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+/*
+ 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"
+
+NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+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 &;
+ operator value_and_holder &() { return *value; }
+ static PYBIND11_DESCR name() { return type_descr(_<value_and_holder>()); }
+
+private:
+ value_and_holder *value = nullptr;
+};
+
+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 initiailization 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) {
+ 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) {
+ auto *ptr = holder_helper<Holder<Class>>::get(holder);
+ // 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) {
+ static_assert(std::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(std::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;
+
+ 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);
+ setattr((PyObject *) v_h.inst, "__dict__", result.second);
+}
+
+/// 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...);
+ }
+};
+
+NAMESPACE_END(initimpl)
+NAMESPACE_END(detail)
+NAMESPACE_END(pybind11)