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pybind11/include/pybind11/cast.h
Lalaland 8ea75ab4d7
Fix casts to void* (#4275) 
* Fix casts to void*

* Improve tests

* style: pre-commit fixes

* remove c style cast

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Aaron Gokaslan <aaronGokaslan@gmail.com>
2022-10-22 16:52:35 -07:00

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/*
pybind11/cast.h: Partial template specializations to cast between
C++ and Python types
Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.
*/
#pragma once
#include "detail/common.h"
#include "detail/descr.h"
#include "detail/type_caster_base.h"
#include "detail/typeid.h"
#include "pytypes.h"
#include <array>
#include <cstring>
#include <functional>
#include <iosfwd>
#include <iterator>
#include <memory>
#include <string>
#include <tuple>
#include <type_traits>
#include <utility>
#include <vector>
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
PYBIND11_NAMESPACE_BEGIN(detail)
template <typename type, typename SFINAE = void>
class type_caster : public type_caster_base<type> {};
template <typename type>
using make_caster = type_caster<intrinsic_t<type>>;
// Shortcut for calling a caster's `cast_op_type` cast operator for casting a type_caster to a T
template <typename T>
typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &caster) {
return caster.operator typename make_caster<T>::template cast_op_type<T>();
}
template <typename T>
typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>
cast_op(make_caster<T> &&caster) {
return std::move(caster).operator typename make_caster<T>::
template cast_op_type<typename std::add_rvalue_reference<T>::type>();
}
template <typename type>
class type_caster<std::reference_wrapper<type>> {
private:
using caster_t = make_caster<type>;
caster_t subcaster;
using reference_t = type &;
using subcaster_cast_op_type = typename caster_t::template cast_op_type<reference_t>;
static_assert(
std::is_same<typename std::remove_const<type>::type &, subcaster_cast_op_type>::value
|| std::is_same<reference_t, subcaster_cast_op_type>::value,
"std::reference_wrapper<T> caster requires T to have a caster with an "
"`operator T &()` or `operator const T &()`");
public:
bool load(handle src, bool convert) { return subcaster.load(src, convert); }
static constexpr auto name = caster_t::name;
static handle
cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
// It is definitely wrong to take ownership of this pointer, so mask that rvp
if (policy == return_value_policy::take_ownership
|| policy == return_value_policy::automatic) {
policy = return_value_policy::automatic_reference;
}
return caster_t::cast(&src.get(), policy, parent);
}
template <typename T>
using cast_op_type = std::reference_wrapper<type>;
explicit operator std::reference_wrapper<type>() { return cast_op<type &>(subcaster); }
};
#define PYBIND11_TYPE_CASTER(type, py_name) \
protected: \
type value; \
\
public: \
static constexpr auto name = py_name; \
template <typename T_, \
::pybind11::detail::enable_if_t< \
std::is_same<type, ::pybind11::detail::remove_cv_t<T_>>::value, \
int> = 0> \
static ::pybind11::handle cast( \
T_ *src, ::pybind11::return_value_policy policy, ::pybind11::handle parent) { \
if (!src) \
return ::pybind11::none().release(); \
if (policy == ::pybind11::return_value_policy::take_ownership) { \
auto h = cast(std::move(*src), policy, parent); \
delete src; \
return h; \
} \
return cast(*src, policy, parent); \
} \
operator type *() { return &value; } /* NOLINT(bugprone-macro-parentheses) */ \
operator type &() { return value; } /* NOLINT(bugprone-macro-parentheses) */ \
operator type &&() && { return std::move(value); } /* NOLINT(bugprone-macro-parentheses) */ \
template <typename T_> \
using cast_op_type = ::pybind11::detail::movable_cast_op_type<T_>
template <typename CharT>
using is_std_char_type = any_of<std::is_same<CharT, char>, /* std::string */
#if defined(PYBIND11_HAS_U8STRING)
std::is_same<CharT, char8_t>, /* std::u8string */
#endif
std::is_same<CharT, char16_t>, /* std::u16string */
std::is_same<CharT, char32_t>, /* std::u32string */
std::is_same<CharT, wchar_t> /* std::wstring */
>;
template <typename T>
struct type_caster<T, enable_if_t<std::is_arithmetic<T>::value && !is_std_char_type<T>::value>> {
using _py_type_0 = conditional_t<sizeof(T) <= sizeof(long), long, long long>;
using _py_type_1 = conditional_t<std::is_signed<T>::value,
_py_type_0,
typename std::make_unsigned<_py_type_0>::type>;
using py_type = conditional_t<std::is_floating_point<T>::value, double, _py_type_1>;
public:
bool load(handle src, bool convert) {
py_type py_value;
if (!src) {
return false;
}
#if !defined(PYPY_VERSION)
auto index_check = [](PyObject *o) { return PyIndex_Check(o); };
#else
// In PyPy 7.3.3, `PyIndex_Check` is implemented by calling `__index__`,
// while CPython only considers the existence of `nb_index`/`__index__`.
auto index_check = [](PyObject *o) { return hasattr(o, "__index__"); };
#endif
if (std::is_floating_point<T>::value) {
if (convert || PyFloat_Check(src.ptr())) {
py_value = (py_type) PyFloat_AsDouble(src.ptr());
} else {
return false;
}
} else if (PyFloat_Check(src.ptr())
|| (!convert && !PYBIND11_LONG_CHECK(src.ptr()) && !index_check(src.ptr()))) {
return false;
} else {
handle src_or_index = src;
// PyPy: 7.3.7's 3.8 does not implement PyLong_*'s __index__ calls.
