xo-gc stack: + ACollector.shallow_copy()

idl/Collector.json5

@@ -267,6 +267,22 @@
             noexcept: false,
             attributes: [],
         },
+        // 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: false,
+            noexcept: false,
+            attributes: [],
+        },
         // void forward_inplace(AGCObject * lhs_iface, void ** lhs_data);
         {
             name: "forward_inplace",
@@ -288,7 +304,23 @@
         },
     ],
     router_facet_explicit_content: [
-        "/** forward op in place. Defined in GCObject.hpp to avoid #include cycle **/",
+        "/** convenience template for gc object copy **/",
+        "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 template for move-constructible T (this is common) **/",
+        "template <typename T>",
+        "void * std_copy_for(const T * src) noexcept {",
+        "    void * mem = this->alloc_copy_for(src);",
+        "    if (mem) {",
+        "        new (mem) T(std::move(*src));",
+        "    }",
+        "    return (T *)mem;",
+        "}",
+        "",
+        "/** forward faceted object pointer in place. Defined in GCObject.hpp to avoid #include cycle **/",
         "template <typename DRepr>",
         "void forward_inplace(obj<AGCObject,DRepr> * p_obj);",
         "",

include/xo/alloc2/gc/ACollector.hpp

@@ -119,6 +119,10 @@ Return false if installation fails (e.g. memory exhausted) **/
 
 Require: gc not in progress **/
     virtual void assign_member(Opaque data, void * parent, obj<AGCObject> * p_lhs, obj<AGCObject> & rhs)  = 0;
+    /** allocate copy of source object at address @p src.
+Source must be owned by this collector.
+Increments object age **/
+    virtual void * alloc_copy(Opaque data, std::byte * src)  = 0;
     /** evacuate @p *lhs, that refers to state with interface @p lhs_iface,
 to collector @p d's to-space. Replace *lhs_data with forwarding pointer
 

include/xo/alloc2/gc/ICollector_Any.hpp

@@ -75,6 +75,7 @@ namespace mm {
         [[noreturn]] void remove_gc_root_poly(Opaque, obj<AGCObject> *)  override;
         [[noreturn]] void request_gc(Opaque, Generation)  override;
         [[noreturn]] void assign_member(Opaque, void *, obj<AGCObject> *, obj<AGCObject> &)  override;
+        [[noreturn]] void * alloc_copy(Opaque, std::byte *)  override;
         [[noreturn]] void forward_inplace(Opaque, AGCObject *, void **)  override;
 
         ///@}

include/xo/alloc2/gc/ICollector_Xfer.hpp

@@ -90,6 +90,9 @@ namespace mm {
         void assign_member(Opaque data, void * parent, obj<AGCObject> * p_lhs, obj<AGCObject> & rhs)  override {
             return I::assign_member(_dcast(data), parent, p_lhs, rhs);
         }
+        void * alloc_copy(Opaque data, std::byte * src)  override {
+            return I::alloc_copy(_dcast(data), src);
+        }
         void forward_inplace(Opaque data, AGCObject * lhs_iface, void ** lhs_data)  override {
             return I::forward_inplace(_dcast(data), lhs_iface, lhs_data);
         }

include/xo/alloc2/gc/RCollector.hpp

@@ -47,7 +47,23 @@ public:
     ///@{
 
     // explicit injected content
-    /** forward op in place. Defined in GCObject.hpp to avoid #include cycle **/
+    /** convenience template for gc object copy **/
+    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 template for move-constructible T (this is common) **/
+    template <typename T>
+    void * std_copy_for(const T * src) noexcept {
+        void * mem = this->alloc_copy_for(src);
+        if (mem) {
+            new (mem) T(std::move(*src));
+        }
+        return (T *)mem;
+    }
+    
+    /** forward faceted object pointer in place. Defined in GCObject.hpp to avoid #include cycle **/
     template <typename DRepr>
     void forward_inplace(obj<AGCObject,DRepr> * p_obj);
     
@@ -123,6 +139,9 @@ public:
     void assign_member(void * parent, obj<AGCObject> * p_lhs, obj<AGCObject> & rhs)  {
         return O::iface()->assign_member(O::data(), parent, p_lhs, rhs);
     }
+    void * alloc_copy(std::byte * src)  {
+        return O::iface()->alloc_copy(O::data(), src);
+    }
     void forward_inplace(AGCObject * lhs_iface, void ** lhs_data)  {
         return O::iface()->forward_inplace(O::data(), lhs_iface, lhs_data);
     }

src/alloc2/facet/ICollector_Any.cpp

@@ -65,6 +65,12 @@ ICollector_Any::assign_member(Opaque, void *, obj<AGCObject> *, obj<AGCObject> &
     _fatal();
 }
 
+auto
+ICollector_Any::alloc_copy(Opaque, std::byte *)  -> void *
+{
+    _fatal();
+}
+
 auto
 ICollector_Any::forward_inplace(Opaque, AGCObject *, void **)  -> void
 {