232 lines
8.3 KiB
C++
232 lines
8.3 KiB
C++
/** @file FacetRegistry.hpp
|
|
*
|
|
* @brief Runtime facet implementation lookup
|
|
*
|
|
* @author Roland Conybeare, Jan 2026
|
|
**/
|
|
|
|
#pragma once
|
|
|
|
#include "facet_implementation.hpp"
|
|
#include "typeseq.hpp"
|
|
#include "obj.hpp"
|
|
#include <xo/indentlog/scope.hpp>
|
|
#include <xo/indentlog/print/tostr.hpp>
|
|
#include <unordered_map>
|
|
#include <utility>
|
|
|
|
namespace xo {
|
|
namespace facet {
|
|
|
|
/** @class FacetRegistry
|
|
*
|
|
* @brief Runtime registry for facet implementations
|
|
*
|
|
* Enables late-binding between facets. For example, given an
|
|
* obj<AGCObject> with unknown concrete type at compile time,
|
|
* look up the APrintable implementation at runtime.
|
|
*
|
|
* Example:
|
|
* // Registration (at initialization time)
|
|
* FacetRegistry::instance().register_impl<APrintable, DFloat>();
|
|
* FacetRegistry::instance().register_impl<APrintable, DList>();
|
|
*
|
|
* // Lookup (at runtime)
|
|
* typeseq repr_id = obj->_typeseq();
|
|
* const APrintable* printable = runtime_impl_for<APrintable>(repr_id);
|
|
* printable->print(obj.data(), out);
|
|
**/
|
|
class FacetRegistry {
|
|
public:
|
|
using typeseq = xo::reflect::typeseq;
|
|
using key_type = std::pair<typeseq, typeseq>;
|
|
|
|
/** hash function for key_type **/
|
|
struct KeyHash {
|
|
std::size_t operator()(const key_type & k) const noexcept {
|
|
// combine the two seqno values
|
|
std::size_t h1 = std::hash<int32_t>{}(k.first.seqno());
|
|
std::size_t h2 = std::hash<int32_t>{}(k.second.seqno());
|
|
return h1 ^ (h2 << 1);
|
|
}
|
|
};
|
|
|
|
/** singleton instance **/
|
|
static FacetRegistry & instance() {
|
|
static FacetRegistry s_instance;
|
|
return s_instance;
|
|
}
|
|
|
|
/** Type-safe registration
|
|
*
|
|
* Registers the compile-time FacetImplementation<AFacet, DRepr>
|
|
* for runtime lookup.
|
|
*
|
|
* @tparam AFacet abstract facet type
|
|
* @tparam DRepr data representation type
|
|
**/
|
|
template <typename AFacet, typename DRepr>
|
|
static void register_impl() {
|
|
static FacetImplType<AFacet, DRepr> impl;
|
|
|
|
instance()._register_impl(typeseq::id<AFacet>(),
|
|
typeseq::id<DRepr>(),
|
|
&impl);
|
|
}
|
|
|
|
/** Convenience function for runtime lookup
|
|
*
|
|
* @tparam AFacet abstract facet type
|
|
* @param repr_id typeseq for data representation
|
|
* @return pointer to AFacet implementation, or nullptr
|
|
**/
|
|
template <typename AFacet>
|
|
static inline const AFacet * impl_for(typeseq repr_id) {
|
|
return FacetRegistry::instance().lookup<AFacet>(repr_id);
|
|
}
|
|
|
|
/** Number of registered (facet, repr) pairs **/
|
|
std::size_t size() const { return registry_.size(); }
|
|
|
|
/** Check if implementation is registered **/
|
|
bool contains(typeseq facet_id,
|
|
typeseq repr_id) const
|
|
{
|
|
return (registry_.find(key_type(facet_id, repr_id))
|
|
!= registry_.end());
|
|
}
|
|
|
|
/** Type-safe lookup
|
|
*
|
|
* @tparam AFacet abstract facet type
|
|
* @param repr_id typeseq for data representation
|
|
* @return pointer to AFacet implementation, or nullptr
|
|
**/
|
|
template <typename AFacet>
|
|
const AFacet * lookup(typeseq repr_id) const {
|
|
return static_cast<const AFacet *>
|
|
(this->_lookup(typeseq::id<AFacet>(), repr_id));
|
|
}
|
|
|
|
/** Runtime polymorphism:
|
|
* Switch @param from from interface @tp AFrom to interface @tp ATo.
