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https://github.com/NixOS/nix
synced 2025-07-05 20:41:47 +02:00
bc83b9dc1f
Known behavior changes: - `MemorySourceAccessor`'s comparison operators no longer forget to compare the `SourceAccessor` base class. Progress on #10832 What remains for that issue is hopefully much easier!
50 lines
1.6 KiB
C++
50 lines
1.6 KiB
C++
#pragma once
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///@file
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#define GENERATE_ONE_CMP(PRE, RET, QUAL, COMPARATOR, MY_TYPE, ...) \
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PRE RET QUAL operator COMPARATOR(const MY_TYPE & other) const noexcept { \
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__VA_OPT__(const MY_TYPE * me = this;) \
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auto fields1 = std::tie( __VA_ARGS__ ); \
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__VA_OPT__(me = &other;) \
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auto fields2 = std::tie( __VA_ARGS__ ); \
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return fields1 COMPARATOR fields2; \
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}
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#define GENERATE_EQUAL(prefix, qualification, my_type, args...) \
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GENERATE_ONE_CMP(prefix, bool, qualification, ==, my_type, args)
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#define GENERATE_SPACESHIP(prefix, ret, qualification, my_type, args...) \
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GENERATE_ONE_CMP(prefix, ret, qualification, <=>, my_type, args)
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/**
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* Awful hacky generation of the comparison operators by doing a lexicographic
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* comparison between the choosen fields.
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*
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* ```
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* GENERATE_CMP(ClassName, me->field1, me->field2, ...)
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* ```
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*
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* will generate comparison operators semantically equivalent to:
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*
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* ```
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* auto operator<=>(const ClassName& other) const noexcept {
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* if (auto cmp = field1 <=> other.field1; cmp != 0)
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* return cmp;
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* if (auto cmp = field2 <=> other.field2; cmp != 0)
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* return cmp;
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* ...
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* return 0;
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* }
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* ```
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*/
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#define GENERATE_CMP(args...) \
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GENERATE_EQUAL(,,args) \
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GENERATE_SPACESHIP(,auto,,args)
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/**
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* @param prefix This is for something before each declaration like
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* `template<classname Foo>`.
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*
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* @param my_type the type are defining operators for.
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*/
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#define GENERATE_CMP_EXT(prefix, ret, my_type, args...) \
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GENERATE_EQUAL(prefix, my_type ::, my_type, args) \
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GENERATE_SPACESHIP(prefix, ret, my_type ::, my_type, args)
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