From fd11b71a79fbbb1cc36e5aa73bce1a37acbbf9d0 Mon Sep 17 00:00:00 2001 From: "Ralf W. Grosse-Kunstleve" Date: Fri, 15 Jan 2021 16:22:18 -0800 Subject: [PATCH] Using factored-out make_constructor (PR #2798), removing duplicate code. --- include/pybind11/cast.h | 915 ++++++++++++++++++++++++++++++++++++++ tests/test_classh_wip.cpp | 31 +- 2 files changed, 917 insertions(+), 29 deletions(-) diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h index 64b4022be3..b28acb8a66 100644 --- a/include/pybind11/cast.h +++ b/include/pybind11/cast.h @@ -47,6 +47,921 @@ PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE) PYBIND11_NAMESPACE_BEGIN(detail) +/// A life support system for temporary objects created by `type_caster::load()`. +/// Adding a patient will keep it alive up until the enclosing function returns. +class loader_life_support { +public: + /// A new patient frame is created when a function is entered + loader_life_support() { + get_internals().loader_patient_stack.push_back(nullptr); + } + + /// ... and destroyed after it returns + ~loader_life_support() { + auto &stack = get_internals().loader_patient_stack; + if (stack.empty()) + pybind11_fail("loader_life_support: internal error"); + + auto ptr = stack.back(); + stack.pop_back(); + Py_CLEAR(ptr); + + // A heuristic to reduce the stack's capacity (e.g. after long recursive calls) + if (stack.capacity() > 16 && !stack.empty() && stack.capacity() / stack.size() > 2) + stack.shrink_to_fit(); + } + + /// This can only be used inside a pybind11-bound function, either by `argument_loader` + /// at argument preparation time or by `py::cast()` at execution time. + PYBIND11_NOINLINE static void add_patient(handle h) { + auto &stack = get_internals().loader_patient_stack; + if (stack.empty()) + throw cast_error("When called outside a bound function, py::cast() cannot " + "do Python -> C++ conversions which require the creation " + "of temporary values"); + + auto &list_ptr = stack.back(); + if (list_ptr == nullptr) { + list_ptr = PyList_New(1); + if (!list_ptr) + pybind11_fail("loader_life_support: error allocating list"); + PyList_SET_ITEM(list_ptr, 0, h.inc_ref().ptr()); + } else { + auto result = PyList_Append(list_ptr, h.ptr()); + if (result == -1) + pybind11_fail("loader_life_support: error adding patient"); + } + } +}; + +// Gets the cache entry for the given type, creating it if necessary. The return value is the pair +// returned by emplace, i.e. an iterator for the entry and a bool set to `true` if the entry was +// just created. +inline std::pair all_type_info_get_cache(PyTypeObject *type); + +// Populates a just-created cache entry. +PYBIND11_NOINLINE inline void all_type_info_populate(PyTypeObject *t, std::vector &bases) { + std::vector check; + for (handle parent : reinterpret_borrow(t->tp_bases)) + check.push_back((PyTypeObject *) parent.ptr()); + + auto const &type_dict = get_internals().registered_types_py; + for (size_t i = 0; i < check.size(); i++) { + auto type = check[i]; + // Ignore Python2 old-style class super type: + if (!PyType_Check((PyObject *) type)) continue; + + // Check `type` in the current set of registered python types: + auto it = type_dict.find(type); + if (it != type_dict.end()) { + // We found a cache entry for it, so it's either pybind-registered or has pre-computed + // pybind bases, but we have to make sure we haven't already seen the type(s) before: we + // want to follow Python/virtual C++ rules that there should only be one instance of a + // common base. + for (auto *tinfo : it->second) { + // NB: Could use a second set here, rather than doing a linear search, but since + // having a large number of immediate pybind11-registered types seems fairly + // unlikely, that probably isn't worthwhile. + bool found = false; + for (auto *known : bases) { + if (known == tinfo) { found = true; break; } + } + if (!found) bases.push_back(tinfo); + } + } + else if (type->tp_bases) { + // It's some python type, so keep follow its bases classes to look for one or more + // registered types + if (i + 1 == check.size()) { + // When we're at the end, we can pop off the current