2 pybind11/detail/common.h -- Basic macros
4 Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
6 All rights reserved. Use of this source code is governed by a
7 BSD-style license that can be found in the LICENSE file.
12 #if !defined(NAMESPACE_BEGIN)
13 # define NAMESPACE_BEGIN(name) namespace name {
15 #if !defined(NAMESPACE_END)
16 # define NAMESPACE_END(name) }
19 // Robust support for some features and loading modules compiled against different pybind versions
20 // requires forcing hidden visibility on pybind code, so we enforce this by setting the attribute on
21 // the main `pybind11` namespace.
22 #if !defined(PYBIND11_NAMESPACE)
24 # define PYBIND11_NAMESPACE pybind11 __attribute__((visibility("hidden")))
26 # define PYBIND11_NAMESPACE pybind11
30 #if !(defined(_MSC_VER) && __cplusplus == 199711L) && !defined(__INTEL_COMPILER)
31 # if __cplusplus >= 201402L
32 # define PYBIND11_CPP14
33 # if __cplusplus >= 201703L
34 # define PYBIND11_CPP17
37 #elif defined(_MSC_VER) && __cplusplus == 199711L
38 // MSVC sets _MSVC_LANG rather than __cplusplus (supposedly until the standard is fully implemented)
39 // Unless you use the /Zc:__cplusplus flag on Visual Studio 2017 15.7 Preview 3 or newer
40 # if _MSVC_LANG >= 201402L
41 # define PYBIND11_CPP14
42 # if _MSVC_LANG > 201402L && _MSC_VER >= 1910
43 # define PYBIND11_CPP17
48 // Compiler version assertions
49 #if defined(__INTEL_COMPILER)
50 # if __INTEL_COMPILER < 1700
51 # error pybind11 requires Intel C++ compiler v17 or newer
53 #elif defined(__clang__) && !defined(__apple_build_version__)
54 # if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 3)
55 # error pybind11 requires clang 3.3 or newer
57 #elif defined(__clang__)
58 // Apple changes clang version macros to its Xcode version; the first Xcode release based on
59 // (upstream) clang 3.3 was Xcode 5:
60 # if __clang_major__ < 5
61 # error pybind11 requires Xcode/clang 5.0 or newer
63 #elif defined(__GNUG__)
64 # if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
65 # error pybind11 requires gcc 4.8 or newer
67 #elif defined(_MSC_VER)
68 // Pybind hits various compiler bugs in 2015u2 and earlier, and also makes use of some stl features
69 // (e.g. std::negation) added in 2015u3:
70 # if _MSC_FULL_VER < 190024210
71 # error pybind11 requires MSVC 2015 update 3 or newer
75 #if !defined(PYBIND11_EXPORT)
76 # if defined(WIN32) || defined(_WIN32)
77 # define PYBIND11_EXPORT __declspec(dllexport)
79 # define PYBIND11_EXPORT __attribute__ ((visibility("default")))
84 # define PYBIND11_NOINLINE __declspec(noinline)
86 # define PYBIND11_NOINLINE __attribute__ ((noinline))
89 #if defined(PYBIND11_CPP14)
90 # define PYBIND11_DEPRECATED(reason) [[deprecated(reason)]]
92 # define PYBIND11_DEPRECATED(reason) __attribute__((deprecated(reason)))
95 #define PYBIND11_VERSION_MAJOR 2
96 #define PYBIND11_VERSION_MINOR 2
97 #define PYBIND11_VERSION_PATCH 4
99 /// Include Python header, disable linking to pythonX_d.lib on Windows in debug mode
100 #if defined(_MSC_VER)
101 # if (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION < 4)
102 # define HAVE_ROUND 1
104 # pragma warning(push)
105 # pragma warning(disable: 4510 4610 4512 4005)
107 # define PYBIND11_DEBUG_MARKER
113 #include <frameobject.h>
114 #include <pythread.h>
116 #if defined(_WIN32) && (defined(min) || defined(max))
117 # error Macro clash with min and max -- define NOMINMAX when compiling your program on Windows