#if PY_VERSION_HEX < 0x03080000 || defined(PYPY_VERSION)
object index;
if (!PYBIND11_LONG_CHECK(src.ptr())) { // So: index_check(src.ptr())
index = reinterpret_steal<object>(PyNumber_Index(src.ptr()));
if (!index) {
PyErr_Clear();
if (!convert)
return false;
} else {
src_or_index = index;
}
}
#endif
if (std::is_unsigned<py_type>::value) {
py_value = as_unsigned<py_type>(src_or_index.ptr());
} else { // signed integer:
py_value = sizeof(T) <= sizeof(long)
? (py_type) PyLong_AsLong(src_or_index.ptr())
: (py_type) PYBIND11_LONG_AS_LONGLONG(src_or_index.ptr());
}
}
// Python API reported an error
bool py_err = py_value == (py_type) -1 && PyErr_Occurred();
// Check to see if the conversion is valid (integers should match exactly)
// Signed/unsigned checks happen elsewhere
if (py_err
|| (std::is_integral<T>::value && sizeof(py_type) != sizeof(T)
&& py_value != (py_type) (T) py_value)) {
PyErr_Clear();
if (py_err && convert && (PyNumber_Check(src.ptr()) != 0)) {
auto tmp = reinterpret_steal<object>(std::is_floating_point<T>::value
? PyNumber_Float(src.ptr())
: PyNumber_Long(src.ptr()));
PyErr_Clear();
return load(tmp, false);
}
return false;
}
value = (T) py_value;
return true;
}
template <typename U = T>
static typename std::enable_if<std::is_floating_point<U>::value, handle>::type
cast(U src, return_value_policy /* policy */, handle /* parent */) {
return PyFloat_FromDouble((double) src);
}
template <typename U = T>
static typename std::enable_if<!std::is_floating_point<U>::value && std::is_signed<U>::value
&& (sizeof(U) <= sizeof(long)),
handle>::type
cast(U src, return_value_policy /* policy */, handle /* parent */) {
return PYBIND11_LONG_FROM_SIGNED((long) src);
}
template <typename U = T>
static typename std::enable_if<!std::is_floating_point<U>::value && std::is_unsigned<U>::value
&& (sizeof(U) <= sizeof(unsigned long)),
handle>::type
cast(U src, return_value_policy /* policy */, handle /* parent */) {
return PYBIND11_LONG_FROM_UNSIGNED((unsigned long) src);
}
template <typename U = T>
static typename std::enable_if<!std::is_floating_point<U>::value && std::is_signed<U>::value
&& (sizeof(U) > sizeof(long)),
handle>::type
cast(U src, return_value_policy /* policy */, handle /* parent */) {
return PyLong_FromLongLong((long long) src);
}
template <typename U = T>
static typename std::enable_if<!std::is_floating_point<U>::value && std::is_unsigned<U>::value
&& (sizeof(U) > sizeof(unsigned long)),
handle>::type
cast(U src, return_value_policy /* policy */, handle /* parent */) {
return PyLong_FromUnsignedLongLong((unsigned long long) src);
}
PYBIND11_TYPE_CASTER(T, const_name<std::is_integral<T>::value>("int", "float"));
};
template <typename T>
struct void_caster {
public:
bool load(handle src, bool) {
if (src && src.is_none()) {
return true;
}
return false;
}
static handle cast(T, return_value_policy /* policy */, handle /* parent */) {
return none().release();
}
PYBIND11_TYPE_CASTER(T, const_name("None"));
};
template <>
class type_caster<void_type> : public void_caster<void_type> {};
template <>
class type_caster<void> : public type_caster<void_type> {
public:
using type_caster<void_type>::cast;
bool load(handle h, bool) {
if (!h) {
return false;
}
if (h.is_none()) {
value = nullptr;
return true;
}
/* Check if this is a capsule */
if (isinstance<capsule>(h)) {
value = reinterpret_borrow<capsule>(h);
return true;
}
/* Check if this is a C++ type */
const auto &bases = all_type_info((PyTypeObject *) type::handle_of(h).ptr());
if (bases.size() == 1) { // Only allowing loading from a single-value type
value = values_and_holders(reinterpret_cast<instance *>(h.ptr())).begin()->value_ptr();
return true;
}
/* Fail */
return false;
}
static handle cast(const void *ptr, return_value_policy /* policy */, handle /* parent */) {
if (ptr) {
return capsule(ptr).release();
}
return none().release();
}
template <typename T>
using cast_op_type = void *&;
explicit operator void *&() { return value; }
static constexpr auto name = const_name("capsule");
private:
void *value = nullptr;
};
template <>
class type_caster<std::nullptr_t> : public void_caster<std::nullptr_t> {};
template <>
class type_caster<bool> {
public:
bool load(handle src, bool convert) {
if (!src) {
return false;
}
if (src.ptr() == Py_True) {
value = true;
return true;
}
if (src.ptr() == Py_False) {
value = false;
return true;
}
if (convert || (std::strcmp("numpy.bool_", Py_TYPE(src.ptr())->tp_name) == 0)) {
// (allow non-implicit conversion for numpy booleans)
Py_ssize_t res = -1;
if (src.is_none()) {
res = 0; // None is implicitly converted to False
}
#if defined(PYPY_VERSION)
// On PyPy, check that "__bool__" attr exists
else if (hasattr(src, PYBIND11_BOOL_ATTR)) {
res = PyObject_IsTrue(src.ptr());
}
#else
// Alternate approach for CPython: this does the same as the above, but optimized
// using the CPython API so as to avoid an unneeded attribute lookup.
else if (auto *tp_as_number = src.ptr()->ob_type->tp_as_number) {
if (PYBIND11_NB_BOOL(tp_as_number)) {
res = (*PYBIND11_NB_BOOL(tp_as_number))(src.ptr());
}
}
#endif
if (res == 0 || res == 1) {
value = (res != 0);
return true;
}
PyErr_Clear();
}
return false;
}
static handle cast(bool src, return_value_policy /* policy */, handle /* parent */) {
return handle(src ? Py_True : Py_False).inc_ref();
}
PYBIND11_TYPE_CASTER(bool, const_name("bool"));
};
// Helper class for UTF-{8,16,32} C++ stl strings:
template <typename StringType, bool IsView = false>
struct string_caster {
using CharT = typename StringType::value_type;
// Simplify life by being able to assume standard char sizes (the standard only guarantees
// minimums, but Python requires exact sizes)
static_assert(!std::is_same<CharT, char>::value || sizeof(CharT) == 1,
"Unsupported char size != 1");
#if defined(PYBIND11_HAS_U8STRING)
static_assert(!std::is_same<CharT, char8_t>::value || sizeof(CharT) == 1,
"Unsupported char8_t size != 1");
#endif
static_assert(!std::is_same<CharT, char16_t>::value || sizeof(CharT) == 2,
"Unsupported char16_t size != 2");
static_assert(!std::is_same<CharT, char32_t>::value || sizeof(CharT) == 4,
"Unsupported char32_t size != 4");
// wchar_t can be either 16 bits (Windows) or 32 (everywhere else)
static_assert(!std::is_same<CharT, wchar_t>::value || sizeof(CharT) == 2 || sizeof(CharT) == 4,
"Unsupported wchar_t size != 2/4");
static constexpr size_t UTF_N = 8 * sizeof(CharT);
bool load(handle src, bool) {
handle load_src = src;
if (!src) {
return false;
}
if (!PyUnicode_Check(load_src.ptr())) {
return load_raw(load_src);
}
// For UTF-8 we avoid the need for a temporary `bytes` object by using
// `PyUnicode_AsUTF8AndSize`.
