435 lines
17 KiB
C++
435 lines
17 KiB
C++
/*
|
|
pybind11/detail/init.h: init factory function implementation and support code.
|
|
|
|
Copyright (c) 2017 Jason Rhinelander <jason@imaginary.ca>
|
|
|
|
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 "class.h"
|
|
|
|
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
|
|
|
|
PYBIND11_WARNING_DISABLE_MSVC(4127)
|
|
|
|
PYBIND11_NAMESPACE_BEGIN(detail)
|
|
|
|
template <>
|
|
class type_caster<value_and_holder> {
|
|
public:
|
|
bool load(handle h, bool) {
|
|
value = reinterpret_cast<value_and_holder *>(h.ptr());
|
|
return true;
|
|
}
|
|
|
|
template <typename>
|
|
using cast_op_type = value_and_holder &;
|
|
explicit operator value_and_holder &() { return *value; }
|
|
static constexpr auto name = const_name<value_and_holder>();
|
|
|
|
private:
|
|
value_and_holder *value = nullptr;
|
|
};
|
|
|
|
PYBIND11_NAMESPACE_BEGIN(initimpl)
|
|
|
|
inline void no_nullptr(void *ptr) {
|
|
if (!ptr) {
|
|
throw type_error("pybind11::init(): factory function returned nullptr");
|
|
}
|
|
}
|
|
|
|
// Implementing functions for all forms of py::init<...> and py::init(...)
|
|
template <typename Class>
|
|
using Cpp = typename Class::type;
|
|
template <typename Class>
|
|
using Alias = typename Class::type_alias;
|
|
template <typename Class>
|
|
using Holder = typename Class::holder_type;
|
|
|
|
template <typename Class>
|
|
using is_alias_constructible = std::is_constructible<Alias<Class>, Cpp<Class> &&>;
|
|
|
|
// Takes a Cpp pointer and returns true if it actually is a polymorphic Alias instance.
|
|
template <typename Class, enable_if_t<Class::has_alias, int> = 0>
|
|
bool is_alias(Cpp<Class> *ptr) {
|
|
return dynamic_cast<Alias<Class> *>(ptr) != nullptr;
|
|
}
|
|
// Failing fallback version of the above for a no-alias class (always returns false)
|
|
template <typename /*Class*/>
|
|
constexpr bool is_alias(void *) {
|
|
return false;
|
|
}
|
|
|
|
// Constructs and returns a new object; if the given arguments don't map to a constructor, we fall
|
|
// back to brace aggregate initialization so that for aggregate initialization can be used with
|
|
// py::init, e.g. `py::init<int, int>` to initialize a `struct T { int a; int b; }`. For
|
|
// non-aggregate types, we need to use an ordinary T(...) constructor (invoking as `T{...}` usually
|
|
// works, but will not do the expected thing when `T` has an `initializer_list<T>` constructor).
|
|
template <typename Class,
|
|
typename... Args,
|
|
detail::enable_if_t<std::is_constructible<Class, Args...>::value, int> = 0>
|
|
inline Class *construct_or_initialize(Args &&...args) {
|
|
return new Class(std::forward<Args>(args)...);
|
|
}
|
|
template <typename Class,
|
|
typename... Args,
|
|
detail::enable_if_t<!std::is_constructible<Class, Args...>::value, int> = 0>
|
|
inline Class *construct_or_initialize(Args &&...args) {
|
|
return new Class{std::forward<Args>(args)...};
|
|
}
|
|
|
|
// Attempts to constructs an alias using a `Alias(Cpp &&)` constructor. This allows types with
|
|
// an alias to provide only a single Cpp factory function as long as the Alias can be
|
|
// constructed from an rvalue reference of the base Cpp type. This means that Alias classes
|
|
// can, when appropriate, simply define a `Alias(Cpp &&)` constructor rather than needing to
|
|
// inherit all the base class constructors.