130 #if defined(_MSC_VER)
131 # if defined(PYBIND11_DEBUG_MARKER)
133 # undef PYBIND11_DEBUG_MARKER
135 # pragma warning(pop)
140 #include <forward_list>
144 #include <unordered_set>
145 #include <unordered_map>
148 #include <type_traits>
150 #if PY_MAJOR_VERSION >= 3 /// Compatibility macros for various Python versions
151 #define PYBIND11_INSTANCE_METHOD_NEW(ptr, class_) PyInstanceMethod_New(ptr)
152 #define PYBIND11_INSTANCE_METHOD_CHECK PyInstanceMethod_Check
153 #define PYBIND11_INSTANCE_METHOD_GET_FUNCTION PyInstanceMethod_GET_FUNCTION
154 #define PYBIND11_BYTES_CHECK PyBytes_Check
155 #define PYBIND11_BYTES_FROM_STRING PyBytes_FromString
156 #define PYBIND11_BYTES_FROM_STRING_AND_SIZE PyBytes_FromStringAndSize
157 #define PYBIND11_BYTES_AS_STRING_AND_SIZE PyBytes_AsStringAndSize
158 #define PYBIND11_BYTES_AS_STRING PyBytes_AsString
159 #define PYBIND11_BYTES_SIZE PyBytes_Size
160 #define PYBIND11_LONG_CHECK(o) PyLong_Check(o)
161 #define PYBIND11_LONG_AS_LONGLONG(o) PyLong_AsLongLong(o)
162 #define PYBIND11_BYTES_NAME "bytes"
163 #define PYBIND11_STRING_NAME "str"
164 #define PYBIND11_SLICE_OBJECT PyObject
165 #define PYBIND11_FROM_STRING PyUnicode_FromString
166 #define PYBIND11_STR_TYPE ::pybind11::str
167 #define PYBIND11_BOOL_ATTR "__bool__"
168 #define PYBIND11_NB_BOOL(ptr) ((ptr)->nb_bool)
169 #define PYBIND11_PLUGIN_IMPL(name) \
170 extern "C" PYBIND11_EXPORT PyObject *PyInit_##name()
173 #define PYBIND11_INSTANCE_METHOD_NEW(ptr, class_) PyMethod_New(ptr, nullptr, class_)
174 #define PYBIND11_INSTANCE_METHOD_CHECK PyMethod_Check
175 #define PYBIND11_INSTANCE_METHOD_GET_FUNCTION PyMethod_GET_FUNCTION
176 #define PYBIND11_BYTES_CHECK PyString_Check
177 #define PYBIND11_BYTES_FROM_STRING PyString_FromString
178 #define PYBIND11_BYTES_FROM_STRING_AND_SIZE PyString_FromStringAndSize
179 #define PYBIND11_BYTES_AS_STRING_AND_SIZE PyString_AsStringAndSize
180 #define PYBIND11_BYTES_AS_STRING PyString_AsString
181 #define PYBIND11_BYTES_SIZE PyString_Size
182 #define PYBIND11_LONG_CHECK(o) (PyInt_Check(o) || PyLong_Check(o))
183 #define PYBIND11_LONG_AS_LONGLONG(o) (PyInt_Check(o) ? (long long) PyLong_AsLong(o) : PyLong_AsLongLong(o))
184 #define PYBIND11_BYTES_NAME "str"
185 #define PYBIND11_STRING_NAME "unicode"
186 #define PYBIND11_SLICE_OBJECT PySliceObject
187 #define PYBIND11_FROM_STRING PyString_FromString
188 #define PYBIND11_STR_TYPE ::pybind11::bytes
189 #define PYBIND11_BOOL_ATTR "__nonzero__"
190 #define PYBIND11_NB_BOOL(ptr) ((ptr)->nb_nonzero)
191 #define PYBIND11_PLUGIN_IMPL(name) \
192 static PyObject *pybind11_init_wrapper(); \
193 extern "C" PYBIND11_EXPORT void init##name() { \
194 (void)pybind11_init_wrapper(); \
196 PyObject *pybind11_init_wrapper()
199 #if PY_VERSION_HEX >= 0x03050000 && PY_VERSION_HEX < 0x03050200
201 struct _Py_atomic_address { void *value; };
202 PyAPI_DATA(_Py_atomic_address) _PyThreadState_Current;
206 #define PYBIND11_TRY_NEXT_OVERLOAD ((PyObject *) 1) // special failure return code
207 #define PYBIND11_STRINGIFY(x) #x
208 #define PYBIND11_TOSTRING(x) PYBIND11_STRINGIFY(x)
209 #define PYBIND11_CONCAT(first, second) first##second
212 ***Deprecated in favor of PYBIND11_MODULE***
214 This macro creates the entry point that will be invoked when the Python interpreter
215 imports a plugin library. Please create a `module` in the function body and return
216 the pointer to its underlying Python object at the end.
