)
valueptr = move_constructor(src);
else if (copy_constructor)
valueptr = copy_constructor(src);
else {
#if defined(NDEBUG)
throw cast_error("return_value_policy = move, but type is neither "
"movable nor copyable! "
"(compile in debug mode for details)");
#else
std::string type_name(tinfo->cpptype->name());
detail::clean_type_id(type_name);
throw cast_error("return_value_policy = move, but type " +
type_name + " is neither movable nor copyable!");
#endif
}
wrapper->owned = true;
break;
case return_value_policy::reference_internal:
valueptr = src;
wrapper->owned = false;
keep_alive_impl(inst, parent);
break;
default:
throw cast_error("unhandled return_value_policy: should not happen!");
}
tinfo->init_instance(wrapper, existing_holder);
return inst.release();
}
// Base methods for generic caster; there are overridden in copyable_holder_caster
void load_value(value_and_holder &&v_h) {
auto *&vptr = v_h.value_ptr();
// Lazy allocation for unallocated values:
if (vptr == nullptr) {
auto *type = v_h.type ? v_h.type : typeinfo;
if (type->operator_new) {
vptr = type->operator_new(type->type_size);
} else {
#if defined(__cpp_aligned_new) && (!defined(_MSC_VER) || _MSC_VER >= 1912)
if (type->type_align > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
vptr = ::operator new(type->type_size,
std::align_val_t(type->type_align));
else
#endif
vptr = ::operator new(type->type_size);
}
}
value = vptr;
}
bool try_implicit_casts(handle src, bool convert) {
for (auto &cast : typeinfo->implicit_casts) {
type_caster_generic sub_caster(*cast.first);
if (sub_caster.load(src, convert)) {
value = cast.second(sub_caster.value);
return true;
}
}
return false;
}
bool try_direct_conversions(handle src) {
for (auto &converter : *typeinfo->direct_conversions) {
if (converter(src.ptr(), value))
return true;
}
return false;
}
void check_holder_compat() {}
PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) {
auto caster = type_caster_generic(ti);
if (caster.load(src, false))
return caster.value;
return nullptr;
}
/// Try to load with foreign typeinfo, if available. Used when there is no
/// native typeinfo, or when the native one wasn't able to produce a value.
PYBIND11_NOINLINE bool try_load_foreign_module_local(handle src) {
constexpr auto *local_key = PYBIND11_MODULE_LOCAL_ID;
const auto pytype = type::handle_of(src);
if (!hasattr(pytype, local_key))
return false;
type_info *foreign_typeinfo = reinterpret_borrow<capsule>(getattr(pytype, local_key));
// Only consider this foreign loader if actually foreign and is a loader of the correct cpp type
if (foreign_typeinfo->module_local_load == &local_load
|| (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype)))
return false;
if (auto result = foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo)) {
value = result;
return true;
}
return false;
}
// Implementation of `load`; this takes the type of `this` so that it can dispatch the relevant
// bits of code between here and copyable_holder_caster where the two classes need different
// logic (without having to resort to virtual inheritance).
template <typename ThisT>
PYBIND11_NOINLINE bool load_impl(handle src, bool convert) {
if (!src) return false;
if (!typeinfo) return try_load_foreign_module_local(src);
if (src.is_none()) {
// Defer accepting None to other overloads (if we aren't in convert mode):
if (!convert) return false;
value = nullptr;
return true;
}
auto &this_ = static_cast<ThisT &>(*this);
this_.check_holder_compat();
PyTypeObject *srctype = Py_TYPE(src.ptr());
// Case 1: If src is an exact type match for the target type then we can reinterpret_cast
// the instance's value pointer to the target type:
if (srctype == typeinfo->type) {
this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
return true;
}
// Case 2: We have a derived class
else if (PyType_IsSubtype(srctype, typeinfo->type)) {
auto &bases = all_type_info(srctype);
bool no_cpp_mi = typeinfo->simple_type;
// Case 2a: the python type is a Python-inherited derived class that inherits from just
// one simple (no MI) pybind11 class, or is an exact match, so the C++ instance is of
// the right type and we can use reinterpret_cast.
