Roland Conybeare
912ae40550
In particular: drop casual assignment to DList.rest_, will break acyclic assumption of DList.size()
91 lines
3.1 KiB
C++
91 lines
3.1 KiB
C++
/** @file DList.hpp
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*
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* @author Roland Conybeare, Dec 2025
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**/
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#pragma once
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#include <xo/alloc2/Collector.hpp>
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#include <xo/alloc2/GCObject.hpp>
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#include <xo/facet/obj.hpp>
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#include <xo/indentlog/print/ppindentinfo.hpp>
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namespace xo {
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namespace scm {
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// TODO: consider renaming to DCons
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// See also ListOps in ListOps.hpp
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//
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struct DList {
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using size_type = std::size_t;
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using AGCObject = xo::mm::AGCObject;
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using AAllocator = xo::mm::AAllocator;
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using ACollector = xo::mm::ACollector;
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using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
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using VisitReason = xo::mm::VisitReason;
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using ppindentinfo = xo::print::ppindentinfo;
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public:
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DList(xo::obj<AGCObject> h,
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DList * r) : head_{h}, rest_{r} {}
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/** sentinel for null list. Idempotent.
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* Application code may prefer ListOps::nil()
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**/
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static DList * _nil();
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/** like _nil(), but retrn fop wrapper **/
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static obj<AGCObject,DList> nil();
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/** list with first element @p car,
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* followed by contents of list @p cdr.
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* Shares structure with @p cdr
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* Application code may prefer ListOps::cons()
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**/
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static DList * _cons(obj<AAllocator> mm,
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obj<AGCObject> car,
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DList * cdr);
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/** like @c _cons(mm,car,cdr), but return fop wrapper **/
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static obj<AGCObject,DList> cons(obj<AAllocator> mm,
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obj<AGCObject> car,
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DList * cdr);
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obj<AGCObject> head() const noexcept { return head_; }
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DList * rest() const noexcept { return rest_; }
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/** DList length is at least 1 **/
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bool is_empty() const noexcept;
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/** DList models a finite sequence **/
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bool is_finite() const noexcept { return true; };
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/** return number of elements in this DList **/
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size_type size() const noexcept;
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/** return element at 0-based index @p ix **/
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obj<AGCObject> at(size_type ix) const;
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/** assign head **/
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void assign_head(obj<ACollector> gc, obj<AGCObject> h);
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/** assign rest-pointer. Caller responsible for preserving acyclic property! **/
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void _assign_rest(DList * r);
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/** pretty-printing driver; combine layout+printing **/
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bool pretty(const ppindentinfo & ppii) const;
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// GCObject facet
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/** @defgroup xo-scm-list-gcobject-facet gcobject facet **/
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///@{
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DList * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
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void visit_gco_children(VisitReason reason, obj<AGCObjectVisitor> gc) noexcept;
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///@}
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/** first member of list **/
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obj<AGCObject> head_;
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/** remainder of list **/
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DList * rest_ = nullptr;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end DList.hpp */
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