HepMC3 event record library
cast.h
1 /*
2  pybind11/cast.h: Partial template specializations to cast between
3  C++ and Python types
4 
5  Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
6 
7  All rights reserved. Use of this source code is governed by a
8  BSD-style license that can be found in the LICENSE file.
9 */
10 
11 #pragma once
12 
13 #include "pytypes.h"
14 #include "detail/typeid.h"
15 #include "detail/descr.h"
16 #include "detail/internals.h"
17 #include <array>
18 #include <limits>
19 #include <tuple>
20 #include <type_traits>
21 
22 #if defined(PYBIND11_CPP17)
23 # if defined(__has_include)
24 # if __has_include(<string_view>)
25 # define PYBIND11_HAS_STRING_VIEW
26 # endif
27 # elif defined(_MSC_VER)
28 # define PYBIND11_HAS_STRING_VIEW
29 # endif
30 #endif
31 #ifdef PYBIND11_HAS_STRING_VIEW
32 #include <string_view>
33 #endif
34 
35 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
36 # define PYBIND11_HAS_U8STRING
37 #endif
38 
39 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
40 PYBIND11_NAMESPACE_BEGIN(detail)
41 
42 /// A life support system for temporary objects created by `type_caster::load()`.
43 /// Adding a patient will keep it alive up until the enclosing function returns.
45 public:
46  /// A new patient frame is created when a function is entered
48  get_internals().loader_patient_stack.push_back(nullptr);
49  }
50 
51  /// ... and destroyed after it returns
53  auto &stack = get_internals().loader_patient_stack;
54  if (stack.empty())
55  pybind11_fail("loader_life_support: internal error");
56 
57  auto ptr = stack.back();
58  stack.pop_back();
59  Py_CLEAR(ptr);
60 
61  // A heuristic to reduce the stack's capacity (e.g. after long recursive calls)
62  if (stack.capacity() > 16 && !stack.empty() && stack.capacity() / stack.size() > 2)
63  stack.shrink_to_fit();
64  }
65 
66  /// This can only be used inside a pybind11-bound function, either by `argument_loader`
67  /// at argument preparation time or by `py::cast()` at execution time.
68  PYBIND11_NOINLINE static void add_patient(handle h) {
69  auto &stack = get_internals().loader_patient_stack;
70  if (stack.empty())
71  throw cast_error("When called outside a bound function, py::cast() cannot "
72  "do Python -> C++ conversions which require the creation "
73  "of temporary values");
74 
75  auto &list_ptr = stack.back();
76  if (list_ptr == nullptr) {
77  list_ptr = PyList_New(1);
78  if (!list_ptr)
79  pybind11_fail("loader_life_support: error allocating list");
80  PyList_SET_ITEM(list_ptr, 0, h.inc_ref().ptr());
81  } else {
82  auto result = PyList_Append(list_ptr, h.ptr());
83  if (result == -1)
84  pybind11_fail("loader_life_support: error adding patient");
85  }
86  }
87 };
88 
89 // Gets the cache entry for the given type, creating it if necessary. The return value is the pair
90 // returned by emplace, i.e. an iterator for the entry and a bool set to `true` if the entry was
91 // just created.
92 inline std::pair<decltype(internals::registered_types_py)::iterator, bool> all_type_info_get_cache(PyTypeObject *type);
93 
94 // Populates a just-created cache entry.
95 PYBIND11_NOINLINE inline void all_type_info_populate(PyTypeObject *t, std::vector<type_info *> &bases) {
96  std::vector<PyTypeObject *> check;
97  for (handle parent : reinterpret_borrow<tuple>(t->tp_bases))
98  check.push_back((PyTypeObject *) parent.ptr());
99 
100  auto const &type_dict = get_internals().registered_types_py;
101  for (size_t i = 0; i < check.size(); i++) {
102  auto type = check[i];
103  // Ignore Python2 old-style class super type:
104  if (!PyType_Check((PyObject *) type)) continue;
105 
106  // Check `type` in the current set of registered python types:
107  auto it = type_dict.find(type);
108  if (it != type_dict.end()) {
109  // We found a cache entry for it, so it's either pybind-registered or has pre-computed
110  // pybind bases, but we have to make sure we haven't already seen the type(s) before: we
111  // want to follow Python/virtual C++ rules that there should only be one instance of a
112  // common base.
113  for (auto *tinfo : it->second) {
114  // NB: Could use a second set here, rather than doing a linear search, but since
115  // having a large number of immediate pybind11-registered types seems fairly
116  // unlikely, that probably isn't worthwhile.
117  bool found = false;
118  for (auto *known : bases) {
119  if (known == tinfo) { found = true; break; }
120  }
121  if (!found) bases.push_back(tinfo);
122  }
123  }
124  else if (type->tp_bases) {
125  // It's some python type, so keep follow its bases classes to look for one or more
126  // registered types
127  if (i + 1 == check.size()) {
128  // When we're at the end, we can pop off the current element to avoid growing
129  // `check` when adding just one base (which is typical--i.e. when there is no
130  // multiple inheritance)
131  check.pop_back();
132  i--;
133  }
134  for (handle parent : reinterpret_borrow<tuple>(type->tp_bases))
135  check.push_back((PyTypeObject *) parent.ptr());
136  }
137  }
138 }
139 
140 /**
141  * Extracts vector of type_info pointers of pybind-registered roots of the given Python type. Will
142  * be just 1 pybind type for the Python type of a pybind-registered class, or for any Python-side
143  * derived class that uses single inheritance. Will contain as many types as required for a Python
144  * class that uses multiple inheritance to inherit (directly or indirectly) from multiple
145  * pybind-registered classes. Will be empty if neither the type nor any base classes are
146  * pybind-registered.
147  *
148  * The value is cached for the lifetime of the Python type.
149  */
150 inline const std::vector<detail::type_info *> &all_type_info(PyTypeObject *type) {
151  auto ins = all_type_info_get_cache(type);
152  if (ins.second)
153  // New cache entry: populate it
154  all_type_info_populate(type, ins.first->second);
155 
156  return ins.first->second;
157 }
158 
159 /**
160  * Gets a single pybind11 type info for a python type. Returns nullptr if neither the type nor any
161  * ancestors are pybind11-registered. Throws an exception if there are multiple bases--use
162  * `all_type_info` instead if you want to support multiple bases.
163  */
164 PYBIND11_NOINLINE inline detail::type_info* get_type_info(PyTypeObject *type) {
165  auto &bases = all_type_info(type);
166  if (bases.empty())
167  return nullptr;
168  if (bases.size() > 1)
169  pybind11_fail("pybind11::detail::get_type_info: type has multiple pybind11-registered bases");
170  return bases.front();
171 }
172 
173 inline detail::type_info *get_local_type_info(const std::type_index &tp) {
174  auto &locals = registered_local_types_cpp();
175  auto it = locals.find(tp);
176  if (it != locals.end())
177  return it->second;
178  return nullptr;
179 }
180 
181 inline detail::type_info *get_global_type_info(const std::type_index &tp) {
182  auto &types = get_internals().registered_types_cpp;
183  auto it = types.find(tp);
184  if (it != types.end())
185  return it->second;
186  return nullptr;
187 }
188 
189 /// Return the type info for a given C++ type; on lookup failure can either throw or return nullptr.
190 PYBIND11_NOINLINE inline detail::type_info *get_type_info(const std::type_index &tp,
191  bool throw_if_missing = false) {
192  if (auto ltype = get_local_type_info(tp))
193  return ltype;
194  if (auto gtype = get_global_type_info(tp))
195  return gtype;
196 
197  if (throw_if_missing) {
198  std::string tname = tp.name();
199  detail::clean_type_id(tname);
200  pybind11_fail("pybind11::detail::get_type_info: unable to find type info for \"" + tname + "\"");
201  }
202  return nullptr;
203 }
204 
205 PYBIND11_NOINLINE inline handle get_type_handle(const std::type_info &tp, bool throw_if_missing) {
206  detail::type_info *type_info = get_type_info(tp, throw_if_missing);
207  return handle(type_info ? ((PyObject *) type_info->type) : nullptr);
208 }
209 
211  instance *inst = nullptr;
212  size_t index = 0u;
213  const detail::type_info *type = nullptr;
214  void **vh = nullptr;
215 
216  // Main constructor for a found value/holder:
217  value_and_holder(instance *i, const detail::type_info *type, size_t vpos, size_t index) :
218  inst{i}, index{index}, type{type},
219  vh{inst->simple_layout ? inst->simple_value_holder : &inst->nonsimple.values_and_holders[vpos]}
220  {}
221 
222  // Default constructor (used to signal a value-and-holder not found by get_value_and_holder())
223  value_and_holder() = default;
224 
225  // Used for past-the-end iterator
226  value_and_holder(size_t index) : index{index} {}
227 
228  template <typename V = void> V *&value_ptr() const {
229  return reinterpret_cast<V *&>(vh[0]);
230  }
231  // True if this `value_and_holder` has a non-null value pointer
232  explicit operator bool() const { return value_ptr(); }
233 
234  template <typename H> H &holder() const {
235  return reinterpret_cast<H &>(vh[1]);
236  }
237  bool holder_constructed() const {
238  return inst->simple_layout
240  : inst->nonsimple.status[index] & instance::status_holder_constructed;
241  }
242  void set_holder_constructed(bool v = true) {
243  if (inst->simple_layout)
244  inst->simple_holder_constructed = v;
245  else if (v)
246  inst->nonsimple.status[index] |= instance::status_holder_constructed;
247  else
248  inst->nonsimple.status[index] &= (uint8_t) ~instance::status_holder_constructed;
249  }
250  bool instance_registered() const {
251  return inst->simple_layout
253  : inst->nonsimple.status[index] & instance::status_instance_registered;
254  }
255  void set_instance_registered(bool v = true) {
256  if (inst->simple_layout)
257  inst->simple_instance_registered = v;
258  else if (v)
259  inst->nonsimple.status[index] |= instance::status_instance_registered;
260  else
261  inst->nonsimple.status[index] &= (uint8_t) ~instance::status_instance_registered;
262  }
263 };
264 
265 // Container for accessing and iterating over an instance's values/holders
267 private:
268  instance *inst;
269  using type_vec = std::vector<detail::type_info *>;
270  const type_vec &tinfo;
271 
272 public:
273  values_and_holders(instance *inst) : inst{inst}, tinfo(all_type_info(Py_TYPE(inst))) {}
274 
275  struct iterator {
276  private:
277  instance *inst = nullptr;
278  const type_vec *types = nullptr;
279  value_and_holder curr;
280  friend struct values_and_holders;
281  iterator(instance *inst, const type_vec *tinfo)
282  : inst{inst}, types{tinfo},
283  curr(inst /* instance */,
284  types->empty() ? nullptr : (*types)[0] /* type info */,
285  0, /* vpos: (non-simple types only): the first vptr comes first */
286  0 /* index */)
287  {}
288  // Past-the-end iterator:
289  iterator(size_t end) : curr(end) {}
290  public:
291  bool operator==(const iterator &other) const { return curr.index == other.curr.index; }
292  bool operator!=(const iterator &other) const { return curr.index != other.curr.index; }
293  iterator &operator++() {
294  if (!inst->simple_layout)
295  curr.vh += 1 + (*types)[curr.index]->holder_size_in_ptrs;
296  ++curr.index;
297  curr.type = curr.index < types->size() ? (*types)[curr.index] : nullptr;
298  return *this;
299  }
300  value_and_holder &operator*() { return curr; }
301  value_and_holder *operator->() { return &curr; }
302  };
303 
304  iterator begin() { return iterator(inst, &tinfo); }
305  iterator end() { return iterator(tinfo.size()); }
306 
307  iterator find(const type_info *find_type) {
308  auto it = begin(), endit = end();
309  while (it != endit && it->type != find_type) ++it;
310  return it;
311  }
312 
313  size_t size() { return tinfo.size(); }
314 };
315 
316 /**
317  * Extracts C++ value and holder pointer references from an instance (which may contain multiple
318  * values/holders for python-side multiple inheritance) that match the given type. Throws an error
319  * if the given type (or ValueType, if omitted) is not a pybind11 base of the given instance. If
320  * `find_type` is omitted (or explicitly specified as nullptr) the first value/holder are returned,
321  * regardless of type (and the resulting .type will be nullptr).