// (This is essentially the same as case 2b, but because not using multiple inheritance
// is extremely common, we handle it specially to avoid the loop iterator and type
// pointer lookup overhead)
if (bases.size() == 1 && (no_cpp_mi || bases.front()->type == typeinfo->type)) {
this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
return true;
}
// Case 2b: the python type inherits from multiple C++ bases. Check the bases to see if
// we can find an exact match (or, for a simple C++ type, an inherited match); if so, we
// can safely reinterpret_cast to the relevant pointer.
else if (bases.size() > 1) {
for (auto base : bases) {
if (no_cpp_mi ? PyType_IsSubtype(base->type, typeinfo->type) : base->type == typeinfo->type) {
this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder(base));
return true;
}
}
}
// Case 2c: C++ multiple inheritance is involved and we couldn't find an exact type match
// in the registered bases, above, so try implicit casting (needed for proper C++ casting
// when MI is involved).
if (this_.try_implicit_casts(src, convert))
return true;
}
// Perform an implicit conversion
if (convert) {
for (auto &converter : typeinfo->implicit_conversions) {
auto temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
if (load_impl<ThisT>(temp, false)) {
loader_life_support::add_patient(temp);
return true;
}
}
if (this_.try_direct_conversions(src))
return true;
}
// Failed to match local typeinfo. Try again with global.
if (typeinfo->module_local) {
if (auto gtype = get_global_type_info(*typeinfo->cpptype)) {
typeinfo = gtype;
return load(src, false);
}
}
// Global typeinfo has precedence over foreign module_local
return try_load_foreign_module_local(src);
}
// Called to do type lookup and wrap the pointer and type in a pair when a dynamic_cast
// isn't needed or can't be used. If the type is unknown, sets the error and returns a pair
// with .second = nullptr. (p.first = nullptr is not an error: it becomes None).
PYBIND11_NOINLINE static std::pair<const void *, const type_info *> src_and_type(
const void *src, const std::type_info &cast_type, const std::type_info *rtti_type = nullptr) {
if (auto *tpi = get_type_info(cast_type))
return {src, const_cast<const type_info *>(tpi)};
// Not found, set error:
std::string tname = rtti_type ? rtti_type->name() : cast_type.name();
detail::clean_type_id(tname);
std::string msg = "Unregistered type : " + tname;
PyErr_SetString(PyExc_TypeError, msg.c_str());
return {nullptr, nullptr};
}
const type_info *typeinfo = nullptr;
const std::type_info *cpptype = nullptr;
void *value = nullptr;
};
/**
* Determine suitable casting operator for pointer-or-lvalue-casting type casters. The type caster
* needs to provide `operator T*()` and `operator T&()` operators.
*
* If the type supports moving the value away via an `operator T&&() &&` method, it should use
* `movable_cast_op_type` instead.
*/
template <typename T>
using cast_op_type =
conditional_t<std::is_pointer<remove_reference_t<T>>::value,
typename std::add_pointer<intrinsic_t<T>>::type,
typename std::add_lvalue_reference<intrinsic_t<T>>::type>;
/**
* Determine suitable casting operator for a type caster with a movable value. Such a type caster
* needs to provide `operator T*()`, `operator T&()`, and `operator T&&() &&`. The latter will be
* called in appropriate contexts where the value can be moved rather than copied.
*
* These operator are automatically provided when using the PYBIND11_TYPE_CASTER macro.
*/
template <typename T>
using movable_cast_op_type =
conditional_t<std::is_pointer<typename std::remove_reference<T>::type>::value,
typename std::add_pointer<intrinsic_t<T>>::type,
conditional_t<std::is_rvalue_reference<T>::value,
typename std::add_rvalue_reference<intrinsic_t<T>>::type,
typename std::add_lvalue_reference<intrinsic_t<T>>::type>>;
// std::is_copy_constructible isn't quite enough: it lets std::vector<T> (and similar) through when
// T is non-copyable, but code containing such a copy constructor fails to actually compile.
template <typename T, typename SFINAE = void> struct is_copy_constructible : std::is_copy_constructible<T> {};
// Specialization for types that appear to be copy constructible but also look like stl containers
// (we specifically check for: has `value_type` and `reference` with `reference = value_type&`): if
// so, copy constructability depends on whether the value_type is copy constructible.
template <typename Container> struct is_copy_constructible<Container, enable_if_t<all_of<
std::is_copy_constructible<Container>,
std::is_same<typename Container::value_type &, typename Container::reference>,
// Avoid infinite recursion
negation<std::is_same<Container, typename Container::value_type>>
>::value>> : is_copy_constructible<typename Container::value_type> {};
// Likewise for std::pair
// (after C++17 it is mandatory that the copy constructor not exist when the two types aren't themselves
// copy constructible, but this can not be relied upon when T1 or T2 are themselves containers).