220 PYBIND11_PLUGIN(example) {
221 pybind11::module m("example", "pybind11 example plugin");
222 /// Set up bindings here
226 #define PYBIND11_PLUGIN(name) \
227 PYBIND11_DEPRECATED("PYBIND11_PLUGIN is deprecated, use PYBIND11_MODULE") \
228 static PyObject *pybind11_init(); \
229 PYBIND11_PLUGIN_IMPL(name) { \
231 if (sscanf(Py_GetVersion(), "%i.%i", &major, &minor) != 2) { \
232 PyErr_SetString(PyExc_ImportError, "Can't parse Python version."); \
234 } else if (major != PY_MAJOR_VERSION || minor != PY_MINOR_VERSION) { \
235 PyErr_Format(PyExc_ImportError, \
236 "Python version mismatch: module was compiled for " \
237 "version %i.%i, while the interpreter is running " \
238 "version %i.%i.", PY_MAJOR_VERSION, PY_MINOR_VERSION, \
243 return pybind11_init(); \
244 } catch (pybind11::error_already_set &e) { \
245 PyErr_SetString(PyExc_ImportError, e.what()); \
247 } catch (const std::exception &e) { \
248 PyErr_SetString(PyExc_ImportError, e.what()); \
252 PyObject *pybind11_init()
255 This macro creates the entry point that will be invoked when the Python interpreter
256 imports an extension module. The module name is given as the fist argument and it
257 should not be in quotes. The second macro argument defines a variable of type
258 `py::module` which can be used to initialize the module.
262 PYBIND11_MODULE(example, m) {
263 m.doc() = "pybind11 example module";
267 return "Hello, World!";
271 #define PYBIND11_MODULE(name, variable) \
272 static void PYBIND11_CONCAT(pybind11_init_, name)(pybind11::module &); \
273 PYBIND11_PLUGIN_IMPL(name) { \
275 if (sscanf(Py_GetVersion(), "%i.%i", &major, &minor) != 2) { \
276 PyErr_SetString(PyExc_ImportError, "Can't parse Python version."); \
278 } else if (major != PY_MAJOR_VERSION || minor != PY_MINOR_VERSION) { \
279 PyErr_Format(PyExc_ImportError, \
280 "Python version mismatch: module was compiled for " \
281 "version %i.%i, while the interpreter is running " \
282 "version %i.%i.", PY_MAJOR_VERSION, PY_MINOR_VERSION, \
286 auto m = pybind11::module(PYBIND11_TOSTRING(name)); \
288 PYBIND11_CONCAT(pybind11_init_, name)(m); \
290 } catch (pybind11::error_already_set &e) { \
291 PyErr_SetString(PyExc_ImportError, e.what()); \
293 } catch (const std::exception &e) { \
294 PyErr_SetString(PyExc_ImportError, e.what()); \
298 void PYBIND11_CONCAT(pybind11_init_, name)(pybind11::module &variable)
301 NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
303 using ssize_t = Py_ssize_t;
304 using size_t = std::size_t;
306 /// Approach used to cast a previously unknown C++ instance into a Python object
307 enum class return_value_policy : uint8_t {
308 /** This is the default return value policy, which falls back to the policy
309 return_value_policy::take_ownership when the return value is a pointer.
310 Otherwise, it uses return_value::move or return_value::copy for rvalue
311 and lvalue references, respectively. See below for a description of what
312 all of these different policies do. */
315 /** As above, but use policy return_value_policy::reference when the return
316 value is a pointer. This is the default conversion policy for function
317 arguments when calling Python functions manually from C++ code (i.e. via
318 handle::operator()). You probably won't need to use this. */
321 /** Reference an existing object (i.e. do not create a new copy) and take
322 ownership. Python will call the destructor and delete operator when the
323 object’s reference count reaches zero. Undefined behavior ensues when
324 the C++ side does the same.. */
327 /** Create a new copy of the returned object, which will be owned by
328 Python. This policy is comparably safe because the lifetimes of the two
329 instances are decoupled. */
332 /** Use std::move to move the return value contents into a new instance
333 that will be owned by Python. This policy is comparably safe because the
334 lifetimes of the two instances (move source and destination) are
338 /** Reference an existing object, but do not take ownership. The C++ side
339 is responsible for managing the object’s lifetime and deallocating it
340 when it is no longer used. Warning: undefined behavior will ensue when
341 the C++ side deletes an object that is still referenced and used by
345 /** This policy only applies to methods and properties. It references the
346 object without taking ownership similar to the above
347 return_value_policy::reference policy. In contrast to that policy, the
348 function or property’s implicit this argument (called the parent) is
349 considered to be the the owner of the return value (the child).
