Pure copy of `class class_` implementation in pybind11.h (master commit...

Pure copy of `class class_` implementation in pybind11.h (master commit 98f1bbb8).

include/pybind11/classh.h

+template <typename type_, typename... options>
+class class_ : public detail::generic_type {
+    template <typename T> using is_holder = detail::is_holder_type<type_, T>;
+    template <typename T> using is_subtype = detail::is_strict_base_of<type_, T>;
+    template <typename T> using is_base = detail::is_strict_base_of<T, type_>;
+    // struct instead of using here to help MSVC:
+    template <typename T> struct is_valid_class_option :
+        detail::any_of<is_holder<T>, is_subtype<T>, is_base<T>> {};
+
+public:
+    using type = type_;
+    using type_alias = detail::exactly_one_t<is_subtype, void, options...>;
+    constexpr static bool has_alias = !std::is_void<type_alias>::value;
+    using holder_type = detail::exactly_one_t<is_holder, std::unique_ptr<type>, options...>;
+
+    static_assert(detail::all_of<is_valid_class_option<options>...>::value,
+            "Unknown/invalid class_ template parameters provided");
+
+    static_assert(!has_alias || std::is_polymorphic<type>::value,
+            "Cannot use an alias class with a non-polymorphic type");
+
+    PYBIND11_OBJECT(class_, generic_type, PyType_Check)
+
+    template <typename... Extra>
+    class_(handle scope, const char *name, const Extra &... extra) {
+        using namespace detail;
+
+        // MI can only be specified via class_ template options, not constructor parameters
+        static_assert(
+            none_of<is_pyobject<Extra>...>::value || // no base class arguments, or:
+            (   constexpr_sum(is_pyobject<Extra>::value...) == 1 && // Exactly one base
+                constexpr_sum(is_base<options>::value...)   == 0 && // no template option bases
+                none_of<std::is_same<multiple_inheritance, Extra>...>::value), // no multiple_inheritance attr
+            "Error: multiple inheritance bases must be specified via class_ template options");
+
+        type_record record;
+        record.scope = scope;
+        record.name = name;
+        record.type = &typeid(type);
+        record.type_size = sizeof(conditional_t<has_alias, type_alias, type>);
+        record.type_align = alignof(conditional_t<has_alias, type_alias, type>&);
+        record.holder_size = sizeof(holder_type);
+        record.init_instance = init_instance;
+        record.dealloc = dealloc;
+        record.default_holder = detail::is_instantiation<std::unique_ptr, holder_type>::value;
+
+        set_operator_new<type>(&record);
+
+        /* Register base classes specified via template arguments to class_, if any */
+        PYBIND11_EXPAND_SIDE_EFFECTS(add_base<options>(record));
+
+        /* Process optional arguments, if any */
+        process_attributes<Extra...>::init(extra..., &record);
+
+        generic_type::initialize(record);
+
+        if (has_alias) {
+            auto &instances = record.module_local ? registered_local_types_cpp() : get_internals().registered_types_cpp;
+            instances[std::type_index(typeid(type_alias))] = instances[std::type_index(typeid(type))];
+        }
+    }
+
+    template <typename Base, detail::enable_if_t<is_base<Base>::value, int> = 0>
+    static void add_base(detail::type_record &rec) {
+        rec.add_base(typeid(Base), [](void *src) -> void * {
+            return static_cast<Base *>(reinterpret_cast<type *>(src));
+        });
+    }
+
+    template <typename Base, detail::enable_if_t<!is_base<Base>::value, int> = 0>
+    static void add_base(detail::type_record &) { }
+
+    template <typename Func, typename... Extra>
+    class_ &def(const char *name_, Func&& f, const Extra&... extra) {
+        cpp_function cf(method_adaptor<type>(std::forward<Func>(f)), name(name_), is_method(*this),
+                        sibling(getattr(*this, name_, none())), extra...);
+        add_class_method(*this, name_, cf);
+        return *this;
+    }
+
+    template <typename Func, typename... Extra> class_ &
+    def_static(const char *name_, Func &&f, const Extra&... extra) {
+        static_assert(!std::is_member_function_pointer<Func>::value,
+                "def_static(...) called with a non-static member function pointer");