if (PYBIND11_SILENCE_MSVC_C4127(UTF_N == 8)) {
Py_ssize_t size = -1;
const auto *buffer
= reinterpret_cast<const CharT *>(PyUnicode_AsUTF8AndSize(load_src.ptr(), &size));
if (!buffer) {
PyErr_Clear();
return false;
}
value = StringType(buffer, static_cast<size_t>(size));
return true;
}
auto utfNbytes
= reinterpret_steal<object>(PyUnicode_AsEncodedString(load_src.ptr(),
UTF_N == 8 ? "utf-8"
: UTF_N == 16 ? "utf-16"
: "utf-32",
nullptr));
if (!utfNbytes) {
PyErr_Clear();
return false;
}
const auto *buffer
= reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
size_t length = (size_t) PYBIND11_BYTES_SIZE(utfNbytes.ptr()) / sizeof(CharT);
// Skip BOM for UTF-16/32
if (PYBIND11_SILENCE_MSVC_C4127(UTF_N > 8)) {
buffer++;
length--;
}
value = StringType(buffer, length);
// If we're loading a string_view we need to keep the encoded Python object alive:
if (IsView) {
loader_life_support::add_patient(utfNbytes);
}
return true;
}
static handle
cast(const StringType &src, return_value_policy /* policy */, handle /* parent */) {
const char *buffer = reinterpret_cast<const char *>(src.data());
auto nbytes = ssize_t(src.size() * sizeof(CharT));
handle s = decode_utfN(buffer, nbytes);
if (!s) {
throw error_already_set();
}
return s;
}
PYBIND11_TYPE_CASTER(StringType, const_name(PYBIND11_STRING_NAME));
private:
static handle decode_utfN(const char *buffer, ssize_t nbytes) {
#if !defined(PYPY_VERSION)
return UTF_N == 8 ? PyUnicode_DecodeUTF8(buffer, nbytes, nullptr)
: UTF_N == 16 ? PyUnicode_DecodeUTF16(buffer, nbytes, nullptr, nullptr)
: PyUnicode_DecodeUTF32(buffer, nbytes, nullptr, nullptr);
#else
// PyPy segfaults when on PyUnicode_DecodeUTF16 (and possibly on PyUnicode_DecodeUTF32 as
// well), so bypass the whole thing by just passing the encoding as a string value, which
// works properly:
return PyUnicode_Decode(buffer,
nbytes,
UTF_N == 8 ? "utf-8"
: UTF_N == 16 ? "utf-16"
: "utf-32",
nullptr);
#endif
}
// When loading into a std::string or char*, accept a bytes/bytearray object as-is (i.e.
// without any encoding/decoding attempt). For other C++ char sizes this is a no-op.
// which supports loading a unicode from a str, doesn't take this path.
template <typename C = CharT>
bool load_raw(enable_if_t<std::is_same<C, char>::value, handle> src) {
if (PYBIND11_BYTES_CHECK(src.ptr())) {
// We were passed raw bytes; accept it into a std::string or char*
// without any encoding attempt.
const char *bytes = PYBIND11_BYTES_AS_STRING(src.ptr());
if (!bytes) {
pybind11_fail("Unexpected PYBIND11_BYTES_AS_STRING() failure.");
}
value = StringType(bytes, (size_t) PYBIND11_BYTES_SIZE(src.ptr()));
return true;
}
if (PyByteArray_Check(src.ptr())) {
// We were passed a bytearray; accept it into a std::string or char*
// without any encoding attempt.
const char *bytearray = PyByteArray_AsString(src.ptr());
if (!bytearray) {
pybind11_fail("Unexpected PyByteArray_AsString() failure.");
}
value = StringType(bytearray, (size_t) PyByteArray_Size(src.ptr()));
return true;
}
return false;
}
template <typename C = CharT>
bool load_raw(enable_if_t<!std::is_same<C, char>::value, handle>) {
return false;
}
};
template <typename CharT, class Traits, class Allocator>
struct type_caster<std::basic_string<CharT, Traits, Allocator>,
enable_if_t<is_std_char_type<CharT>::value>>
: string_caster<std::basic_string<CharT, Traits, Allocator>> {};
#ifdef PYBIND11_HAS_STRING_VIEW
template <typename CharT, class Traits>
struct type_caster<std::basic_string_view<CharT, Traits>,
enable_if_t<is_std_char_type<CharT>::value>>
: string_caster<std::basic_string_view<CharT, Traits>, true> {};
#endif
// Type caster for C-style strings. We basically use a std::string type caster, but also add the
// ability to use None as a nullptr char* (which the string caster doesn't allow).
template <typename CharT>
struct type_caster<CharT, enable_if_t<is_std_char_type<CharT>::value>> {
using StringType = std::basic_string<CharT>;
using StringCaster = make_caster<StringType>;
StringCaster str_caster;
bool none = false;
CharT one_char = 0;
public:
bool load(handle src, bool convert) {
if (!src) {
return false;
}
if (src.is_none()) {
// Defer accepting None to other overloads (if we aren't in convert mode):
if (!convert) {
return false;
}
none = true;
return true;
}
return str_caster.load(src, convert);
}
static handle cast(const CharT *src, return_value_policy policy, handle parent) {
if (src == nullptr) {
return pybind11::none().release();
}
return StringCaster::cast(StringType(src), policy, parent);
}
static handle cast(CharT src, return_value_policy policy, handle parent) {
if (std::is_same<char, CharT>::value) {
handle s = PyUnicode_DecodeLatin1((const char *) &src, 1, nullptr);
if (!s) {
throw error_already_set();
}
return s;
}
return StringCaster::cast(StringType(1, src), policy, parent);
}
explicit operator CharT *() {
return none ? nullptr : const_cast<CharT *>(static_cast<StringType &>(str_caster).c_str());
}
explicit operator CharT &() {
if (none) {
throw value_error("Cannot convert None to a character");
}
auto &value = static_cast<StringType &>(str_caster);
size_t str_len = value.size();
if (str_len == 0) {
throw value_error("Cannot convert empty string to a character");
}
// If we're in UTF-8 mode, we have two possible failures: one for a unicode character that
// is too high, and one for multiple unicode characters (caught later), so we need to
// figure out how long the first encoded character is in bytes to distinguish between these
// two errors. We also allow want to allow unicode characters U+0080 through U+00FF, as
// those can fit into a single char value.
if (PYBIND11_SILENCE_MSVC_C4127(StringCaster::UTF_N == 8) && str_len > 1 && str_len <= 4) {
auto v0 = static_cast<unsigned char>(value[0]);
// low bits only: 0-127
// 0b110xxxxx - start of 2-byte sequence
// 0b1110xxxx - start of 3-byte sequence
// 0b11110xxx - start of 4-byte sequence
size_t char0_bytes = (v0 & 0x80) == 0 ? 1
: (v0 & 0xE0) == 0xC0 ? 2
: (v0 & 0xF0) == 0xE0 ? 3
: 4;
if (char0_bytes == str_len) {
// If we have a 128-255 value, we can decode it into a single char:
if (char0_bytes == 2 && (v0 & 0xFC) == 0xC0) { // 0x110000xx 0x10xxxxxx
one_char = static_cast<CharT>(((v0 & 3) << 6)
+ (static_cast<unsigned char>(value[1]) & 0x3F));
return one_char;
}
// Otherwise we have a single character, but it's > U+00FF
throw value_error("Character code point not in range(0x100)");
}
}
// UTF-16 is much easier: we can only have a surrogate pair for values above U+FFFF, thus a
// surrogate pair with total length 2 instantly indicates a range error (but not a "your
// string was too long" error).
