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