Roland Conybeare
35c761dee4
subrepo: subdir: "xo-allocutil" merged: "24d6e1d0" upstream: origin: "git@github.com:Rconybea/xo-allocutil.git" branch: "main" commit: "24d6e1d0" git-subrepo: version: "0.4.9" origin: "???" commit: "???"
57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
/** @file ObjectVisitor.hpp
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*
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**/
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#pragma once
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#include "IAlloc.hpp"
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#include <cstdint>
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namespace xo {
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namespace gc {
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/** @class ObjectVisitor
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* @brief visit IObject* members of a T instance
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*
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* Garbage collector relies on being able to navigate to
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* an IObject-instance to find+update embedded pointers to
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* other IObjects.
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*
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* An IObject implemnetation must override
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* IObject::_forward_children(IAlloc * gc)
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* and call
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* gc->forward_inplace(&child_)
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* for each such child pointer.
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*
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* For non-template classes this is straightforward
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* See for example
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* xo::obj::List in object/List.hpp
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*
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* For a template class Foo<T> that contains T-instances,
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* need to handle case where T contains IObject pointers.
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* See for example the
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* xo::tree::RedBlackTree in ordinaltree/RedBlackTree.hpp
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*
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* Use ObjectVisitor<T>::forward_children() to pick up
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* navigation code for such template arguments.
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**/
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template <typename T>
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class ObjectVisitor {
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// public:
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// void forward_children(T & target,
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// IAlloc * gc) { (void)target; (void)gc; }
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};
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#define XO_TRIVIAL_OBJECT_VISITOR(TYPE) \
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template <> \
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class ObjectVisitor<TYPE> { \
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public: \
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static void forward_children(TYPE &, IAlloc *) {} \
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}
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XO_TRIVIAL_OBJECT_VISITOR(int32_t);
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XO_TRIVIAL_OBJECT_VISITOR(double);
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} /*namespace gc*/
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} /*namespace xo*/
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/* ObjectVisitor.hpp */
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