else if (PYBIND11_SILENCE_MSVC_C4127(StringCaster::UTF_N == 16) && str_len == 2) {
one_char = static_cast<CharT>(value[0]);
if (one_char >= 0xD800 && one_char < 0xE000) {
throw value_error("Character code point not in range(0x10000)");
}
}
if (str_len != 1) {
throw value_error("Expected a character, but multi-character string found");
}
one_char = value[0];
return one_char;
}
static constexpr auto name = const_name(PYBIND11_STRING_NAME);
template <typename _T>
using cast_op_type = pybind11::detail::cast_op_type<_T>;
};
// Base implementation for std::tuple and std::pair
template <template <typename...> class Tuple, typename... Ts>
class tuple_caster {
using type = Tuple<Ts...>;
static constexpr auto size = sizeof...(Ts);
using indices = make_index_sequence<size>;
public:
bool load(handle src, bool convert) {
if (!isinstance<sequence>(src)) {
return false;
}
const auto seq = reinterpret_borrow<sequence>(src);
if (seq.size() != size) {
return false;
}
return load_impl(seq, convert, indices{});
}
template <typename T>
static handle cast(T &&src, return_value_policy policy, handle parent) {
return cast_impl(std::forward<T>(src), policy, parent, indices{});
}
// copied from the PYBIND11_TYPE_CASTER macro
template <typename T>
static handle cast(T *src, return_value_policy policy, handle parent) {
if (!src) {
return none().release();
}
if (policy == return_value_policy::take_ownership) {
auto h = cast(std::move(*src), policy, parent);
delete src;
return h;
}
return cast(*src, policy, parent);
}
static constexpr auto name
= const_name("Tuple[") + concat(make_caster<Ts>::name...) + const_name("]");
template <typename T>
using cast_op_type = type;
explicit operator type() & { return implicit_cast(indices{}); }
explicit operator type() && { return std::move(*this).implicit_cast(indices{}); }
protected:
template <size_t... Is>
type implicit_cast(index_sequence<Is...>) & {
return type(cast_op<Ts>(std::get<Is>(subcasters))...);
}
template <size_t... Is>
type implicit_cast(index_sequence<Is...>) && {
return type(cast_op<Ts>(std::move(std::get<Is>(subcasters)))...);
}
static constexpr bool load_impl(const sequence &, bool, index_sequence<>) { return true; }
template <size_t... Is>
bool load_impl(const sequence &seq, bool convert, index_sequence<Is...>) {
#ifdef __cpp_fold_expressions
if ((... || !std::get<Is>(subcasters).load(seq[Is], convert))) {
return false;
}
#else
for (bool r : {std::get<Is>(subcasters).load(seq[Is], convert)...}) {
if (!r) {
return false;
}
}
#endif
return true;
}
/* Implementation: Convert a C++ tuple into a Python tuple */
template <typename T, size_t... Is>
static handle
cast_impl(T &&src, return_value_policy policy, handle parent, index_sequence<Is...>) {
PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(src, policy, parent);
PYBIND11_WORKAROUND_INCORRECT_GCC_UNUSED_BUT_SET_PARAMETER(policy, parent);
std::array<object, size> entries{{reinterpret_steal<object>(
make_caster<Ts>::cast(std::get<Is>(std::forward<T>(src)), policy, parent))...}};
for (const auto &entry : entries) {
if (!entry) {
return handle();
}
}
tuple result(size);
int counter = 0;
for (auto &entry : entries) {
PyTuple_SET_ITEM(result.ptr(), counter++, entry.release().ptr());
}
return result.release();
}
Tuple<make_caster<Ts>...> subcasters;
};
template <typename T1, typename T2>
class type_caster<std::pair<T1, T2>> : public tuple_caster<std::pair, T1, T2> {};
template <typename... Ts>
class type_caster<std::tuple<Ts...>> : public tuple_caster<std::tuple, Ts...> {};
/// Helper class which abstracts away certain actions. Users can provide specializations for
/// custom holders, but it's only necessary if the type has a non-standard interface.
template <typename T>
struct holder_helper {
static auto get(const T &p) -> decltype(p.get()) { return p.get(); }
};
/// Type caster for holder types like std::shared_ptr, etc.
/// The SFINAE hook is provided to help work around the current lack of support
/// for smart-pointer interoperability. Please consider it an implementation
/// detail that may change in the future, as formal support for smart-pointer
/// interoperability is added into pybind11.
template <typename type, typename holder_type, typename SFINAE = void>
struct copyable_holder_caster : public type_caster_base<type> {
public:
using base = type_caster_base<type>;
static_assert(std::is_base_of<base, type_caster<type>>::value,
"Holder classes are only supported for custom types");
using base::base;
using base::cast;
using base::typeinfo;
using base::value;
bool load(handle src, bool convert) {
return base::template load_impl<copyable_holder_caster<type, holder_type>>(src, convert);
}
explicit operator type *() { return this->value; }
// static_cast works around compiler error with MSVC 17 and CUDA 10.2
// see issue #2180
explicit operator type &() { return *(static_cast<type *>(this->value)); }
explicit operator holder_type *() { return std::addressof(holder); }
explicit operator holder_type &() { return holder; }
static handle cast(const holder_type &src, return_value_policy, handle) {
const auto *ptr = holder_helper<holder_type>::get(src);
return type_caster_base<type>::cast_holder(ptr, &src);
}
protected:
friend class type_caster_generic;
void check_holder_compat() {
if (typeinfo->default_holder) {
throw cast_error("Unable to load a custom holder type from a default-holder instance");
}
}
bool load_value(value_and_holder &&v_h) {
if (v_h.holder_constructed()) {
value = v_h.value_ptr();
holder = v_h.template holder<holder_type>();
return true;
}
throw cast_error("Unable to cast from non-held to held instance (T& to Holder<T>) "
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
"(#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for "
"type information)");
#else
"of type '"
+ type_id<holder_type>() + "''");
#endif
}
template <typename T = holder_type,
detail::enable_if_t<!std::is_constructible<T, const T &, type *>::value, int> = 0>
bool try_implicit_casts(handle, bool) {
return false;
}
template <typename T = holder_type,
detail::enable_if_t<std::is_constructible<T, const T &, type *>::value, int> = 0>
bool try_implicit_casts(handle src, bool convert) {
for (auto &cast : typeinfo->implicit_casts) {
copyable_holder_caster sub_caster(*cast.first);
if (sub_caster.load(src, convert)) {
value = cast.second(sub_caster.value);
holder = holder_type(sub_caster.holder, (type *) value);
return true;
}
}
return false;
}
static bool try_direct_conversions(handle) { return false; }
holder_type holder;
};
/// Specialize for the common std::shared_ptr, so users don't need to
template <typename T>
class type_caster<std::shared_ptr<T>> : public copyable_holder_caster<T, std::shared_ptr<T>> {};
/// Type caster for holder types like std::unique_ptr.