322  *
323  * The returned object should be short-lived: in particular, it must not outlive the called-upon
324  * instance.
325  */
326 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*/) {
327  // Optimize common case:
328  if (!find_type || Py_TYPE(this) == find_type->type)
329  return value_and_holder(this, find_type, 0, 0);
330 
331  detail::values_and_holders vhs(this);
332  auto it = vhs.find(find_type);
333  if (it != vhs.end())
334  return *it;
335 
336  if (!throw_if_missing)
337  return value_and_holder();
338 
339 #if defined(NDEBUG)
340  pybind11_fail("pybind11::detail::instance::get_value_and_holder: "
341  "type is not a pybind11 base of the given instance "
342  "(compile in debug mode for type details)");
343 #else
344  pybind11_fail("pybind11::detail::instance::get_value_and_holder: `" +
345  get_fully_qualified_tp_name(find_type->type) + "' is not a pybind11 base of the given `" +
346  get_fully_qualified_tp_name(Py_TYPE(this)) + "' instance");
347 #endif
348 }
349 
350 PYBIND11_NOINLINE inline void instance::allocate_layout() {
351  auto &tinfo = all_type_info(Py_TYPE(this));
352 
353  const size_t n_types = tinfo.size();
354 
355  if (n_types == 0)
356  pybind11_fail("instance allocation failed: new instance has no pybind11-registered base types");
357 
358  simple_layout =
359  n_types == 1 && tinfo.front()->holder_size_in_ptrs <= instance_simple_holder_in_ptrs();
360 
361  // Simple path: no python-side multiple inheritance, and a small-enough holder
362  if (simple_layout) {
363  simple_value_holder[0] = nullptr;
366  }
367  else { // multiple base types or a too-large holder
368  // Allocate space to hold: [v1*][h1][v2*][h2]...[bb...] where [vN*] is a value pointer,
369  // [hN] is the (uninitialized) holder instance for value N, and [bb...] is a set of bool
370  // values that tracks whether each associated holder has been initialized. Each [block] is
371  // padded, if necessary, to an integer multiple of sizeof(void *).
372  size_t space = 0;
373  for (auto t : tinfo) {
374  space += 1; // value pointer
375  space += t->holder_size_in_ptrs; // holder instance
376  }
377  size_t flags_at = space;
378  space += size_in_ptrs(n_types); // status bytes (holder_constructed and instance_registered)
379 
380  // Allocate space for flags, values, and holders, and initialize it to 0 (flags and values,
381  // in particular, need to be 0). Use Python's memory allocation functions: in Python 3.6
382  // they default to using pymalloc, which is designed to be efficient for small allocations
383  // like the one we're doing here; in earlier versions (and for larger allocations) they are
384  // just wrappers around malloc.
385 #if PY_VERSION_HEX >= 0x03050000
386  nonsimple.values_and_holders = (void **) PyMem_Calloc(space, sizeof(void *));
387  if (!nonsimple.values_and_holders) throw std::bad_alloc();
388 #else
389  nonsimple.values_and_holders = (void **) PyMem_New(void *, space);
390  if (!nonsimple.values_and_holders) throw std::bad_alloc();
391  std::memset(nonsimple.values_and_holders, 0, space * sizeof(void *));
392 #endif
393  nonsimple.status = reinterpret_cast<uint8_t *>(&nonsimple.values_and_holders[flags_at]);
394  }
395  owned = true;
396 }
397 
398 PYBIND11_NOINLINE inline void instance::deallocate_layout() {
399  if (!simple_layout)
400  PyMem_Free(nonsimple.values_and_holders);
401 }
402 
403 PYBIND11_NOINLINE inline bool isinstance_generic(handle obj, const std::type_info &tp) {
404  handle type = detail::get_type_handle(tp, false);
405  if (!type)
406  return false;
407  return isinstance(obj, type);
408 }
409 
410 PYBIND11_NOINLINE inline std::string error_string() {
411  if (!PyErr_Occurred()) {
412  PyErr_SetString(PyExc_RuntimeError, "Unknown internal error occurred");
413  return "Unknown internal error occurred";
414  }
415 
416  error_scope scope; // Preserve error state
417 
418  std::string errorString;
419  if (scope.type) {
420  errorString += handle(scope.type).attr("__name__").cast<std::string>();
421  errorString += ": ";
422  }
423  if (scope.value)
424  errorString += (std::string) str(scope.value);
425 
426  PyErr_NormalizeException(&scope.type, &scope.value, &scope.trace);
427 
428 #if PY_MAJOR_VERSION >= 3
429  if (scope.trace != nullptr)
430  PyException_SetTraceback(scope.value, scope.trace);
431 #endif
432 
433 #if !defined(PYPY_VERSION)
434  if (scope.trace) {
435  auto *trace = (PyTracebackObject *) scope.trace;
436 
437  /* Get the deepest trace possible */
438  while (trace->tb_next)
439  trace = trace->tb_next;
440 
441  PyFrameObject *frame = trace->tb_frame;
442  errorString += "\n\nAt:\n";
443  while (frame) {
444  int lineno = PyFrame_GetLineNumber(frame);
445  errorString +=
446  " " + handle(frame->f_code->co_filename).cast<std::string>() +
447  "(" + std::to_string(lineno) + "): " +
448  handle(frame->f_code->co_name).cast<std::string>() + "\n";
449  frame = frame->f_back;
450  }
451  }
452 #endif
453 
454  return errorString;
455 }
456 
457 PYBIND11_NOINLINE inline handle get_object_handle(const void *ptr, const detail::type_info *type ) {
458  auto &instances = get_internals().registered_instances;
459  auto range = instances.equal_range(ptr);
460  for (auto it = range.first; it != range.second; ++it) {
461  for (const auto &vh : values_and_holders(it->second)) {
462  if (vh.type == type)
463  return handle((PyObject *) it->second);
464  }
465  }
466  return handle();
467 }
468 
469 inline PyThreadState *get_thread_state_unchecked() {
470 #if defined(PYPY_VERSION)
471  return PyThreadState_GET();
472 #elif PY_VERSION_HEX < 0x03000000
473  return _PyThreadState_Current;
474 #elif PY_VERSION_HEX < 0x03050000
475  return (PyThreadState*) _Py_atomic_load_relaxed(&_PyThreadState_Current);
476 #elif PY_VERSION_HEX < 0x03050200
477  return (PyThreadState*) _PyThreadState_Current.value;
478 #else
479  return _PyThreadState_UncheckedGet();
480 #endif
481 }
482 
483 // Forward declarations
484 inline void keep_alive_impl(handle nurse, handle patient);
485 inline PyObject *make_new_instance(PyTypeObject *type);
486 
488 public:
489  PYBIND11_NOINLINE type_caster_generic(const std::type_info &type_info)
490  : typeinfo(get_type_info(type_info)), cpptype(&type_info) { }
491 
492  type_caster_generic(const type_info *typeinfo)
493  : typeinfo(typeinfo), cpptype(typeinfo ? typeinfo->cpptype : nullptr) { }
494 
495  bool load(handle src, bool convert) {
496  return load_impl<type_caster_generic>(src, convert);
497  }
498 
499  PYBIND11_NOINLINE static handle cast(const void *_src, return_value_policy policy, handle parent,
500  const detail::type_info *tinfo,
501  void *(*copy_constructor)(const void *),
502  void *(*move_constructor)(const void *),
503  const void *existing_holder = nullptr) {
504  if (!tinfo) // no type info: error will be set already
505  return handle();
506 
507  void *src = const_cast<void *>(_src);
508  if (src == nullptr)
509  return none().release();
510 
511  auto it_instances = get_internals().registered_instances.equal_range(src);
512  for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
513  for (auto instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
514  if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype))
515  return handle((PyObject *) it_i->second).inc_ref();
516  }
517  }
518 
519  auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type));
520  auto wrapper = reinterpret_cast<instance *>(inst.ptr());
521  wrapper->owned = false;
522  void *&valueptr = values_and_holders(wrapper).begin()->value_ptr();
523 
524  switch (policy) {
525  case return_value_policy::automatic:
526  case return_value_policy::take_ownership:
527  valueptr = src;
528  wrapper->owned = true;
529  break;
530 
531  case return_value_policy::automatic_reference:
532  case return_value_policy::reference:
533  valueptr = src;
534  wrapper->owned = false;
535  break;
536 
537  case return_value_policy::copy:
538  if (copy_constructor)
539  valueptr = copy_constructor(src);
540  else {
541 #if defined(NDEBUG)
542  throw cast_error("return_value_policy = copy, but type is "
543  "non-copyable! (compile in debug mode for details)");
544 #else
545  std::string type_name(tinfo->cpptype->name());
546  detail::clean_type_id(type_name);
547  throw cast_error("return_value_policy = copy, but type " +
548  type_name + " is non-copyable!");
549 #endif
550  }
551  wrapper->owned = true;
552  break;
553 
554  case return_value_policy::move:
555  if (move_constructor)
556  valueptr = move_constructor(src);
557  else if (copy_constructor)
558  valueptr = copy_constructor(src);
559  else {
560 #if defined(NDEBUG)
561  throw cast_error("return_value_policy = move, but type is neither "
562  "movable nor copyable! "
563  "(compile in debug mode for details)");
564 #else
565  std::string type_name(tinfo->cpptype->name());
566  detail::clean_type_id(type_name);
567  throw cast_error("return_value_policy = move, but type " +
568  type_name + " is neither movable nor copyable!");
569 #endif
570  }
571  wrapper->owned = true;
572  break;
573 
574  case return_value_policy::reference_internal:
575  valueptr = src;
576  wrapper->owned = false;
577  keep_alive_impl(inst, parent);
578  break;
579 
580  default:
581  throw cast_error("unhandled return_value_policy: should not happen!");
582  }
583 
584  tinfo->init_instance(wrapper, existing_holder);
585 
586  return inst.release();
587  }
588 
589  // Base methods for generic caster; there are overridden in copyable_holder_caster
590  void load_value(value_and_holder &&v_h) {
591  auto *&vptr = v_h.value_ptr();
592  // Lazy allocation for unallocated values:
593  if (vptr == nullptr) {
594  auto *type = v_h.type ? v_h.type : typeinfo;
595  if (type->operator_new) {
596  vptr = type->operator_new(type->type_size);
597  } else {
598  #if defined(__cpp_aligned_new) && (!defined(_MSC_VER) || _MSC_VER >= 1912)
599  if (type->type_align > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
600  vptr = ::operator new(type->type_size,
601  std::align_val_t(type->type_align));
602  else
603  #endif
604  vptr = ::operator new(type->type_size);
605  }
606  }
607  value = vptr;
608  }
609  bool try_implicit_casts(handle src, bool convert) {
610  for (auto &cast : typeinfo->implicit_casts) {
611  type_caster_generic sub_caster(*cast.first);
612  if (sub_caster.load(src, convert)) {
613  value = cast.second(sub_caster.value);
614  return true;
615  }
616  }
617  return false;
618  }
619  bool try_direct_conversions(handle src) {
620  for (auto &converter : *typeinfo->direct_conversions) {
621  if (converter(src.ptr(), value))
622  return true;
623  }
624  return false;
625  }
626  void check_holder_compat() {}
627 
628  PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) {
629  auto caster = type_caster_generic(ti);
630  if (caster.load(src, false))
631  return caster.value;
632  return nullptr;
633  }
634 
635  /// Try to load with foreign typeinfo, if available. Used when there is no
636  /// native typeinfo, or when the native one wasn't able to produce a value.
637  PYBIND11_NOINLINE bool try_load_foreign_module_local(handle src) {
638  constexpr auto *local_key = PYBIND11_MODULE_LOCAL_ID;
639  const auto pytype = type::handle_of(src);
640  if (!hasattr(pytype, local_key))
641  return false;
642 
643  type_info *foreign_typeinfo = reinterpret_borrow<capsule>(getattr(pytype, local_key));
644  // Only consider this foreign loader if actually foreign and is a loader of the correct cpp type
645  if (foreign_typeinfo->module_local_load == &local_load
646  || (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype)))
647  return false;
648 
649  if (auto result = foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo)) {
650  value = result;
651  return true;
652  }
653  return false;
654  }
655 
656  // Implementation of `load`; this takes the type of `this` so that it can dispatch the relevant
657  // bits of code between here and copyable_holder_caster where the two classes need different
658  // logic (without having to resort to virtual inheritance).
