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pybind11/include/pybind11/cast.h
Jason Rhinelander 501135fa76 Add static_assert to holder casters 
The holder casters assume but don't check that a `holder<type>`'s `type`
is really a `type_caster_base<type>`; this adds a static_assert to make
sure this is really the case, to turn things like
`std::shared_ptr<array>` into a compilation failure.

Fixes #785
2017-04-08 10:55:51 -04:00

1611 lines
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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 "pytypes.h"
#include "typeid.h"
#include "descr.h"
#include <array>
#include <limits>
NAMESPACE_BEGIN(pybind11)
NAMESPACE_BEGIN(detail)
inline PyTypeObject *make_static_property_type();
inline PyTypeObject *make_default_metaclass();
/// Additional type information which does not fit into the PyTypeObject
struct type_info {
PyTypeObject *type;
size_t type_size;
void *(*operator_new)(size_t);
void (*init_holder)(PyObject *, const void *);
void (*dealloc)(PyObject *);
std::vector<PyObject *(*)(PyObject *, PyTypeObject *)> implicit_conversions;
std::vector<std::pair<const std::type_info *, void *(*)(void *)>> implicit_casts;
std::vector<bool (*)(PyObject *, void *&)> *direct_conversions;
buffer_info *(*get_buffer)(PyObject *, void *) = nullptr;
void *get_buffer_data = nullptr;
/** A simple type never occurs as a (direct or indirect) parent
* of a class that makes use of multiple inheritance */
bool simple_type = true;
/* for base vs derived holder_type checks */
bool default_holder = true;
};
PYBIND11_NOINLINE inline internals &get_internals() {
static internals *internals_ptr = nullptr;
if (internals_ptr)
return *internals_ptr;
handle builtins(PyEval_GetBuiltins());
const char *id = PYBIND11_INTERNALS_ID;
if (builtins.contains(id) && isinstance<capsule>(builtins[id])) {
internals_ptr = capsule(builtins[id]);
} else {
internals_ptr = new internals();
#if defined(WITH_THREAD)
PyEval_InitThreads();
PyThreadState *tstate = PyThreadState_Get();
internals_ptr->tstate = PyThread_create_key();
PyThread_set_key_value(internals_ptr->tstate, tstate);
internals_ptr->istate = tstate->interp;
#endif
builtins[id] = capsule(internals_ptr);
internals_ptr->registered_exception_translators.push_front(
[](std::exception_ptr p) -> void {
try {
if (p) std::rethrow_exception(p);
} catch (error_already_set &e) { e.restore(); return;
} catch (const builtin_exception &e) { e.set_error(); return;
} catch (const std::bad_alloc &e) { PyErr_SetString(PyExc_MemoryError, e.what()); return;
} catch (const std::domain_error &e) { PyErr_SetString(PyExc_ValueError, e.what()); return;
} catch (const std::invalid_argument &e) { PyErr_SetString(PyExc_ValueError, e.what()); return;
} catch (const std::length_error &e) { PyErr_SetString(PyExc_ValueError, e.what()); return;
} catch (const std::out_of_range &e) { PyErr_SetString(PyExc_IndexError, e.what()); return;
} catch (const std::range_error &e) { PyErr_SetString(PyExc_ValueError, e.what()); return;
} catch (const std::exception &e) { PyErr_SetString(PyExc_RuntimeError, e.what()); return;
} catch (...) {
PyErr_SetString(PyExc_RuntimeError, "Caught an unknown exception!");
return;
}
}
);
internals_ptr->static_property_type = make_static_property_type();
internals_ptr->default_metaclass = make_default_metaclass();
}
return *internals_ptr;
}
PYBIND11_NOINLINE inline detail::type_info* get_type_info(PyTypeObject *type) {
auto const &type_dict = get_internals().registered_types_py;
do {
auto it = type_dict.find(type);
if (it != type_dict.end())
return (detail::type_info *) it->second;
type = type->tp_base;
if (!type)
return nullptr;
} while (true);
}
PYBIND11_NOINLINE inline detail::type_info *get_type_info(const std::type_info &tp,
bool throw_if_missing = false) {
auto &types = get_internals().registered_types_cpp;
auto it = types.find(std::type_index(tp));
if (it != types.end())
return (detail::type_info *) it->second;
if (throw_if_missing) {
std::string tname = tp.name();
detail::clean_type_id(tname);