350 pybind11 then couples the lifetime of the parent to the child via a
351 reference relationship that ensures that the parent cannot be garbage
352 collected while Python is still using the child. More advanced
353 variations of this scheme are also possible using combinations of
354 return_value_policy::reference and the keep_alive call policy */
358 NAMESPACE_BEGIN(detail)
360 inline static constexpr int log2(size_t n, int k = 0) { return (n <= 1) ? k : log2(n >> 1, k + 1); }
362 // Returns the size as a multiple of sizeof(void *), rounded up.
363 inline static constexpr size_t size_in_ptrs(size_t s) { return 1 + ((s - 1) >> log2(sizeof(void *))); }
366 * The space to allocate for simple layout instance holders (see below) in multiple of the size of
367 * a pointer (e.g. 2 means 16 bytes on 64-bit architectures). The default is the minimum required
368 * to holder either a std::unique_ptr or std::shared_ptr (which is almost always
369 * sizeof(std::shared_ptr<T>)).
371 constexpr size_t instance_simple_holder_in_ptrs() {
372 static_assert(sizeof(std::shared_ptr<int>) >= sizeof(std::unique_ptr<int>),
373 "pybind assumes std::shared_ptrs are at least as big as std::unique_ptrs");
374 return size_in_ptrs(sizeof(std::shared_ptr<int>));
377 // Forward declarations
379 struct value_and_holder;
381 struct nonsimple_values_and_holders {
382 void **values_and_holders;
386 /// The 'instance' type which needs to be standard layout (need to be able to use 'offsetof')
389 /// Storage for pointers and holder; see simple_layout, below, for a description
391 void *simple_value_holder[1 + instance_simple_holder_in_ptrs()];
392 nonsimple_values_and_holders nonsimple;
394 /// Weak references (needed for keep alive):
396 /// If true, the pointer is owned which means we're free to manage it with a holder.
399 * An instance has two possible value/holder layouts.
401 * Simple layout (when this flag is true), means the `simple_value_holder` is set with a pointer
402 * and the holder object governing that pointer, i.e. [val1*][holder]. This layout is applied
403 * whenever there is no python-side multiple inheritance of bound C++ types *and* the type's
404 * holder will fit in the default space (which is large enough to hold either a std::unique_ptr
405 * or std::shared_ptr).
407 * Non-simple layout applies when using custom holders that require more space than `shared_ptr`
408 * (which is typically the size of two pointers), or when multiple inheritance is used on the
409 * python side. Non-simple layout allocates the required amount of memory to have multiple
410 * bound C++ classes as parents. Under this layout, `nonsimple.values_and_holders` is set to a
411 * pointer to allocated space of the required space to hold a a sequence of value pointers and
412 * holders followed `status`, a set of bit flags (1 byte each), i.e.
413 * [val1*][holder1][val2*][holder2]...[bb...] where each [block] is rounded up to a multiple of
414 * `sizeof(void *)`. `nonsimple.holder_constructed` is, for convenience, a pointer to the
415 * beginning of the [bb...] block (but not independently allocated).
417 * Status bits indicate whether the associated holder is constructed (&
418 * status_holder_constructed) and whether the value pointer is registered (&
419 * status_instance_registered) in `registered_instances`.
421 bool simple_layout : 1;
422 /// For simple layout, tracks whether the holder has been constructed
423 bool simple_holder_constructed : 1;
424 /// For simple layout, tracks whether the instance is registered in `registered_instances`
425 bool simple_instance_registered : 1;
426 /// If true, get_internals().patients has an entry for this object
427 bool has_patients : 1;
429 /// Initializes all of the above type/values/holders data (but not the instance values themselves)
430 void allocate_layout();
432 /// Destroys/deallocates all of the above
433 void deallocate_layout();
435 /// Returns the value_and_holder wrapper for the given type (or the first, if `find_type`
436 /// omitted). Returns a default-constructed (with `.inst = nullptr`) object on failure if
437 /// `throw_if_missing` is false.
