2 pybind11/std_bind.h: Binding generators for STL data types
4 Copyright (c) 2016 Sergey Lyskov and Wenzel Jakob
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 #include "detail/common.h"
13 #include "operators.h"
18 NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
19 NAMESPACE_BEGIN(detail)
21 /* SFINAE helper class used by 'is_comparable */
22 template <typename T> struct container_traits {
23 template <typename T2> static std::true_type test_comparable(decltype(std::declval<const T2 &>() == std::declval<const T2 &>())*);
24 template <typename T2> static std::false_type test_comparable(...);
25 template <typename T2> static std::true_type test_value(typename T2::value_type *);
26 template <typename T2> static std::false_type test_value(...);
27 template <typename T2> static std::true_type test_pair(typename T2::first_type *, typename T2::second_type *);
28 template <typename T2> static std::false_type test_pair(...);
30 static constexpr const bool is_comparable = std::is_same<std::true_type, decltype(test_comparable<T>(nullptr))>::value;
31 static constexpr const bool is_pair = std::is_same<std::true_type, decltype(test_pair<T>(nullptr, nullptr))>::value;
32 static constexpr const bool is_vector = std::is_same<std::true_type, decltype(test_value<T>(nullptr))>::value;
33 static constexpr const bool is_element = !is_pair && !is_vector;
36 /* Default: is_comparable -> std::false_type */
37 template <typename T, typename SFINAE = void>
38 struct is_comparable : std::false_type { };
40 /* For non-map data structures, check whether operator== can be instantiated */
43 T, enable_if_t<container_traits<T>::is_element &&
44 container_traits<T>::is_comparable>>
47 /* For a vector/map data structure, recursively check the value type (which is std::pair for maps) */
49 struct is_comparable<T, enable_if_t<container_traits<T>::is_vector>> {
50 static constexpr const bool value =
51 is_comparable<typename T::value_type>::value;
54 /* For pairs, recursively check the two data types */
56 struct is_comparable<T, enable_if_t<container_traits<T>::is_pair>> {
57 static constexpr const bool value =
58 is_comparable<typename T::first_type>::value &&
59 is_comparable<typename T::second_type>::value;
62 /* Fallback functions */
63 template <typename, typename, typename... Args> void vector_if_copy_constructible(const Args &...) { }
64 template <typename, typename, typename... Args> void vector_if_equal_operator(const Args &...) { }
65 template <typename, typename, typename... Args> void vector_if_insertion_operator(const Args &...) { }
66 template <typename, typename, typename... Args> void vector_modifiers(const Args &...) { }
68 template<typename Vector, typename Class_>
69 void vector_if_copy_constructible(enable_if_t<is_copy_constructible<Vector>::value, Class_> &cl) {
70 cl.def(init<const Vector &>(), "Copy constructor");
73 template<typename Vector, typename Class_>
74 void vector_if_equal_operator(enable_if_t<is_comparable<Vector>::value, Class_> &cl) {
75 using T = typename Vector::value_type;
81 [](const Vector &v, const T &x) {
82 return std::count(v.begin(), v.end(), x);
85 "Return the number of times ``x`` appears in the list"
88 cl.def("remove", [](Vector &v, const T &x) {
89 auto p = std::find(v.begin(), v.end(), x);
96 "Remove the first item from the list whose value is x. "
97 "It is an error if there is no such item."
100 cl.def("__contains__",
101 [](const Vector &v, const T &x) {
102 return std::find(v.begin(), v.end(), x) != v.end();
105 "Return true the container contains ``x``"
109 // Vector modifiers -- requires a copyable vector_type:
110 // (Technically, some of these (pop and __delitem__) don't actually require copyability, but it seems
111 // silly to allow deletion but not insertion, so include them here too.)
112 template <typename Vector, typename Class_>
113 void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_type>::value, Class_> &cl) {
114 using T = typename Vector::value_type;
115 using SizeType = typename Vector::size_type;
116 using DiffType = typename Vector::difference_type;
118 auto wrap_i = [](DiffType i, SizeType n) {
121 if (i < 0 || (SizeType)i >= n)
127 [](Vector &v, const T &value) { v.push_back(value); },
129 "Add an item to the end of the list");
131 cl.def(init([](iterable it) {
132 auto v = std::unique_ptr<Vector>(new Vector());
133 v->reserve(len_hint(it));
135 v->push_back(h.cast<T>());
147 [](Vector &v, const Vector &src) {
148 v.insert(v.end(), src.begin(), src.end());
151 "Extend the list by appending all the items in the given list"
155 [](Vector &v, iterable it) {
156 const size_t old_size = v.size();
157 v.reserve(old_size + len_hint(it));
159 for (handle h : it) {
160 v.push_back(h.cast<T>());
162 } catch (const cast_error &) {
163 v.erase(v.begin() + static_cast<typename Vector::difference_type>(old_size), v.end());
166 } catch (const std::exception &) {
173 "Extend the list by appending all the items in the given list"
177 [](Vector &v, DiffType i, const T &x) {
178 // Can't use wrap_i; i == v.size() is OK
181 if (i < 0 || (SizeType)i > v.size())
183 v.insert(v.begin() + i, x);
186 "Insert an item at a given position."