element to avoid growing + // `check` when adding just one base (which is typical--i.e. when there is no + // multiple inheritance) + check.pop_back(); + i--; + } + for (handle parent : reinterpret_borrow(type->tp_bases)) + check.push_back((PyTypeObject *) parent.ptr()); + } + } +} + +/** + * Extracts vector of type_info pointers of pybind-registered roots of the given Python type. Will + * be just 1 pybind type for the Python type of a pybind-registered class, or for any Python-side + * derived class that uses single inheritance. Will contain as many types as required for a Python + * class that uses multiple inheritance to inherit (directly or indirectly) from multiple + * pybind-registered classes. Will be empty if neither the type nor any base classes are + * pybind-registered. + * + * The value is cached for the lifetime of the Python type. + */ +inline const std::vector &all_type_info(PyTypeObject *type) { + auto ins = all_type_info_get_cache(type); + if (ins.second) + // New cache entry: populate it + all_type_info_populate(type, ins.first->second); + + return ins.first->second; +} + +/** + * Gets a single pybind11 type info for a python type. Returns nullptr if neither the type nor any + * ancestors are pybind11-registered. Throws an exception if there are multiple bases--use + * `all_type_info` instead if you want to support multiple bases. + */ +PYBIND11_NOINLINE inline detail::type_info* get_type_info(PyTypeObject *type) { + auto &bases = all_type_info(type); + if (bases.empty()) + return nullptr; + if (bases.size() > 1) + pybind11_fail("pybind11::detail::get_type_info: type has multiple pybind11-registered bases"); + return bases.front(); +} + +inline detail::type_info *get_local_type_info(const std::type_index &tp) { + auto &locals = registered_local_types_cpp(); + auto it = locals.find(tp); + if (it != locals.end()) + return it->second; + return nullptr; +} + +inline detail::type_info *get_global_type_info(const std::type_index &tp) { + auto &types = get_internals().registered_types_cpp; + auto it = types.find(tp); + if (it != types.end()) + return it->second; + return nullptr; +} + +/// Return the type info for a given C++ type; on lookup failure can either throw or return nullptr. +PYBIND11_NOINLINE inline detail::type_info *get_type_info(const std::type_index &tp, + bool throw_if_missing = false) { + if (auto ltype = get_local_type_info(tp)) + return ltype; + if (auto gtype = get_global_type_info(tp)) + return gtype; + + 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); +} + +// Searches the inheritance graph for a registered Python instance, using all_type_info(). +PYBIND11_NOINLINE inline handle find_registered_python_instance(void *src, + const detail::type_info *tinfo) { + auto it_instances = get_internals().registered_instances.equal_range(src); + for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) { + for (auto instance_type : detail::all_type_info(Py_TYPE(it_i->second))) { + if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype)) + return handle((PyObject *) it_i->second).inc_ref(); + } + } + return handle(); +} + +struct value_and_holder { + instance *inst = nullptr; + size_t index = 0u; + const detail::type_info *type = nullptr; + void **vh = nullptr; + + // Main constructor for a found value/holder: + value_and_holder(instance *i, const detail::type_info *type, size_t vpos, size_t index) : + inst{i}, index{index}, type{type}, + vh{inst->simple_layout ? inst->simple_value_holder : &inst->nonsimple.values_and_holders[vpos]} + {} + + // Default constructor (used to signal a value-and-holder not found by get_value_and_holder()) + value_and_holder() = default; + + // Used for past-the-end iterator + value_and_holder(size_t index) : index{index} {} + + template V *&value_ptr() const { + return reinterpret_cast(vh[0]); + } + // True if this `value_and_holder` has a non-null value pointer + explicit operator bool() const { return value_ptr(); } + + template H &holder() const { + return reinterpret_cast(vh[1]); + } + bool holder_constructed() const { + return inst->simple_layout + ? inst->simple_holder_constructed + : inst->nonsimple.status[index] & instance::status_holder_constructed; + } + void set_holder_constructed(bool v = true) { + if (inst->simple_layout) + inst->simple_holder_constructed = v; + else if (v) + inst->nonsimple.status[index] |= instance::status_holder_constructed; + else + inst->nonsimple.status[index] &= (uint8_t) ~instance::status_holder_constructed; + } + bool instance_registered() const { + return inst->simple_layout + ? inst->simple_instance_registered + : inst->nonsimple.status[index] & instance::status_instance_registered; + } + void set_instance_registered(bool v = true) { + if (inst->simple_layout) + inst->simple_instance_registered = v; + else if (v) + inst->nonsimple.status[index] |= instance::status_instance_registered; + else + inst->nonsimple.status[index] &= (uint8_t) ~instance::status_instance_registered; + } +}; + +// Container for accessing and iterating over an instance's values/holders +struct values_and_holders { +private: + instance *inst; + using type_vec = std::vector; + const type_vec &tinfo; + +public: + values_and_holders(instance *inst) : inst{inst}, tinfo(all_type_info(Py_TYPE(inst))) {} + + struct iterator { + private: + instance *inst = nullptr; + const type_vec *types = nullptr; + value_and_holder curr; + friend struct values_and_holders; + iterator(instance *inst, const type_vec *tinfo) + : inst{inst}, types{tinfo}, + curr(inst /* instance */, + types->empty() ? nullptr : (*types)[0] /* type info */, + 0, /* vpos: (non-simple types only): the first vptr comes first */ + 0 /* index */) + {} + // Past-the-end iterator: + iterator(size_t end) : curr(end) {} + public: + bool operator==(const iterator &other) const { return curr.index == other.curr.index; } + bool operator!=(const iterator &other) const { return curr.index != other.curr.index; } + iterator &operator++() { + if (!inst->simple_layout) + curr.vh += 1 + (*types)[curr.index]->holder_size_in_ptrs; + ++curr.index; + curr.type = curr.index < types->size() ? (*types)[curr.index] : nullptr; + return *this; + } + value_and_holder &operator*() { return curr; } + value_and_holder *operator->() { return &curr; } + }; + + iterator begin() { return iterator(inst, &tinfo); } + iterator end() { return iterator(tinfo.size()); } + + iterator find(const type_info *find_type) { + auto it = begin(), endit = end(); + while (it != endit && it->type != find_type) ++it; + return it; + } + + size_t size() { return tinfo.size(); } +}; + +/** + * Extracts C++ value and holder pointer references from an instance (which may contain multiple + * values/holders for python-side multiple inheritance) that match the given type. Throws an error + * if the given type (or ValueType, if omitted) is not a pybind11 base of the given instance. If + * `find_type` is omitted (or explicitly specified as nullptr) the first value/holder are returned, + * regardless of type (and the resulting .type will be nullptr). + * + * The returned object should be short-lived: in particular, it must not outlive the called-upon + * instance. + */ +PYBIND11_NOINLINE inline value_and_holder instance::get_value_and_holder(const type_info *find_type /*= nullptr default in common.h*/, bool throw_if_missing /*= true in common.h*/) { + // Optimize common case: + if (!find_type || Py_TYPE(this) == find_type->type) + return value_and_holder(this, find_type, 0, 0); + + detail::values_and_holders vhs(this); + auto it = vhs.find(find_type); + if (it != vhs.end()) + return *it; + + if (!throw_if_missing) + return value_and_holder(); + +#if defined(NDEBUG) + pybind11_fail("pybind11::detail::instance::get_value_and_holder: " + "type is not a pybind11 base of the given instance " + "(compile in debug mode for type details)"); +#else + pybind11_fail("pybind11::detail::instance::get_value_and_holder: `" + + get_fully_qualified_tp_name(find_type->type) + "' is not a pybind11 base of the given `" + + get_fully_qualified_tp_name(Py_TYPE(this)) + "' instance"); +#endif +} + +PYBIND11_NOINLINE inline void instance::allocate_layout() { + auto &tinfo = all_type_info(Py_TYPE(this)); + + const size_t n_types = tinfo.size(); + + if (n_types == 0) + pybind11_fail("instance allocation failed: new instance has no pybind11-registered base types"); + + simple_layout = + n_types == 1 && tinfo.front()->holder_size_in_ptrs <= instance_simple_holder_in_ptrs(); + + // Simple path: no python-side multiple inheritance, and a small-enough holder + if (simple_layout) { + simple_value_holder[0] = nullptr; + simple_holder_constructed = false; + simple_instance_registered = false; + } + else { // multiple base types or a too-large holder + // Allocate space to hold: [v1*][h1][v2*][h2]...