110 lines
3 KiB
C++
110 lines
3 KiB
C++
/** @file dp.hpp
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*
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* @author Roland Conybeare, Feb 2026
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**/
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#pragma once
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#include "Allocator.hpp"
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#include <xo/facet/obj.hpp>
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#include <cassert>
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namespace xo {
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namespace mm {
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/** unimorphic "data pointer" with known representation and owned memory.
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* runs dtor *but not delete*. Does not store allocator!
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*
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* Compare with abox<AFacet,DRepr>
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**/
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template <typename DRepr>
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struct dp {
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dp() = default;
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/** dp takes ownership of data @p ptr;
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* will run dtor when dp goes out of scope.
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*
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* Note this is not useful when DRepr=DVariablePlaceholder
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**/
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explicit dp(DRepr * ptr) : ptr_{ptr} {}
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/** (copy ctor not supported -- ownership is unique) **/
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dp(const dp & other) = delete;
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/** Move constructor **/
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dp(dp<DRepr> && other)
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{
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ptr_ = other.ptr_;
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other.ptr_ = nullptr;
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}
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/** allocates for sizeof(DRepr), so DRepr must not use flexible array **/
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template <typename... Args>
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static dp make(obj<AAllocator> alloc, Args&&... args) {
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void * mem = alloc.alloc_for<DRepr>();
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if (mem) {
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DRepr * data = ::new (mem) DRepr(std::forward<Args>(args)...);
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assert(data);
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return dp(data);
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} else {
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assert(false);
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return dp();
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}
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}
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dp<DRepr> & operator=(const dp<DRepr> & x) = delete;
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/** move assignment **/
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dp<DRepr> & operator=(dp<DRepr> && x) {
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ptr_ = x.ptr_;
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x.ptr_ = nullptr;
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}
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// --------------------------------
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DRepr * data() const noexcept { return ptr_; }
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operator bool() const noexcept { return ptr_ != nullptr; }
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DRepr * operator->() const noexcept { return ptr_; }
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DRepr & operator*() const noexcept { return *ptr_; }
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#ifdef NOT_YET
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/** explicit conversion to obj<AFacet,DRepr> **/
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obj<AFacet, DRepr> to_op() const noexcept {
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return obj<AFacet, DRepr>(this->iface(), this->data());
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}
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#endif
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#ifdef NOT_YET
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/** Take ownership from unowned object **/
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template <typename AFacet>
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dp & adopt(const obj<AFacet, DRepr> & other)
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requires (std::is_same_v<DRepr, DVariantPlaceholder>
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|| std::is_same_v<DRepr, DOther>)
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{
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/* replace .iface_ along w/ .data_ */
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this->from_obj(other);
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return *this;
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}
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#endif
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~dp() {
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if (ptr_) {
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ptr_->~DRepr();
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}
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}
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private:
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DRepr * ptr_ = nullptr;
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};
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} /*namespace mm*/
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using mm::dp;
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} /*namespace xo*/
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/* end dp.hpp */
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