/// Please consider the SFINAE hook an implementation detail, as explained
/// in the comment for the copyable_holder_caster.
template <typename type, typename holder_type, typename SFINAE = void>
struct move_only_holder_caster {
static_assert(std::is_base_of<type_caster_base<type>, type_caster<type>>::value,
"Holder classes are only supported for custom types");
static handle cast(holder_type &&src, return_value_policy, handle) {
auto *ptr = holder_helper<holder_type>::get(src);
return type_caster_base<type>::cast_holder(ptr, std::addressof(src));
}
static constexpr auto name = type_caster_base<type>::name;
};
template <typename type, typename deleter>
class type_caster<std::unique_ptr<type, deleter>>
: public move_only_holder_caster<type, std::unique_ptr<type, deleter>> {};
template <typename type, typename holder_type>
using type_caster_holder = conditional_t<is_copy_constructible<holder_type>::value,
copyable_holder_caster<type, holder_type>,
move_only_holder_caster<type, holder_type>>;
template <typename T, bool Value = false>
struct always_construct_holder {
static constexpr bool value = Value;
};
/// Create a specialization for custom holder types (silently ignores std::shared_ptr)
#define PYBIND11_DECLARE_HOLDER_TYPE(type, holder_type, ...) \
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE) \
namespace detail { \
template <typename type> \
struct always_construct_holder<holder_type> : always_construct_holder<void, ##__VA_ARGS__> { \
}; \
template <typename type> \
class type_caster<holder_type, enable_if_t<!is_shared_ptr<holder_type>::value>> \
: public type_caster_holder<type, holder_type> {}; \
} \
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
// PYBIND11_DECLARE_HOLDER_TYPE holder types:
template <typename base, typename holder>
struct is_holder_type
: std::is_base_of<detail::type_caster_holder<base, holder>, detail::type_caster<holder>> {};
// Specialization for always-supported unique_ptr holders:
template <typename base, typename deleter>
struct is_holder_type<base, std::unique_ptr<base, deleter>> : std::true_type {};
template <typename T>
struct handle_type_name {
static constexpr auto name = const_name<T>();
};
template <>
struct handle_type_name<bool_> {
static constexpr auto name = const_name("bool");
};
template <>
struct handle_type_name<bytes> {
static constexpr auto name = const_name(PYBIND11_BYTES_NAME);
};
template <>
struct handle_type_name<int_> {
static constexpr auto name = const_name("int");
};
template <>
struct handle_type_name<iterable> {
static constexpr auto name = const_name("Iterable");
};
template <>
struct handle_type_name<iterator> {
static constexpr auto name = const_name("Iterator");
};
template <>
struct handle_type_name<float_> {
static constexpr auto name = const_name("float");
};
template <>
struct handle_type_name<none> {
static constexpr auto name = const_name("None");
};
template <>
struct handle_type_name<args> {
static constexpr auto name = const_name("*args");
};
template <>
struct handle_type_name<kwargs> {
static constexpr auto name = const_name("**kwargs");
};
template <typename type>
struct pyobject_caster {
template <typename T = type, enable_if_t<std::is_same<T, handle>::value, int> = 0>
pyobject_caster() : value() {}
// `type` may not be default constructible (e.g. frozenset, anyset). Initializing `value`
// to a nil handle is safe since it will only be accessed if `load` succeeds.
template <typename T = type, enable_if_t<std::is_base_of<object, T>::value, int> = 0>
pyobject_caster() : value(reinterpret_steal<type>(handle())) {}
template <typename T = type, enable_if_t<std::is_same<T, handle>::value, int> = 0>
bool load(handle src, bool /* convert */) {
value = src;
return static_cast<bool>(value);
}
template <typename T = type, enable_if_t<std::is_base_of<object, T>::value, int> = 0>
bool load(handle src, bool /* convert */) {
if (!isinstance<type>(src)) {
return false;
}
value = reinterpret_borrow<type>(src);
return true;
}
static handle cast(const handle &src, return_value_policy /* policy */, handle /* parent */) {
return src.inc_ref();
}
PYBIND11_TYPE_CASTER(type, handle_type_name<type>::name);
};
template <typename T>
class type_caster<T, enable_if_t<is_pyobject<T>::value>> : public pyobject_caster<T> {};
// Our conditions for enabling moving are quite restrictive:
// At compile time:
// - T needs to be a non-const, non-pointer, non-reference type
// - type_caster<T>::operator T&() must exist
// - the type must be move constructible (obviously)
// At run-time:
// - if the type is non-copy-constructible, the object must be the sole owner of the type (i.e. it
// must have ref_count() == 1)h
// If any of the above are not satisfied, we fall back to copying.
template <typename T>
using move_is_plain_type
= satisfies_none_of<T, std::is_void, std::is_pointer, std::is_reference, std::is_const>;
template <typename T, typename SFINAE = void>
struct move_always : std::false_type {};
template <typename T>
struct move_always<
T,
enable_if_t<
all_of<move_is_plain_type<T>,
negation<is_copy_constructible<T>>,
std::is_move_constructible<T>,
std::is_same<decltype(std::declval<make_caster<T>>().operator T &()), T &>>::value>>
: std::true_type {};
template <typename T, typename SFINAE = void>
struct move_if_unreferenced : std::false_type {};
template <typename T>
struct move_if_unreferenced<
T,
enable_if_t<
all_of<move_is_plain_type<T>,
negation<move_always<T>>,
std::is_move_constructible<T>,
std::is_same<decltype(std::declval<make_caster<T>>().operator T &()), T &>>::value>>
: std::true_type {};
template <typename T>
using move_never = none_of<move_always<T>, move_if_unreferenced<T>>;
// Detect whether returning a `type` from a cast on type's type_caster is going to result in a
// reference or pointer to a local variable of the type_caster. Basically, only
// non-reference/pointer `type`s and reference/pointers from a type_caster_generic are safe;
// everything else returns a reference/pointer to a local variable.
template <typename type>
using cast_is_temporary_value_reference
= bool_constant<(std::is_reference<type>::value || std::is_pointer<type>::value)
&& !std::is_base_of<type_caster_generic, make_caster<type>>::value
&& !std::is_same<intrinsic_t<type>, void>::value>;
// When a value returned from a C++ function is being cast back to Python, we almost always want to
// force `policy = move`, regardless of the return value policy the function/method was declared
// with.