[bb...] where [vN*] is a value pointer, + // [hN] is the (uninitialized) holder instance for value N, and [bb...] is a set of bool + // values that tracks whether each associated holder has been initialized. Each [block] is + // padded, if necessary, to an integer multiple of sizeof(void *). + size_t space = 0; + for (auto t : tinfo) { + space += 1; // value pointer + space += t->holder_size_in_ptrs; // holder instance + } + size_t flags_at = space; + space += size_in_ptrs(n_types); // status bytes (holder_constructed and instance_registered) + + // Allocate space for flags, values, and holders, and initialize it to 0 (flags and values, + // in particular, need to be 0). Use Python's memory allocation functions: in Python 3.6 + // they default to using pymalloc, which is designed to be efficient for small allocations + // like the one we're doing here; in earlier versions (and for larger allocations) they are + // just wrappers around malloc. +#if PY_VERSION_HEX >= 0x03050000 + nonsimple.values_and_holders = (void **) PyMem_Calloc(space, sizeof(void *)); + if (!nonsimple.values_and_holders) throw std::bad_alloc(); +#else + nonsimple.values_and_holders = (void **) PyMem_New(void *, space); + if (!nonsimple.values_and_holders) throw std::bad_alloc(); + std::memset(nonsimple.values_and_holders, 0, space * sizeof(void *)); +#endif + nonsimple.status = reinterpret_cast(&nonsimple.values_and_holders[flags_at]); + } + owned = true; +} + +PYBIND11_NOINLINE inline void instance::deallocate_layout() { + if (!simple_layout) + PyMem_Free(nonsimple.values_and_holders); +} + +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(); + 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) { + auto *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::to_string(lineno) + "): " + + handle(frame->f_code->co_name).cast() + "\n"; + frame = frame->f_back; + } + } +#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) { + for (const auto &vh : values_and_holders(it->second)) { + if (vh.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 declarations +inline void keep_alive_impl(handle nurse, handle patient); +inline PyObject *make_new_instance(PyTypeObject *type); + +class type_caster_generic { +public: + PYBIND11_NOINLINE type_caster_generic(const std::type_info &type_info) + : typeinfo(get_type_info(type_info)), cpptype(&type_info) { } + + type_caster_generic(const type_info *typeinfo) + : typeinfo(typeinfo), cpptype(typeinfo ? typeinfo->cpptype : nullptr) { } + + bool load(handle src, bool convert) { + return load_impl(src, convert); + } + + PYBIND11_NOINLINE static handle cast(const void *_src, return_value_policy policy, handle parent, + const detail::type_info *tinfo, + void *(*copy_constructor)(const void *), + void *(*move_constructor)(const void *), + const void *existing_holder = nullptr) { + if (!tinfo) // no type info: error will be set already + return handle(); + + void *src = const_cast(_src); + if (src == nullptr) + return none().release(); + + if (handle registered_inst = find_registered_python_instance(src, tinfo)) + return registered_inst; + + auto inst = reinterpret_steal(make_new_instance(tinfo->type)); + auto wrapper = reinterpret_cast(inst.ptr()); + wrapper->owned = false; + void *&valueptr = values_and_holders(wrapper).begin()->value_ptr(); + + switch (policy) { + case return_value_policy::automatic: + case return_value_policy::take_ownership: + valueptr = src; + wrapper->owned = true; + break; + + case return_value_policy::automatic_reference: + case return_value_policy::reference: + valueptr = src; + wrapper->owned = false; + break; + + case return_value_policy::copy: + if (copy_constructor) + valueptr = copy_constructor(src); + else { +#if defined(NDEBUG) + throw cast_error("return_value_policy = copy, but type is " + "non-copyable! (compile in debug mode for details)"); +#else + std::string type_name(tinfo->cpptype->name()); + detail::clean_type_id(type_name); + throw cast_error("return_value_policy = copy, but type " + + type_name + " is non-copyable!"); +#endif + } + wrapper->owned = true; + break; + + case return_value_policy::move: + if (move_constructor) + valueptr = move_constructor(src); + else if (copy_constructor) + valueptr = copy_constructor(src); + else { +#if defined(NDEBUG) + throw cast_error("return_value_policy = move, but type is neither " + "movable nor copyable! " + "(compile in debug mode for details)"); +#else + std::string type_name(tinfo->cpptype->name()); + detail::clean_type_id(type_name); + throw cast_error("return_value_policy = move, but type " + + type_name + " is neither movable nor copyable!"); +#endif + } + wrapper->owned = true; + break; + + case return_value_policy::reference_internal: + valueptr = src; + wrapper->owned = false; + keep_alive_impl(inst, parent); + break; + + default: + throw cast_error("unhandled return_value_policy: should not happen!"); + } + + tinfo->init_instance(wrapper, existing_holder); + + return inst.release(); + } + + // Base methods for generic caster; there are overridden in copyable_holder_caster + void load_value(value_and_holder &&v_h) { + auto *&vptr = v_h.value_ptr(); + // Lazy allocation for unallocated values: + if (vptr == nullptr) { + auto *type = v_h.type ? v_h.type : typeinfo; + if (type->operator_new) { + vptr = type->operator_new(type->type_size); + } else { + #if defined(__cpp_aligned_new) && (!defined(_MSC_VER) || _MSC_VER >= 1912) + if (type->type_align > __STDCPP_DEFAULT_NEW_ALIGNMENT__) + vptr = ::operator new(type->type_size, + std::align_val_t(type->type_align)); + else + #endif + vptr = ::operator new(type->type_size); + } + } + value = vptr; + } + bool try_implicit_casts(handle src, bool convert) { + 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; + } + } + return false; + } + bool try_direct_conversions(handle src) { + for (auto &converter : *typeinfo->direct_conversions) { + if (converter(src.ptr(), value)) + return true; + } + return false; + } + void check_holder_compat() {} + + PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) { + auto caster = type_caster_generic(ti); + if (caster.load(src, false)) + return caster.value; + return nullptr; + } + + /// Try to load with foreign typeinfo, if available. Used when there is no + /// native typeinfo, or when the native one wasn't able to produce a value. + PYBIND11_NOINLINE bool try_load_foreign_module_local(handle src) { + constexpr auto *local_key = PYBIND11_MODULE_LOCAL_ID; + const auto pytype = type::handle_of(src); + if (!hasattr(pytype, local_key)) + return false; + + type_info *foreign_typeinfo = reinterpret_borrow(getattr(pytype, local_key)); + // Only consider this foreign loader if actually foreign and is a loader of the correct cpp type + if (foreign_typeinfo->module_local_load == &local_load + || (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype))) + return false; + + if (auto result = foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo)) { + value = result; + return true; + } + return false; + } + + // Implementation of `load`; this takes the type of `this` so that it can dispatch the relevant + // bits of code between here and copyable_holder_caster where the two classes need different + // logic (without having to resort to virtual inheritance). + template + PYBIND11_NOINLINE bool load_impl(handle src, bool convert) { + if (!src) return false; + if (!typeinfo) return try_load_foreign_module_local(src); + if (src.is_none()) { + // Defer accepting None to other overloads (if we aren't in convert mode): + if (!convert) return false; + value = nullptr; + return true; + } + + auto &this_ = static_cast(*this); + this_.check_holder_compat(); + + PyTypeObject *srctype = Py_TYPE(src.ptr()); + + // Case 