+        cpp_function cf(std::forward<Func>(f), name(name_), scope(*this),
+                        sibling(getattr(*this, name_, none())), extra...);
+        attr(cf.name()) = staticmethod(cf);
+        return *this;
+    }
+
+    template <detail::op_id id, detail::op_type ot, typename L, typename R, typename... Extra>
+    class_ &def(const detail::op_<id, ot, L, R> &op, const Extra&... extra) {
+        op.execute(*this, extra...);
+        return *this;
+    }
+
+    template <detail::op_id id, detail::op_type ot, typename L, typename R, typename... Extra>
+    class_ & def_cast(const detail::op_<id, ot, L, R> &op, const Extra&... extra) {
+        op.execute_cast(*this, extra...);
+        return *this;
+    }
+
+    template <typename... Args, typename... Extra>
+    class_ &def(const detail::initimpl::constructor<Args...> &init, const Extra&... extra) {
+        init.execute(*this, extra...);
+        return *this;
+    }
+
+    template <typename... Args, typename... Extra>
+    class_ &def(const detail::initimpl::alias_constructor<Args...> &init, const Extra&... extra) {
+        init.execute(*this, extra...);
+        return *this;
+    }
+
+    template <typename... Args, typename... Extra>
+    class_ &def(detail::initimpl::factory<Args...> &&init, const Extra&... extra) {
+        std::move(init).execute(*this, extra...);
+        return *this;
+    }
+
+    template <typename... Args, typename... Extra>
+    class_ &def(detail::initimpl::pickle_factory<Args...> &&pf, const Extra &...extra) {
+        std::move(pf).execute(*this, extra...);
+        return *this;
+    }
+
+    template <typename Func>
+    class_& def_buffer(Func &&func) {
+        struct capture { Func func; };
+        auto *ptr = new capture { std::forward<Func>(func) };
+        install_buffer_funcs([](PyObject *obj, void *ptr) -> buffer_info* {
+            detail::make_caster<type> caster;
+            if (!caster.load(obj, false))
+                return nullptr;
+            return new buffer_info(((capture *) ptr)->func(caster));
+        }, ptr);
+        weakref(m_ptr, cpp_function([ptr](handle wr) {
+            delete ptr;
+            wr.dec_ref();
+        })).release();
+        return *this;
+    }
+
+    template <typename Return, typename Class, typename... Args>
+    class_ &def_buffer(Return (Class::*func)(Args...)) {
+        return def_buffer([func] (type &obj) { return (obj.*func)(); });
+    }
+
+    template <typename Return, typename Class, typename... Args>
+    class_ &def_buffer(Return (Class::*func)(Args...) const) {
+        return def_buffer([func] (const type &obj) { return (obj.*func)(); });
+    }
+
+    template <typename C, typename D, typename... Extra>
+    class_ &def_readwrite(const char *name, D C::*pm, const Extra&... extra) {
+        static_assert(std::is_same<C, type>::value || std::is_base_of<C, type>::value, "def_readwrite() requires a class member (or base class member)");
+        cpp_function fget([pm](const type &c) -> const D &{ return c.*pm; }, is_method(*this)),
+                     fset([pm](type &c, const D &value) { c.*pm = value; }, is_method(*this));
+        def_property(name, fget, fset, return_value_policy::reference_internal, extra...);
+        return *this;
+    }
+
+    template <typename C, typename D, typename... Extra>
+    class_ &def_readonly(const char *name, const D C::*pm, const Extra& ...extra) {
+        static_assert(std::is_same<C, type>::value || std::is_base_of<C, type>::value, "def_readonly() requires a class member (or base class member)");
+        cpp_function fget([pm](const type &c) -> const D &{ return c.*pm; }, is_method(*this));
+        def_property_readonly(name, fget, return_value_policy::reference_internal, extra...);
+        return *this;
+    }
+
+    template <typename D, typename... Extra>
+    class_ &def_readwrite_static(const char *name, D *pm, const Extra& ...extra) {
+        cpp_function fget([pm](object) -> const D &{ return *pm; }, scope(*this)),
+                     fset([pm](object, const D &value) { *pm = value; }, scope(*this));
+        def_property_static(name, fget, fset, return_value_policy::reference, extra...);
+        return *this;
+    }
+
+    template <typename D, typename... Extra>