pybind11_fail("pybind11::detail::get_type_info: unable to find type info for \"" + tname + "\"");
}
return nullptr;
}
PYBIND11_NOINLINE inline handle get_type_handle(const std::type_info &tp, bool throw_if_missing) {
detail::type_info *type_info = get_type_info(tp, throw_if_missing);
return handle(type_info ? ((PyObject *) type_info->type) : nullptr);
}
PYBIND11_NOINLINE inline bool isinstance_generic(handle obj, const std::type_info &tp) {
handle type = detail::get_type_handle(tp, false);
if (!type)
return false;
return isinstance(obj, type);
}
PYBIND11_NOINLINE inline std::string error_string() {
if (!PyErr_Occurred()) {
PyErr_SetString(PyExc_RuntimeError, "Unknown internal error occurred");
return "Unknown internal error occurred";
}
error_scope scope; // Preserve error state
std::string errorString;
if (scope.type) {
errorString += handle(scope.type).attr("__name__").cast<std::string>();
errorString += ": ";
}
if (scope.value)
errorString += (std::string) str(scope.value);
PyErr_NormalizeException(&scope.type, &scope.value, &scope.trace);
#if PY_MAJOR_VERSION >= 3
if (scope.trace != nullptr)
PyException_SetTraceback(scope.value, scope.trace);
#endif
#if !defined(PYPY_VERSION)
if (scope.trace) {
PyTracebackObject *trace = (PyTracebackObject *) scope.trace;
/* Get the deepest trace possible */
while (trace->tb_next)
trace = trace->tb_next;
PyFrameObject *frame = trace->tb_frame;
errorString += "\n\nAt:\n";
while (frame) {
int lineno = PyFrame_GetLineNumber(frame);
errorString +=
" " + handle(frame->f_code->co_filename).cast<std::string>() +
"(" + std::to_string(lineno) + "): " +
handle(frame->f_code->co_name).cast<std::string>() + "\n";
frame = frame->f_back;
}
trace = trace->tb_next;
}
#endif
return errorString;
}
PYBIND11_NOINLINE inline handle get_object_handle(const void *ptr, const detail::type_info *type ) {
auto &instances = get_internals().registered_instances;
auto range = instances.equal_range(ptr);
for (auto it = range.first; it != range.second; ++it) {
auto instance_type = detail::get_type_info(Py_TYPE(it->second));
if (instance_type && instance_type == type)
return handle((PyObject *) it->second);
}
return handle();
}
inline PyThreadState *get_thread_state_unchecked() {
#if defined(PYPY_VERSION)
return PyThreadState_GET();
#elif PY_VERSION_HEX < 0x03000000
return _PyThreadState_Current;
#elif PY_VERSION_HEX < 0x03050000
return (PyThreadState*) _Py_atomic_load_relaxed(&_PyThreadState_Current);
#elif PY_VERSION_HEX < 0x03050200
return (PyThreadState*) _PyThreadState_Current.value;
#else
return _PyThreadState_UncheckedGet();
#endif
}
// Forward declaration
inline void keep_alive_impl(handle nurse, handle patient);
class type_caster_generic {
public:
PYBIND11_NOINLINE type_caster_generic(const std::type_info &type_info)
: typeinfo(get_type_info(type_info)) { }
PYBIND11_NOINLINE bool load(handle src, bool convert) {
if (!src)
return false;
return load(src, convert, Py_TYPE(src.ptr()));
}
bool load(handle src, bool convert, PyTypeObject *tobj) {
if (!src || !typeinfo)
return false;
if (src.is_none()) {
value = nullptr;
return true;
}
if (typeinfo->simple_type) { /* Case 1: no multiple inheritance etc. involved */
/* Check if we can safely perform a reinterpret-style cast */
if (PyType_IsSubtype(tobj, typeinfo->type)) {
value = reinterpret_cast<instance<void> *>(src.ptr())->value;
return true;
}
} else { /* Case 2: multiple inheritance */
/* Check if we can safely perform a reinterpret-style cast */
if (tobj == typeinfo->type) {
value = reinterpret_cast<instance<void> *>(src.ptr())->value;
return true;
}
/* If this is a python class, also check the parents recursively */
auto const &type_dict = get_internals().registered_types_py;
bool new_style_class = PyType_Check((PyObject *) tobj);
if (type_dict.find(tobj) == type_dict.end() && new_style_class && tobj->tp_bases) {
auto parents = reinterpret_borrow<tuple>(tobj->tp_bases);
for (handle parent : parents) {
bool result = load(src, convert, (PyTypeObject *) parent.ptr());
if (result)
return true;
}
}
/* Try implicit casts */