197 "Remove and return the last item"
201 [wrap_i](Vector &v, DiffType i) {
202 i = wrap_i(i, v.size());
203 T t = v[(SizeType) i];
204 v.erase(v.begin() + i);
208 "Remove and return the item at index ``i``"
211 cl.def("__setitem__",
212 [wrap_i](Vector &v, DiffType i, const T &t) {
213 i = wrap_i(i, v.size());
219 cl.def("__getitem__",
220 [](const Vector &v, slice slice) -> Vector * {
221 size_t start, stop, step, slicelength;
223 if (!slice.compute(v.size(), &start, &stop, &step, &slicelength))
224 throw error_already_set();
226 Vector *seq = new Vector();
227 seq->reserve((size_t) slicelength);
229 for (size_t i=0; i<slicelength; ++i) {
230 seq->push_back(v[start]);
236 "Retrieve list elements using a slice object"
239 cl.def("__setitem__",
240 [](Vector &v, slice slice, const Vector &value) {
241 size_t start, stop, step, slicelength;
242 if (!slice.compute(v.size(), &start, &stop, &step, &slicelength))
243 throw error_already_set();
245 if (slicelength != value.size())
246 throw std::runtime_error("Left and right hand size of slice assignment have different sizes!");
248 for (size_t i=0; i<slicelength; ++i) {
253 "Assign list elements using a slice object"
256 cl.def("__delitem__",
257 [wrap_i](Vector &v, DiffType i) {
258 i = wrap_i(i, v.size());
259 v.erase(v.begin() + i);
261 "Delete the list elements at index ``i``"
264 cl.def("__delitem__",
265 [](Vector &v, slice slice) {
266 size_t start, stop, step, slicelength;
268 if (!slice.compute(v.size(), &start, &stop, &step, &slicelength))
269 throw error_already_set();
271 if (step == 1 && false) {
272 v.erase(v.begin() + (DiffType) start, v.begin() + DiffType(start + slicelength));
274 for (size_t i = 0; i < slicelength; ++i) {
275 v.erase(v.begin() + DiffType(start));
280 "Delete list elements using a slice object"
285 // If the type has an operator[] that doesn't return a reference (most notably std::vector<bool>),
286 // we have to access by copying; otherwise we return by reference.
287 template <typename Vector> using vector_needs_copy = negation<
288 std::is_same<decltype(std::declval<Vector>()[typename Vector::size_type()]), typename Vector::value_type &>>;
290 // The usual case: access and iterate by reference
291 template <typename Vector, typename Class_>
292 void vector_accessor(enable_if_t<!vector_needs_copy<Vector>::value, Class_> &cl) {
293 using T = typename Vector::value_type;
294 using SizeType = typename Vector::size_type;
295 using DiffType = typename Vector::difference_type;
296 using ItType = typename Vector::iterator;
298 auto wrap_i = [](DiffType i, SizeType n) {
301 if (i < 0 || (SizeType)i >= n)
306 cl.def("__getitem__",
307 [wrap_i](Vector &v, DiffType i) -> T & {
308 i = wrap_i(i, v.size());
309 return v[(SizeType)i];
311 return_value_policy::reference_internal // ref + keepalive
316 return make_iterator<
317 return_value_policy::reference_internal, ItType, ItType, T&>(
320 keep_alive<0, 1>() /* Essential: keep list alive while iterator exists */
324 // The case for special objects, like std::vector<bool>, that have to be returned-by-copy:
325 template <typename Vector, typename Class_>
326 void vector_accessor(enable_if_t<vector_needs_copy<Vector>::value, Class_> &cl) {
327 using T = typename Vector::value_type;
328 using SizeType = typename Vector::size_type;
329 using DiffType = typename Vector::difference_type;
330 using ItType = typename Vector::iterator;
331 cl.def("__getitem__",
332 [](const Vector &v, DiffType i) -> T {
333 if (i < 0 && (i += v.size()) < 0)
335 if ((SizeType)i >= v.size())
337 return v[(SizeType)i];
343 return make_iterator<
344 return_value_policy::copy, ItType, ItType, T>(
347 keep_alive<0, 1>() /* Essential: keep list alive while iterator exists */
351 template <typename Vector, typename Class_> auto vector_if_insertion_operator(Class_ &cl, std::string const &name)
352 -> decltype(std::declval<std::ostream&>() << std::declval<typename Vector::value_type>(), void()) {
353 using size_type = typename Vector::size_type;
357 std::ostringstream s;
359 for (size_type i=0; i < v.size(); ++i) {
361 if (i != v.size() - 1)
367 "Return the canonical string representation of this list."