438 value_and_holder get_value_and_holder(const type_info *find_type = nullptr, bool throw_if_missing = true);
440 /// Bit values for the non-simple status flags
441 static constexpr uint8_t status_holder_constructed = 1;
442 static constexpr uint8_t status_instance_registered = 2;
445 static_assert(std::is_standard_layout<instance>::value, "Internal error: `pybind11::detail::instance` is not standard layout!");
447 /// from __cpp_future__ import (convenient aliases from C++14/17)
448 #if defined(PYBIND11_CPP14) && (!defined(_MSC_VER) || _MSC_VER >= 1910)
449 using std::enable_if_t;
450 using std::conditional_t;
451 using std::remove_cv_t;
452 using std::remove_reference_t;
454 template <bool B, typename T = void> using enable_if_t = typename std::enable_if<B, T>::type;
455 template <bool B, typename T, typename F> using conditional_t = typename std::conditional<B, T, F>::type;
456 template <typename T> using remove_cv_t = typename std::remove_cv<T>::type;
457 template <typename T> using remove_reference_t = typename std::remove_reference<T>::type;
461 #if defined(PYBIND11_CPP14)
462 using std::index_sequence;
463 using std::make_index_sequence;
465 template<size_t ...> struct index_sequence { };
466 template<size_t N, size_t ...S> struct make_index_sequence_impl : make_index_sequence_impl <N - 1, N - 1, S...> { };
467 template<size_t ...S> struct make_index_sequence_impl <0, S...> { typedef index_sequence<S...> type; };
468 template<size_t N> using make_index_sequence = typename make_index_sequence_impl<N>::type;
471 /// Make an index sequence of the indices of true arguments
472 template <typename ISeq, size_t, bool...> struct select_indices_impl { using type = ISeq; };
473 template <size_t... IPrev, size_t I, bool B, bool... Bs> struct select_indices_impl<index_sequence<IPrev...>, I, B, Bs...>
474 : select_indices_impl<conditional_t<B, index_sequence<IPrev..., I>, index_sequence<IPrev...>>, I + 1, Bs...> {};
475 template <bool... Bs> using select_indices = typename select_indices_impl<index_sequence<>, 0, Bs...>::type;
477 /// Backports of std::bool_constant and std::negation to accommodate older compilers
478 template <bool B> using bool_constant = std::integral_constant<bool, B>;
479 template <typename T> struct negation : bool_constant<!T::value> { };
481 template <typename...> struct void_t_impl { using type = void; };
482 template <typename... Ts> using void_t = typename void_t_impl<Ts...>::type;
484 /// Compile-time all/any/none of that check the boolean value of all template types
485 #if defined(__cpp_fold_expressions) && !(defined(_MSC_VER) && (_MSC_VER < 1916))
486 template <class... Ts> using all_of = bool_constant<(Ts::value && ...)>;
487 template <class... Ts> using any_of = bool_constant<(Ts::value || ...)>;
488 #elif !defined(_MSC_VER)
489 template <bool...> struct bools {};
490 template <class... Ts> using all_of = std::is_same<
491 bools<Ts::value..., true>,
492 bools<true, Ts::value...>>;
493 template <class... Ts> using any_of = negation<all_of<negation<Ts>...>>;
495 // MSVC has trouble with the above, but supports std::conjunction, which we can use instead (albeit
496 // at a slight loss of compilation efficiency).
497 template <class... Ts> using all_of = std::conjunction<Ts...>;
498 template <class... Ts> using any_of = std::disjunction<Ts...>;
500 template <class... Ts> using none_of = negation<any_of<Ts...>>;
502 template <class T, template<class> class... Predicates> using satisfies_all_of = all_of<Predicates<T>...>;
503 template <class T, template<class> class... Predicates> using satisfies_any_of = any_of<Predicates<T>...>;
504 template <class T, template<class> class... Predicates> using satisfies_none_of = none_of<Predicates<T>...>;
506 /// Strip the class from a method type
507 template <typename T> struct remove_class { };
508 template <typename C, typename R, typename... A> struct remove_class<R (C::*)(A...)> { typedef R type(A...); };
509 template <typename C, typename R, typename... A> struct remove_class<R (C::*)(A...) const> { typedef R type(A...); };
511 /// Helper template to strip away type modifiers
512 template <typename T> struct intrinsic_type { typedef T type; };
513 template <typename T> struct intrinsic_type<const T> { typedef typename intrinsic_type<T>::type type; };
514 template <typename T> struct intrinsic_type<T*> { typedef typename intrinsic_type<T>::type type; };
515 template <typename T> struct intrinsic_type<T&> { typedef typename intrinsic_type<T>::type type; };
516 template <typename T> struct intrinsic_type<T&&> { typedef typename intrinsic_type<T>::type type; };
517 template <typename T, size_t N> struct intrinsic_type<const T[N]> { typedef typename intrinsic_type<T>::type type; };
518 template <typename T, size_t N> struct intrinsic_type<T[N]> { typedef typename intrinsic_type<T>::type type; };
519 template <typename T> using intrinsic_t = typename intrinsic_type<T>::type;
521 /// Helper type to replace 'void' in some expressions
522 struct void_type { };
524 /// Helper template which holds a list of types
525 template <typename...> struct type_list { };
527 /// Compile-time integer sum
528 #ifdef __cpp_fold_expressions
529 template <typename... Ts> constexpr size_t constexpr_sum(Ts... ns) { return (0 + ... + size_t{ns}); }
531 constexpr size_t constexpr_sum() { return 0; }
532 template <typename T, typename... Ts>
533 constexpr size_t constexpr_sum(T n, Ts... ns) { return size_t{n} + constexpr_sum(ns...); }
536 NAMESPACE_BEGIN(constexpr_impl)
537 /// Implementation details for constexpr functions
538 constexpr int first(int i) { return i; }
539 template <typename T, typename... Ts>
540 constexpr int first(int i, T v, Ts... vs) { return v ? i : first(i + 1, vs...); }
542 constexpr int last(int /*i*/, int result) { return result; }
543 template <typename T, typename... Ts>
544 constexpr int last(int i, int result, T v, Ts... vs) { return last(i + 1, v ? i : result, vs...); }
545 NAMESPACE_END(constexpr_impl)
547 /// Return the index of the first type in Ts which satisfies Predicate<T>. Returns sizeof...(Ts) if
549 template <template<typename> class Predicate, typename... Ts>
550 constexpr int constexpr_first() { return constexpr_impl::first(0, Predicate<Ts>::value...); }
552 /// Return the index of the last type in Ts which satisfies Predicate<T>, or -1 if none match.
