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Reusing type_caster_base make_copy_constructor, make_move_constructor with a trick.

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This commit is contained in:
Ralf W. Grosse-Kunstleve 2021-01-25 23:47:40 -08:00
parent 56a71520b5
commit 94eeb34b01
1 changed files with 9 additions and 30 deletions
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39
include/pybind11/detail/smart_holder_type_casters.h
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@ -23,7 +23,7 @@ namespace detail {
inline std::pair<bool, handle> find_existing_python_instance(void *src_void_ptr,
const detail::type_info *tinfo) {
// Loop copied from type_caster_generic::cast.
// IMPROVEABLE: Factor out of type_caster_generic::cast.
// IMPROVABLE: Factor out of type_caster_generic::cast.
auto it_instances = get_internals().registered_instances.equal_range(src_void_ptr);
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))) {
@ -54,7 +54,7 @@ public:
void load_value_and_holder(value_and_holder &&v_h) {
loaded_v_h = std::move(v_h);
if (!loaded_v_h.holder_constructed()) {
// IMPROVEABLE: Error message. A change to the existing internals is
// IMPROVABLE: Error message. A change to the existing internals is
// needed to cleanly distinguish between uninitialized or disowned.
throw std::runtime_error("Missing value for wrapped C++ type:"
" Python instance is uninitialized or was disowned.");
@ -307,33 +307,12 @@ private:
}
};
// type_caster_base BEGIN
// clang-format off
// Helper factored out of 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 <typename T, typename = enable_if_t<is_copy_constructible<T>::value>>
static auto make_copy_constructor(const T *x) -> decltype(new T(*x), Constructor{}) {
return [](const void *arg) -> void * {
return new T(*reinterpret_cast<const T *>(arg));
};
}
template <typename T, typename = enable_if_t<std::is_move_constructible<T>::value>>
static auto make_move_constructor(const T *x) -> decltype(new T(std::move(*const_cast<T *>(x))), Constructor{}) {
return [](const void *arg) -> void * {
return new T(std::move(*const_cast<T *>(reinterpret_cast<const T *>(arg))));
};
}
static Constructor make_copy_constructor(...) { return nullptr; }
static Constructor make_move_constructor(...) { return nullptr; }
// IMPROVABLE: Formally factor out of type_caster_base.
struct make_constructor : private type_caster_base<int> { // Any type, nothing special about int.
using type_caster_base<int>::Constructor;
using type_caster_base<int>::make_copy_constructor;
using type_caster_base<int>::make_move_constructor;
};
// clang-format on
// type_caster_base END
template <typename T>
struct smart_holder_type_caster : smart_holder_type_caster_load<T> {
@ -500,7 +479,7 @@ struct smart_holder_type_caster<std::shared_ptr<T>> : smart_holder_type_caster_l
static handle cast(const std::shared_ptr<T> &src, return_value_policy policy, handle parent) {
if (policy != return_value_policy::automatic
&& policy != return_value_policy::reference_internal) {
// IMPROVEABLE: Error message.
// IMPROVABLE: Error message.
throw cast_error("Invalid return_value_policy for shared_ptr.");
}
@ -563,7 +542,7 @@ struct smart_holder_type_caster<std::unique_ptr<T>> : smart_holder_type_caster_l
static handle cast(std::unique_ptr<T> &&src, return_value_policy policy, handle parent) {
if (policy != return_value_policy::automatic
&& policy != return_value_policy::reference_internal) {
// IMPROVEABLE: Error message.
// IMPROVABLE: Error message.
throw cast_error("Invalid return_value_policy for unique_ptr.");
}