for (auto &cast : typeinfo->implicit_casts) {
type_caster_generic sub_caster(*cast.first);
if (sub_caster.load(src, convert)) {
value = cast.second(sub_caster.value);
return true;
}
}
}
/* Perform an implicit conversion */
if (convert) {
for (auto &converter : typeinfo->implicit_conversions) {
temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
if (load(temp, false))
return true;
}
for (auto &converter : *typeinfo->direct_conversions) {
if (converter(src.ptr(), value))
return true;
}
}
return false;
}
PYBIND11_NOINLINE static handle cast(const void *_src, return_value_policy policy, handle parent,
const std::type_info *type_info,
const std::type_info *type_info_backup,
void *(*copy_constructor)(const void *),
void *(*move_constructor)(const void *),
const void *existing_holder = nullptr) {
void *src = const_cast<void *>(_src);
if (src == nullptr)
return none().inc_ref();
auto &internals = get_internals();
auto it = internals.registered_types_cpp.find(std::type_index(*type_info));
if (it == internals.registered_types_cpp.end()) {
type_info = type_info_backup;
it = internals.registered_types_cpp.find(std::type_index(*type_info));
}
if (it == internals.registered_types_cpp.end()) {
std::string tname = type_info->name();
detail::clean_type_id(tname);
std::string msg = "Unregistered type : " + tname;
PyErr_SetString(PyExc_TypeError, msg.c_str());
return handle();
}
auto tinfo = (const detail::type_info *) it->second;
auto it_instances = internals.registered_instances.equal_range(src);
for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
auto instance_type = detail::get_type_info(Py_TYPE(it_i->second));
if (instance_type && instance_type == tinfo)
return handle((PyObject *) it_i->second).inc_ref();
}
auto inst = reinterpret_steal<object>(PyType_GenericAlloc(tinfo->type, 0));
auto wrapper = (instance<void> *) inst.ptr();
wrapper->value = nullptr;
wrapper->owned = false;
switch (policy) {
case return_value_policy::automatic:
case return_value_policy::take_ownership:
wrapper->value = src;
wrapper->owned = true;
break;
case return_value_policy::automatic_reference:
case return_value_policy::reference:
wrapper->value = src;
wrapper->owned = false;
break;
case return_value_policy::copy:
if (copy_constructor)
wrapper->value = copy_constructor(src);
else
throw cast_error("return_value_policy = copy, but the "
"object is non-copyable!");
wrapper->owned = true;
break;
case return_value_policy::move:
if (move_constructor)
wrapper->value = move_constructor(src);
else if (copy_constructor)
wrapper->value = copy_constructor(src);
else
throw cast_error("return_value_policy = move, but the "
"object is neither movable nor copyable!");
wrapper->owned = true;
break;
case return_value_policy::reference_internal:
wrapper->value = src;
wrapper->owned = false;
detail::keep_alive_impl(inst, parent);
break;
default:
throw cast_error("unhandled return_value_policy: should not happen!");
}
tinfo->init_holder(inst.ptr(), existing_holder);
internals.registered_instances.emplace(wrapper->value, inst.ptr());
return inst.release();
}
protected:
const type_info *typeinfo = nullptr;
void *value = nullptr;
object temp;
};
/* Determine suitable casting operator */
template <typename T>
using cast_op_type = typename std::conditional<std::is_pointer<typename std::remove_reference<T>::type>::value,
typename std::add_pointer<intrinsic_t<T>>::type,
typename std::add_lvalue_reference<intrinsic_t<T>>::type>::type;
// std::is_copy_constructible isn't quite enough: it lets std::vector<T> (and similar) through when
// T is non-copyable, but code containing such a copy constructor fails to actually compile.
template <typename T, typename SFINAE = void> struct is_copy_constructible : std::is_copy_constructible<T> {};
// Specialization for types that appear to be copy constructible but also look like stl containers
// (we specifically check for: has `value_type` and `reference` with `reference = value_type&`): if
// so, copy constructability depends on whether the value_type is copy constructible.