553 template <template<typename> class Predicate, typename... Ts>
554 constexpr int constexpr_last() { return constexpr_impl::last(0, -1, Predicate<Ts>::value...); }
556 /// Return the Nth element from the parameter pack
557 template <size_t N, typename T, typename... Ts>
558 struct pack_element { using type = typename pack_element<N - 1, Ts...>::type; };
559 template <typename T, typename... Ts>
560 struct pack_element<0, T, Ts...> { using type = T; };
562 /// Return the one and only type which matches the predicate, or Default if none match.
563 /// If more than one type matches the predicate, fail at compile-time.
564 template <template<typename> class Predicate, typename Default, typename... Ts>
566 static constexpr auto found = constexpr_sum(Predicate<Ts>::value...);
567 static_assert(found <= 1, "Found more than one type matching the predicate");
569 static constexpr auto index = found ? constexpr_first<Predicate, Ts...>() : 0;
570 using type = conditional_t<found, typename pack_element<index, Ts...>::type, Default>;
572 template <template<typename> class P, typename Default>
573 struct exactly_one<P, Default> { using type = Default; };
575 template <template<typename> class Predicate, typename Default, typename... Ts>
576 using exactly_one_t = typename exactly_one<Predicate, Default, Ts...>::type;
578 /// Defer the evaluation of type T until types Us are instantiated
579 template <typename T, typename... /*Us*/> struct deferred_type { using type = T; };
580 template <typename T, typename... Us> using deferred_t = typename deferred_type<T, Us...>::type;
582 /// Like is_base_of, but requires a strict base (i.e. `is_strict_base_of<T, T>::value == false`,
583 /// unlike `std::is_base_of`)
584 template <typename Base, typename Derived> using is_strict_base_of = bool_constant<
585 std::is_base_of<Base, Derived>::value && !std::is_same<Base, Derived>::value>;
587 template <template<typename...> class Base>
588 struct is_template_base_of_impl {
589 template <typename... Us> static std::true_type check(Base<Us...> *);
590 static std::false_type check(...);
593 /// Check if a template is the base of a type. For example:
594 /// `is_template_base_of<Base, T>` is true if `struct T : Base<U> {}` where U can be anything
595 template <template<typename...> class Base, typename T>
596 #if !defined(_MSC_VER)
597 using is_template_base_of = decltype(is_template_base_of_impl<Base>::check((intrinsic_t<T>*)nullptr));
598 #else // MSVC2015 has trouble with decltype in template aliases
599 struct is_template_base_of : decltype(is_template_base_of_impl<Base>::check((intrinsic_t<T>*)nullptr)) { };
602 /// Check if T is an instantiation of the template `Class`. For example:
603 /// `is_instantiation<shared_ptr, T>` is true if `T == shared_ptr<U>` where U can be anything.
604 template <template<typename...> class Class, typename T>
605 struct is_instantiation : std::false_type { };
606 template <template<typename...> class Class, typename... Us>
607 struct is_instantiation<Class, Class<Us...>> : std::true_type { };
609 /// Check if T is std::shared_ptr<U> where U can be anything
610 template <typename T> using is_shared_ptr = is_instantiation<std::shared_ptr, T>;
612 /// Check if T looks like an input iterator
613 template <typename T, typename = void> struct is_input_iterator : std::false_type {};
614 template <typename T>
615 struct is_input_iterator<T, void_t<decltype(*std::declval<T &>()), decltype(++std::declval<T &>())>>
618 template <typename T> using is_function_pointer = bool_constant<
619 std::is_pointer<T>::value && std::is_function<typename std::remove_pointer<T>::type>::value>;
621 template <typename F> struct strip_function_object {
622 using type = typename remove_class<decltype(&F::operator())>::type;
625 // Extracts the function signature from a function, function pointer or lambda.