|
|
template <typename Class>
|
|
void construct_alias_from_cpp(std::true_type /*is_alias_constructible*/,
|
|
value_and_holder &v_h,
|
|
Cpp<Class> &&base) {
|
|
v_h.value_ptr() = new Alias<Class>(std::move(base));
|
|
}
|
|
template <typename Class>
|
|
[[noreturn]] void construct_alias_from_cpp(std::false_type /*!is_alias_constructible*/,
|
|
value_and_holder &,
|
|
Cpp<Class> &&) {
|
|
throw type_error("pybind11::init(): unable to convert returned instance to required "
|
|
"alias class: no `Alias<Class>(Class &&)` constructor available");
|
|
}
|
|
|
|
// Error-generating fallback for factories that don't match one of the below construction
|
|
// mechanisms.
|
|
template <typename Class>
|
|
void construct(...) {
|
|
static_assert(!std::is_same<Class, Class>::value /* always false */,
|
|
"pybind11::init(): init function must return a compatible pointer, "
|
|
"holder, or value");
|
|
}
|
|
|
|
// Pointer return v1: the factory function returns a class pointer for a registered class.
|
|
// If we don't need an alias (because this class doesn't have one, or because the final type is
|
|
// inherited on the Python side) we can simply take over ownership. Otherwise we need to try to
|
|
// construct an Alias from the returned base instance.
|
|
template <typename Class>
|
|
void construct(value_and_holder &v_h, Cpp<Class> *ptr, bool need_alias) {
|
|
PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(need_alias);
|
|
no_nullptr(ptr);
|
|
if (Class::has_alias && need_alias && !is_alias<Class>(ptr)) {
|
|
// We're going to try to construct an alias by moving the cpp type. Whether or not
|
|
// that succeeds, we still need to destroy the original cpp pointer (either the
|
|
// moved away leftover, if the alias construction works, or the value itself if we
|
|
// throw an error), but we can't just call `delete ptr`: it might have a special
|
|
// deleter, or might be shared_from_this. So we construct a holder around it as if
|
|
// it was a normal instance, then steal the holder away into a local variable; thus
|
|
// the holder and destruction happens when we leave the C++ scope, and the holder
|
|
// class gets to handle the destruction however it likes.
|
|
v_h.value_ptr() = ptr;
|
|
v_h.set_instance_registered(true); // To prevent init_instance from registering it
|
|
v_h.type->init_instance(v_h.inst, nullptr); // Set up the holder
|
|
Holder<Class> temp_holder(std::move(v_h.holder<Holder<Class>>())); // Steal the holder
|
|
v_h.type->dealloc(v_h); // Destroys the moved-out holder remains, resets value ptr to null
|
|
v_h.set_instance_registered(false);
|
|
|
|
construct_alias_from_cpp<Class>(is_alias_constructible<Class>{}, v_h, std::move(*ptr));
|
|
} else {
|
|
// Otherwise the type isn't inherited, so we don't need an Alias
|
|
v_h.value_ptr() = ptr;
|
|
}
|
|
}
|
|
|
|
// Pointer return v2: a factory that always returns an alias instance ptr. We simply take over
|
|
// ownership of the pointer.
|
|
template <typename Class, enable_if_t<Class::has_alias, int> = 0>
|
|
void construct(value_and_holder &v_h, Alias<Class> *alias_ptr, bool) {
|
|
no_nullptr(alias_ptr);
|
|
v_h.value_ptr() = static_cast<Cpp<Class> *>(alias_ptr);
|
|
}
|
|
|
|
// Holder return: copy its pointer, and move or copy the returned holder into the new instance's
|
|
// holder. This also handles types like std::shared_ptr<T> and std::unique_ptr<T> where T is a
|
|
// derived type (through those holder's implicit conversion from derived class holder
|
|
// constructors).