659  template <typename ThisT>
660  PYBIND11_NOINLINE bool load_impl(handle src, bool convert) {
661  if (!src) return false;
662  if (!typeinfo) return try_load_foreign_module_local(src);
663  if (src.is_none()) {
664  // Defer accepting None to other overloads (if we aren't in convert mode):
665  if (!convert) return false;
666  value = nullptr;
667  return true;
668  }
669 
670  auto &this_ = static_cast<ThisT &>(*this);
671  this_.check_holder_compat();
672 
673  PyTypeObject *srctype = Py_TYPE(src.ptr());
674 
675  // Case 1: If src is an exact type match for the target type then we can reinterpret_cast
676  // the instance's value pointer to the target type:
677  if (srctype == typeinfo->type) {
678  this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
679  return true;
680  }
681  // Case 2: We have a derived class
682  else if (PyType_IsSubtype(srctype, typeinfo->type)) {
683  auto &bases = all_type_info(srctype);
684  bool no_cpp_mi = typeinfo->simple_type;
685 
686  // Case 2a: the python type is a Python-inherited derived class that inherits from just
687  // one simple (no MI) pybind11 class, or is an exact match, so the C++ instance is of
688  // the right type and we can use reinterpret_cast.
689  // (This is essentially the same as case 2b, but because not using multiple inheritance
690  // is extremely common, we handle it specially to avoid the loop iterator and type
691  // pointer lookup overhead)
692  if (bases.size() == 1 && (no_cpp_mi || bases.front()->type == typeinfo->type)) {
693  this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
694  return true;
695  }
696  // Case 2b: the python type inherits from multiple C++ bases. Check the bases to see if
697  // we can find an exact match (or, for a simple C++ type, an inherited match); if so, we
698  // can safely reinterpret_cast to the relevant pointer.
699  else if (bases.size() > 1) {
700  for (auto base : bases) {
701  if (no_cpp_mi ? PyType_IsSubtype(base->type, typeinfo->type) : base->type == typeinfo->type) {
702  this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder(base));
703  return true;
704  }
705  }
706  }
707 
708  // Case 2c: C++ multiple inheritance is involved and we couldn't find an exact type match
709  // in the registered bases, above, so try implicit casting (needed for proper C++ casting
710  // when MI is involved).
711  if (this_.try_implicit_casts(src, convert))
712  return true;
713  }
714 
715  // Perform an implicit conversion
716  if (convert) {
717  for (auto &converter : typeinfo->implicit_conversions) {
718  auto temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
719  if (load_impl<ThisT>(temp, false)) {
721  return true;
722  }
723  }
724  if (this_.try_direct_conversions(src))
725  return true;
726  }
727 
728  // Failed to match local typeinfo. Try again with global.
729  if (typeinfo->module_local) {
730  if (auto gtype = get_global_type_info(*typeinfo->cpptype)) {
731  typeinfo = gtype;
732  return load(src, false);
733  }
734  }
735 
736  // Global typeinfo has precedence over foreign module_local
737  return try_load_foreign_module_local(src);
738  }
739 
740 
741  // Called to do type lookup and wrap the pointer and type in a pair when a dynamic_cast
742  // isn't needed or can't be used. If the type is unknown, sets the error and returns a pair
743  // with .second = nullptr. (p.first = nullptr is not an error: it becomes None).
744  PYBIND11_NOINLINE static std::pair<const void *, const type_info *> src_and_type(
745  const void *src, const std::type_info &cast_type, const std::type_info *rtti_type = nullptr) {
746  if (auto *tpi = get_type_info(cast_type))
747  return {src, const_cast<const type_info *>(tpi)};
748 
749  // Not found, set error:
750  std::string tname = rtti_type ? rtti_type->name() : cast_type.name();
751  detail::clean_type_id(tname);
752  std::string msg = "Unregistered type : " + tname;
753  PyErr_SetString(PyExc_TypeError, msg.c_str());
754  return {nullptr, nullptr};
755  }
756 
757  const type_info *typeinfo = nullptr;
758  const std::type_info *cpptype = nullptr;
759  void *value = nullptr;
760 };
761 
762 /**
763  * Determine suitable casting operator for pointer-or-lvalue-casting type casters. The type caster
764  * needs to provide `operator T*()` and `operator T&()` operators.
765  *
766  * If the type supports moving the value away via an `operator T&&() &&` method, it should use
767  * `movable_cast_op_type` instead.
768  */
769 template <typename T>
770 using cast_op_type =
771  conditional_t<std::is_pointer<remove_reference_t<T>>::value,
772  typename std::add_pointer<intrinsic_t<T>>::type,
773  typename std::add_lvalue_reference<intrinsic_t<T>>::type>;
774 
775 /**
776  * Determine suitable casting operator for a type caster with a movable value. Such a type caster
777  * needs to provide `operator T*()`, `operator T&()`, and `operator T&&() &&`. The latter will be
778  * called in appropriate contexts where the value can be moved rather than copied.
779  *
780  * These operator are automatically provided when using the PYBIND11_TYPE_CASTER macro.
781  */
782 template <typename T>
783 using movable_cast_op_type =
784  conditional_t<std::is_pointer<typename std::remove_reference<T>::type>::value,
785  typename std::add_pointer<intrinsic_t<T>>::type,
786  conditional_t<std::is_rvalue_reference<T>::value,
787  typename std::add_rvalue_reference<intrinsic_t<T>>::type,
788  typename std::add_lvalue_reference<intrinsic_t<T>>::type>>;
789 
790 // std::is_copy_constructible isn't quite enough: it lets std::vector<T> (and similar) through when
791 // T is non-copyable, but code containing such a copy constructor fails to actually compile.
792 template <typename T, typename SFINAE = void> struct is_copy_constructible : std::is_copy_constructible<T> {};
793 
794 // Specialization for types that appear to be copy constructible but also look like stl containers
795 // (we specifically check for: has `value_type` and `reference` with `reference = value_type&`): if
796 // so, copy constructability depends on whether the value_type is copy constructible.
797 template <typename Container> struct is_copy_constructible<Container, enable_if_t<all_of<
798  std::is_copy_constructible<Container>,
799  std::is_same<typename Container::value_type &, typename Container::reference>,
800  // Avoid infinite recursion
801  negation<std::is_same<Container, typename Container::value_type>>
802  >::value>> : is_copy_constructible<typename Container::value_type> {};
803 
804 // Likewise for std::pair
805 // (after C++17 it is mandatory that the copy constructor not exist when the two types aren't themselves
806 // copy constructible, but this can not be relied upon when T1 or T2 are themselves containers).
807 template <typename T1, typename T2> struct is_copy_constructible<std::pair<T1, T2>>
808  : all_of<is_copy_constructible<T1>, is_copy_constructible<T2>> {};
809 
810 // The same problems arise with std::is_copy_assignable, so we use the same workaround.
811 template <typename T, typename SFINAE = void> struct is_copy_assignable : std::is_copy_assignable<T> {};
812 template <typename Container> struct is_copy_assignable<Container, enable_if_t<all_of<
813  std::is_copy_assignable<Container>,
814  std::is_same<typename Container::value_type &, typename Container::reference>
815  >::value>> : is_copy_assignable<typename Container::value_type> {};
816 template <typename T1, typename T2> struct is_copy_assignable<std::pair<T1, T2>>
817  : all_of<is_copy_assignable<T1>, is_copy_assignable<T2>> {};
818 
819 PYBIND11_NAMESPACE_END(detail)
820 
821 // polymorphic_type_hook<itype>::get(src, tinfo) determines whether the object pointed
822 // to by `src` actually is an instance of some class derived from `itype`.
823 // If so, it sets `tinfo` to point to the std::type_info representing that derived
824 // type, and returns a pointer to the start of the most-derived object of that type
825 // (in which `src` is a subobject; this will be the same address as `src` in most
826 // single inheritance cases). If not, or if `src` is nullptr, it simply returns `src`
827 // and leaves `tinfo` at its default value of nullptr.
828 //
829 // The default polymorphic_type_hook just returns src. A specialization for polymorphic
830 // types determines the runtime type of the passed object and adjusts the this-pointer
831 // appropriately via dynamic_cast<void*>. This is what enables a C++ Animal* to appear
832 // to Python as a Dog (if Dog inherits from Animal, Animal is polymorphic, Dog is
833 // registered with pybind11, and this Animal is in fact a Dog).
834 //
835 // You may specialize polymorphic_type_hook yourself for types that want to appear
836 // polymorphic to Python but do not use C++ RTTI. (This is a not uncommon pattern
837 // in performance-sensitive applications, used most notably in LLVM.)
838 //
839 // polymorphic_type_hook_base allows users to specialize polymorphic_type_hook with
840 // std::enable_if. User provided specializations will always have higher priority than
841 // the default implementation and specialization provided in polymorphic_type_hook_base.
842 template <typename itype, typename SFINAE = void>
844 {
845  static const void *get(const itype *src, const std::type_info*&) { return src; }
846 };
847 template <typename itype>
848 struct polymorphic_type_hook_base<itype, detail::enable_if_t<std::is_polymorphic<itype>::value>>
849 {
850  static const void *get(const itype *src, const std::type_info*& type) {
851  type = src ? &typeid(*src) : nullptr;
852  return dynamic_cast<const void*>(src);
853  }
854 };
855 template <typename itype, typename SFINAE = void>
857 
858 PYBIND11_NAMESPACE_BEGIN(detail)
859 
860 /// Generic type caster for objects stored on the heap
861 template <typename type> class type_caster_base : public type_caster_generic {
862  using itype = intrinsic_t<type>;
863 
864 public:
865  static constexpr auto name = _<type>();
866 
867  type_caster_base() : type_caster_base(typeid(type)) { }
868  explicit type_caster_base(const std::type_info &info) : type_caster_generic(info) { }
869 
870  static handle cast(const itype &src, return_value_policy policy, handle parent) {
871  if (policy == return_value_policy::automatic || policy == return_value_policy::automatic_reference)
872  policy = return_value_policy::copy;
873  return cast(&src, policy, parent);
874  }
875 
876  static handle cast(itype &&src, return_value_policy, handle parent) {
877  return cast(&src, return_value_policy::move, parent);
878  }
879 
880  // Returns a (pointer, type_info) pair taking care of necessary type lookup for a
881  // polymorphic type (using RTTI by default, but can be overridden by specializing
882  // polymorphic_type_hook). If the instance isn't derived, returns the base version.
883  static std::pair<const void *, const type_info *> src_and_type(const itype *src) {
884  auto &cast_type = typeid(itype);
885  const std::type_info *instance_type = nullptr;
886  const void *vsrc = polymorphic_type_hook<itype>::get(src, instance_type);
887  if (instance_type && !same_type(cast_type, *instance_type)) {
888  // This is a base pointer to a derived type. If the derived type is registered
889  // with pybind11, we want to make the full derived object available.
890  // In the typical case where itype is polymorphic, we get the correct
891  // derived pointer (which may be != base pointer) by a dynamic_cast to
892  // most derived type. If itype is not polymorphic, we won't get here
893  // except via a user-provided specialization of polymorphic_type_hook,
894  // and the user has promised that no this-pointer adjustment is
895  // required in that case, so it's OK to use static_cast.