template <typename T1, typename T2> struct is_copy_constructible<std::pair<T1, T2>>
: all_of<is_copy_constructible<T1>, is_copy_constructible<T2>> {};
// The same problems arise with std::is_copy_assignable, so we use the same workaround.
template <typename T, typename SFINAE = void> struct is_copy_assignable : std::is_copy_assignable<T> {};
template <typename Container> struct is_copy_assignable<Container, enable_if_t<all_of<
std::is_copy_assignable<Container>,
std::is_same<typename Container::value_type &, typename Container::reference>
>::value>> : is_copy_assignable<typename Container::value_type> {};
template <typename T1, typename T2> struct is_copy_assignable<std::pair<T1, T2>>
: all_of<is_copy_assignable<T1>, is_copy_assignable<T2>> {};
PYBIND11_NAMESPACE_END(detail)
// polymorphic_type_hook<itype>::get(src, tinfo) determines whether the object pointed
// to by `src` actually is an instance of some class derived from `itype`.
// If so, it sets `tinfo` to point to the std::type_info representing that derived
// type, and returns a pointer to the start of the most-derived object of that type
// (in which `src` is a subobject; this will be the same address as `src` in most
// single inheritance cases). If not, or if `src` is nullptr, it simply returns `src`
// and leaves `tinfo` at its default value of nullptr.
//
// The default polymorphic_type_hook just returns src. A specialization for polymorphic
// types determines the runtime type of the passed object and adjusts the this-pointer
// appropriately via dynamic_cast<void*>. This is what enables a C++ Animal* to appear
// to Python as a Dog (if Dog inherits from Animal, Animal is polymorphic, Dog is
// registered with pybind11, and this Animal is in fact a Dog).
//
// You may specialize polymorphic_type_hook yourself for types that want to appear
// polymorphic to Python but do not use C++ RTTI. (This is a not uncommon pattern
// in performance-sensitive applications, used most notably in LLVM.)
//
// polymorphic_type_hook_base allows users to specialize polymorphic_type_hook with
// std::enable_if. User provided specializations will always have higher priority than
// the default implementation and specialization provided in polymorphic_type_hook_base.
template <typename itype, typename SFINAE = void>
struct polymorphic_type_hook_base
{
static const void *get(const itype *src, const std::type_info*&) { return src; }
};
template <typename itype>
struct polymorphic_type_hook_base<itype, detail::enable_if_t<std::is_polymorphic<itype>::value>>
{
static const void *get(const itype *src, const std::type_info*& type) {
type = src ? &typeid(*src) : nullptr;
return dynamic_cast<const void*>(src);
}
};
template <typename itype, typename SFINAE = void>
struct polymorphic_type_hook : public polymorphic_type_hook_base<itype> {};
PYBIND11_NAMESPACE_BEGIN(detail)
/// Generic type caster for objects stored on the heap
template <typename type> class type_caster_base : public type_caster_generic {
using itype = intrinsic_t<type>;
public:
static constexpr auto name = _<type>();
type_caster_base() : type_caster_base(typeid(type)) { }
explicit type_caster_base(const std::type_info &info) : type_caster_generic(info) { }
static handle cast(const itype &src, return_value_policy policy, handle parent) {
if (policy == return_value_policy::automatic || policy == return_value_policy::automatic_reference)
policy = return_value_policy::copy;
return cast(&src, policy, parent);
}
static handle cast(itype &&src, return_value_policy, handle parent) {
return cast(&src, return_value_policy::move, parent);
}
// Returns a (pointer, type_info) pair taking care of necessary type lookup for a
// polymorphic type (using RTTI by default, but can be overridden by specializing
// polymorphic_type_hook). If the instance isn't derived, returns the base version.
static std::pair<const void *, const type_info *> src_and_type(const itype *src) {
auto &cast_type = typeid(itype);
const std::type_info *instance_type = nullptr;
const void *vsrc = polymorphic_type_hook<itype>::get(src, instance_type);
if (instance_type && !same_type(cast_type, *instance_type)) {
// This is a base pointer to a derived type. If the derived type is registered
// with pybind11, we want to make the full derived object available.