371 // Provide the buffer interface for vectors if we have data() and we have a format for it
372 // GCC seems to have "void std::vector<bool>::data()" - doing SFINAE on the existence of data() is insufficient, we need to check it returns an appropriate pointer
373 template <typename Vector, typename = void>
374 struct vector_has_data_and_format : std::false_type {};
375 template <typename Vector>
376 struct vector_has_data_and_format<Vector, enable_if_t<std::is_same<decltype(format_descriptor<typename Vector::value_type>::format(), std::declval<Vector>().data()), typename Vector::value_type*>::value>> : std::true_type {};
378 // Add the buffer interface to a vector
379 template <typename Vector, typename Class_, typename... Args>
380 enable_if_t<detail::any_of<std::is_same<Args, buffer_protocol>...>::value>
381 vector_buffer(Class_& cl) {
382 using T = typename Vector::value_type;
384 static_assert(vector_has_data_and_format<Vector>::value, "There is not an appropriate format descriptor for this vector");
386 // numpy.h declares this for arbitrary types, but it may raise an exception and crash hard at runtime if PYBIND11_NUMPY_DTYPE hasn't been called, so check here
387 format_descriptor<T>::format();
389 cl.def_buffer([](Vector& v) -> buffer_info {
390 return buffer_info(v.data(), static_cast<ssize_t>(sizeof(T)), format_descriptor<T>::format(), 1, {v.size()}, {sizeof(T)});
393 cl.def(init([](buffer buf) {
394 auto info = buf.request();
395 if (info.ndim != 1 || info.strides[0] % static_cast<ssize_t>(sizeof(T)))
396 throw type_error("Only valid 1D buffers can be copied to a vector");
397 if (!detail::compare_buffer_info<T>::compare(info) || (ssize_t) sizeof(T) != info.itemsize)
398 throw type_error("Format mismatch (Python: " + info.format + " C++: " + format_descriptor<T>::format() + ")");
400 auto vec = std::unique_ptr<Vector>(new Vector());
401 vec->reserve((size_t) info.shape[0]);
402 T *p = static_cast<T*>(info.ptr);
403 ssize_t step = info.strides[0] / static_cast<ssize_t>(sizeof(T));
404 T *end = p + info.shape[0] * step;
405 for (; p != end; p += step)
407 return vec.release();
413 template <typename Vector, typename Class_, typename... Args>
414 enable_if_t<!detail::any_of<std::is_same<Args, buffer_protocol>...>::value> vector_buffer(Class_&) {}
416 NAMESPACE_END(detail)
421 template <typename Vector, typename holder_type = std::unique_ptr<Vector>, typename... Args>
422 class_<Vector, holder_type> bind_vector(handle scope, std::string const &name, Args&&... args) {
423 using Class_ = class_<Vector, holder_type>;
425 // If the value_type is unregistered (e.g. a converting type) or is itself registered
426 // module-local then make the vector binding module-local as well:
427 using vtype = typename Vector::value_type;
428 auto vtype_info = detail::get_type_info(typeid(vtype));
429 bool local = !vtype_info || vtype_info->module_local;
431 Class_ cl(scope, name.c_str(), pybind11::module_local(local), std::forward<Args>(args)...);
433 // Declare the buffer interface if a buffer_protocol() is passed in
434 detail::vector_buffer<Vector, Class_, Args...>(cl);
438 // Register copy constructor (if possible)
439 detail::vector_if_copy_constructible<Vector, Class_>(cl);
441 // Register comparison-related operators and functions (if possible)
442 detail::vector_if_equal_operator<Vector, Class_>(cl);
444 // Register stream insertion operator (if possible)
445 detail::vector_if_insertion_operator<Vector, Class_>(cl, name);
447 // Modifiers require copyable vector value type
448 detail::vector_modifiers<Vector, Class_>(cl);
450 // Accessor and iterator; return by value if copyable, otherwise we return by ref + keep-alive
451 detail::vector_accessor<Vector, Class_>(cl);
454 [](const Vector &v) -> bool {
457 "Check whether the list is nonempty"
460 cl.def("__len__", &Vector::size);
466 // C++ style functions deprecated, leaving it here as an example
467 cl.def(init<size_type>());
470 (void (Vector::*) (size_type count)) & Vector::resize,
471 "changes the number of elements stored");
474 [](Vector &v, SizeType i) {
477 v.erase(v.begin() + i);
478 }, "erases element at index ``i``");
480 cl.def("empty", &Vector::empty, "checks whether the container is empty");
481 cl.def("size", &Vector::size, "returns the number of elements");
482 cl.def("push_back", (void (Vector::*)(const T&)) &Vector::push_back, "adds an element to the end");