1: If src is an exact type match for the target type then we can reinterpret_cast + // the instance's value pointer to the target type: + if (srctype == typeinfo->type) { + this_.load_value(reinterpret_cast(src.ptr())->get_value_and_holder()); + return true; + } + // Case 2: We have a derived class + else if (PyType_IsSubtype(srctype, typeinfo->type)) { + auto &bases = all_type_info(srctype); + bool no_cpp_mi = typeinfo->simple_type; + + // Case 2a: the python type is a Python-inherited derived class that inherits from just + // one simple (no MI) pybind11 class, or is an exact match, so the C++ instance is of + // the right type and we can use reinterpret_cast. + // (This is essentially the same as case 2b, but because not using multiple inheritance + // is extremely common, we handle it specially to avoid the loop iterator and type + // pointer lookup overhead) + if (bases.size() == 1 && (no_cpp_mi || bases.front()->type == typeinfo->type)) { + this_.load_value(reinterpret_cast(src.ptr())->get_value_and_holder()); + return true; + } + // Case 2b: the python type inherits from multiple C++ bases. Check the bases to see if + // we can find an exact match (or, for a simple C++ type, an inherited match); if so, we + // can safely reinterpret_cast to the relevant pointer. + else if (bases.size() > 1) { + for (auto base : bases) { + if (no_cpp_mi ? PyType_IsSubtype(base->type, typeinfo->type) : base->type == typeinfo->type) { + this_.load_value(reinterpret_cast(src.ptr())->get_value_and_holder(base)); + return true; + } + } + } + + // Case 2c: C++ multiple inheritance is involved and we couldn't find an exact type match + // in the registered bases, above, so try implicit casting (needed for proper C++ casting + // when MI is involved). + if (this_.try_implicit_casts(src, convert)) + return true; + } + + // Perform an implicit conversion + if (convert) { + for (auto &converter : typeinfo->implicit_conversions) { + auto temp = reinterpret_steal(converter(src.ptr(), typeinfo->type)); + if (load_impl(temp, false)) { + loader_life_support::add_patient(temp); + return true; + } + } + if (this_.try_direct_conversions(src)) + return true; + } + + // Failed to match local typeinfo. Try again with global. + if (typeinfo->module_local) { + if (auto gtype = get_global_type_info(*typeinfo->cpptype)) { + typeinfo = gtype; + return load(src, false); + } + } + + // Global typeinfo has precedence over foreign module_local + return try_load_foreign_module_local(src); + } + + + // Called to do type lookup and wrap the pointer and type in a pair when a dynamic_cast + // isn't needed or can't be used. If the type is unknown, sets the error and returns a pair + // with .second = nullptr. (p.first = nullptr is not an error: it becomes None). + PYBIND11_NOINLINE static std::pair src_and_type( + const void *src, const std::type_info &cast_type, const std::type_info *rtti_type = nullptr) { + if (auto *tpi = get_type_info(cast_type)) + return {src, const_cast(tpi)}; + + // Not found, set error: + std::string tname = rtti_type ? rtti_type->name() : cast_type.name(); + detail::clean_type_id(tname); + std::string msg = "Unregistered type : " + tname; + PyErr_SetString(PyExc_TypeError, msg.c_str()); + return {nullptr, nullptr}; + } + + const type_info *typeinfo = nullptr; + const std::type_info *cpptype = nullptr; + void *value = nullptr; +}; + +/** + * Determine suitable casting operator for pointer-or-lvalue-casting type casters. The type caster + * needs to provide `operator T*()` and `operator T&()` operators. + * + * If the type supports moving the value away via an `operator T&&() &&` method, it should use + * `movable_cast_op_type` instead. + */ +template +using cast_op_type = + conditional_t>::value, + typename std::add_pointer>::type, + typename std::add_lvalue_reference>::type>; + +/** + * Determine suitable casting operator for a type caster with a movable value. Such a type caster + * needs to provide `operator T*()`, `operator T&()`, and `operator T&&() &&`. The latter will be + * called in appropriate contexts where the value can be moved rather than copied. + * + * These