+    class_ &def_readonly_static(const char *name, const D *pm, const Extra& ...extra) {
+        cpp_function fget([pm](object) -> const D &{ return *pm; }, scope(*this));
+        def_property_readonly_static(name, fget, return_value_policy::reference, extra...);
+        return *this;
+    }
+
+    /// Uses return_value_policy::reference_internal by default
+    template <typename Getter, typename... Extra>
+    class_ &def_property_readonly(const char *name, const Getter &fget, const Extra& ...extra) {
+        return def_property_readonly(name, cpp_function(method_adaptor<type>(fget)),
+                                     return_value_policy::reference_internal, extra...);
+    }
+
+    /// Uses cpp_function's return_value_policy by default
+    template <typename... Extra>
+    class_ &def_property_readonly(const char *name, const cpp_function &fget, const Extra& ...extra) {
+        return def_property(name, fget, nullptr, extra...);
+    }
+
+    /// Uses return_value_policy::reference by default
+    template <typename Getter, typename... Extra>
+    class_ &def_property_readonly_static(const char *name, const Getter &fget, const Extra& ...extra) {
+        return def_property_readonly_static(name, cpp_function(fget), return_value_policy::reference, extra...);
+    }
+
+    /// Uses cpp_function's return_value_policy by default
+    template <typename... Extra>
+    class_ &def_property_readonly_static(const char *name, const cpp_function &fget, const Extra& ...extra) {
+        return def_property_static(name, fget, nullptr, extra...);
+    }
+
+    /// Uses return_value_policy::reference_internal by default
+    template <typename Getter, typename Setter, typename... Extra>
+    class_ &def_property(const char *name, const Getter &fget, const Setter &fset, const Extra& ...extra) {
+        return def_property(name, fget, cpp_function(method_adaptor<type>(fset)), extra...);
+    }
+    template <typename Getter, typename... Extra>
+    class_ &def_property(const char *name, const Getter &fget, const cpp_function &fset, const Extra& ...extra) {
+        return def_property(name, cpp_function(method_adaptor<type>(fget)), fset,
+                            return_value_policy::reference_internal, extra...);
+    }
+
+    /// Uses cpp_function's return_value_policy by default
+    template <typename... Extra>
+    class_ &def_property(const char *name, const cpp_function &fget, const cpp_function &fset, const Extra& ...extra) {
+        return def_property_static(name, fget, fset, is_method(*this), extra...);
+    }
+
+    /// Uses return_value_policy::reference by default
+    template <typename Getter, typename... Extra>
+    class_ &def_property_static(const char *name, const Getter &fget, const cpp_function &fset, const Extra& ...extra) {
+        return def_property_static(name, cpp_function(fget), fset, return_value_policy::reference, extra...);
+    }
+
+    /// Uses cpp_function's return_value_policy by default
+    template <typename... Extra>
+    class_ &def_property_static(const char *name, const cpp_function &fget, const cpp_function &fset, const Extra& ...extra) {
+        static_assert( 0 == detail::constexpr_sum(std::is_base_of<arg, Extra>::value...),
+                      "Argument annotations are not allowed for properties");
+        auto rec_fget = get_function_record(fget), rec_fset = get_function_record(fset);
+        auto *rec_active = rec_fget;
+        if (rec_fget) {
+           char *doc_prev = rec_fget->doc; /* 'extra' field may include a property-specific documentation string */
+           detail::process_attributes<Extra...>::init(extra..., rec_fget);
+           if (rec_fget->doc && rec_fget->doc != doc_prev) {
+              free(doc_prev);
+              rec_fget->doc = strdup(rec_fget->doc);
+           }
+        }
+        if (rec_fset) {
+            char *doc_prev = rec_fset->doc;
+            detail::process_attributes<Extra...>::init(extra..., rec_fset);
+            if (rec_fset->doc && rec_fset->doc != doc_prev) {
+                free(doc_prev);
+                rec_fset->doc = strdup(rec_fset->doc);
+            }
+            if (! rec_active) rec_active = rec_fset;
+        }
+        def_property_static_impl(name, fget, fset, rec_active);
+        return *this;