626 template <typename Function, typename F = remove_reference_t<Function>>
627 using function_signature_t = conditional_t<
628 std::is_function<F>::value,
630 typename conditional_t<
631 std::is_pointer<F>::value || std::is_member_pointer<F>::value,
632 std::remove_pointer<F>,
633 strip_function_object<F>
637 /// Returns true if the type looks like a lambda: that is, isn't a function, pointer or member
638 /// pointer. Note that this can catch all sorts of other things, too; this is intended to be used
639 /// in a place where passing a lambda makes sense.
640 template <typename T> using is_lambda = satisfies_none_of<remove_reference_t<T>,
641 std::is_function, std::is_pointer, std::is_member_pointer>;
643 /// Ignore that a variable is unused in compiler warnings
644 inline void ignore_unused(const int *) { }
646 /// Apply a function over each element of a parameter pack
647 #ifdef __cpp_fold_expressions
648 #define PYBIND11_EXPAND_SIDE_EFFECTS(PATTERN) (((PATTERN), void()), ...)
650 using expand_side_effects = bool[];
651 #define PYBIND11_EXPAND_SIDE_EFFECTS(PATTERN) pybind11::detail::expand_side_effects{ ((PATTERN), void(), false)..., false }
654 NAMESPACE_END(detail)
656 /// C++ bindings of builtin Python exceptions
657 class builtin_exception : public std::runtime_error {
659 using std::runtime_error::runtime_error;
660 /// Set the error using the Python C API
661 virtual void set_error() const = 0;
664 #define PYBIND11_RUNTIME_EXCEPTION(name, type) \
665 class name : public builtin_exception { public: \
666 using builtin_exception::builtin_exception; \
667 name() : name("") { } \
668 void set_error() const override { PyErr_SetString(type, what()); } \
671 PYBIND11_RUNTIME_EXCEPTION(stop_iteration, PyExc_StopIteration)
672 PYBIND11_RUNTIME_EXCEPTION(index_error, PyExc_IndexError)
673 PYBIND11_RUNTIME_EXCEPTION(key_error, PyExc_KeyError)
674 PYBIND11_RUNTIME_EXCEPTION(value_error, PyExc_ValueError)
675 PYBIND11_RUNTIME_EXCEPTION(type_error, PyExc_TypeError)
676 PYBIND11_RUNTIME_EXCEPTION(cast_error, PyExc_RuntimeError) /// Thrown when pybind11::cast or handle::call fail due to a type casting error
677 PYBIND11_RUNTIME_EXCEPTION(reference_cast_error, PyExc_RuntimeError) /// Used internally
679 [[noreturn]] PYBIND11_NOINLINE inline void pybind11_fail(const char *reason) { throw std::runtime_error(reason); }
680 [[noreturn]] PYBIND11_NOINLINE inline void pybind11_fail(const std::string &reason) { throw std::runtime_error(reason); }
682 template <typename T, typename SFINAE = void> struct format_descriptor { };
684 NAMESPACE_BEGIN(detail)
685 // Returns the index of the given type in the type char array below, and in the list in numpy.h
686 // The order here is: bool; 8 ints ((signed,unsigned)x(8,16,32,64)bits); float,double,long double;
687 // complex float,double,long double. Note that the long double types only participate when long
688 // double is actually longer than double (it isn't under MSVC).
689 // NB: not only the string below but also complex.h and numpy.h rely on this order.