896  if (const auto *tpi = get_type_info(*instance_type))
897  return {vsrc, tpi};
898  }
899  // Otherwise we have either a nullptr, an `itype` pointer, or an unknown derived pointer, so
900  // don't do a cast
901  return type_caster_generic::src_and_type(src, cast_type, instance_type);
902  }
903 
904  static handle cast(const itype *src, return_value_policy policy, handle parent) {
905  auto st = src_and_type(src);
906  return type_caster_generic::cast(
907  st.first, policy, parent, st.second,
908  make_copy_constructor(src), make_move_constructor(src));
909  }
910 
911  static handle cast_holder(const itype *src, const void *holder) {
912  auto st = src_and_type(src);
913  return type_caster_generic::cast(
914  st.first, return_value_policy::take_ownership, {}, st.second,
915  nullptr, nullptr, holder);
916  }
917 
918  template <typename T> using cast_op_type = detail::cast_op_type<T>;
919 
920  operator itype*() { return (type *) value; }
921  operator itype&() { if (!value) throw reference_cast_error(); return *((itype *) value); }
922 
923 protected:
924  using Constructor = void *(*)(const void *);
925 
926  /* Only enabled when the types are {copy,move}-constructible *and* when the type
927  does not have a private operator new implementation. */
928  template <typename T, typename = enable_if_t<is_copy_constructible<T>::value>>
929  static auto make_copy_constructor(const T *x) -> decltype(new T(*x), Constructor{}) {
930  return [](const void *arg) -> void * {
931  return new T(*reinterpret_cast<const T *>(arg));
932  };
933  }
934 
935  template <typename T, typename = enable_if_t<std::is_move_constructible<T>::value>>
936  static auto make_move_constructor(const T *x) -> decltype(new T(std::move(*const_cast<T *>(x))), Constructor{}) {
937  return [](const void *arg) -> void * {
938  return new T(std::move(*const_cast<T *>(reinterpret_cast<const T *>(arg))));
939  };
940  }
941 
942  static Constructor make_copy_constructor(...) { return nullptr; }
943  static Constructor make_move_constructor(...) { return nullptr; }
944 };
945 
946 template <typename type, typename SFINAE = void> class type_caster : public type_caster_base<type> { };
947 template <typename type> using make_caster = type_caster<intrinsic_t<type>>;
948 
949 // Shortcut for calling a caster's `cast_op_type` cast operator for casting a type_caster to a T
950 template <typename T> typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &caster) {
951  return caster.operator typename make_caster<T>::template cast_op_type<T>();
952 }
953 template <typename T> typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>
954 cast_op(make_caster<T> &&caster) {
955  return std::move(caster).operator
956  typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>();
957 }
958 
959 template <typename type> class type_caster<std::reference_wrapper<type>> {
960 private:
961  using caster_t = make_caster<type>;
962  caster_t subcaster;
963  using subcaster_cast_op_type = typename caster_t::template cast_op_type<type>;
964  static_assert(std::is_same<typename std::remove_const<type>::type &, subcaster_cast_op_type>::value,
965  "std::reference_wrapper<T> caster requires T to have a caster with an `T &` operator");
966 public:
967  bool load(handle src, bool convert) { return subcaster.load(src, convert); }
968  static constexpr auto name = caster_t::name;
969  static handle cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
970  // It is definitely wrong to take ownership of this pointer, so mask that rvp
971  if (policy == return_value_policy::take_ownership || policy == return_value_policy::automatic)
972  policy = return_value_policy::automatic_reference;
973  return caster_t::cast(&src.get(), policy, parent);
974  }
975  template <typename T> using cast_op_type = std::reference_wrapper<type>;
976  operator std::reference_wrapper<type>() { return subcaster.operator subcaster_cast_op_type&(); }
977 };
978 
979 #define PYBIND11_TYPE_CASTER(type, py_name) \
980  protected: \
981  type value; \
982  public: \
983  static constexpr auto name = py_name; \
984  template <typename T_, enable_if_t<std::is_same<type, remove_cv_t<T_>>::value, int> = 0> \
985  static handle cast(T_ *src, return_value_policy policy, handle parent) { \
986  if (!src) return none().release(); \
987  if (policy == return_value_policy::take_ownership) { \
988  auto h = cast(std::move(*src), policy, parent); delete src; return h; \
989  } else { \
990  return cast(*src, policy, parent); \
991  } \
992  } \
993  operator type*() { return &value; } \
994  operator type&() { return value; } \
995  operator type&&() && { return std::move(value); } \
996  template <typename T_> using cast_op_type = pybind11::detail::movable_cast_op_type<T_>
997 
998 
999 template <typename CharT> using is_std_char_type = any_of<
1000  std::is_same<CharT, char>, /* std::string */
1001 #if defined(PYBIND11_HAS_U8STRING)
1002  std::is_same<CharT, char8_t>, /* std::u8string */
1003 #endif
1004  std::is_same<CharT, char16_t>, /* std::u16string */
1005  std::is_same<CharT, char32_t>, /* std::u32string */
1006  std::is_same<CharT, wchar_t> /* std::wstring */
1007 >;
1008 
1009 
1010 template <typename T>
1011 struct type_caster<T, enable_if_t<std::is_arithmetic<T>::value && !is_std_char_type<T>::value>> {
1012  using _py_type_0 = conditional_t<sizeof(T) <= sizeof(long), long, long long>;
1013  using _py_type_1 = conditional_t<std::is_signed<T>::value, _py_type_0, typename std::make_unsigned<_py_type_0>::type>;
1014  using py_type = conditional_t<std::is_floating_point<T>::value, double, _py_type_1>;
1015 public:
1016 
1017  bool load(handle src, bool convert) {
1018  py_type py_value;
1019 
1020  if (!src)
1021  return false;
1022 
1023  if (std::is_floating_point<T>::value) {
1024  if (convert || PyFloat_Check(src.ptr()))
1025  py_value = (py_type) PyFloat_AsDouble(src.ptr());
1026  else
1027  return false;
1028  } else if (PyFloat_Check(src.ptr())) {
1029  return false;
1030  } else if (std::is_unsigned<py_type>::value) {
1031  py_value = as_unsigned<py_type>(src.ptr());
1032  } else { // signed integer:
1033  py_value = sizeof(T) <= sizeof(long)
1034  ? (py_type) PyLong_AsLong(src.ptr())
1035  : (py_type) PYBIND11_LONG_AS_LONGLONG(src.ptr());
1036  }
1037 
1038  // Python API reported an error
1039  bool py_err = py_value == (py_type) -1 && PyErr_Occurred();
1040 
1041  // Check to see if the conversion is valid (integers should match exactly)
1042  // Signed/unsigned checks happen elsewhere
1043  if (py_err || (std::is_integral<T>::value && sizeof(py_type) != sizeof(T) && py_value != (py_type) (T) py_value)) {
1044  bool type_error = py_err && PyErr_ExceptionMatches(
1045 #if PY_VERSION_HEX < 0x03000000 && !defined(PYPY_VERSION)
1046  PyExc_SystemError
1047 #else
1048  PyExc_TypeError
1049 #endif
1050  );
1051  PyErr_Clear();
1052  if (type_error && convert && PyNumber_Check(src.ptr())) {
1053  auto tmp = reinterpret_steal<object>(std::is_floating_point<T>::value
1054  ? PyNumber_Float(src.ptr())
1055  : PyNumber_Long(src.ptr()));
1056  PyErr_Clear();
1057  return load(tmp, false);
1058  }
1059  return false;
1060  }
1061 
1062  value = (T) py_value;
1063  return true;
1064  }
1065 
1066  template<typename U = T>
1067  static typename std::enable_if<std::is_floating_point<U>::value, handle>::type
1068  cast(U src, return_value_policy /* policy */, handle /* parent */) {
1069  return PyFloat_FromDouble((double) src);
1070  }
1071 
1072  template<typename U = T>
1073  static typename std::enable_if<!std::is_floating_point<U>::value && std::is_signed<U>::value && (sizeof(U) <= sizeof(long)), handle>::type
1074  cast(U src, return_value_policy /* policy */, handle /* parent */) {
1075  return PYBIND11_LONG_FROM_SIGNED((long) src);
1076  }
1077 
1078  template<typename U = T>
1079  static typename std::enable_if<!std::is_floating_point<U>::value && std::is_unsigned<U>::value && (sizeof(U) <= sizeof(unsigned long)), handle>::type
1080  cast(U src, return_value_policy /* policy */, handle /* parent */) {
1081  return PYBIND11_LONG_FROM_UNSIGNED((unsigned long) src);
1082  }
1083 
1084  template<typename U = T>
1085  static typename std::enable_if<!std::is_floating_point<U>::value && std::is_signed<U>::value && (sizeof(U) > sizeof(long)), handle>::type
1086  cast(U src, return_value_policy /* policy */, handle /* parent */) {
1087  return PyLong_FromLongLong((long long) src);
1088  }
1089 
1090  template<typename U = T>
1091  static typename std::enable_if<!std::is_floating_point<U>::value && std::is_unsigned<U>::value && (sizeof(U) > sizeof(unsigned long)), handle>::type
1092  cast(U src, return_value_policy /* policy */, handle /* parent */) {
1093  return PyLong_FromUnsignedLongLong((unsigned long long) src);
1094  }
1095 
1096  PYBIND11_TYPE_CASTER(T, _<std::is_integral<T>::value>("int", "float"));
1097 };
1098 
1099 template<typename T> struct void_caster {
1100 public:
1101  bool load(handle src, bool) {
1102  if (src && src.is_none())
1103  return true;
1104  return false;
1105  }
1106  static handle cast(T, return_value_policy /* policy */, handle /* parent */) {
1107  return none().inc_ref();
1108  }
1109  PYBIND11_TYPE_CASTER(T, _("None"));
1110 };
1111 
1112 template <> class type_caster<void_type> : public void_caster<void_type> {};
1113 
1114 template <> class type_caster<void> : public type_caster<void_type> {
1115 public:
1117 
1118  bool load(handle h, bool) {
1119  if (!h) {
1120  return false;
1121  } else if (h.is_none()) {
1122  value = nullptr;
1123  return true;
1124  }
1125 
1126  /* Check if this is a capsule */
1127  if (isinstance<capsule>(h)) {
1128  value = reinterpret_borrow<capsule>(h);
1129  return true;
1130  }
1131 
1132  /* Check if this is a C++ type */
1133  auto &bases = all_type_info((PyTypeObject *) type::handle_of(h).ptr());
1134  if (bases.size() == 1) { // Only allowing loading from a single-value type
1135  value = values_and_holders(reinterpret_cast<instance *>(h.ptr())).begin()->value_ptr();
1136  return true;
1137  }
1138 
1139  /* Fail */
1140  return false;
1141  }
1142 
1143  static handle cast(const void *ptr, return_value_policy /* policy */, handle /* parent */) {
1144  if (ptr)
1145  return capsule(ptr).release();
1146  else
1147  return none().inc_ref();
1148  }
1149 
1150  template <typename T> using cast_op_type = void*&;
1151  operator void *&() { return value; }
1152  static constexpr auto name = _("capsule");
1153 private:
1154  void *value = nullptr;
1155 };
1156 
1157 template <> class type_caster<std::nullptr_t> : public void_caster<std::nullptr_t> { };
1158 
1159 template <> class type_caster<bool> {
1160 public:
1161  bool load(handle src, bool convert) {
1162  if (!src) return false;
1163  else if (src.ptr() == Py_True) { value = true; return true; }
1164  else if (src.ptr() == Py_False) { value = false; return true; }
1165  else if (convert || !strcmp("numpy.bool_", Py_TYPE(src.ptr())->tp_name)) {
1166  // (allow non-implicit conversion for numpy booleans)
1167 
1168  Py_ssize_t res = -1;
1169  if (src.is_none()) {
1170  res = 0; // None is implicitly converted to False
1171  }
1172  #if defined(PYPY_VERSION)
1173  // On PyPy, check that "__bool__" (or "__nonzero__" on Python 2.7) attr exists
1174  else if (hasattr(src, PYBIND11_BOOL_ATTR)) {
1175  res = PyObject_IsTrue(src.ptr());
1176  }
1177  #else
1178  // Alternate approach for CPython: this does the same as the above, but optimized
1179  // using the CPython API so as to avoid an unneeded attribute lookup.