|
|
template <typename Class>
|
|
void construct(value_and_holder &v_h, Holder<Class> holder, bool need_alias) {
|
|
PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(need_alias);
|
|
auto *ptr = holder_helper<Holder<Class>>::get(holder);
|
|
no_nullptr(ptr);
|
|
// If we need an alias, check that the held pointer is actually an alias instance
|
|
if (Class::has_alias && need_alias && !is_alias<Class>(ptr)) {
|
|
throw type_error("pybind11::init(): construction failed: returned holder-wrapped instance "
|
|
"is not an alias instance");
|
|
}
|
|
|
|
v_h.value_ptr() = ptr;
|
|
v_h.type->init_instance(v_h.inst, &holder);
|
|
}
|
|
|
|
// return-by-value version 1: returning a cpp class by value. If the class has an alias and an
|
|
// alias is required the alias must have an `Alias(Cpp &&)` constructor so that we can construct
|
|
// the alias from the base when needed (i.e. because of Python-side inheritance). When we don't
|
|
// need it, we simply move-construct the cpp value into a new instance.
|
|
template <typename Class>
|
|
void construct(value_and_holder &v_h, Cpp<Class> &&result, bool need_alias) {
|
|
PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(need_alias);
|
|
static_assert(is_move_constructible<Cpp<Class>>::value,
|
|
"pybind11::init() return-by-value factory function requires a movable class");
|
|
if (Class::has_alias && need_alias) {
|
|
construct_alias_from_cpp<Class>(is_alias_constructible<Class>{}, v_h, std::move(result));
|
|
} else {
|
|
v_h.value_ptr() = new Cpp<Class>(std::move(result));
|
|
}
|
|
}
|
|
|
|
// return-by-value version 2: returning a value of the alias type itself. We move-construct an
|
|
// Alias instance (even if no the python-side inheritance is involved). The is intended for
|
|
// cases where Alias initialization is always desired.
|
|
template <typename Class>
|
|
void construct(value_and_holder &v_h, Alias<Class> &&result, bool) {
|
|
static_assert(
|
|
is_move_constructible<Alias<Class>>::value,
|
|
"pybind11::init() return-by-alias-value factory function requires a movable alias class");
|
|
v_h.value_ptr() = new Alias<Class>(std::move(result));
|
|
}
|
|
|
|
// Implementing class for py::init<...>()
|
|
template <typename... Args>
|
|
struct constructor {
|
|
template <typename Class, typename... Extra, enable_if_t<!Class::has_alias, int> = 0>
|
|
static void execute(Class &cl, const Extra &...extra) {
|
|
cl.def(
|
|
"__init__",
|
|
[](value_and_holder &v_h, Args... args) {
|
|
v_h.value_ptr() = construct_or_initialize<Cpp<Class>>(std::forward<Args>(args)...);
|
|
},
|
|
is_new_style_constructor(),
|
|
extra...);
|
|
}
|
|
|
|
template <
|
|
typename Class,
|
|
typename... Extra,
|
|
enable_if_t<Class::has_alias && std::is_constructible<Cpp<Class>, Args...>::value, int>
|
|
= 0>
|
|
static void execute(Class &cl, const Extra &...extra) {
|
|
cl.def(
|
|
"__init__",
|
|
[](value_and_holder &v_h, Args... args) {
|
|
if (Py_TYPE(v_h.inst) == v_h.type->type) {
|
|
v_h.value_ptr()
|
|
= construct_or_initialize<Cpp<Class>>(std::forward<Args>(args)...);
|
|
} else {
|
|
v_h.value_ptr()
|
|
= construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
|
|
}
|
|
},
|
|
is_new_style_constructor(),
|
|
extra...);
|
|
}
|
|
|
|
template <
|
|
typename Class,
|
|
typename... Extra,
|
|
enable_if_t<Class::has_alias && !std::is_constructible<Cpp<Class>, Args...>::value, int>
|
|
= 0>
|
|