template <typename Container> struct is_copy_constructible<Container, enable_if_t<
std::is_copy_constructible<Container>::value &&
std::is_same<typename Container::value_type &, typename Container::reference>::value
>> : std::is_copy_constructible<typename Container::value_type> {};
/// Generic type caster for objects stored on the heap
template <typename type> class type_caster_base : public type_caster_generic {
using itype = intrinsic_t<type>;
public:
static PYBIND11_DESCR name() { return type_descr(_<type>()); }
type_caster_base() : type_caster_base(typeid(type)) { }
explicit type_caster_base(const std::type_info &info) : type_caster_generic(info) { }
static handle cast(const itype &src, return_value_policy policy, handle parent) {
if (policy == return_value_policy::automatic || policy == return_value_policy::automatic_reference)
policy = return_value_policy::copy;
return cast(&src, policy, parent);
}
static handle cast(itype &&src, return_value_policy, handle parent) {
return cast(&src, return_value_policy::move, parent);
}
static handle cast(const itype *src, return_value_policy policy, handle parent) {
return type_caster_generic::cast(
src, policy, parent, src ? &typeid(*src) : nullptr, &typeid(type),
make_copy_constructor(src), make_move_constructor(src));
}
static handle cast_holder(const itype *src, const void *holder) {
return type_caster_generic::cast(
src, return_value_policy::take_ownership, {},
src ? &typeid(*src) : nullptr, &typeid(type),
nullptr, nullptr, holder);
}
template <typename T> using cast_op_type = pybind11::detail::cast_op_type<T>;
operator itype*() { return (type *) value; }
operator itype&() { if (!value) throw reference_cast_error(); return *((itype *) value); }
protected:
typedef void *(*Constructor)(const void *stream);
#if !defined(_MSC_VER)
/* Only enabled when the types are {copy,move}-constructible *and* when the type
does not have a private operator new implementaton. */
template <typename T = type, typename = enable_if_t<is_copy_constructible<T>::value>> static auto make_copy_constructor(const T *value) -> decltype(new T(*value), Constructor(nullptr)) {
return [](const void *arg) -> void * { return new T(*((const T *) arg)); }; }
template <typename T = type> static auto make_move_constructor(const T *value) -> decltype(new T(std::move(*((T *) value))), Constructor(nullptr)) {
return [](const void *arg) -> void * { return (void *) new T(std::move(*const_cast<T *>(reinterpret_cast<const T *>(arg)))); }; }
#else
/* Visual Studio 2015's SFINAE implementation doesn't yet handle the above robustly in all situations.
Use a workaround that only tests for constructibility for now. */
template <typename T = type, typename = enable_if_t<is_copy_constructible<T>::value>>
static Constructor make_copy_constructor(const T *value) {
return [](const void *arg) -> void * { return new T(*((const T *)arg)); }; }
template <typename T = type, typename = enable_if_t<std::is_move_constructible<T>::value>>
static Constructor make_move_constructor(const T *value) {
return [](const void *arg) -> void * { return (void *) new T(std::move(*((T *)arg))); }; }
#endif
static Constructor make_copy_constructor(...) { return nullptr; }
static Constructor make_move_constructor(...) { return nullptr; }
};
template <typename type, typename SFINAE = void> class type_caster : public type_caster_base<type> { };
template <typename type> using make_caster = type_caster<intrinsic_t<type>>;
// Shortcut for calling a caster's `cast_op_type` cast operator for casting a type_caster to a T
template <typename T> typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &caster) {
return caster.operator typename make_caster<T>::template cast_op_type<T>();
}
template <typename T> typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &&caster) {
return cast_op<T>(caster);
}
template <typename type> class type_caster<std::reference_wrapper<type>> : public type_caster_base<type> {
public:
static handle cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
return type_caster_base<type>::cast(&src.get(), policy, parent);
}
template <typename T> using cast_op_type = std::reference_wrapper<type>;
operator std::reference_wrapper<type>() { return std::ref(*((type *) this->value)); }
};
#define PYBIND11_TYPE_CASTER(type, py_name) \
protected: \
type value; \
public: \
static PYBIND11_DESCR name() { return type_descr(py_name); } \
static handle cast(const type *src, return_value_policy policy, handle parent) { \