1180  else if (auto tp_as_number = src.ptr()->ob_type->tp_as_number) {
1181  if (PYBIND11_NB_BOOL(tp_as_number)) {
1182  res = (*PYBIND11_NB_BOOL(tp_as_number))(src.ptr());
1183  }
1184  }
1185  #endif
1186  if (res == 0 || res == 1) {
1187  value = (bool) res;
1188  return true;
1189  } else {
1190  PyErr_Clear();
1191  }
1192  }
1193  return false;
1194  }
1195  static handle cast(bool src, return_value_policy /* policy */, handle /* parent */) {
1196  return handle(src ? Py_True : Py_False).inc_ref();
1197  }
1198  PYBIND11_TYPE_CASTER(bool, _("bool"));
1199 };
1200 
1201 // Helper class for UTF-{8,16,32} C++ stl strings:
1202 template <typename StringType, bool IsView = false> struct string_caster {
1203  using CharT = typename StringType::value_type;
1204 
1205  // Simplify life by being able to assume standard char sizes (the standard only guarantees
1206  // minimums, but Python requires exact sizes)
1207  static_assert(!std::is_same<CharT, char>::value || sizeof(CharT) == 1, "Unsupported char size != 1");
1208 #if defined(PYBIND11_HAS_U8STRING)
1209  static_assert(!std::is_same<CharT, char8_t>::value || sizeof(CharT) == 1, "Unsupported char8_t size != 1");
1210 #endif
1211  static_assert(!std::is_same<CharT, char16_t>::value || sizeof(CharT) == 2, "Unsupported char16_t size != 2");
1212  static_assert(!std::is_same<CharT, char32_t>::value || sizeof(CharT) == 4, "Unsupported char32_t size != 4");
1213  // wchar_t can be either 16 bits (Windows) or 32 (everywhere else)
1214  static_assert(!std::is_same<CharT, wchar_t>::value || sizeof(CharT) == 2 || sizeof(CharT) == 4,
1215  "Unsupported wchar_t size != 2/4");
1216  static constexpr size_t UTF_N = 8 * sizeof(CharT);
1217 
1218  bool load(handle src, bool) {
1219 #if PY_MAJOR_VERSION < 3
1220  object temp;
1221 #endif
1222  handle load_src = src;
1223  if (!src) {
1224  return false;
1225  } else if (!PyUnicode_Check(load_src.ptr())) {
1226 #if PY_MAJOR_VERSION >= 3
1227  return load_bytes(load_src);
1228 #else
1229  if (std::is_same<CharT, char>::value) {
1230  return load_bytes(load_src);
1231  }
1232 
1233  // The below is a guaranteed failure in Python 3 when PyUnicode_Check returns false
1234  if (!PYBIND11_BYTES_CHECK(load_src.ptr()))
1235  return false;
1236 
1237  temp = reinterpret_steal<object>(PyUnicode_FromObject(load_src.ptr()));
1238  if (!temp) { PyErr_Clear(); return false; }
1239  load_src = temp;
1240 #endif
1241  }
1242 
1243  object utfNbytes = reinterpret_steal<object>(PyUnicode_AsEncodedString(
1244  load_src.ptr(), UTF_N == 8 ? "utf-8" : UTF_N == 16 ? "utf-16" : "utf-32", nullptr));
1245  if (!utfNbytes) { PyErr_Clear(); return false; }
1246 
1247  const auto *buffer = reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
1248  size_t length = (size_t) PYBIND11_BYTES_SIZE(utfNbytes.ptr()) / sizeof(CharT);
1249  if (UTF_N > 8) { buffer++; length--; } // Skip BOM for UTF-16/32
1250  value = StringType(buffer, length);
1251 
1252  // If we're loading a string_view we need to keep the encoded Python object alive:
1253  if (IsView)
1255 
1256  return true;
1257  }
1258 
1259  static handle cast(const StringType &src, return_value_policy /* policy */, handle /* parent */) {
1260  const char *buffer = reinterpret_cast<const char *>(src.data());
1261  auto nbytes = ssize_t(src.size() * sizeof(CharT));
1262  handle s = decode_utfN(buffer, nbytes);
1263  if (!s) throw error_already_set();
1264  return s;
1265  }
1266 
1267  PYBIND11_TYPE_CASTER(StringType, _(PYBIND11_STRING_NAME));
1268 
1269 private:
1270  static handle decode_utfN(const char *buffer, ssize_t nbytes) {
1271 #if !defined(PYPY_VERSION)
1272  return
1273  UTF_N == 8 ? PyUnicode_DecodeUTF8(buffer, nbytes, nullptr) :
1274  UTF_N == 16 ? PyUnicode_DecodeUTF16(buffer, nbytes, nullptr, nullptr) :
1275  PyUnicode_DecodeUTF32(buffer, nbytes, nullptr, nullptr);
1276 #else
1277  // PyPy segfaults when on PyUnicode_DecodeUTF16 (and possibly on PyUnicode_DecodeUTF32 as well),
1278  // so bypass the whole thing by just passing the encoding as a string value, which works properly:
1279  return PyUnicode_Decode(buffer, nbytes, UTF_N == 8 ? "utf-8" : UTF_N == 16 ? "utf-16" : "utf-32", nullptr);
1280 #endif
1281  }
1282 
1283  // When loading into a std::string or char*, accept a bytes object as-is (i.e.
1284  // without any encoding/decoding attempt). For other C++ char sizes this is a no-op.
1285  // which supports loading a unicode from a str, doesn't take this path.
1286  template <typename C = CharT>
1287  bool load_bytes(enable_if_t<std::is_same<C, char>::value, handle> src) {
1288  if (PYBIND11_BYTES_CHECK(src.ptr())) {
1289  // We were passed a Python 3 raw bytes; accept it into a std::string or char*
1290  // without any encoding attempt.
1291  const char *bytes = PYBIND11_BYTES_AS_STRING(src.ptr());
1292  if (bytes) {
1293  value = StringType(bytes, (size_t) PYBIND11_BYTES_SIZE(src.ptr()));
1294  return true;
1295  }
1296  }
1297 
1298  return false;
1299  }
1300 
1301  template <typename C = CharT>
1302  bool load_bytes(enable_if_t<!std::is_same<C, char>::value, handle>) { return false; }
1303 };
1304 
1305 template <typename CharT, class Traits, class Allocator>
1306 struct type_caster<std::basic_string<CharT, Traits, Allocator>, enable_if_t<is_std_char_type<CharT>::value>>
1307  : string_caster<std::basic_string<CharT, Traits, Allocator>> {};
1308 
1309 #ifdef PYBIND11_HAS_STRING_VIEW
1310 template <typename CharT, class Traits>
1311 struct type_caster<std::basic_string_view<CharT, Traits>, enable_if_t<is_std_char_type<CharT>::value>>
1312  : string_caster<std::basic_string_view<CharT, Traits>, true> {};
1313 #endif
1314 
1315 // Type caster for C-style strings. We basically use a std::string type caster, but also add the
1316 // ability to use None as a nullptr char* (which the string caster doesn't allow).
1317 template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type<CharT>::value>> {
1318  using StringType = std::basic_string<CharT>;
1320  StringCaster str_caster;
1321  bool none = false;
1322  CharT one_char = 0;
1323 public:
1324  bool load(handle src, bool convert) {
1325  if (!src) return false;
1326  if (src.is_none()) {
1327  // Defer accepting None to other overloads (if we aren't in convert mode):
1328  if (!convert) return false;
1329  none = true;
1330  return true;
1331  }
1332  return str_caster.load(src, convert);
1333  }
1334 
1335  static handle cast(const CharT *src, return_value_policy policy, handle parent) {
1336  if (src == nullptr) return pybind11::none().inc_ref();
1337  return StringCaster::cast(StringType(src), policy, parent);
1338  }
1339 
1340  static handle cast(CharT src, return_value_policy policy, handle parent) {
1341  if (std::is_same<char, CharT>::value) {
1342  handle s = PyUnicode_DecodeLatin1((const char *) &src, 1, nullptr);
1343  if (!s) throw error_already_set();
1344  return s;
1345  }
1346  return StringCaster::cast(StringType(1, src), policy, parent);
1347  }
1348 
1349  operator CharT*() { return none ? nullptr : const_cast<CharT *>(static_cast<StringType &>(str_caster).c_str()); }
1350  operator CharT&() {
1351  if (none)
1352  throw value_error("Cannot convert None to a character");
1353 
1354  auto &value = static_cast<StringType &>(str_caster);
1355  size_t str_len = value.size();
1356  if (str_len == 0)
1357  throw value_error("Cannot convert empty string to a character");
1358 
1359  // If we're in UTF-8 mode, we have two possible failures: one for a unicode character that
1360  // is too high, and one for multiple unicode characters (caught later), so we need to figure
1361  // out how long the first encoded character is in bytes to distinguish between these two
1362  // errors. We also allow want to allow unicode characters U+0080 through U+00FF, as those
1363  // can fit into a single char value.
1364  if (StringCaster::UTF_N == 8 && str_len > 1 && str_len <= 4) {
1365  auto v0 = static_cast<unsigned char>(value[0]);
1366  size_t char0_bytes = !(v0 & 0x80) ? 1 : // low bits only: 0-127
1367  (v0 & 0xE0) == 0xC0 ? 2 : // 0b110xxxxx - start of 2-byte sequence
1368  (v0 & 0xF0) == 0xE0 ? 3 : // 0b1110xxxx - start of 3-byte sequence
1369  4; // 0b11110xxx - start of 4-byte sequence
1370 
1371  if (char0_bytes == str_len) {
1372  // If we have a 128-255 value, we can decode it into a single char:
1373  if (char0_bytes == 2 && (v0 & 0xFC) == 0xC0) { // 0x110000xx 0x10xxxxxx
1374  one_char = static_cast<CharT>(((v0 & 3) << 6) + (static_cast<unsigned char>(value[1]) & 0x3F));
1375  return one_char;
1376  }
1377  // Otherwise we have a single character, but it's > U+00FF
1378  throw value_error("Character code point not in range(0x100)");
1379  }
1380  }
1381 
1382  // UTF-16 is much easier: we can only have a surrogate pair for values above U+FFFF, thus a
1383  // surrogate pair with total length 2 instantly indicates a range error (but not a "your
1384  // string was too long" error).
1385  else if (StringCaster::UTF_N == 16 && str_len == 2) {
1386  one_char = static_cast<CharT>(value[0]);
1387  if (one_char >= 0xD800 && one_char < 0xE000)
1388  throw value_error("Character code point not in range(0x10000)");
1389  }
1390 
1391  if (str_len != 1)
1392  throw value_error("Expected a character, but multi-character string found");
1393 
1394  one_char = value[0];
1395  return one_char;
1396  }
1397 
1398  static constexpr auto name = _(PYBIND11_STRING_NAME);
1399  template <typename _T> using cast_op_type = pybind11::detail::cast_op_type<_T>;
1400 };
1401 
1402 // Base implementation for std::tuple and std::pair
1403 template <template<typename...> class Tuple, typename... Ts> class tuple_caster {
1404  using type = Tuple<Ts...>;
1405  static constexpr auto size = sizeof...(Ts);
1406  using indices = make_index_sequence<size>;
1407 public:
1408 
1409  bool load(handle src, bool convert) {
1410  if (!isinstance<sequence>(src))
1411  return false;
1412  const auto seq = reinterpret_borrow<sequence>(src);
1413  if (seq.size() != size)
1414  return false;
1415  return load_impl(seq, convert, indices{});
1416  }
1417 
1418  template <typename T>
1419  static handle cast(T &&src, return_value_policy policy, handle parent) {
1420  return cast_impl(std::forward<T>(src), policy, parent, indices{});
1421  }
1422 
1423  // copied from the PYBIND11_TYPE_CASTER macro
1424  template <typename T>
1425  static handle cast(T *src, return_value_policy policy, handle parent) {
1426  if (!src) return none().release();
1427  if (policy == return_value_policy::take_ownership) {
1428  auto h = cast(std::move(*src), policy, parent); delete src; return h;
1429  } else {
1430  return cast(*src, policy, parent);
1431  }
1432  }
1433 
1434  static constexpr auto name = _("Tuple[") + concat(make_caster<Ts>::name...) + _("]");
1435 
1436  template <typename T> using cast_op_type = type;
1437 
1438  operator type() & { return implicit_cast(indices{}); }
1439  operator type() && { return std::move(*this).implicit_cast(indices{}); }
1440 
1441 protected:
1442  template <size_t... Is>
1443  type implicit_cast(index_sequence<Is...>) & { return type(cast_op<Ts>(std::get<Is>(subcasters))...); }
1444  template <size_t... Is>
1445  type implicit_cast(index_sequence<Is...>) && { return type(cast_op<Ts>(std::move(std::get<Is>(subcasters)))...); }
1446 
1447  static constexpr bool load_impl(const sequence &, bool, index_sequence<>) { return true; }
1448 
1449  template <size_t... Is>
1450  bool load_impl(const sequence &seq, bool convert, index_sequence<Is...>) {
1451 #ifdef __cpp_fold_expressions
1452  if ((... || !std::get<Is>(subcasters).load(seq[Is], convert)))
1453  return false;
1454 #else
1455  for (bool r : {std::get<Is>(subcasters).load(seq[Is], convert)...})
1456  if (!r)
1457  return false;
1458 #endif
1459  return true;
1460  }
1461 
1462  /* Implementation: Convert a C++ tuple into a Python tuple */
1463  template <typename T, size_t... Is>
1464  static handle cast_impl(T &&src, return_value_policy policy, handle parent, index_sequence<Is...>) {
1465  std::array<object, size> entries{{
1466  reinterpret_steal<object>(make_caster<Ts>::cast(std::get<Is>(std::forward<T>(src)), policy, parent))...
