69 lines
2.2 KiB
C++
69 lines
2.2 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/gc/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 ppindentinfo = xo::print::ppindentinfo;
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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 **/
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static 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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**/
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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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#ifdef OBSOLETE
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/** list with one element @p h1, allocated from @p mm **/
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static DList * list(obj<AAllocator> mm,
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obj<AGCObject> h1);
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/** list with two elements @p h1, @p h2, allocated from @p mm **/
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static DList * list(obj<AAllocator> mm,
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obj<AGCObject> h1,
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obj<AGCObject> h2);
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#endif
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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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/** pretty-printing driver; combine layout+printing **/
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bool pretty(const ppindentinfo & ppii) const;
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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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