|
|
*
|
|
* Use:
|
|
* obj<AFoo> foo
|
|
* = ...; // Foo instance with variant impl
|
|
* obj<ABar> bar
|
|
* = FacetRegistry::variant<ABar,AFoo>(foo);
|
|
*
|
|
* // exception thrown if bar has null data
|
|
*
|
|
* assert(bar);
|
|
**/
|
|
template <typename ATo, typename AFrom>
|
|
obj<ATo> variant(obj<AFrom> from) {
|
|
auto retval = try_variant<ATo>(from);
|
|
|
|
if (!retval)
|
|
throw std::runtime_error(tostr("FacetRegistry::try_variant failed",
|
|
xtag("AFrom.tseq", typeseq::id<AFrom>()),
|
|
xtag("ATo.tseq", typeseq::id<ATo>())));
|
|
|
|
return retval;
|
|
}
|
|
|
|
/** Runtime polymorphism:
|
|
* Switch @param from from interface @tp AFrom to interface @tp ATo.
|
|
*
|
|
* Use:
|
|
* obj<AFoo> foo
|
|
* = ...; // Foo instance with variant impl
|
|
* obj<ABar> bar
|
|
* = FacetRegistry::try_variant<ABar,AFoo>(foo);
|
|
* if (bar) {
|
|
* // success
|
|
* } else {
|
|
* // foo::DataType doesn't appear to support ABar
|
|
* }
|
|
**/
|
|
template <typename ATo, typename AFrom>
|
|
obj<ATo> try_variant(obj<AFrom> from) {
|
|
return try_variant<ATo>(from._typeseq(), from.data());
|
|
}
|
|
|
|
/** Runtime polymorphism:
|
|
* Create variant from representation @p data
|
|
* with actual type @p repr_id.
|
|
*
|
|
* Use:
|
|
* obj<AFoo> foo = ...; // Foo instance with variant impl
|
|
* obj<ABar> bar
|
|
* = FacetRegistry::variant<ABar>(foo._typeseq(), foo.opaque_data());
|
|
**/
|
|
template <typename AFacet>
|
|
obj<AFacet> try_variant(typeseq repr_id, void * data) {
|
|
const AFacet * iface = this->lookup<AFacet>(repr_id);
|
|
|
|
if (iface)
|
|
return obj<AFacet>(iface, data);
|
|
else
|
|
return obj<AFacet>();
|
|
}
|
|
|
|
void dump(std::ostream * p_out) {
|
|
(*p_out) << std::endl;
|
|
(*p_out) << "<FacetRegistry" << std::endl;
|
|
for (auto & kv : registry_) {
|
|
(*p_out)
|
|
<< " [" << kv.first.first << "," << kv.first.second << "]"
|
|
<< " -> " << kv.second << std::endl;
|
|
}
|
|
(*p_out) << ">" << std::endl;
|
|
}
|
|
|
|
private:
|
|
/** Register a facet implementation (type-erased)
|
|
*
|
|
* @param facet_id typeseq for abstract facet (e.g., APrintable)
|
|
* @param repr_id typeseq for data representation (e.g., DFloat)
|
|
* @param impl pointer to stateless implementation instance
|
|
**/
|
|
void _register_impl(typeseq facet_id,
|
|
typeseq repr_id,
|
|
const void * impl)
|
|
{
|
|
registry_[key_type(facet_id, repr_id)] = impl;
|
|
}
|
|
|
|
/** Lookup facet implementation (type-erased)
|
|
*
|
|
* @return pointer to implementation, or nullptr if not registered
|
|
**/
|
|
const void * _lookup(typeseq facet_id,
|
|
typeseq repr_id) const
|
|
{
|
|
scope log(XO_DEBUG(false));
|
|
log && log(xtag("facet_id", facet_id),
|
|
xtag("repr_id", repr_id));
|
|
|
|
auto ix = registry_.find(key_type(facet_id, repr_id));
|
|
|
|
const void *retval = nullptr;
|
|
|
|
if (ix != registry_.end())
|
|
retval = ix->second;
|
|
|
|
log && log(xtag("retval", retval));
|
|
|
|
return retval;
|
|
}
|
|
|
|
private:
|
|
FacetRegistry() = default;
|
|
|
|
/** runtime lookup table (AFacet,DRepr) -> impl **/
|
|
std::unordered_map<key_type, const void *, KeyHash> registry_;
|
|
};
|
|
|
|
} /*namespace facet*/
|
|
} /*namespace xo*/
|
|
|
|
/* end FacetRegistry.hpp */
|