483 cl.def("pop_back", &Vector::pop_back, "removes the last element");
485 cl.def("max_size", &Vector::max_size, "returns the maximum possible number of elements");
486 cl.def("reserve", &Vector::reserve, "reserves storage");
487 cl.def("capacity", &Vector::capacity, "returns the number of elements that can be held in currently allocated storage");
488 cl.def("shrink_to_fit", &Vector::shrink_to_fit, "reduces memory usage by freeing unused memory");
490 cl.def("clear", &Vector::clear, "clears the contents");
491 cl.def("swap", &Vector::swap, "swaps the contents");
493 cl.def("front", [](Vector &v) {
494 if (v.size()) return v.front();
495 else throw index_error();
496 }, "access the first element");
498 cl.def("back", [](Vector &v) {
499 if (v.size()) return v.back();
500 else throw index_error();
501 }, "access the last element ");
511 // std::map, std::unordered_map
514 NAMESPACE_BEGIN(detail)
516 /* Fallback functions */
517 template <typename, typename, typename... Args> void map_if_insertion_operator(const Args &...) { }
518 template <typename, typename, typename... Args> void map_assignment(const Args &...) { }
520 // Map assignment when copy-assignable: just copy the value
521 template <typename Map, typename Class_>
522 void map_assignment(enable_if_t<is_copy_assignable<typename Map::mapped_type>::value, Class_> &cl) {
523 using KeyType = typename Map::key_type;
524 using MappedType = typename Map::mapped_type;
526 cl.def("__setitem__",
527 [](Map &m, const KeyType &k, const MappedType &v) {
529 if (it != m.end()) it->second = v;
530 else m.emplace(k, v);
535 // Not copy-assignable, but still copy-constructible: we can update the value by erasing and reinserting
536 template<typename Map, typename Class_>
537 void map_assignment(enable_if_t<
538 !is_copy_assignable<typename Map::mapped_type>::value &&
539 is_copy_constructible<typename Map::mapped_type>::value,
541 using KeyType = typename Map::key_type;
542 using MappedType = typename Map::mapped_type;
544 cl.def("__setitem__",
545 [](Map &m, const KeyType &k, const MappedType &v) {
546 // We can't use m[k] = v; because value type might not be default constructable
547 auto r = m.emplace(k, v);
549 // value type is not copy assignable so the only way to insert it is to erase it first...
558 template <typename Map, typename Class_> auto map_if_insertion_operator(Class_ &cl, std::string const &name)
559 -> decltype(std::declval<std::ostream&>() << std::declval<typename Map::key_type>() << std::declval<typename Map::mapped_type>(), void()) {
563 std::ostringstream s;
566 for (auto const &kv : m) {
569 s << kv.first << ": " << kv.second;
575 "Return the canonical string representation of this map."
580 NAMESPACE_END(detail)
582 template <typename Map, typename holder_type = std::unique_ptr<Map>, typename... Args>
583 class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args&&... args) {
584 using KeyType = typename Map::key_type;
585 using MappedType = typename Map::mapped_type;
586 using Class_ = class_<Map, holder_type>;
588 // If either type is a non-module-local bound type then make the map binding non-local as well;
589 // otherwise (e.g. both types are either module-local or converting) the map will be
591 auto tinfo = detail::get_type_info(typeid(MappedType));
592 bool local = !tinfo || tinfo->module_local;
594 tinfo = detail::get_type_info(typeid(KeyType));
595 local = !tinfo || tinfo->module_local;
598 Class_ cl(scope, name.c_str(), pybind11::module_local(local), std::forward<Args>(args)...);
602 // Register stream insertion operator (if possible)
603 detail::map_if_insertion_operator<Map, Class_>(cl, name);
606 [](const Map &m) -> bool { return !m.empty(); },
607 "Check whether the map is nonempty"
611 [](Map &m) { return make_key_iterator(m.begin(), m.end()); },
612 keep_alive<0, 1>() /* Essential: keep list alive while iterator exists */
616 [](Map &m) { return make_iterator(m.begin(), m.end()); },
617 keep_alive<0, 1>() /* Essential: keep list alive while iterator exists */
620 cl.def("__getitem__",
621 [](Map &m, const KeyType &k) -> MappedType & {
627 return_value_policy::reference_internal // ref + keepalive
630 cl.def("__contains__",
631 [](Map &m, const KeyType &k) -> bool {
639 // Assignment provided only if the type is copyable
640 detail::map_assignment<Map, Class_>(cl);
642 cl.def("__delitem__",
643 [](Map &m, const KeyType &k) {
651 cl.def("__len__", &Map::size);
656 NAMESPACE_END(PYBIND11_NAMESPACE)