if (!src) return none().release(); \
return cast(*src, policy, parent); \
} \
operator type*() { return &value; } \
operator type&() { return value; } \
template <typename _T> using cast_op_type = pybind11::detail::cast_op_type<_T>
template <typename CharT> using is_std_char_type = any_of<
std::is_same<CharT, char>, /* std::string */
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 (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 (sizeof(T) <= sizeof(long)) {
if (PyFloat_Check(src.ptr()))
return false;
if (std::is_signed<T>::value)
py_value = (py_type) PyLong_AsLong(src.ptr());
else
py_value = (py_type) PyLong_AsUnsignedLong(src.ptr());
} else {
if (PyFloat_Check(src.ptr()))
return false;
if (std::is_signed<T>::value)
py_value = (py_type) PYBIND11_LONG_AS_LONGLONG(src.ptr());
else
py_value = (py_type) PYBIND11_LONG_AS_UNSIGNED_LONGLONG(src.ptr());
}
if ((py_value == (py_type) -1 && PyErr_Occurred()) ||
(std::is_integral<T>::value && sizeof(py_type) != sizeof(T) &&
(py_value < (py_type) std::numeric_limits<T>::min() ||
py_value > (py_type) std::numeric_limits<T>::max()))) {
#if PY_VERSION_HEX < 0x03000000
bool type_error = PyErr_ExceptionMatches(PyExc_SystemError);
#else
bool type_error = PyErr_ExceptionMatches(PyExc_TypeError);
#endif
PyErr_Clear();
if (type_error && convert && PyNumber_Check(src.ptr())) {
auto tmp = reinterpret_borrow<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;
}
static handle cast(T src, return_value_policy /* policy */, handle /* parent */) {
if (std::is_floating_point<T>::value) {
return PyFloat_FromDouble((double) src);
} else if (sizeof(T) <= sizeof(long)) {
if (std::is_signed<T>::value)
return PyLong_FromLong((long) src);
else
return PyLong_FromUnsignedLong((unsigned long) src);
} else {
if (std::is_signed<T>::value)
return PyLong_FromLongLong((long long) src);
else
return PyLong_FromUnsignedLongLong((unsigned long long) src);
}
}
PYBIND11_TYPE_CASTER(T, _<std::is_integral<T>::value>("int", "float"));
};
template<typename T> struct void_caster {
public:
bool load(handle, bool) { return false; }
static handle cast(T, return_value_policy /* policy */, handle /* parent */) {
return none().inc_ref();
}
PYBIND11_TYPE_CASTER(T, _("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;
} else 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 */
if (get_type_info((PyTypeObject *) h.get_type().ptr())) {
value = ((instance<void> *) h.ptr())->value;
return true;
}
/* Fail */
return false;
}
static handle cast(const void *ptr, return_value_policy /* policy */, handle /* parent */) {
if (ptr)
return capsule(ptr).release();
else
return none().inc_ref();
}
template <typename T> using cast_op_type = void*&;
operator void *&() { return value; }
static PYBIND11_DESCR name() { return type_descr(_("capsule")); }
private:
void *value = nullptr;
};
template <> class type_caster<std::nullptr_t> : public type_caster<void_type> { };
template <> class type_caster<bool> {
public:
bool load(handle src, bool) {
if (!src) return false;
else if (src.ptr() == Py_True) { value = true; return true; }
else if (src.ptr() == Py_False) { value = false; return true; }
else 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, _("bool"));
};
// Helper class for UTF-{8,16,32} C++ stl strings:
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>> {
// 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");
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);
using StringType = std::basic_string<CharT, Traits, Allocator>;
bool load(handle src, bool) {
#if PY_MAJOR_VERSION < 3
object temp;
#endif
handle load_src = src;
if (!src) {
return false;
} else if (!PyUnicode_Check(load_src.ptr())) {
#if PY_MAJOR_VERSION >= 3
return false;
// The below is a guaranteed failure in Python 3 when PyUnicode_Check returns false
#else
if (!PYBIND11_BYTES_CHECK(load_src.ptr()))
return false;
temp = reinterpret_steal<object>(PyUnicode_FromObject(load_src.ptr()));
if (!temp) { PyErr_Clear(); return false; }
load_src = temp;
#endif
}
object 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 CharT *buffer = reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
size_t length = (size_t) PYBIND11_BYTES_SIZE(utfNbytes.ptr()) / sizeof(CharT);
if (UTF_N > 8) { buffer++; length--; } // Skip BOM for UTF-16/32
value = StringType(buffer, length);
return true;
}
static handle cast(const StringType &src, return_value_policy /* policy */, handle /* parent */) {