1467  }};
1468  for (const auto &entry: entries)
1469  if (!entry)
1470  return handle();
1471  tuple result(size);
1472  int counter = 0;
1473  for (auto & entry: entries)
1474  PyTuple_SET_ITEM(result.ptr(), counter++, entry.release().ptr());
1475  return result.release();
1476  }
1477 
1478  Tuple<make_caster<Ts>...> subcasters;
1479 };
1480 
1481 template <typename T1, typename T2> class type_caster<std::pair<T1, T2>>
1482  : public tuple_caster<std::pair, T1, T2> {};
1483 
1484 template <typename... Ts> class type_caster<std::tuple<Ts...>>
1485  : public tuple_caster<std::tuple, Ts...> {};
1486 
1487 /// Helper class which abstracts away certain actions. Users can provide specializations for
1488 /// custom holders, but it's only necessary if the type has a non-standard interface.
1489 template <typename T>
1491  static auto get(const T &p) -> decltype(p.get()) { return p.get(); }
1492 };
1493 
1494 /// Type caster for holder types like std::shared_ptr, etc.
1495 template <typename type, typename holder_type>
1497 public:
1498  using base = type_caster_base<type>;
1499  static_assert(std::is_base_of<base, type_caster<type>>::value,
1500  "Holder classes are only supported for custom types");
1501  using base::base;
1502  using base::cast;
1503  using base::typeinfo;
1504  using base::value;
1505 
1506  bool load(handle src, bool convert) {
1507  return base::template load_impl<copyable_holder_caster<type, holder_type>>(src, convert);
1508  }
1509 
1510  explicit operator type*() { return this->value; }
1511  // static_cast works around compiler error with MSVC 17 and CUDA 10.2
1512  // see issue #2180
1513  explicit operator type&() { return *(static_cast<type *>(this->value)); }
1514  explicit operator holder_type*() { return std::addressof(holder); }
1515  explicit operator holder_type&() { return holder; }
1516 
1517  static handle cast(const holder_type &src, return_value_policy, handle) {
1518  const auto *ptr = holder_helper<holder_type>::get(src);
1519  return type_caster_base<type>::cast_holder(ptr, &src);
1520  }
1521 
1522 protected:
1523  friend class type_caster_generic;
1524  void check_holder_compat() {
1525  if (typeinfo->default_holder)
1526  throw cast_error("Unable to load a custom holder type from a default-holder instance");
1527  }
1528 
1529  bool load_value(value_and_holder &&v_h) {
1530  if (v_h.holder_constructed()) {
1531  value = v_h.value_ptr();
1532  holder = v_h.template holder<holder_type>();
1533  return true;
1534  } else {
1535  throw cast_error("Unable to cast from non-held to held instance (T& to Holder<T>) "
1536 #if defined(NDEBUG)
1537  "(compile in debug mode for type information)");
1538 #else
1539  "of type '" + type_id<holder_type>() + "''");
1540 #endif
1541  }
1542  }
1543 
1544  template <typename T = holder_type, detail::enable_if_t<!std::is_constructible<T, const T &, type*>::value, int> = 0>
1545  bool try_implicit_casts(handle, bool) { return false; }
1546 
1547  template <typename T = holder_type, detail::enable_if_t<std::is_constructible<T, const T &, type*>::value, int> = 0>
1548  bool try_implicit_casts(handle src, bool convert) {
1549  for (auto &cast : typeinfo->implicit_casts) {
1550  copyable_holder_caster sub_caster(*cast.first);
1551  if (sub_caster.load(src, convert)) {
1552  value = cast.second(sub_caster.value);
1553  holder = holder_type(sub_caster.holder, (type *) value);
1554  return true;
1555  }
1556  }
1557  return false;
1558  }
1559 
1560  static bool try_direct_conversions(handle) { return false; }
1561 
1562 
1563  holder_type holder;
1564 };
1565 
1566 /// Specialize for the common std::shared_ptr, so users don't need to
1567 template <typename T>
1568 class type_caster<std::shared_ptr<T>> : public copyable_holder_caster<T, std::shared_ptr<T>> { };
1569 
1570 template <typename type, typename holder_type>
1572  static_assert(std::is_base_of<type_caster_base<type>, type_caster<type>>::value,
1573  "Holder classes are only supported for custom types");
1574 
1575  static handle cast(holder_type &&src, return_value_policy, handle) {
1576  auto *ptr = holder_helper<holder_type>::get(src);
1577  return type_caster_base<type>::cast_holder(ptr, std::addressof(src));
1578  }
1579  static constexpr auto name = type_caster_base<type>::name;
1580 };
1581 
1582 template <typename type, typename deleter>
1583 class type_caster<std::unique_ptr<type, deleter>>
1584  : public move_only_holder_caster<type, std::unique_ptr<type, deleter>> { };
1585 
1586 template <typename type, typename holder_type>
1587 using type_caster_holder = conditional_t<is_copy_constructible<holder_type>::value,
1590 
1591 template <typename T, bool Value = false> struct always_construct_holder { static constexpr bool value = Value; };
1592 
1593 /// Create a specialization for custom holder types (silently ignores std::shared_ptr)
1594 #define PYBIND11_DECLARE_HOLDER_TYPE(type, holder_type, ...) \
1595  namespace pybind11 { namespace detail { \
1596  template <typename type> \
1597  struct always_construct_holder<holder_type> : always_construct_holder<void, ##__VA_ARGS__> { }; \
1598  template <typename type> \
1599  class type_caster<holder_type, enable_if_t<!is_shared_ptr<holder_type>::value>> \
1600  : public type_caster_holder<type, holder_type> { }; \
1601  }}
1602 
1603 // PYBIND11_DECLARE_HOLDER_TYPE holder types:
1604 template <typename base, typename holder> struct is_holder_type :
1605  std::is_base_of<detail::type_caster_holder<base, holder>, detail::type_caster<holder>> {};
1606 // Specialization for always-supported unique_ptr holders:
1607 template <typename base, typename deleter> struct is_holder_type<base, std::unique_ptr<base, deleter>> :
1608  std::true_type {};
1609 
1610 template <typename T> struct handle_type_name { static constexpr auto name = _<T>(); };
1611 template <> struct handle_type_name<bytes> { static constexpr auto name = _(PYBIND11_BYTES_NAME); };
1612 template <> struct handle_type_name<int_> { static constexpr auto name = _("int"); };
1613 template <> struct handle_type_name<iterable> { static constexpr auto name = _("Iterable"); };
1614 template <> struct handle_type_name<iterator> { static constexpr auto name = _("Iterator"); };
1615 template <> struct handle_type_name<none> { static constexpr auto name = _("None"); };
1616 template <> struct handle_type_name<args> { static constexpr auto name = _("*args"); };
1617 template <> struct handle_type_name<kwargs> { static constexpr auto name = _("**kwargs"); };
1618 
1619 template <typename type>
1621  template <typename T = type, enable_if_t<std::is_same<T, handle>::value, int> = 0>
1622  bool load(handle src, bool /* convert */) { value = src; return static_cast<bool>(value); }
1623 
1624  template <typename T = type, enable_if_t<std::is_base_of<object, T>::value, int> = 0>
1625  bool load(handle src, bool /* convert */) {
1626  if (!isinstance<type>(src))
1627  return false;
1628  value = reinterpret_borrow<type>(src);
1629  return true;
1630  }
1631 
1632  static handle cast(const handle &src, return_value_policy /* policy */, handle /* parent */) {
1633  return src.inc_ref();
1634  }
1635  PYBIND11_TYPE_CASTER(type, handle_type_name<type>::name);
1636 };
1637 
1638 template <typename T>
1639 class type_caster<T, enable_if_t<is_pyobject<T>::value>> : public pyobject_caster<T> { };
1640 
1641 // Our conditions for enabling moving are quite restrictive:
1642 // At compile time:
1643 // - T needs to be a non-const, non-pointer, non-reference type
1644 // - type_caster<T>::operator T&() must exist
1645 // - the type must be move constructible (obviously)
1646 // At run-time:
1647 // - if the type is non-copy-constructible, the object must be the sole owner of the type (i.e. it
1648 // must have ref_count() == 1)h
1649 // If any of the above are not satisfied, we fall back to copying.
1650 template <typename T> using move_is_plain_type = satisfies_none_of<T,
1651  std::is_void, std::is_pointer, std::is_reference, std::is_const
1652 >;
1653 template <typename T, typename SFINAE = void> struct move_always : std::false_type {};
1654 template <typename T> struct move_always<T, enable_if_t<all_of<
1655  move_is_plain_type<T>,
1657  std::is_move_constructible<T>,
1658  std::is_same<decltype(std::declval<make_caster<T>>().operator T&()), T&>
1659 >::value>> : std::true_type {};
1660 template <typename T, typename SFINAE = void> struct move_if_unreferenced : std::false_type {};
1661 template <typename T> struct move_if_unreferenced<T, enable_if_t<all_of<
1662  move_is_plain_type<T>,
1663  negation<move_always<T>>,
1664  std::is_move_constructible<T>,
1665  std::is_same<decltype(std::declval<make_caster<T>>().operator T&()), T&>
1666 >::value>> : std::true_type {};
1667 template <typename T> using move_never = none_of<move_always<T>, move_if_unreferenced<T>>;
1668 
1669 // Detect whether returning a `type` from a cast on type's type_caster is going to result in a
1670 // reference or pointer to a local variable of the type_caster. Basically, only
1671 // non-reference/pointer `type`s and reference/pointers from a type_caster_generic are safe;
1672 // everything else returns a reference/pointer to a local variable.
1673 template <typename type> using cast_is_temporary_value_reference = bool_constant<
1674  (std::is_reference<type>::value || std::is_pointer<type>::value) &&
1675  !std::is_base_of<type_caster_generic, make_caster<type>>::value &&
1676  !std::is_same<intrinsic_t<type>, void>::value
1677 >;
1678 
1679 // When a value returned from a C++ function is being cast back to Python, we almost always want to
1680 // force `policy = move`, regardless of the return value policy the function/method was declared
1681 // with.