template <typename Return, typename SFINAE = void>
struct return_value_policy_override {
static return_value_policy policy(return_value_policy p) { return p; }
};
template <typename Return>
struct return_value_policy_override<
Return,
detail::enable_if_t<std::is_base_of<type_caster_generic, make_caster<Return>>::value, void>> {
static return_value_policy policy(return_value_policy p) {
return !std::is_lvalue_reference<Return>::value && !std::is_pointer<Return>::value
? return_value_policy::move
: p;
}
};
// Basic python -> C++ casting; throws if casting fails
template <typename T, typename SFINAE>
type_caster<T, SFINAE> &load_type(type_caster<T, SFINAE> &conv, const handle &handle) {
static_assert(!detail::is_pyobject<T>::value,
"Internal error: type_caster should only be used for C++ types");
if (!conv.load(handle, true)) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
throw cast_error("Unable to cast Python instance to C++ type (#define "
"PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details)");
#else
throw cast_error("Unable to cast Python instance of type "
+ (std::string) str(type::handle_of(handle)) + " to C++ type '"
+ type_id<T>() + "'");
#endif
}
return conv;
}
// Wrapper around the above that also constructs and returns a type_caster
template <typename T>
make_caster<T> load_type(const handle &handle) {
make_caster<T> conv;
load_type(conv, handle);
return conv;
}
PYBIND11_NAMESPACE_END(detail)
// pytype -> C++ type
template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
T cast(const handle &handle) {
using namespace detail;
static_assert(!cast_is_temporary_value_reference<T>::value,
"Unable to cast type to reference: value is local to type caster");
return cast_op<T>(load_type<T>(handle));
}
// pytype -> pytype (calls converting constructor)
template <typename T, detail::enable_if_t<detail::is_pyobject<T>::value, int> = 0>
T cast(const handle &handle) {
return T(reinterpret_borrow<object>(handle));
}
// C++ type -> py::object
template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
object cast(T &&value,
return_value_policy policy = return_value_policy::automatic_reference,
handle parent = handle()) {
using no_ref_T = typename std::remove_reference<T>::type;
if (policy == return_value_policy::automatic) {
policy = std::is_pointer<no_ref_T>::value ? return_value_policy::take_ownership
: std::is_lvalue_reference<T>::value ? return_value_policy::copy
: return_value_policy::move;
} else if (policy == return_value_policy::automatic_reference) {
policy = std::is_pointer<no_ref_T>::value ? return_value_policy::reference
: std::is_lvalue_reference<T>::value ? return_value_policy::copy
: return_value_policy::move;
}
return reinterpret_steal<object>(
detail::make_caster<T>::cast(std::forward<T>(value), policy, parent));
}
template <typename T>
T handle::cast() const {
return pybind11::cast<T>(*this);
}
template <>
inline void handle::cast() const {
return;
}
template <typename T>
detail::enable_if_t<!detail::move_never<T>::value, T> move(object &&obj) {
if (obj.ref_count() > 1) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
throw cast_error(
"Unable to cast Python instance to C++ rvalue: instance has multiple references"
" (#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details)");
#else
throw cast_error("Unable to move from Python " + (std::string) str(type::handle_of(obj))
+ " instance to C++ " + type_id<T>()
+ " instance: instance has multiple references");
#endif
}
// Move into a temporary and return that, because the reference may be a local value of `conv`
T ret = std::move(detail::load_type<T>(obj).operator T &());
return ret;
}
// Calling cast() on an rvalue calls pybind11::cast with the object rvalue, which does:
// - If we have to move (because T has no copy constructor), do it. This will fail if the moved
// object has multiple references, but trying to copy will fail to compile.
// - If both movable and copyable, check ref count: if 1, move; otherwise copy
// - Otherwise (not movable), copy.
template <typename T>
detail::enable_if_t<!detail::is_pyobject<T>::value && detail::move_always<T>::value, T>
cast(object &&object) {
return move<T>(std::move(object));
}
template <typename T>
detail::enable_if_t<!detail::is_pyobject<T>::value && detail::move_if_unreferenced<T>::value, T>
cast(object &&object) {
if (object.ref_count() > 1) {
return cast<T>(object);
}
return move<T>(std::move(object));
}
template <typename T>
detail::enable_if_t<!detail::is_pyobject<T>::value && detail::move_never<T>::value, T>
cast(object &&object) {
return cast<T>(object);
}
// pytype rvalue -> pytype (calls converting constructor)
template <typename T>
detail::enable_if_t<detail::is_pyobject<T>::value, T> cast(object &&object) {
return T(std::move(object));
}
template <typename T>
T object::cast() const & {
return pybind11::cast<T>(*this);
}
template <typename T>
T object::cast() && {
return pybind11::cast<T>(std::move(*this));
}
template <>
inline void object::cast() const & {
return;
}
template <>
inline void object::cast() && {
return;
}
PYBIND11_NAMESPACE_BEGIN(detail)
// Declared in pytypes.h:
template <typename T, enable_if_t<!is_pyobject<T>::value, int>>
object object_or_cast(T &&o) {
return pybind11::cast(std::forward<T>(o));
}
// Placeholder type for the unneeded (and dead code) static variable in the
// PYBIND11_OVERRIDE_OVERRIDE macro
struct override_unused {};
template <typename ret_type>
using override_caster_t = conditional_t<cast_is_temporary_value_reference<ret_type>::value,
make_caster<ret_type>,
override_unused>;
// Trampoline use: for reference/pointer types to value-converted values, we do a value cast, then
// store the result in the given variable. For other types, this is a no-op.
template <typename T>
enable_if_t<cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&o,
make_caster<T> &caster) {
return cast_op<T>(load_type(caster, o));
}
template <typename T>
enable_if_t<!cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&,
override_unused &) {
pybind11_fail("Internal error: cast_ref fallback invoked");
}
// Trampoline use: Having a pybind11::cast with an invalid reference type is going to
// static_assert, even though if it's in dead code, so we provide a "trampoline" to pybind11::cast
// that only does anything in cases where pybind11::cast is valid.
template <typename T>
enable_if_t<cast_is_temporary_value_reference<T>::value, T> cast_safe(object &&) {
pybind11_fail("Internal error: cast_safe fallback invoked");
}
template <typename T>
enable_if_t<std::is_void<T>::value, void> cast_safe(object &&) {}
template <typename T>
enable_if_t<detail::none_of<cast_is_temporary_value_reference<T>, std::is_void<T>>::value, T>
cast_safe(object &&o) {
return pybind11::cast<T>(std::move(o));
}
PYBIND11_NAMESPACE_END(detail)
// The overloads could coexist, i.e. the #if is not strictly speaking needed,
// but it is an easy minor optimization.
