87 lines
2.7 KiB
C++
87 lines
2.7 KiB
C++
/** @file cmpresult.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 <iostream>
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#include <cstdint>
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namespace xo {
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namespace mm {
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enum class comparison : int32_t {
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invalid = -1,
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comparable = 0,
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incomparable = +1,
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};
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extern const char * comparison2str(comparison x);
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inline std::ostream &
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operator<<(std::ostream & os, comparison x) {
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os << comparison2str(x);
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return os;
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}
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/** Result of a generic comparison operation
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**/
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struct cmpresult {
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/** @defgroup mm-cmpresult-ctors cmpresult ctors **/
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///@{
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cmpresult() : err_{comparison::invalid}, cmp_{0} {}
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cmpresult(comparison err, std::int16_t cmp) : err_{err}, cmp_{cmp} {}
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static cmpresult incomparable() { return cmpresult(comparison::incomparable, 0); }
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static cmpresult lesser() { return cmpresult(comparison::comparable, -1); }
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static cmpresult equal() { return cmpresult(comparison::comparable, 0); }
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static cmpresult greater() { return cmpresult(comparison::comparable, +1); }
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template<typename T>
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static cmpresult from_cmp(T && x, T && y) {
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if (x < y)
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return cmpresult::lesser();
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else if (x == y)
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return cmpresult::equal();
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else
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return cmpresult::greater();
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}
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///@}
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/** @defgroup mm-cmpresult-methods cmpresult methods **/
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///@{
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/** print to stream **/
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void display(std::ostream & os) const;
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bool is_lesser() const {
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return (err_ == comparison::comparable) && (cmp_ < 0);
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}
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bool is_equal() const {
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return (err_ == comparison::comparable) && (cmp_ == 0);
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}
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///@}
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/** @defgroup mm-cmpresult-instance-vars cmpresult instance vars **/
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///@{
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/** -1 -> invalid (sentinel)
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* 0 -> comparable
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* +1 -> incomparable (e.g. iterators from different arenas)
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**/
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comparison err_ = comparison::invalid;
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/** <0 -> lesser; 0 -> equal, >0 -> greater **/
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std::int16_t cmp_ = 0;
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///@}
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};
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inline std::ostream & operator<<(std::ostream & os,
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const cmpresult & x)
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{
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x.display(os);
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return os;
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}
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} /*namespace mm*/
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} /*namespace xo*/
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/* end cmpresult.hpp */
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