{
    mode: "facet",
    output_cpp_dir: "src/alloc2/facet",
    output_hpp_dir: "include/xo/alloc2",
    output_impl_subdir: "gc",
    includes: [
        "<xo/alloc2/Generation.hpp>",
        "<xo/alloc2/role.hpp>",
        "<xo/alloc2/VisitReason.hpp>",
        "<xo/arena/AllocInfo.hpp>",
    ],
    // extra includes in GCObject.hpp, if any
    user_hpp_includes: [
//        "\"gc/RCollector_aux.hpp\"",
    ],
    namespace1: "xo",
    namespace2: "mm",
    pretext: [
        "// see GCObject.hpp, also in xo-alloc2/",
        "namespace xo { namespace mm { class AGCObject; }}",
        "namespace xo { namespace mm { class AllocInfo; }}",
        "namespace xo { namespace mm { class Generation; }}",
    ],
    facet: "GCObjectVisitor",
    detail_subdir: "gc",
    brief: "gc-aware object visitor",
    using_doxygen: true,
    doc: [
        "Visit a gc-aware object. Visitor can traverse and update child pointers in-place."
    ],
    types: [
        // using size_type = std::size_t
//        {
//            name: "size_type",
//            doc: ["type for an amount of memory"],
//            definition: "std::size_t",
//        },
    ],
    const_methods: [
        // AllocInfo alloc_info(void * gco) const noexcept;
        {
            name: "alloc_info",
            doc: [
                "allocation metadata for gc-aware data at address @p gco.",
                "@p gco must be the result of a call to collector's alloc() function",
                "note: load-bearing for xo-gc/MutationLogStore",
            ],
            return_type: "AllocInfo",
            args: [
                {type: "void *", name: "addr"},
            ],
            const: true,
            noexcept: false,
            attributes: [],
        },
        // Generation generation_of(Role r, const void * addr) const noexcept;
        {
            name: "generation_of",
            doc: [
                "generation to which pointer @p addr belongs, given role @p r;",
                "sentinel if @p addr is not owned by collector.",
                "note: load-bearing for xo-gc/MutationLogStore",
            ],
            return_type: "Generation",
            args: [
                {type: "Role", name: "r"},
                {type: "const void *", name: "addr"},
            ],
            const: true,
            noexcept: true,
            attributes: [],
        },
    ],
    nonconst_methods: [
        // void alloc_copy(void * src)
        {
            name: "alloc_copy",
            doc: [
                "allocate copy of source object at address @p src.",
                "Source must be owned by this collector.",
                "Increments object age"
            ],
            return_type: "void *",
            args: [
                {type: "std::byte *", name: "src"},
            ],
            const: true,  // refers to interface.
            noexcept: false,
            attributes: [],
        },
        // void visit_child(VisitReason reason, AGCObject * iface, void ** pp_data) noexcept;
        {
            name: "visit_child",
            doc: ["visit child of a gc-aware object. May update child in-place!"],
            return_type: "void",
            args:[
                {type: "VisitReason", name: "reason"},
                {type: "AGCObject *", name: "iface"},
                {type: "void **", name: "pp_data"},
            ],
            const: true,  // technical const. I/face not modified
            noexcept: true,
            attributes: [],
        },
    ],
    router_facet_explicit_content: [
        "/** convenience: allocate copy for typed pointer **/",
        "template <typename T>",
        "void * alloc_copy_for(const T * src) noexcept {",
        "    return O::iface()->alloc_copy(O::data(), (std::byte *)const_cast<T *>(src));",
        "}",
        "",
        "/** convenience: move typed pointer **/",
        "template <typename T>",
        "T * std_move_for(T * src) noexcept {",
        "    void * mem = this->alloc_copy_for(src);",
        "    if (mem) {",
        "        return new (mem) T(std::move(*src));",
        "    }",
        "    return nullptr;",
        "}",
        "",
        "/** visit a gcobject child pointer in place.",
        "    Defined in RCollector_aux.hpp to avoid #include cycle",
        "    (for historical reasons - coul d be in RGCObject_aux.hpp?)",
        " **/",
        "template <typename DRepr>",
        "void visit_child(VisitReason reason, xo::facet::obj<AGCObject,DRepr> * p_obj);",
        "",
        "/** visit typed child data pointer in place.",
        "    Defined in RGCObject.hpp to avoid #include cycle",
        " **/",
        "template <typename DRepr>",
        "void visit_child(VisitReason reason, DRepr ** pp_data);",
        "",
        "/** visit faceted object pointer stored using some facet",
        "    other than AGCObject",
        " **/",
        "template <typename AFacet, typename DRepr>",
        "requires (!std::is_same_v<AFacet, AGCObject>)",
        "void visit_poly_child(VisitReason reason, obj<AFacet,DRepr> * p_pivot);",
        "",
    ]
}