75 lines
2.9 KiB
C++
75 lines
2.9 KiB
C++
/** @file gc_allocator_traits.hpp
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*
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* @author Roland Conybeare, Nov 2025
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**/
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#pragma once
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#include <type_traits>
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#include <memory>
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namespace xo {
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namespace gc {
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/** Extended version of
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* std::allocator_traits<Allocator>
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* Introduces additional i/face methods
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* for garbage-collector-enabled allocators
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*
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* allocator A can identify itself as a copying collector:
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* 1. provide A::object_interface
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* A::object_interface = xo::Object
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* 2. provide A::is_incremental_collector
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* A::is_incremental_collector = std::true_type
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* Collectible objects must:
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* 2a. inherit A::object_interface
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* 2b. implement A::object_interface::_shallow_size()
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* 2c. implement A::object_interface::_shallow_copy(alloc)
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* 2d. implement A::object_interface::_forward_children(alloc)
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**/
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template <typename Allocator>
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struct gc_allocator_traits : std::allocator_traits<Allocator> {
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using super = std::allocator_traits<Allocator>;
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using pointer = typename super::pointer;
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using value_type = typename super::value_type;
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// default: allocator A fallback to standard non-gc allocator behavior
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template <typename A, typename = void>
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struct is_incremental_collector : std::false_type {};
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// opt-in: A provides nested type 'is_incremental_collector':
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// struct A {
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// using is_incremental_collector = std::true_type;
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// };
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template <typename A>
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struct is_incremental_collector<A, std::void_t<typename A::is_incremental_collector>> :
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A::is_incremental_collector {};
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// default: empty object interface.
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// classes that want to conditionally support GC
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// (e.g. see xo::tree::RedBlackTree, xo::tree::Node
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// in xo-ordinal-tree)
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// can inherit
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// gc_allocator_traits<Allocator>::template object_interface<Allocator>
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//
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template <typename A, typename = void>
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struct object_interface {};
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// specialization when A provides gc_object_interface
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template <typename A>
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struct object_interface<A, std::void_t<typename A::gc_object_interface>>
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: A::gc_object_interface {};
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/** true iff this allocator advertises itself as an incremental collector
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* allocator will include:
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*
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* struct GC {
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* using is_incremental_collector = std::true_type;
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* };
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**/
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static inline constexpr bool is_incremental_collector_v = is_incremental_collector<Allocator>::value;
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};
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} /*namespace gc*/
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} /*namespace xo*/
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/* end gc_allocator_traits.hpp */
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