const char *buffer = reinterpret_cast<const char *>(src.c_str());
ssize_t 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, _(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 seems to have multiple problems related to PyUnicode_UTF*: the UTF8 version
// sometimes segfaults for unknown reasons, while the UTF16 and 32 versions require a
// non-const char * arguments, which is also a nuissance, 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
}
};
// 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 = type_caster<StringType>;
StringCaster str_caster;
bool none = false;
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().inc_ref();
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);
}
operator CharT*() { return none ? nullptr : const_cast<CharT *>(static_cast<StringType &>(str_caster).c_str()); }
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 (StringCaster::UTF_N == 8 && str_len > 1 && str_len <= 4) {
unsigned char v0 = static_cast<unsigned char>(value[0]);
size_t char0_bytes = !(v0 & 0x80) ? 1 : // low bits only: 0-127
(v0 & 0xE0) == 0xC0 ? 2 : // 0b110xxxxx - start of 2-byte sequence
(v0 & 0xF0) == 0xE0 ? 3 : // 0b1110xxxx - start of 3-byte sequence
4; // 0b11110xxx - start of 4-byte sequence
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
return static_cast<CharT>(((v0 & 3) << 6) + (static_cast<unsigned char>(value[1]) & 0x3F));
}
// 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 (StringCaster::UTF_N == 16 && str_len == 2) {
char16_t v0 = static_cast<char16_t>(value[0]);
if (v0 >= 0xD800 && v0 < 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");
return value[0];
}
static PYBIND11_DESCR name() { return type_descr(_(PYBIND11_STRING_NAME)); }
template <typename _T> using cast_op_type = typename std::remove_reference<pybind11::detail::cast_op_type<_T>>::type;
};
template <typename T1, typename T2> class type_caster<std::pair<T1, T2>> {
typedef std::pair<T1, T2> type;
public:
bool load(handle src, bool convert) {
if (!isinstance<sequence>(src))
return false;
const auto seq = reinterpret_borrow<sequence>(src);
if (seq.size() != 2)
return false;
return first.load(seq[0], convert) && second.load(seq[1], convert);
}
static handle cast(const type &src, return_value_policy policy, handle parent) {
auto o1 = reinterpret_steal<object>(make_caster<T1>::cast(src.first, policy, parent));
auto o2 = reinterpret_steal<object>(make_caster<T2>::cast(src.second, policy, parent));
if (!o1 || !o2)
return handle();
tuple result(2);
PyTuple_SET_ITEM(result.ptr(), 0, o1.release().ptr());
PyTuple_SET_ITEM(result.ptr(), 1, o2.release().ptr());
return result.release();
}
static PYBIND11_DESCR name() {
return type_descr(
_("Tuple[") + make_caster<T1>::name() + _(", ") + make_caster<T2>::name() + _("]")
);
}
template <typename T> using cast_op_type = type;
operator type() {
return type(cast_op<T1>(first), cast_op<T2>(second));
}
protected:
make_caster<T1> first;
make_caster<T2> second;
};
template <typename... Tuple> class type_caster<std::tuple<Tuple...>> {
using type = std::tuple<Tuple...>;
using indices = make_index_sequence<sizeof...(Tuple)>;
static constexpr auto size = sizeof...(Tuple);
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{});
}
static handle cast(const type &src, return_value_policy policy, handle parent) {
return cast_impl(src, policy, parent, indices{});
}
static PYBIND11_DESCR name() {
return type_descr(_("Tuple[") + detail::concat(make_caster<Tuple>::name()...) + _("]"));
}
template <typename T> using cast_op_type = type;
operator type() { return implicit_cast(indices{}); }
protected:
template <size_t... Is>
type implicit_cast(index_sequence<Is...>) { return type(cast_op<Tuple>(std::get<Is>(value))...); }
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...>) {
for (bool r : {std::get<Is>(value).load(seq[Is], convert)...})
if (!r)
return false;
return true;
}
static handle cast_impl(const type &, return_value_policy, handle,
index_sequence<>) { return tuple().release(); }
/* Implementation: Convert a C++ tuple into a Python tuple */
template <size_t... Is>
static handle cast_impl(const type &src, return_value_policy policy, handle parent, index_sequence<Is...>) {
std::array<object, size> entries {{
reinterpret_steal<object>(make_caster<Tuple>::cast(std::get<Is>(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();
}
std::tuple<make_caster<Tuple>...> value;
};
/// 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.