1682 template <typename Return, typename SFINAE = void> struct return_value_policy_override {
1683  static return_value_policy policy(return_value_policy p) { return p; }
1684 };
1685 
1686 template <typename Return> struct return_value_policy_override<Return,
1687  detail::enable_if_t<std::is_base_of<type_caster_generic, make_caster<Return>>::value, void>> {
1688  static return_value_policy policy(return_value_policy p) {
1689  return !std::is_lvalue_reference<Return>::value &&
1690  !std::is_pointer<Return>::value
1691  ? return_value_policy::move : p;
1692  }
1693 };
1694 
1695 // Basic python -> C++ casting; throws if casting fails
1696 template <typename T, typename SFINAE> type_caster<T, SFINAE> &load_type(type_caster<T, SFINAE> &conv, const handle &handle) {
1697  if (!conv.load(handle, true)) {
1698 #if defined(NDEBUG)
1699  throw cast_error("Unable to cast Python instance to C++ type (compile in debug mode for details)");
1700 #else
1701  throw cast_error("Unable to cast Python instance of type " +
1702  (std::string) str(type::handle_of(handle)) + " to C++ type '" + type_id<T>() + "'");
1703 #endif
1704  }
1705  return conv;
1706 }
1707 // Wrapper around the above that also constructs and returns a type_caster
1708 template <typename T> make_caster<T> load_type(const handle &handle) {
1709  make_caster<T> conv;
1710  load_type(conv, handle);
1711  return conv;
1712 }
1713 
1714 PYBIND11_NAMESPACE_END(detail)
1715 
1716 // pytype -> C++ type
1717 template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
1718 T cast(const handle &handle) {
1719  using namespace detail;
1720  static_assert(!cast_is_temporary_value_reference<T>::value,
1721  "Unable to cast type to reference: value is local to type caster");
1722  return cast_op<T>(load_type<T>(handle));
1723 }
1724 
1725 // pytype -> pytype (calls converting constructor)
1726 template <typename T, detail::enable_if_t<detail::is_pyobject<T>::value, int> = 0>
1727 T cast(const handle &handle) { return T(reinterpret_borrow<object>(handle)); }
1728 
1729 // C++ type -> py::object
1730 template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
1731 object cast(T &&value, return_value_policy policy = return_value_policy::automatic_reference,
1732  handle parent = handle()) {
1733  using no_ref_T = typename std::remove_reference<T>::type;
1734  if (policy == return_value_policy::automatic)
1735  policy = std::is_pointer<no_ref_T>::value ? return_value_policy::take_ownership :
1736  std::is_lvalue_reference<T>::value ? return_value_policy::copy : return_value_policy::move;
1737  else if (policy == return_value_policy::automatic_reference)
1738  policy = std::is_pointer<no_ref_T>::value ? return_value_policy::reference :
1739  std::is_lvalue_reference<T>::value ? return_value_policy::copy : return_value_policy::move;
1740  return reinterpret_steal<object>(detail::make_caster<T>::cast(std::forward<T>(value), policy, parent));
1741 }
1742 
1743 template <typename T> T handle::cast() const { return pybind11::cast<T>(*this); }
1744 template <> inline void handle::cast() const { return; }
1745 
1746 template <typename T>
1747 detail::enable_if_t<!detail::move_never<T>::value, T> move(object &&obj) {
1748  if (obj.ref_count() > 1)
1749 #if defined(NDEBUG)
1750  throw cast_error("Unable to cast Python instance to C++ rvalue: instance has multiple references"
1751  " (compile in debug mode for details)");
1752 #else
1753  throw cast_error("Unable to move from Python " + (std::string) str(type::handle_of(obj)) +
1754  " instance to C++ " + type_id<T>() + " instance: instance has multiple references");
1755 #endif
1756 
1757  // Move into a temporary and return that, because the reference may be a local value of `conv`
1758  T ret = std::move(detail::load_type<T>(obj).operator T&());
1759  return ret;
1760 }
1761 
1762 // Calling cast() on an rvalue calls pybind11::cast with the object rvalue, which does:
1763 // - If we have to move (because T has no copy constructor), do it. This will fail if the moved
1764 // object has multiple references, but trying to copy will fail to compile.
1765 // - If both movable and copyable, check ref count: if 1, move; otherwise copy
1766 // - Otherwise (not movable), copy.
1767 template <typename T> detail::enable_if_t<detail::move_always<T>::value, T> cast(object &&object) {
1768  return move<T>(std::move(object));
1769 }
1770 template <typename T> detail::enable_if_t<detail::move_if_unreferenced<T>::value, T> cast(object &&object) {
1771  if (object.ref_count() > 1)
1772  return cast<T>(object);
1773  else
1774  return move<T>(std::move(object));
1775 }
1776 template <typename T> detail::enable_if_t<detail::move_never<T>::value, T> cast(object &&object) {
1777  return cast<T>(object);
1778 }
1779 
1780 template <typename T> T object::cast() const & { return pybind11::cast<T>(*this); }
1781 template <typename T> T object::cast() && { return pybind11::cast<T>(std::move(*this)); }
1782 template <> inline void object::cast() const & { return; }
1783 template <> inline void object::cast() && { return; }
1784 
1785 PYBIND11_NAMESPACE_BEGIN(detail)
1786 
1787 // Declared in pytypes.h:
1788 template <typename T, enable_if_t<!is_pyobject<T>::value, int>>
1789 object object_or_cast(T &&o) { return pybind11::cast(std::forward<T>(o)); }
1790 
1791 struct override_unused {}; // Placeholder type for the unneeded (and dead code) static variable in the PYBIND11_OVERRIDE_OVERRIDE macro
1792 template <typename ret_type> using override_caster_t = conditional_t<
1793  cast_is_temporary_value_reference<ret_type>::value, make_caster<ret_type>, override_unused>;
1794 
1795 // Trampoline use: for reference/pointer types to value-converted values, we do a value cast, then
1796 // store the result in the given variable. For other types, this is a no-op.
1797 template <typename T> enable_if_t<cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&o, make_caster<T> &caster) {
1798  return cast_op<T>(load_type(caster, o));
1799 }
1800 template <typename T> enable_if_t<!cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&, override_unused &) {
1801  pybind11_fail("Internal error: cast_ref fallback invoked"); }
1802 
1803 // Trampoline use: Having a pybind11::cast with an invalid reference type is going to static_assert, even
1804 // though if it's in dead code, so we provide a "trampoline" to pybind11::cast that only does anything in
1805 // cases where pybind11::cast is valid.
1806 template <typename T> enable_if_t<!cast_is_temporary_value_reference<T>::value, T> cast_safe(object &&o) {
1807  return pybind11::cast<T>(std::move(o)); }
1808 template <typename T> enable_if_t<cast_is_temporary_value_reference<T>::value, T> cast_safe(object &&) {
1809  pybind11_fail("Internal error: cast_safe fallback invoked"); }
1810 template <> inline void cast_safe<void>(object &&) {}
1811 
1812 PYBIND11_NAMESPACE_END(detail)
1813 
1814 template <return_value_policy policy = return_value_policy::automatic_reference>
1815 tuple make_tuple() { return tuple(0); }
1816 
1817 template <return_value_policy policy = return_value_policy::automatic_reference,
1818  typename... Args> tuple make_tuple(Args&&... args_) {
1819  constexpr size_t size = sizeof...(Args);
1820  std::array<object, size> args {
1821  { reinterpret_steal<object>(detail::make_caster<Args>::cast(
1822  std::forward<Args>(args_), policy, nullptr))... }
1823  };
1824  for (size_t i = 0; i < args.size(); i++) {
1825  if (!args[i]) {
1826 #if defined(NDEBUG)
1827  throw cast_error("make_tuple(): unable to convert arguments to Python object (compile in debug mode for details)");
1828 #else
1829  std::array<std::string, size> argtypes { {type_id<Args>()...} };
1830  throw cast_error("make_tuple(): unable to convert argument of type '" +
1831  argtypes[i] + "' to Python object");
1832 #endif
1833  }
1834  }
1835  tuple result(size);
1836  int counter = 0;
1837  for (auto &arg_value : args)
1838  PyTuple_SET_ITEM(result.ptr(), counter++, arg_value.release().ptr());
1839  return result;
1840 }
1841 
1842 /// \ingroup annotations
1843 /// Annotation for arguments
1844 struct arg {
1845  /// Constructs an argument with the name of the argument; if null or omitted, this is a positional argument.
1846  constexpr explicit arg(const char *name = nullptr) : name(name), flag_noconvert(false), flag_none(true) { }
1847  /// Assign a value to this argument
1848  template <typename T> arg_v operator=(T &&value) const;
1849  /// Indicate that the type should not be converted in the type caster
1850  arg &noconvert(bool flag = true) { flag_noconvert = flag; return *this; }
1851  /// Indicates that the argument should/shouldn't allow None (e.g. for nullable pointer args)
1852  arg &none(bool flag = true) { flag_none = flag; return *this; }
1853 
1854  const char *name; ///< If non-null, this is a named kwargs argument
1855  bool flag_noconvert : 1; ///< If set, do not allow conversion (requires a supporting type caster!)
1856  bool flag_none : 1; ///< If set (the default), allow None to be passed to this argument
1857 };
1858 
1859 /// \ingroup annotations
1860 /// Annotation for arguments with values
1861 struct arg_v : arg {
1862 private:
1863  template <typename T>
1864  arg_v(arg &&base, T &&x, const char *descr = nullptr)
1865  : arg(base),
1866  value(reinterpret_steal<object>(
1867  detail::make_caster<T>::cast(x, return_value_policy::automatic, {})
1868  )),
1869  descr(descr)
1870 #if !defined(NDEBUG)
1871  , type(type_id<T>())
1872 #endif
1873  { }
1874 
1875 public:
1876  /// Direct construction with name, default, and description
1877  template <typename T>
1878  arg_v(const char *name, T &&x, const char *descr = nullptr)
1879  : arg_v(arg(name), std::forward<T>(x), descr) { }
1880 
1881  /// Called internally when invoking `py::arg("a") = value`
1882  template <typename T>
1883  arg_v(const arg &base, T &&x, const char *descr = nullptr)
1884  : arg_v(arg(base), std::forward<T>(x), descr) { }
1885 
1886  /// Same as `arg::noconvert()`, but returns *this as arg_v&, not arg&
1887  arg_v &noconvert(bool flag = true) { arg::noconvert(flag); return *this; }
1888 
1889  /// Same as `arg::nonone()`, but returns *this as arg_v&, not arg&
1890  arg_v &none(bool flag = true) { arg::none(flag); return *this; }
1891 
1892  /// The default value
1893  object value;
1894  /// The (optional) description of the default value
1895  const char *descr;
1896 #if !defined(NDEBUG)
1897  /// The C++ type name of the default value (only available when compiled in debug mode)
1898  std::string type;
1899 #endif
1900 };
1901 
1902 /// \ingroup annotations
1903 /// Annotation indicating that all following arguments are keyword-only; the is the equivalent of an
1904 /// unnamed '*' argument (in Python 3)
1905 struct kw_only {};
1906 
1907 /// \ingroup annotations
1908 /// Annotation indicating that all previous arguments are positional-only; the is the equivalent of an
1909 /// unnamed '/' argument (in Python 3.8)
1910 struct pos_only {};
1911 
1912 template <typename T>
1913 arg_v arg::operator=(T &&value) const { return {std::move(*this), std::forward<T>(value)}; }
1914 
1915 /// Alias for backward compatibility -- to be removed in version 2.0
1916 template <typename /*unused*/> using arg_t = arg_v;
1917 
1918 inline namespace literals {
1919 /** \rst
1920  String literal version of `arg`
1921  \endrst */
1922 constexpr arg operator"" _a(const char *name, size_t) { return arg(name); }
1923 } // namespace literals
1924 
1925 PYBIND11_NAMESPACE_BEGIN(detail)
1926 
1927 // forward declaration (definition in attr.h)
1928 struct function_record;
1929 
1930 /// Internal data associated with a single function call
1931 struct function_call {
1932  function_call(const function_record &f, handle p); // Implementation in attr.h
1933 
1934  /// The function data:
1935  const function_record &func;
1936 
1937  /// Arguments passed to the function:
1938  std::vector<handle> args;
1939 
1940  /// The `convert` value the arguments should be loaded with
1941  std::vector<bool> args_convert;
1942 
1943  /// Extra references for the optional `py::args` and/or `py::kwargs` arguments (which, if
1944  /// present, are also in `args` but without a reference).