// In the typical case where itype is polymorphic, we get the correct
// derived pointer (which may be != base pointer) by a dynamic_cast to
// most derived type. If itype is not polymorphic, we won't get here
// except via a user-provided specialization of polymorphic_type_hook,
// and the user has promised that no this-pointer adjustment is
// required in that case, so it's OK to use static_cast.
if (const auto *tpi = get_type_info(*instance_type))
return {vsrc, tpi};
}
// Otherwise we have either a nullptr, an `itype` pointer, or an unknown derived pointer, so
// don't do a cast
return type_caster_generic::src_and_type(src, cast_type, instance_type);
}
static handle cast(const itype *src, return_value_policy policy, handle parent) {
auto st = src_and_type(src);
return type_caster_generic::cast(
st.first, policy, parent, st.second,
make_copy_constructor(src), make_move_constructor(src));
}
static handle cast_holder(const itype *src, const void *holder) {
auto st = src_and_type(src);
return type_caster_generic::cast(
st.first, return_value_policy::take_ownership, {}, st.second,
nullptr, nullptr, holder);
}
template <typename T> using cast_op_type = detail::cast_op_type<T>;
operator itype*() { return (type *) value; }
operator itype&() { if (!value) throw reference_cast_error(); return *((itype *) value); }
protected:
using Constructor = void *(*)(const void *);
/* Only enabled when the types are {copy,move}-constructible *and* when the type
does not have a private operator new implementation. */
template <typename T, typename = enable_if_t<is_copy_constructible<T>::value>>
static auto make_copy_constructor(const T *x) -> decltype(new T(*x), Constructor{}) {
return [](const void *arg) -> void * {
return new T(*reinterpret_cast<const T *>(arg));
};
}
template <typename T, typename = enable_if_t<std::is_move_constructible<T>::value>>
static auto make_move_constructor(const T *x) -> decltype(new T(std::move(*const_cast<T *>(x))), Constructor{}) {
return [](const void *arg) -> void * {
return new T(std::move(*const_cast<T *>(reinterpret_cast<const T *>(arg))));
};
}
static Constructor make_copy_constructor(...) { return nullptr; }
static Constructor make_move_constructor(...) { return nullptr; }
};
template <typename type, typename SFINAE = void> class type_caster : public type_caster_base<type> { };
template <typename type> using make_caster = type_caster<intrinsic_t<type>>;
// Shortcut for calling a caster's `cast_op_type` cast operator for casting a type_caster to a T
template <typename T> typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &caster) {
return caster.operator typename make_caster<T>::template cast_op_type<T>();
}
template <typename T> typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>
cast_op(make_caster<T> &&caster) {
return std::move(caster).operator
typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>();
}
template <typename type> class type_caster<std::reference_wrapper<type>> {
private:
using caster_t = make_caster<type>;
caster_t subcaster;
using reference_t = type&;
using subcaster_cast_op_type =
typename caster_t::template cast_op_type<reference_t>;
static_assert(std::is_same<typename std::remove_const<type>::type &, subcaster_cast_op_type>::value ||
std::is_same<reference_t, subcaster_cast_op_type>::value,
"std::reference_wrapper<T> caster requires T to have a caster with an "
"`operator T &()` or `operator const T &()`");
public:
bool load(handle src, bool convert) { return subcaster.load(src, convert); }
static constexpr auto name = caster_t::name;
static handle cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
// It is definitely wrong to take ownership of this pointer, so mask that rvp
if (policy == return_value_policy::take_ownership || policy == return_value_policy::automatic)
policy = return_value_policy::automatic_reference;
return caster_t::cast(&src.get(), policy, parent);
}
template <typename T> using cast_op_type = std::reference_wrapper<type>;
operator std::reference_wrapper<type>() { return cast_op<type &>(subcaster); }
};
#define PYBIND11_TYPE_CASTER(type, py_name) \
protected: \
type value; \
public: \
static constexpr auto name = py_name; \
template <typename T_, enable_if_t<std::is_same<type, remove_cv_t<T_>>::value, int> = 0> \
static handle cast(T_ *src, return_value_policy policy, handle parent) { \
if (!src) return none().release(); \
if (policy == return_value_policy::take_ownership) { \
auto h = cast(std::move(*src), policy, parent); delete src; return h; \
} else { \
return cast(*src, policy, parent); \
} \
} \
operator type*() { return &value; } \
operator type&() { return value; } \
operator type&&() && { return std::move(value); } \