template <typename type, typename holder_type>
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;
using base::temp;
PYBIND11_NOINLINE bool load(handle src, bool convert) {
return load(src, convert, Py_TYPE(src.ptr()));
}
bool load(handle src, bool convert, PyTypeObject *tobj) {
if (!src || !typeinfo)
return false;
if (src.is_none()) {
value = nullptr;
return true;
}
if (typeinfo->default_holder)
throw cast_error("Unable to load a custom holder type from a default-holder instance");
if (typeinfo->simple_type) { /* Case 1: no multiple inheritance etc. involved */
/* Check if we can safely perform a reinterpret-style cast */
if (PyType_IsSubtype(tobj, typeinfo->type))
return load_value_and_holder(src);
} else { /* Case 2: multiple inheritance */
/* Check if we can safely perform a reinterpret-style cast */
if (tobj == typeinfo->type)
return load_value_and_holder(src);
/* If this is a python class, also check the parents recursively */
auto const &type_dict = get_internals().registered_types_py;
bool new_style_class = PyType_Check((PyObject *) tobj);
if (type_dict.find(tobj) == type_dict.end() && new_style_class && tobj->tp_bases) {
auto parents = reinterpret_borrow<tuple>(tobj->tp_bases);
for (handle parent : parents) {
bool result = load(src, convert, (PyTypeObject *) parent.ptr());
if (result)
return true;
}
}
if (try_implicit_casts(src, convert))
return true;
}
if (convert) {
for (auto &converter : typeinfo->implicit_conversions) {
temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
if (load(temp, false))
return true;
}
}
return false;
}
bool load_value_and_holder(handle src) {
auto inst = (instance<type, holder_type> *) src.ptr();
value = (void *) inst->value;
if (inst->holder_constructed) {
holder = inst->holder;
return true;
} else {
throw cast_error("Unable to cast from non-held to held instance (T& to Holder<T>) "
#if defined(NDEBUG)
"(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;
}
explicit operator type*() { return this->value; }
explicit operator type&() { return *(this->value); }
explicit operator holder_type*() { return &holder; }
// Workaround for Intel compiler bug
// see pybind11 issue 94
#if defined(__ICC) || defined(__INTEL_COMPILER)
operator holder_type&() { return holder; }
#else
explicit operator holder_type&() { return holder; }
#endif
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:
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>> { };
template <typename type, typename holder_type>
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, &src);
}
static PYBIND11_DESCR name() { return 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<std::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, ...) \
namespace pybind11 { 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_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 PYBIND11_DESCR name() { return _<T>(); } };
template <> struct handle_type_name<bytes> { static PYBIND11_DESCR name() { return _(PYBIND11_BYTES_NAME); } };
template <> struct handle_type_name<args> { static PYBIND11_DESCR name() { return _("*args"); } };
template <> struct handle_type_name<kwargs> { static PYBIND11_DESCR name() { return _("**kwargs"); } };
template <typename type>
struct pyobject_caster {
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<std::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
>;
// 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. Some classes (most notably Eigen::Ref and related) need to avoid this, and so can do so by
// specializing this struct.
template <typename Return, typename SFINAE = void> struct return_value_policy_override {
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) {
if (!conv.load(handle, true)) {
#if defined(NDEBUG)
throw cast_error("Unable to cast Python instance to C++ type (compile in debug mode for details)");
#else
throw cast_error("Unable to cast Python instance of type " +
(std::string) str(handle.get_type()) + " 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;
}
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(const T &value, return_value_policy policy = return_value_policy::automatic_reference,
handle parent = handle()) {
if (policy == return_value_policy::automatic)
policy = std::is_pointer<T>::value ? return_value_policy::take_ownership : return_value_policy::copy;
else if (policy == return_value_policy::automatic_reference)
policy = std::is_pointer<T>::value ? return_value_policy::reference : return_value_policy::copy;
return reinterpret_steal<object>(detail::make_caster<T>::cast(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(NDEBUG)
throw cast_error("Unable to cast Python instance to C++ rvalue: instance has multiple references"
" (compile in debug mode for details)");
#else
throw cast_error("Unable to move from Python " + (std::string) str(obj.get_type()) +
" 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 pybind::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::move_always<T>::value, T> cast(object &&object) {
return move<T>(std::move(object));
}
template <typename T> detail::enable_if_t<detail::move_if_unreferenced<T>::value, T> cast(object &&object) {
if (object.ref_count() > 1)
return cast<T>(object);
else
return move<T>(std::move(object));
}
template <typename T> detail::enable_if_t<detail::move_never<T>::value, T> cast(object &&object) {
return cast<T>(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; }
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)); }
struct overload_unused {}; // Placeholder type for the unneeded (and dead code) static variable in the OVERLOAD_INT macro
template <typename ret_type> using overload_caster_t = conditional_t<
cast_is_temporary_value_reference<ret_type>::value, make_caster<ret_type>, overload_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 &&, overload_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 &&o) {
return pybind11::cast<T>(std::move(o)); }
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 <> inline void cast_safe<void>(object &&) {}
NAMESPACE_END(detail)
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(NDEBUG)
throw cast_error("make_tuple(): unable to convert arguments to Python object (compile in debug mode for details)");
#else
std::array<std::string, size> argtypes { {type_id<Args>()...} };
throw cast_error("make_tuple(): unable to convert argument of type '" +
argtypes[i] + "' to Python object");
#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) { }
/// 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; }
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!)