690 template <typename T, typename SFINAE = void> struct is_fmt_numeric { static constexpr bool value = false; };
691 template <typename T> struct is_fmt_numeric<T, enable_if_t<std::is_arithmetic<T>::value>> {
692 static constexpr bool value = true;
693 static constexpr int index = std::is_same<T, bool>::value ? 0 : 1 + (
694 std::is_integral<T>::value ? detail::log2(sizeof(T))*2 + std::is_unsigned<T>::value : 8 + (
695 std::is_same<T, double>::value ? 1 : std::is_same<T, long double>::value ? 2 : 0));
697 NAMESPACE_END(detail)
699 template <typename T> struct format_descriptor<T, detail::enable_if_t<std::is_arithmetic<T>::value>> {
700 static constexpr const char c = "?bBhHiIqQfdg"[detail::is_fmt_numeric<T>::index];
701 static constexpr const char value[2] = { c, '\0' };
702 static std::string format() { return std::string(1, c); }
705 template <typename T> constexpr const char format_descriptor<
706 T, detail::enable_if_t<std::is_arithmetic<T>::value>>::value[2];
708 /// RAII wrapper that temporarily clears any Python error state
710 PyObject *type, *value, *trace;
711 error_scope() { PyErr_Fetch(&type, &value, &trace); }
712 ~error_scope() { PyErr_Restore(type, value, trace); }
715 /// Dummy destructor wrapper that can be used to expose classes with a private destructor
716 struct nodelete { template <typename T> void operator()(T*) { } };
718 // overload_cast requires variable templates: C++14
719 #if defined(PYBIND11_CPP14)
720 #define PYBIND11_OVERLOAD_CAST 1
722 NAMESPACE_BEGIN(detail)
723 template <typename... Args>
724 struct overload_cast_impl {
725 constexpr overload_cast_impl() {} // MSVC 2015 needs this
727 template <typename Return>
728 constexpr auto operator()(Return (*pf)(Args...)) const noexcept
729 -> decltype(pf) { return pf; }
731 template <typename Return, typename Class>
732 constexpr auto operator()(Return (Class::*pmf)(Args...), std::false_type = {}) const noexcept
733 -> decltype(pmf) { return pmf; }
735 template <typename Return, typename Class>
736 constexpr auto operator()(Return (Class::*pmf)(Args...) const, std::true_type) const noexcept
737 -> decltype(pmf) { return pmf; }
739 NAMESPACE_END(detail)
741 /// Syntax sugar for resolving overloaded function pointers:
742 /// - regular: static_cast<Return (Class::*)(Arg0, Arg1, Arg2)>(&Class::func)
743 /// - sweet: overload_cast<Arg0, Arg1, Arg2>(&Class::func)
744 template <typename... Args>
745 static constexpr detail::overload_cast_impl<Args...> overload_cast = {};
746 // MSVC 2015 only accepts this particular initialization syntax for this variable template.
748 /// Const member function selector for overload_cast
749 /// - regular: static_cast<Return (Class::*)(Arg) const>(&Class::func)
750 /// - sweet: overload_cast<Arg>(&Class::func, const_)
751 static constexpr auto const_ = std::true_type{};
753 #else // no overload_cast: providing something that static_assert-fails:
754 template <typename... Args> struct overload_cast {
755 static_assert(detail::deferred_t<std::false_type, Args...>::value,
756 "pybind11::overload_cast<...> requires compiling in C++14 mode");
758 #endif // overload_cast
760 NAMESPACE_BEGIN(detail)
762 // Adaptor for converting arbitrary container arguments into a vector; implicitly convertible from
763 // any standard container (or C-style array) supporting std::begin/std::end, any singleton
764 // arithmetic type (if T is arithmetic), or explicitly constructible from an iterator pair.
765 template <typename T>
766 class any_container {
769 any_container() = default;
771 // Can construct from a pair of iterators
772 template <typename It, typename = enable_if_t<is_input_iterator<It>::value>>
773 any_container(It first, It last) : v(first, last) { }
775 // Implicit conversion constructor from any arbitrary container type with values convertible to T
776 template <typename Container, typename = enable_if_t<std::is_convertible<decltype(*std::begin(std::declval<const Container &>())), T>::value>>
777 any_container(const Container &c) : any_container(std::begin(c), std::end(c)) { }
779 // initializer_list's aren't deducible, so don't get matched by the above template; we need this
780 // to explicitly allow implicit conversion from one:
781 template <typename TIn, typename = enable_if_t<std::is_convertible<TIn, T>::value>>
782 any_container(const std::initializer_list<TIn> &c) : any_container(c.begin(), c.end()) { }
784 // Avoid copying if given an rvalue vector of the correct type.
785 any_container(std::vector<T> &&v) : v(std::move(v)) { }
787 // Moves the vector out of an rvalue any_container
788 operator std::vector<T> &&() && { return std::move(v); }
790 // Dereferencing obtains a reference to the underlying vector
791 std::vector<T> &operator*() { return v; }
792 const std::vector<T> &operator*() const { return v; }
794 // -> lets you call methods on the underlying vector
795 std::vector<T> *operator->() { return &v; }
796 const std::vector<T> *operator->() const { return &v; }
799 NAMESPACE_END(detail)
803 NAMESPACE_END(PYBIND11_NAMESPACE)