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
inline cast_error cast_error_unable_to_convert_call_arg() {
return cast_error("Unable to convert call argument to Python object (#define "
"PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details)");
}
#else
inline cast_error cast_error_unable_to_convert_call_arg(const std::string &name,
const std::string &type) {
return cast_error("Unable to convert call argument '" + name + "' of type '" + type
+ "' to Python object");
}
#endif
template <return_value_policy policy = return_value_policy::automatic_reference>
tuple make_tuple() {
return tuple(0);
}
template <return_value_policy policy = return_value_policy::automatic_reference, typename... Args>
tuple make_tuple(Args &&...args_) {
constexpr size_t size = sizeof...(Args);
std::array<object, size> args{{reinterpret_steal<object>(
detail::make_caster<Args>::cast(std::forward<Args>(args_), policy, nullptr))...}};
for (size_t i = 0; i < args.size(); i++) {
if (!args[i]) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
throw cast_error_unable_to_convert_call_arg();
#else
std::array<std::string, size> argtypes{{type_id<Args>()...}};
throw cast_error_unable_to_convert_call_arg(std::to_string(i), argtypes[i]);
#endif
}
}
tuple result(size);
int counter = 0;
for (auto &arg_value : args) {
PyTuple_SET_ITEM(result.ptr(), counter++, arg_value.release().ptr());
}
return result;
}
/// \ingroup annotations
/// Annotation for arguments
struct arg {
/// Constructs an argument with the name of the argument; if null or omitted, this is a
/// positional argument.
constexpr explicit arg(const char *name = nullptr)
: name(name), flag_noconvert(false), flag_none(true) {}
/// Assign a value to this argument
template <typename T>
arg_v operator=(T &&value) const;
/// Indicate that the type should not be converted in the type caster
arg &noconvert(bool flag = true) {
flag_noconvert = flag;
return *this;
}
/// Indicates that the argument should/shouldn't allow None (e.g. for nullable pointer args)
arg &none(bool flag = true) {
flag_none = flag;
return *this;
}
const char *name; ///< If non-null, this is a named kwargs argument
bool flag_noconvert : 1; ///< If set, do not allow conversion (requires a supporting type
///< caster!)
bool flag_none : 1; ///< If set (the default), allow None to be passed to this argument
};
/// \ingroup annotations
/// Annotation for arguments with values
struct arg_v : arg {
private:
template <typename T>
arg_v(arg &&base, T &&x, const char *descr = nullptr)
: arg(base), value(reinterpret_steal<object>(detail::make_caster<T>::cast(
std::forward<T>(x), return_value_policy::automatic, {}))),
descr(descr)
#if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
,
type(type_id<T>())
#endif
{
// Workaround! See:
// https://github.com/pybind/pybind11/issues/2336
// https://github.com/pybind/pybind11/pull/2685#issuecomment-731286700
if (PyErr_Occurred()) {
PyErr_Clear();
}
}
public:
/// Direct construction with name, default, and description
template <typename T>
arg_v(const char *name, T &&x, const char *descr = nullptr)
: arg_v(arg(name), std::forward<T>(x), descr) {}
/// Called internally when invoking `py::arg("a") = value`
template <typename T>
arg_v(const arg &base, T &&x, const char *descr = nullptr)
: arg_v(arg(base), std::forward<T>(x), descr) {}
/// Same as `arg::noconvert()`, but returns *this as arg_v&, not arg&
arg_v &noconvert(bool flag = true) {
arg::noconvert(flag);
return *this;
}
/// Same as `arg::nonone()`, but returns *this as arg_v&, not arg&
arg_v &none(bool flag = true) {
arg::none(flag);
return *this;
}
/// The default value
object value;
/// The (optional) description of the default value
const char *descr;
#if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
/// The C++ type name of the default value (only available when compiled in debug mode)
std::string type;
#endif
};
/// \ingroup annotations
/// Annotation indicating that all following arguments are keyword-only; the is the equivalent of
/// an unnamed '*' argument
struct kw_only {};
/// \ingroup annotations
/// Annotation indicating that all previous arguments are positional-only; the is the equivalent of
/// an unnamed '/' argument (in Python 3.8)
struct pos_only {};
template <typename T>
arg_v arg::operator=(T &&value) const {
return {*this, std::forward<T>(value)};
}
/// Alias for backward compatibility -- to be removed in version 2.0
template <typename /*unused*/>
using arg_t = arg_v;
inline namespace literals {
/** \rst
String literal version of `arg`
\endrst */
constexpr arg operator"" _a(const char *name, size_t) { return arg(name); }
} // namespace literals
PYBIND11_NAMESPACE_BEGIN(detail)
template <typename T>
using is_kw_only = std::is_same<intrinsic_t<T>, kw_only>;
template <typename T>
using is_pos_only = std::is_same<intrinsic_t<T>, pos_only>;
// forward declaration (definition in attr.h)
struct function_record;
/// Internal data associated with a single function call
struct function_call {
function_call(const function_record &f, handle p); // Implementation in attr.h
/// The function data:
const function_record &func;
/// Arguments passed to the function:
std::vector<handle> args;
/// The `convert` value the arguments should be loaded with
std::vector<bool> args_convert;
/// Extra references for the optional `py::args` and/or `py::kwargs` arguments (which, if
/// present, are also in `args` but without a reference).
object args_ref, kwargs_ref;
/// The parent, if any
handle parent;
/// If this is a call to an initializer, this argument contains `self`
handle init_self;
};
/// Helper class which loads arguments for C++ functions called from Python
template <typename... Args>
class argument_loader {
using indices = make_index_sequence<sizeof...(Args)>;
template <typename Arg>
using argument_is_args = std::is_same<intrinsic_t<Arg>, args>;
template <typename Arg>
using argument_is_kwargs = std::is_same<intrinsic_t<Arg>, kwargs>;
// Get kwargs argument position, or -1 if not present:
static constexpr auto kwargs_pos = constexpr_last<argument_is_kwargs, Args...>();
static_assert(kwargs_pos == -1 || kwargs_pos == (int) sizeof...(Args) - 1,
"py::kwargs is only permitted as the last argument of a function");
public:
static constexpr bool has_kwargs = kwargs_pos != -1;
// py::args argument position; -1 if not present.
static constexpr int args_pos = constexpr_last<argument_is_args, Args...>();
static_assert(args_pos == -1 || args_pos == constexpr_first<argument_is_args, Args...>(),
"py::args cannot be specified more than once");
static constexpr auto arg_names = concat(type_descr(make_caster<Args>::name)...);
bool load_args(function_call &call) { return load_impl_sequence(call, indices{}); }
template <typename Return, typename Guard, typename Func>
// NOLINTNEXTLINE(readability-const-return-type)
enable_if_t<!std::is_void<Return>::value, Return> call(Func &&f) && {
return std::move(*this).template call_impl<remove_cv_t<Return>>(
std::forward<Func>(f), indices{}, Guard{});
}
template <typename Return, typename Guard, typename Func>
enable_if_t<std::is_void<Return>::value, void_type> call(Func &&f) && {
std::move(*this).template call_impl<remove_cv_t<Return>>(
std::forward<Func>(f), indices{}, Guard{});
return void_type();
}
private:
static bool load_impl_sequence(function_call &, index_sequence<>) { return true; }
template <size_t... Is>
bool load_impl_sequence(function_call &call, index_sequence<Is...>) {
#ifdef __cpp_fold_expressions
if ((... || !std::get<Is>(argcasters).load(call.args[Is], call.args_convert[Is]))) {
return false;
}
#else
for (bool r : {std::get<Is>(argcasters).load(call.args[Is], call.args_convert[Is])...}) {
if (!r) {
return false;
}
}
#endif
return true;
}
template <typename Return, typename Func, size_t... Is, typename Guard>
Return call_impl(Func &&f, index_sequence<Is...>, Guard &&) && {
return std::forward<Func>(f)(cast_op<Args>(std::move(std::get<Is>(argcasters)))...);
}
std::tuple<make_caster<Args>...> argcasters;
};
/// Helper class which collects only positional arguments for a Python function call.