static void execute(Class &cl, const Extra &...extra) {
|
|
cl.def(
|
|
"__init__",
|
|
[](value_and_holder &v_h, Args... args) {
|
|
v_h.value_ptr()
|
|
= construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
|
|
},
|
|
is_new_style_constructor(),
|
|
extra...);
|
|
}
|
|
};
|
|
|
|
// Implementing class for py::init_alias<...>()
|
|
template <typename... Args>
|
|
struct alias_constructor {
|
|
template <
|
|
typename Class,
|
|
typename... Extra,
|
|
enable_if_t<Class::has_alias && std::is_constructible<Alias<Class>, Args...>::value, int>
|
|
= 0>
|
|
static void execute(Class &cl, const Extra &...extra) {
|
|
cl.def(
|
|
"__init__",
|
|
[](value_and_holder &v_h, Args... args) {
|
|
v_h.value_ptr()
|
|
= construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
|
|
},
|
|
is_new_style_constructor(),
|
|
extra...);
|
|
}
|
|
};
|
|
|
|
// Implementation class for py::init(Func) and py::init(Func, AliasFunc)
|
|
template <typename CFunc,
|
|
typename AFunc = void_type (*)(),
|
|
typename = function_signature_t<CFunc>,
|
|
typename = function_signature_t<AFunc>>
|
|
struct factory;
|
|
|
|
// Specialization for py::init(Func)
|
|
template <typename Func, typename Return, typename... Args>
|
|
struct factory<Func, void_type (*)(), Return(Args...)> {
|
|
remove_reference_t<Func> class_factory;
|
|
|
|
// NOLINTNEXTLINE(google-explicit-constructor)
|
|
factory(Func &&f) : class_factory(std::forward<Func>(f)) {}
|
|
|
|
// The given class either has no alias or has no separate alias factory;
|
|
// this always constructs the class itself. If the class is registered with an alias
|
|
// type and an alias instance is needed (i.e. because the final type is a Python class
|
|
// inheriting from the C++ type) the returned value needs to either already be an alias
|
|
// instance, or the alias needs to be constructible from a `Class &&` argument.
|
|
template <typename Class, typename... Extra>
|
|
void execute(Class &cl, const Extra &...extra) && {
|
|
#if defined(PYBIND11_CPP14)
|
|
cl.def(
|
|
"__init__",
|
|
[func = std::move(class_factory)]
|
|
#else
|
|
auto &func = class_factory;
|
|
cl.def(
|
|
"__init__",
|
|
[func]
|
|
#endif
|
|
(value_and_holder &v_h, Args... args) {
|
|
construct<Class>(
|
|
v_h, func(std::forward<Args>(args)...), Py_TYPE(v_h.inst) != v_h.type->type);
|
|
},
|
|
is_new_style_constructor(),
|
|
extra...);
|
|
}
|
|
};
|
|
|
|
// Specialization for py::init(Func, AliasFunc)
|
|
template <typename CFunc,
|
|
typename AFunc,
|
|
typename CReturn,
|
|
typename... CArgs,
|
|
typename AReturn,
|
|
typename... AArgs>
|
|
struct factory<CFunc, AFunc, CReturn(CArgs...), AReturn(AArgs...)> {
|
|
static_assert(sizeof...(CArgs) == sizeof...(AArgs),
|
|
"pybind11::init(class_factory, alias_factory): class and alias factories "
|
|
"must have identical argument signatures");
|
|
static_assert(all_of<std::is_same<CArgs, AArgs>...>::value,
|
|
"pybind11::init(class_factory, alias_factory): class and alias factories "
|
|
"must have identical argument signatures");
|
|
|
|
remove_reference_t<CFunc> class_factory;
|
|
remove_reference_t<AFunc> alias_factory;
|
|
|
|
factory(CFunc &&c, AFunc &&a)
|
|
: class_factory(std::forward<CFunc>(c)), alias_factory(std::forward<AFunc>(a)) {}
|
|
|
|
// The class factory is called when the `self` type passed to `__init__` is the direct
|
|
// class (i.e. not inherited), the alias factory when `self` is a Python-side subtype.
