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f5b05cf981
in C++20, compiler generate operator!=() if the corresponding operator==() is already defined, the language now understands that the comparison is symmetric in the new standard. fortunately, our operator!=() is always equivalent to `! operator==()`, this matches the behavior of the default generated operator!=(). so, in this change, all `operator!=` are removed. in addition to the defaulted operator!=, C++20 also brings to us the defaulted operator==() -- it is able to generated the operator==() if the member-wise lexicographical comparison. under some circumstances, this is exactly what we need. so, in this change, if the operator==() is also implemented as a lexicographical comparison of all memeber variables of the class/struct in question, it is implemented using the default generated one by removing its body and mark the function as `default`. moreover, if the class happen to have other comparison operators which are implemented using lexicographical comparison, the default generated `operator<=>` is used in place of the defaulted `operator==`. sometimes, we fail to mark the operator== with the `const` specifier, in this change, to fulfil the need of C++ standard, and to be more correct, the `const` specifier is added. also, to generate the defaulted operator==, the operand should be `const class_name&`, but it is not always the case, in the class of `version`, we use `version` as the parameter type, to fulfill the need of the C++ standard, the parameter type is changed to `const version&` instead. this does not change the semantic of the comparison operator. and is a more idiomatic way to pass non-trivial struct as function parameters. please note, because in C++20, both operator= and operator<=> are symmetric, some of the operators in `multiprecision` are removed. they are the symmetric form of the another variant. if they were not removed, compiler would, for instance, find ambiguous overloaded operator '=='. this change is a cleanup to modernize the code base with C++20 features. Signed-off-by: Kefu Chai <kefu.chai@scylladb.com> Closes #13687
71 lines
1.8 KiB
C++
71 lines
1.8 KiB
C++
/*
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* Copyright (C) 2019-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#pragma once
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#include <map>
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#include <optional>
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#include <seastar/core/sstring.hh>
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#include "seastarx.hh"
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namespace cdc {
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enum class delta_mode : uint8_t {
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keys,
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full,
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};
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/**
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* (for now only pre-) image collection mode.
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* Stating how much info to record.
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* off == none
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* on == changed columns
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* full == all (changed and unmodified columns)
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*/
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enum class image_mode : uint8_t {
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off,
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on,
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full,
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};
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std::ostream& operator<<(std::ostream& os, delta_mode);
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std::ostream& operator<<(std::ostream& os, image_mode);
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class options final {
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std::optional<bool> _enabled;
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image_mode _preimage = image_mode::off;
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bool _postimage = false;
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delta_mode _delta_mode = delta_mode::full;
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int _ttl = 86400; // 24h in seconds
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public:
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options() = default;
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options(const std::map<sstring, sstring>& map);
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std::map<sstring, sstring> to_map() const;
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sstring to_sstring() const;
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bool enabled() const { return _enabled.value_or(false); }
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bool is_enabled_set() const { return _enabled.has_value(); }
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bool preimage() const { return _preimage != image_mode::off; }
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bool full_preimage() const { return _preimage == image_mode::full; }
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bool postimage() const { return _postimage; }
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delta_mode get_delta_mode() const { return _delta_mode; }
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void set_delta_mode(delta_mode m) { _delta_mode = m; }
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int ttl() const { return _ttl; }
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void enabled(bool b) { _enabled = b; }
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void preimage(bool b) { preimage(b ? image_mode::on : image_mode::off); }
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void preimage(image_mode m) { _preimage = m; }
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void postimage(bool b) { _postimage = b; }
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void ttl(int v) { _ttl = v; }
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bool operator==(const options& o) const;
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};
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} // namespace cdc
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