1945  object args_ref, kwargs_ref;
1946 
1947  /// The parent, if any
1948  handle parent;
1949 
1950  /// If this is a call to an initializer, this argument contains `self`
1951  handle init_self;
1952 };
1953 
1954 
1955 /// Helper class which loads arguments for C++ functions called from Python
1956 template <typename... Args>
1957 class argument_loader {
1958  using indices = make_index_sequence<sizeof...(Args)>;
1959 
1960  template <typename Arg> using argument_is_args = std::is_same<intrinsic_t<Arg>, args>;
1961  template <typename Arg> using argument_is_kwargs = std::is_same<intrinsic_t<Arg>, kwargs>;
1962  // Get args/kwargs argument positions relative to the end of the argument list:
1963  static constexpr auto args_pos = constexpr_first<argument_is_args, Args...>() - (int) sizeof...(Args),
1964  kwargs_pos = constexpr_first<argument_is_kwargs, Args...>() - (int) sizeof...(Args);
1965 
1966  static constexpr bool args_kwargs_are_last = kwargs_pos >= - 1 && args_pos >= kwargs_pos - 1;
1967 
1968  static_assert(args_kwargs_are_last, "py::args/py::kwargs are only permitted as the last argument(s) of a function");
1969 
1970 public:
1971  static constexpr bool has_kwargs = kwargs_pos < 0;
1972  static constexpr bool has_args = args_pos < 0;
1973 
1974  static constexpr auto arg_names = concat(type_descr(make_caster<Args>::name)...);
1975 
1976  bool load_args(function_call &call) {
1977  return load_impl_sequence(call, indices{});
1978  }
1979 
1980  template <typename Return, typename Guard, typename Func>
1981  enable_if_t<!std::is_void<Return>::value, Return> call(Func &&f) && {
1982  return std::move(*this).template call_impl<Return>(std::forward<Func>(f), indices{}, Guard{});
1983  }
1984 
1985  template <typename Return, typename Guard, typename Func>
1986  enable_if_t<std::is_void<Return>::value, void_type> call(Func &&f) && {
1987  std::move(*this).template call_impl<Return>(std::forward<Func>(f), indices{}, Guard{});
1988  return void_type();
1989  }
1990 
1991 private:
1992 
1993  static bool load_impl_sequence(function_call &, index_sequence<>) { return true; }
1994 
1995  template <size_t... Is>
1996  bool load_impl_sequence(function_call &call, index_sequence<Is...>) {
1997 #ifdef __cpp_fold_expressions
1998  if ((... || !std::get<Is>(argcasters).load(call.args[Is], call.args_convert[Is])))
1999  return false;
2000 #else
2001  for (bool r : {std::get<Is>(argcasters).load(call.args[Is], call.args_convert[Is])...})
2002  if (!r)
2003  return false;
2004 #endif
2005  return true;
2006  }
2007 
2008  template <typename Return, typename Func, size_t... Is, typename Guard>
2009  Return call_impl(Func &&f, index_sequence<Is...>, Guard &&) && {
2010  return std::forward<Func>(f)(cast_op<Args>(std::move(std::get<Is>(argcasters)))...);
2011  }
2012 
2013  std::tuple<make_caster<Args>...> argcasters;
2014 };
2015 
2016 /// Helper class which collects only positional arguments for a Python function call.
2017 /// A fancier version below can collect any argument, but this one is optimal for simple calls.
2018 template <return_value_policy policy>
2019 class simple_collector {
2020 public:
2021  template <typename... Ts>
2022  explicit simple_collector(Ts &&...values)
2023  : m_args(pybind11::make_tuple<policy>(std::forward<Ts>(values)...)) { }
2024 
2025  const tuple &args() const & { return m_args; }
2026  dict kwargs() const { return {}; }
2027 
2028  tuple args() && { return std::move(m_args); }
2029 
2030  /// Call a Python function and pass the collected arguments
2031  object call(PyObject *ptr) const {
2032  PyObject *result = PyObject_CallObject(ptr, m_args.ptr());
2033  if (!result)
2034  throw error_already_set();
2035  return reinterpret_steal<object>(result);
2036  }
2037 
2038 private:
2039  tuple m_args;
2040 };
2041 
2042 /// Helper class which collects positional, keyword, * and ** arguments for a Python function call
2043 template <return_value_policy policy>
2044 class unpacking_collector {
2045 public:
2046  template <typename... Ts>
2047  explicit unpacking_collector(Ts &&...values) {
2048  // Tuples aren't (easily) resizable so a list is needed for collection,
2049  // but the actual function call strictly requires a tuple.
2050  auto args_list = list();
2051  int _[] = { 0, (process(args_list, std::forward<Ts>(values)), 0)... };
2052  ignore_unused(_);
2053 
2054  m_args = std::move(args_list);
2055  }
2056 
2057  const tuple &args() const & { return m_args; }
2058  const dict &kwargs() const & { return m_kwargs; }
2059 
2060  tuple args() && { return std::move(m_args); }
2061  dict kwargs() && { return std::move(m_kwargs); }
2062 
2063  /// Call a Python function and pass the collected arguments
2064  object call(PyObject *ptr) const {
2065  PyObject *result = PyObject_Call(ptr, m_args.ptr(), m_kwargs.ptr());
2066  if (!result)
2067  throw error_already_set();
2068  return reinterpret_steal<object>(result);
2069  }
2070 
2071 private:
2072  template <typename T>
2073  void process(list &args_list, T &&x) {
2074  auto o = reinterpret_steal<object>(detail::make_caster<T>::cast(std::forward<T>(x), policy, {}));
2075  if (!o) {
2076 #if defined(NDEBUG)
2077  argument_cast_error();
2078 #else
2079  argument_cast_error(std::to_string(args_list.size()), type_id<T>());
2080 #endif
2081  }
2082  args_list.append(o);
2083  }
2084 
2085  void process(list &args_list, detail::args_proxy ap) {
2086  for (auto a : ap)
2087  args_list.append(a);
2088  }
2089 
2090  void process(list &/*args_list*/, arg_v a) {
2091  if (!a.name)
2092 #if defined(NDEBUG)
2093  nameless_argument_error();
2094 #else
2095  nameless_argument_error(a.type);
2096 #endif
2097 
2098  if (m_kwargs.contains(a.name)) {
2099 #if defined(NDEBUG)
2100  multiple_values_error();
2101 #else
2102  multiple_values_error(a.name);
2103 #endif
2104  }
2105  if (!a.value) {
2106 #if defined(NDEBUG)
2107  argument_cast_error();
2108 #else
2109  argument_cast_error(a.name, a.type);
2110 #endif
2111  }
2112  m_kwargs[a.name] = a.value;
2113  }
2114 
2115  void process(list &/*args_list*/, detail::kwargs_proxy kp) {
2116  if (!kp)
2117  return;
2118  for (auto k : reinterpret_borrow<dict>(kp)) {
2119  if (m_kwargs.contains(k.first)) {
2120 #if defined(NDEBUG)
2121  multiple_values_error();
2122 #else
2123  multiple_values_error(str(k.first));
2124 #endif
2125  }
2126  m_kwargs[k.first] = k.second;
2127  }
2128  }
2129 
2130  [[noreturn]] static void nameless_argument_error() {
2131  throw type_error("Got kwargs without a name; only named arguments "
2132  "may be passed via py::arg() to a python function call. "
2133  "(compile in debug mode for details)");
2134  }
2135  [[noreturn]] static void nameless_argument_error(std::string type) {
2136  throw type_error("Got kwargs without a name of type '" + type + "'; only named "
2137  "arguments may be passed via py::arg() to a python function call. ");
2138  }
2139  [[noreturn]] static void multiple_values_error() {
2140  throw type_error("Got multiple values for keyword argument "
2141  "(compile in debug mode for details)");
2142  }
2143 
2144  [[noreturn]] static void multiple_values_error(std::string name) {
2145  throw type_error("Got multiple values for keyword argument '" + name + "'");
2146  }
2147 
2148  [[noreturn]] static void argument_cast_error() {
2149  throw cast_error("Unable to convert call argument to Python object "
2150  "(compile in debug mode for details)");
2151  }
2152 
2153  [[noreturn]] static void argument_cast_error(std::string name, std::string type) {
2154  throw cast_error("Unable to convert call argument '" + name
2155  + "' of type '" + type + "' to Python object");
2156  }
2157 
2158 private:
2159  tuple m_args;
2160  dict m_kwargs;
2161 };
2162 
2163 /// Collect only positional arguments for a Python function call
2164 template <return_value_policy policy, typename... Args,
2165  typename = enable_if_t<all_of<is_positional<Args>...>::value>>
2166 simple_collector<policy> collect_arguments(Args &&...args) {
2167  return simple_collector<policy>(std::forward<Args>(args)...);
2168 }
2169 
2170 /// Collect all arguments, including keywords and unpacking (only instantiated when needed)
2171 template <return_value_policy policy, typename... Args,
2172  typename = enable_if_t<!all_of<is_positional<Args>...>::value>>
2173 unpacking_collector<policy> collect_arguments(Args &&...args) {
2174  // Following argument order rules for generalized unpacking according to PEP 448
2175  static_assert(
2176  constexpr_last<is_positional, Args...>() < constexpr_first<is_keyword_or_ds, Args...>()
2177  && constexpr_last<is_s_unpacking, Args...>() < constexpr_first<is_ds_unpacking, Args...>(),
2178  "Invalid function call: positional args must precede keywords and ** unpacking; "
2179  "* unpacking must precede ** unpacking"
2180  );
2181  return unpacking_collector<policy>(std::forward<Args>(args)...);
2182 }
2183 
2184 template <typename Derived>
2185 template <return_value_policy policy, typename... Args>
2186 object object_api<Derived>::operator()(Args &&...args) const {
2187  return detail::collect_arguments<policy>(std::forward<Args>(args)...).call(derived().ptr());
2188 }
2189 
2190 template <typename Derived>
2191 template <return_value_policy policy, typename... Args>
2192 object object_api<Derived>::call(Args &&...args) const {
2193  return operator()<policy>(std::forward<Args>(args)...);
2194 }
2195 
2196 PYBIND11_NAMESPACE_END(detail)
2197 
2198 
2199 template<typename T>
2200 handle type::handle_of() {
2201  static_assert(
2202  std::is_base_of<detail::type_caster_generic, detail::make_caster<T>>::value,
2203  "py::type::of<T> only supports the case where T is a registered C++ types."
2204  );
2205 
2206  return detail::get_type_handle(typeid(T), true);
2207 }
2208 
2209 
2210 #define PYBIND11_MAKE_OPAQUE(...) \
2211  namespace pybind11 { namespace detail { \
2212  template<> class type_caster<__VA_ARGS__> : public type_caster_base<__VA_ARGS__> { }; \
2213  }}
2214 
2215 /// Lets you pass a type containing a `,` through a macro parameter without needing a separate
2216 /// typedef, e.g.: `PYBIND11_OVERRIDE(PYBIND11_TYPE(ReturnType<A, B>), PYBIND11_TYPE(Parent<C, D>), f, arg)`
2217 #define PYBIND11_TYPE(...) __VA_ARGS__
2218 
2219 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
Annotation for parent scope.
Definition: attr.h:30
Definition: pytypes.h:1341
static constexpr uint8_t status_holder_constructed
Bit values for the non-simple status flags.
handle release()
Definition: pytypes.h:249
Type caster for holder types like std::shared_ptr, etc.
Definition: cast.h:1496
bool isinstance(handle obj)
Definition: pytypes.h:384
object operator()(Args &&...args) const
The &#39;instance&#39; type which needs to be standard layout (need to be able to use &#39;offsetof&#39;) ...
Definition: pytypes.h:1064
PYBIND11_NOINLINE bool try_load_foreign_module_local(handle src)
Definition: cast.h:637
Definition: descr.h:25
Definition: pytypes.h:935
bool simple_layout
void allocate_layout()
Initializes all of the above type/values/holders data (but not the instance values themselves) ...
Definition: cast.h:350
PyObject * ptr() const
Return the underlying PyObject * pointer.
Definition: pytypes.h:184
bool simple_holder_constructed
For simple layout, tracks whether the holder has been constructed.
Index sequences.
const handle & inc_ref() const &
Definition: pytypes.h:192
bool simple_instance_registered
For simple layout, tracks whether the instance is registered in registered_instances ...
Helper type to replace &#39;void&#39; in some expressions.
Definition: pytypes.h:1320
static PYBIND11_NOINLINE void add_patient(handle h)
Definition: cast.h:68
T cast() const
Definition: pytypes.h:1115
value_and_holder get_value_and_holder(const type_info *find_type=nullptr, bool throw_if_missing=true)
Definition: cast.h:326
RAII wrapper that temporarily clears any Python error state.
~loader_life_support()
... and destroyed after it returns
Definition: cast.h:52
Generic type caster for objects stored on the heap.
Definition: cast.h:861
void deallocate_layout()
Destroys/deallocates all of the above.
Definition: cast.h:398
Definition: pytypes.h:1274
Annotation for function names.
Definition: attr.h:36
Annotation indicating that a class derives from another given type.
Definition: attr.h:42
loader_life_support()
A new patient frame is created when a function is entered.
Definition: cast.h:47
static handle handle_of()
Internal data structure which holds metadata about a bound function (signature, overloads, etc.)
Definition: attr.h:141
bool owned
If true, the pointer is owned which means we&#39;re free to manage it with a holder.
Definition: pytypes.h:904