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xo-gc stack: streamline object pointer forwarding

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This commit is contained in:
Roland Conybeare 2026-02-13 15:15:08 -05:00
commit bfae393127
6 changed files with 89 additions and 9 deletions
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13
xo-alloc2/include/xo/alloc2/alloc/RAllocator.hpp
View file

@ -36,6 +36,19 @@ namespace xo {
return O::iface()->alloc(O::data(), typeseq::id<T>(), sizeof(T));
}
template <typename T>
T * std_copy_for(const T * src) noexcept {
// TODO: fix alloc_copy(), should take const std::byte *
T * copy = (T *)O::iface()->alloc_copy(O::data(), (std::byte*)const_cast<T *>(src));
if (copy) {
*copy = *src;
}
return copy;
}
typeseq _typeseq() const noexcept { return O::iface()->_typeseq(); }
void _drop() const noexcept { O::iface()->_drop(O::data()); }
std::string_view name() const noexcept { return O::iface()->name(O::data()); }

39
xo-facet/include/xo/facet/FacetRegistry.hpp
View file

@ -159,7 +159,7 @@ namespace xo {
* }
**/
template <typename ATo, typename AFrom>
obj<ATo> try_variant(obj<AFrom> from) {
obj<ATo> try_variant(obj<AFrom> from) noexcept {
return try_variant<ATo>(from._typeseq(), from.data());
}
@ -173,7 +173,7 @@ namespace xo {
* = FacetRegistry::variant<ABar>(foo._typeseq(), foo.opaque_data());
**/
template <typename AFacet>
obj<AFacet> try_variant(typeseq repr_id, void * data) {
obj<AFacet> try_variant(typeseq repr_id, void * data) noexcept {
const AFacet * iface = this->lookup<AFacet>(repr_id);
if (iface)
@ -246,12 +246,37 @@ namespace xo {
obj<AOther,DRepr>
obj<AFacet,DRepr>::to_facet()
{
if constexpr (std::is_same_v<DRepr, DVariantPlaceholder>) {
// return type has type-erased data
return FacetRegistry::instance().variant<AOther,AFacet>(*this);
if (this->data()) {
if constexpr (std::is_same_v<DRepr, DVariantPlaceholder>) {
// return type has type-erased data
return FacetRegistry::instance().variant<AOther,AFacet>(*this);
} else {
// return type has known data
return obj<AOther,DRepr>(this->data());
}
} else {
// return type has known data
return obj<AOther,DRepr>(this->data());
return obj<AOther,DRepr>();
}
}
// Deferred definitioon of obj<AFacet,DRepr>::to_facet(),
// since implementation requires FacetRegistry
//
template <typename AFacet, typename DRepr>
template <typename AOther>
obj<AOther,DRepr>
obj<AFacet,DRepr>::try_to_facet() noexcept
{
if (this->data()) {
if constexpr (std::is_same_v<DRepr, DVariantPlaceholder>) {
// return type has type-erased data
return FacetRegistry::instance().try_variant<AOther,AFacet>(*this);
} else {
// return type has known data
return obj<AOther,DRepr>(this->data());
}
} else {
return obj<AOther,DRepr>();
}
}

6
xo-facet/include/xo/facet/obj.hpp
View file

@ -137,6 +137,12 @@ namespace xo {
template <typename AOther>
obj<AOther,DRepr> to_facet();
/** like to_facet<AOther>(),
* but on failure return empty obj instead of throwing exception
**/
template <typename AOther>
obj<AOther,DRepr> try_to_facet() noexcept;
/** enabled when RRouter<AFacet> provides _preincrement.
* Note we don't need this trick for comparison operators,
* since return type is fixed.

2
xo-gc/idl/GCObject.json5
View file

@ -76,5 +76,5 @@
attributes: [],
},
],
router_facet_explicit_content: [ ],
router_facet_explicit_content: []
}

28
xo-gc/include/xo/gc/GCObject.hpp
View file

@ -18,5 +18,31 @@
#include "detail/IGCObject_Xfer.hpp"
#include "detail/RGCObject.hpp"
namespace xo {
namespace mm {
/** defined here to avoid #include cycle, since
* template obj<AGCObject,DRepr> awkward to make available there
**/
template <typename Object>
template <typename DRepr>
void
RCollector<Object>::forward_inplace(xo::facet::obj<AGCObject,DRepr> * p_obj)
{
this->forward_inplace(p_obj->iface(), (void **)&(p_obj->data_));
}
template <typename Object>
template <typename DRepr>
void
RCollector<Object>::forward_inplace(DRepr ** p_repr)
{
// fetch static interface for DRepr
auto iface = xo::facet::impl_for<AGCObject,DRepr>();
this->forward_inplace(&iface, (void **)p_repr);
}
}
}
/* end GCObject.hpp */
/* end GCObject.hpp */

10
xo-gc/include/xo/gc/detail/RCollector.hpp
View file

@ -23,6 +23,16 @@ namespace xo {
RCollector() = default;
RCollector(DataPtr data) : Object{std::move(data)} {}
/** forward op in place. Defined in GCObject.hpp to avoid #include cycle **/
template <typename DRepr>
void forward_inplace(obj<AGCObject,DRepr> * p_obj);
/** another convenience template for forwarding.
* Defined in RGCObject.hpp to avoid #include cycle.
**/
template <typename DRepr>
void forward_inplace(DRepr ** pp_repr);
int32_t _typeseq() const noexcept { return O::iface()->_typeseq(); }
size_type allocated(generation g, role r) const noexcept { return O::iface()->allocated(O::data(), g, r); }
size_type reserved(generation g, role r) const noexcept { return O::iface()->reserved(O::data(), g, r); }