};
/// \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(x, return_value_policy::automatic, {})
)),
descr(descr)
#if !defined(NDEBUG)
, type(type_id<T>())
#endif
{ }
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; }
/// The default value
object value;
/// The (optional) description of the default value
const char *descr;
#if !defined(NDEBUG)
/// The C++ type name of the default value (only available when compiled in debug mode)
std::string type;
#endif
};
template <typename T>
arg_v arg::operator=(T &&value) const { return {std::move(*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_BEGIN(detail)
// forward declaration
struct function_record;
/// Internal data associated with a single function call
struct function_call {
function_call(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;
/// The parent, if any
handle parent;
};
/// 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 args/kwargs argument positions relative to the end of the argument list:
static constexpr auto args_pos = constexpr_first<argument_is_args, Args...>() - (int) sizeof...(Args),
kwargs_pos = constexpr_first<argument_is_kwargs, Args...>() - (int) sizeof...(Args);
static constexpr bool args_kwargs_are_last = kwargs_pos >= - 1 && args_pos >= kwargs_pos - 1;
static_assert(args_kwargs_are_last, "py::args/py::kwargs are only permitted as the last argument(s) of a function");
public:
static constexpr bool has_kwargs = kwargs_pos < 0;
static constexpr bool has_args = args_pos < 0;
static PYBIND11_DESCR arg_names() { return detail::concat(make_caster<Args>::name()...); }
bool load_args(function_call &call) {
return load_impl_sequence(call, indices{});
}
template <typename Return, typename Guard, typename Func>
enable_if_t<!std::is_void<Return>::value, Return> call(Func &&f) {
return call_impl<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) {
call_impl<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...>) {
for (bool r : {std::get<Is>(value).load(call.args[Is], call.args_convert[Is])...})
if (!r)
return false;
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::get<Is>(value))...);
}
std::tuple<make_caster<Args>...> value;
};
/// 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();
int _[] = { 0, (process(args_list, std::forward<Ts>(values)), 0)... };
ignore_unused(_);
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(NDEBUG)
argument_cast_error();
#else
argument_cast_error(std::to_string(args_list.size()), type_id<T>());
#endif
}
args_list.append(o);
}
void process(list &args_list, detail::args_proxy ap) {
for (const auto &a : ap)
args_list.append(a);
}
void process(list &/*args_list*/, arg_v a) {
if (!a.name)
#if defined(NDEBUG)
nameless_argument_error();
#else
nameless_argument_error(a.type);
#endif
if (m_kwargs.contains(a.name)) {
#if defined(NDEBUG)
multiple_values_error();
#else
multiple_values_error(a.name);
#endif
}
if (!a.value) {
#if defined(NDEBUG)
argument_cast_error();
#else
argument_cast_error(a.name, a.type);
#endif
}
m_kwargs[a.name] = a.value;
}
void process(list &/*args_list*/, detail::kwargs_proxy kp) {
if (!kp)
return;
for (const auto &k : reinterpret_borrow<dict>(kp)) {
if (m_kwargs.contains(k.first)) {
#if defined(NDEBUG)
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. "
"(compile in debug mode for details)");
}
[[noreturn]] static void nameless_argument_error(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 "
"(compile in debug mode for details)");
}
[[noreturn]] static void multiple_values_error(std::string name) {
throw type_error("Got multiple values for keyword argument '" + name + "'");
}
[[noreturn]] static void argument_cast_error() {
throw cast_error("Unable to convert call argument to Python object "
"(compile in debug mode for details)");
}
[[noreturn]] static void argument_cast_error(std::string name, std::string type) {
throw cast_error("Unable to convert call argument '" + name
+ "' of type '" + type + "' to Python object");
}
private:
tuple m_args;
dict m_kwargs;
};
/// Collect only positional arguments for a Python function call
template <return_value_policy policy, typename... Args,
typename = enable_if_t<all_of<is_positional<Args>...>::value>>
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<!all_of<is_positional<Args>...>::value>>
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 {
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)...);
}
NAMESPACE_END(detail)
#define PYBIND11_MAKE_OPAQUE(Type) \
namespace pybind11 { namespace detail { \
template<> class type_caster<Type> : public type_caster_base<Type> { }; \
}}
NAMESPACE_END(pybind11)
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