|
|
template <typename Class, typename... Extra>
|
|
void execute(Class &cl, const Extra &...extra) && {
|
|
static_assert(Class::has_alias,
|
|
"The two-argument version of `py::init()` can "
|
|
"only be used if the class has an alias");
|
|
#if defined(PYBIND11_CPP14)
|
|
cl.def(
|
|
"__init__",
|
|
[class_func = std::move(class_factory), alias_func = std::move(alias_factory)]
|
|
#else
|
|
auto &class_func = class_factory;
|
|
auto &alias_func = alias_factory;
|
|
cl.def(
|
|
"__init__",
|
|
[class_func, alias_func]
|
|
#endif
|
|
(value_and_holder &v_h, CArgs... args) {
|
|
if (Py_TYPE(v_h.inst) == v_h.type->type) {
|
|
// If the instance type equals the registered type we don't have inheritance,
|
|
// so don't need the alias and can construct using the class function:
|
|
construct<Class>(v_h, class_func(std::forward<CArgs>(args)...), false);
|
|
} else {
|
|
construct<Class>(v_h, alias_func(std::forward<CArgs>(args)...), true);
|
|
}
|
|
},
|
|
is_new_style_constructor(),
|
|
extra...);
|
|
}
|
|
};
|
|
|
|
/// Set just the C++ state. Same as `__init__`.
|
|
template <typename Class, typename T>
|
|
void setstate(value_and_holder &v_h, T &&result, bool need_alias) {
|
|
construct<Class>(v_h, std::forward<T>(result), need_alias);
|
|
}
|
|
|
|
/// Set both the C++ and Python states
|
|
template <typename Class,
|
|
typename T,
|
|
typename O,
|
|
enable_if_t<std::is_convertible<O, handle>::value, int> = 0>
|
|
void setstate(value_and_holder &v_h, std::pair<T, O> &&result, bool need_alias) {
|
|
construct<Class>(v_h, std::move(result.first), need_alias);
|
|
auto d = handle(result.second);
|
|
if (PyDict_Check(d.ptr()) && PyDict_Size(d.ptr()) == 0) {
|
|
// Skipping setattr below, to not force use of py::dynamic_attr() for Class unnecessarily.
|
|
// See PR #2972 for details.
|
|
return;
|
|
}
|
|
setattr((PyObject *) v_h.inst, "__dict__", d);
|
|
}
|
|
|
|
/// Implementation for py::pickle(GetState, SetState)
|
|
template <typename Get,
|
|
typename Set,
|
|
typename = function_signature_t<Get>,
|
|
typename = function_signature_t<Set>>
|
|
struct pickle_factory;
|
|
|
|
template <typename Get,
|
|
typename Set,
|
|
typename RetState,
|
|
typename Self,
|
|
typename NewInstance,
|
|
typename ArgState>
|
|
struct pickle_factory<Get, Set, RetState(Self), NewInstance(ArgState)> {
|
|
static_assert(std::is_same<intrinsic_t<RetState>, intrinsic_t<ArgState>>::value,
|
|
"The type returned by `__getstate__` must be the same "
|
|
"as the argument accepted by `__setstate__`");
|
|
|
|
remove_reference_t<Get> get;
|
|
remove_reference_t<Set> set;
|
|
|
|
pickle_factory(Get get, Set set) : get(std::forward<Get>(get)), set(std::forward<Set>(set)) {}
|
|
|
|
template <typename Class, typename... Extra>
|
|
void execute(Class &cl, const Extra &...extra) && {
|
|
cl.def("__getstate__", std::move(get));
|
|
|
|
#if defined(PYBIND11_CPP14)
|
|
cl.def(
|
|
"__setstate__",
|
|
[func = std::move(set)]
|
|
#else
|
|
auto &func = set;
|
|
cl.def(
|
|
"__setstate__",
|
|
[func]
|
|
#endif
|
|
(value_and_holder &v_h, ArgState state) {
|
|
setstate<Class>(
|
|
v_h, func(std::forward<ArgState>(state)), Py_TYPE(v_h.inst) != v_h.type->type);
|
|
},
|
|
is_new_style_constructor(),
|
|
extra...);
|
|
}
|
|
};
|
|
|
|
PYBIND11_NAMESPACE_END(initimpl)
|
|
PYBIND11_NAMESPACE_END(detail)
|
|
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
|