operator are automatically provided when using the PYBIND11_TYPE_CASTER macro. + */ +template +using movable_cast_op_type = + conditional_t::type>::value, + typename std::add_pointer>::type, + conditional_t::value, + typename std::add_rvalue_reference>::type, + typename std::add_lvalue_reference>::type>>; + +// std::is_copy_constructible isn't quite enough: it lets std::vector (and similar) through when +// T is non-copyable, but code containing such a copy constructor fails to actually compile. +template struct is_copy_constructible : std::is_copy_constructible {}; + +// 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 struct is_copy_constructible, + std::is_same, + // Avoid infinite recursion + negation> + >::value>> : is_copy_constructible {}; + +// Likewise for std::pair +// (after C++17 it is mandatory that the copy constructor not exist when the two types aren't themselves +// copy constructible, but this can not be relied upon when T1 or T2 are themselves containers). +template struct is_copy_constructible> + : all_of, is_copy_constructible> {}; + +// The same problems arise with std::is_copy_assignable, so we use the same workaround. +template struct is_copy_assignable : std::is_copy_assignable {}; +template struct is_copy_assignable, + std::is_same + >::value>> : is_copy_assignable {}; +template struct is_copy_assignable> + : all_of, is_copy_assignable> {}; + +// Helper for type_caster_base. +struct make_constructor { + using Constructor = void *(*)(const void *); + + /* Only enabled when the types are {copy,move}-constructible *and* when the type + does not have a private operator new implementation. */ + template ::value>> + static auto make_copy_constructor(const T *x) -> decltype(new T(*x), Constructor{}) { + return [](const void *arg) -> void * { + return new T(*reinterpret_cast(arg)); + }; + } + + template ::value>> + static auto make_move_constructor(const T *x) -> decltype(new T(std::move(*const_cast(x))), Constructor{}) { + return [](const void *arg) -> void * { + return new T(std::move(*const_cast(reinterpret_cast(arg)))); + }; + } + + static Constructor make_copy_constructor(...) { return nullptr; } + static Constructor make_move_constructor(...) { return nullptr; } +}; + +PYBIND11_NAMESPACE_END(detail) + +// polymorphic_type_hook::get(src, tinfo) determines whether the object pointed +// to by `src` actually is an instance of some class derived from `itype`. +// If so, it sets `tinfo` to point to the std::type_info representing that derived +// type, and returns a pointer to the start of the most-derived object of that type +// (in which `src` is a subobject; this will be the same address as `src` in most +// single inheritance cases). If not, or if `src` is nullptr, it simply returns `src` +// and leaves `tinfo` at its default value of nullptr. +// +// The default polymorphic_type_hook just returns src. A specialization for polymorphic +// types determines the runtime type of the passed object and adjusts the this-pointer +// appropriately via dynamic_cast. This is what enables a C++ Animal* to appear +// to Python as a Dog (if Dog inherits from Animal, Animal is polymorphic, Dog is +// registered with pybind11, and this Animal is in fact a Dog). +// +// You may specialize polymorphic_type_hook yourself for types that want to appear +// polymorphic to Python but do not use C++ RTTI. (This is a not uncommon pattern +// in performance-sensitive applications, used most notably in LLVM.) +// +// polymorphic_type_hook_base allows users to specialize polymorphic_type_hook with +// std::enable_if. User provided specializations will always have higher priority than +// the default implementation and specialization provided in polymorphic_type_hook_base. +template +struct polymorphic_type_hook_base +{ + static const void *get(const itype *src, const std::type_info*&) { return src; } +}; +template +struct polymorphic_type_hook_base::value>> +{ + static const void *get(const itype *src, const std::type_info*& type) { + type = src ? &typeid(*src) : nullptr; + return dynamic_cast(src); + } +}; +template +struct polymorphic_type_hook : public