+    }
+
+private:
+    /// Initialize holder object, variant 1: object derives from enable_shared_from_this
+    template <typename T>
+    static void init_holder(detail::instance *inst, detail::value_and_holder &v_h,
+            const holder_type * /* unused */, const std::enable_shared_from_this<T> * /* dummy */) {
+        try {
+            auto sh = std::dynamic_pointer_cast<typename holder_type::element_type>(
+                    v_h.value_ptr<type>()->shared_from_this());
+            if (sh) {
+                new (std::addressof(v_h.holder<holder_type>())) holder_type(std::move(sh));
+                v_h.set_holder_constructed();
+            }
+        } catch (const std::bad_weak_ptr &) {}
+
+        if (!v_h.holder_constructed() && inst->owned) {
+            new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
+            v_h.set_holder_constructed();
+        }
+    }
+
+    static void init_holder_from_existing(const detail::value_and_holder &v_h,
+            const holder_type *holder_ptr, std::true_type /*is_copy_constructible*/) {
+        new (std::addressof(v_h.holder<holder_type>())) holder_type(*reinterpret_cast<const holder_type *>(holder_ptr));
+    }
+
+    static void init_holder_from_existing(const detail::value_and_holder &v_h,
+            const holder_type *holder_ptr, std::false_type /*is_copy_constructible*/) {
+        new (std::addressof(v_h.holder<holder_type>())) holder_type(std::move(*const_cast<holder_type *>(holder_ptr)));
+    }
+
+    /// Initialize holder object, variant 2: try to construct from existing holder object, if possible
+    static void init_holder(detail::instance *inst, detail::value_and_holder &v_h,
+            const holder_type *holder_ptr, const void * /* dummy -- not enable_shared_from_this<T>) */) {
+        if (holder_ptr) {
+            init_holder_from_existing(v_h, holder_ptr, std::is_copy_constructible<holder_type>());
+            v_h.set_holder_constructed();
+        } else if (inst->owned || detail::always_construct_holder<holder_type>::value) {
+            new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
+            v_h.set_holder_constructed();
+        }
+    }
+
+    /// Performs instance initialization including constructing a holder and registering the known
+    /// instance.  Should be called as soon as the `type` value_ptr is set for an instance.  Takes an
+    /// optional pointer to an existing holder to use; if not specified and the instance is
+    /// `.owned`, a new holder will be constructed to manage the value pointer.
+    static void init_instance(detail::instance *inst, const void *holder_ptr) {
+        auto v_h = inst->get_value_and_holder(detail::get_type_info(typeid(type)));
+        if (!v_h.instance_registered()) {
+            register_instance(inst, v_h.value_ptr(), v_h.type);
+            v_h.set_instance_registered();
+        }
+        init_holder(inst, v_h, (const holder_type *) holder_ptr, v_h.value_ptr<type>());
+    }
+
+    /// Deallocates an instance; via holder, if constructed; otherwise via operator delete.
+    static void dealloc(detail::value_and_holder &v_h) {
+        // We could be deallocating because we are cleaning up after a Python exception.
+        // If so, the Python error indicator will be set. We need to clear that before
+        // running the destructor, in case the destructor code calls more Python.
+        // If we don't, the Python API will exit with an exception, and pybind11 will
+        // throw error_already_set from the C++ destructor which is forbidden and triggers
+        // std::terminate().
+        error_scope scope;
+        if (v_h.holder_constructed()) {
+            v_h.holder<holder_type>().~holder_type();
+            v_h.set_holder_constructed(false);
+        }
+        else {
+            detail::call_operator_delete(v_h.value_ptr<type>(),
+                v_h.type->type_size,
+                v_h.type->type_align
+            );
+        }
+        v_h.value_ptr() = nullptr;
+    }
+
+    static detail::function_record *get_function_record(handle h) {
+        h = detail::get_function(h);
+        return h ? (detail::function_record *) reinterpret_borrow<capsule>(PyCFunction_GET_SELF(h.ptr()))
+                 : nullptr;
+    }
+};