/// A fancier version below can collect any argument, but this one is optimal for simple calls.
template <return_value_policy policy>
class simple_collector {
public:
template <typename... Ts>
explicit simple_collector(Ts &&...values)
: m_args(pybind11::make_tuple<policy>(std::forward<Ts>(values)...)) {}
const tuple &args() const & { return m_args; }
dict kwargs() const { return {}; }
tuple args() && { return std::move(m_args); }
/// Call a Python function and pass the collected arguments
object call(PyObject *ptr) const {
PyObject *result = PyObject_CallObject(ptr, m_args.ptr());
if (!result) {
throw error_already_set();
}
return reinterpret_steal<object>(result);
}
private:
tuple m_args;
};
/// Helper class which collects positional, keyword, * and ** arguments for a Python function call
template <return_value_policy policy>
class unpacking_collector {
public:
template <typename... Ts>
explicit unpacking_collector(Ts &&...values) {
// Tuples aren't (easily) resizable so a list is needed for collection,
// but the actual function call strictly requires a tuple.
auto args_list = list();
using expander = int[];
(void) expander{0, (process(args_list, std::forward<Ts>(values)), 0)...};
m_args = std::move(args_list);
}
const tuple &args() const & { return m_args; }
const dict &kwargs() const & { return m_kwargs; }
tuple args() && { return std::move(m_args); }
dict kwargs() && { return std::move(m_kwargs); }
/// Call a Python function and pass the collected arguments
object call(PyObject *ptr) const {
PyObject *result = PyObject_Call(ptr, m_args.ptr(), m_kwargs.ptr());
if (!result) {
throw error_already_set();
}
return reinterpret_steal<object>(result);
}
private:
template <typename T>
void process(list &args_list, T &&x) {
auto o = reinterpret_steal<object>(
detail::make_caster<T>::cast(std::forward<T>(x), policy, {}));
if (!o) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
throw cast_error_unable_to_convert_call_arg();
#else
throw cast_error_unable_to_convert_call_arg(std::to_string(args_list.size()),
type_id<T>());
#endif
}
args_list.append(std::move(o));
}
void process(list &args_list, detail::args_proxy ap) {
for (auto a : ap) {
args_list.append(a);
}
}
void process(list & /*args_list*/, arg_v a) {
if (!a.name) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
nameless_argument_error();
#else
nameless_argument_error(a.type);
#endif
}
if (m_kwargs.contains(a.name)) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
multiple_values_error();
#else
multiple_values_error(a.name);
#endif
}
if (!a.value) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
throw cast_error_unable_to_convert_call_arg();
#else
throw cast_error_unable_to_convert_call_arg(a.name, a.type);
#endif
}
m_kwargs[a.name] = std::move(a.value);
}
void process(list & /*args_list*/, detail::kwargs_proxy kp) {
if (!kp) {
return;
}
for (auto k : reinterpret_borrow<dict>(kp)) {
if (m_kwargs.contains(k.first)) {
#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
multiple_values_error();
#else
multiple_values_error(str(k.first));
#endif
}
m_kwargs[k.first] = k.second;
}
}
[[noreturn]] static void nameless_argument_error() {
throw type_error(
"Got kwargs without a name; only named arguments "
"may be passed via py::arg() to a python function call. "
"(#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details)");
}
[[noreturn]] static void nameless_argument_error(const std::string &type) {
throw type_error("Got kwargs without a name of type '" + type
+ "'; only named "
"arguments may be passed via py::arg() to a python function call. ");
}
[[noreturn]] static void multiple_values_error() {
throw type_error(
"Got multiple values for keyword argument "
"(#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details)");
}
[[noreturn]] static void multiple_values_error(const std::string &name) {
throw type_error("Got multiple values for keyword argument '" + name + "'");
}
private:
tuple m_args;
dict m_kwargs;
};
// [workaround(intel)] Separate function required here
// We need to put this into a separate function because the Intel compiler
// fails to compile enable_if_t<!all_of<is_positional<Args>...>::value>
// (tested with ICC 2021.1 Beta 20200827).
template <typename... Args>
constexpr bool args_are_all_positional() {
return all_of<is_positional<Args>...>::value;
}
/// Collect only positional arguments for a Python function call
template <return_value_policy policy,
typename... Args,
typename = enable_if_t<args_are_all_positional<Args...>()>>
simple_collector<policy> collect_arguments(Args &&...args) {
return simple_collector<policy>(std::forward<Args>(args)...);
}
/// Collect all arguments, including keywords and unpacking (only instantiated when needed)
template <return_value_policy policy,
typename... Args,
typename = enable_if_t<!args_are_all_positional<Args...>()>>
unpacking_collector<policy> collect_arguments(Args &&...args) {
// Following argument order rules for generalized unpacking according to PEP 448
static_assert(constexpr_last<is_positional, Args...>()
< constexpr_first<is_keyword_or_ds, Args...>()
&& constexpr_last<is_s_unpacking, Args...>()
< constexpr_first<is_ds_unpacking, Args...>(),
"Invalid function call: positional args must precede keywords and ** unpacking; "
"* unpacking must precede ** unpacking");
return unpacking_collector<policy>(std::forward<Args>(args)...);
}
template <typename Derived>
template <return_value_policy policy, typename... Args>
object object_api<Derived>::operator()(Args &&...args) const {
#ifndef NDEBUG
if (!PyGILState_Check()) {
pybind11_fail("pybind11::object_api<>::operator() PyGILState_Check() failure.");
}
#endif
return detail::collect_arguments<policy>(std::forward<Args>(args)...).call(derived().ptr());
}
template <typename Derived>
template <return_value_policy policy, typename... Args>
object object_api<Derived>::call(Args &&...args) const {
return operator()<policy>(std::forward<Args>(args)...);
}
PYBIND11_NAMESPACE_END(detail)
template <typename T>
handle type::handle_of() {
static_assert(std::is_base_of<detail::type_caster_generic, detail::make_caster<T>>::value,
"py::type::of<T> only supports the case where T is a registered C++ types.");
return detail::get_type_handle(typeid(T), true);
}
#define PYBIND11_MAKE_OPAQUE(...) \
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE) \
namespace detail { \
template <> \
class type_caster<__VA_ARGS__> : public type_caster_base<__VA_ARGS__> {}; \
} \
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
/// Lets you pass a type containing a `,` through a macro parameter without needing a separate
/// typedef, e.g.:
/// `PYBIND11_OVERRIDE(PYBIND11_TYPE(ReturnType<A, B>), PYBIND11_TYPE(Parent<C, D>), f, arg)`
#define PYBIND11_TYPE(...) __VA_ARGS__
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
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