polymorphic_type_hook_base {}; + +PYBIND11_NAMESPACE_BEGIN(detail) + +/// Generic type caster for objects stored on the heap +template class type_caster_base : public type_caster_generic, + protected make_constructor { + using itype = intrinsic_t; + +public: + static constexpr auto name = _(); + + 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); + } + + // Returns a (pointer, type_info) pair taking care of necessary type lookup for a + // polymorphic type (using RTTI by default, but can be overridden by specializing + // polymorphic_type_hook). If the instance isn't derived, returns the base version. + static std::pair src_and_type(const itype *src) { + auto &cast_type = typeid(itype); + const std::type_info *instance_type = nullptr; + const void *vsrc = polymorphic_type_hook::get(src, instance_type); + if (instance_type && !same_type(cast_type, *instance_type)) { + // This is a base pointer to a derived type. If the derived type is registered + // with pybind11, we want to make the full derived object available. + // In the typical case where itype is polymorphic, we get the correct + // derived pointer (which may be != base pointer) by a dynamic_cast to + // most derived type. If itype is not polymorphic, we won't get here + // except via a user-provided specialization of polymorphic_type_hook, + // and the user has promised that no this-pointer adjustment is + // required in that case, so it's OK to use static_cast. + if (const auto *tpi = get_type_info(*instance_type)) + return {vsrc, tpi}; + } + // Otherwise we have either a nullptr, an `itype` pointer, or an unknown derived pointer, so + // don't do a cast + return type_caster_generic::src_and_type(src, cast_type, instance_type); + } + + static handle cast(const itype *src, return_value_policy policy, handle parent) { + auto st = src_and_type(src); + return type_caster_generic::cast( + st.first, policy, parent, st.second, + make_copy_constructor(src), make_move_constructor(src)); + } + + static handle cast_holder(const itype *src, const void *holder) { + auto st = src_and_type(src); + return type_caster_generic::cast( + st.first, return_value_policy::take_ownership, {}, st.second, + nullptr, nullptr, holder); + } + + template using cast_op_type = detail::cast_op_type; + + operator itype*() { return (type *) value; } + operator itype&() { if (!value) throw reference_cast_error(); return *((itype *) value); } +}; + template class type_caster : public type_caster_base { }; template using make_caster = type_caster>; diff --git a/tests/test_classh_wip.cpp b/tests/test_classh_wip.cpp index b5a9274fb5..e663df0558 100644 --- a/tests/test_classh_wip.cpp +++ b/tests/test_classh_wip.cpp @@ -123,8 +123,8 @@ struct type_caster : smart_holder_type_caster_load { policy, parent, st.second, - make_copy_constructor(src), - make_move_constructor(src)); + make_constructor::make_copy_constructor(src), + make_constructor::make_move_constructor(src)); } static handle cast(mpty *src, return_value_policy policy, handle parent) { @@ -156,33 +156,6 @@ struct type_caster : smart_holder_type_caster_load { // clang-format on - // type_caster_base BEGIN - // clang-format off - - using Constructor = void *(*)(const void *); - - /* Only enabled when the types are {copy,move}-constructible *and* when the type - does not have a private operator new implementation. */ - template ::value>> - static auto make_copy_constructor(const T *x) -> decltype(new T(*x), Constructor{}) { - return [](const void *arg) -> void * { - return new T(*reinterpret_cast(arg)); - }; - } - - template ::value>> - static auto make_move_constructor(const T *x) -> decltype(new T(std::move(*const_cast(x))), Constructor{}) { - return [](const void *arg) -> void * { - return new T(std::move(*const_cast(reinterpret_cast(arg)))); - }; - } - - static Constructor make_copy_constructor(...) { return nullptr; } - static Constructor make_move_constructor(...) { return nullptr; } - - // clang-format on - // type_caster_base END - // Originally type_caster_generic::cast. PYBIND11_NOINLINE static handle cast_const_raw_ptr(const void *_src, return_value_policy policy,