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
47 lines
1.2 KiB
C++
47 lines
1.2 KiB
C++
/*
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* Copyright (C) 2015-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 <seastar/core/sstring.hh>
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#include <map>
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#include "seastarx.hh"
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class schema;
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class caching_options {
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// For Origin, the default value for the row is "NONE". However, since our
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// row_cache will cache both keys and rows, we will default to ALL.
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//
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// FIXME: We don't yet make any changes to our caching policies based on
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// this (and maybe we shouldn't)
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static constexpr auto default_key = "ALL";
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static constexpr auto default_row = "ALL";
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sstring _key_cache;
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sstring _row_cache;
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bool _enabled = true;
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caching_options(sstring k, sstring r, bool enabled);
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friend class schema;
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caching_options();
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public:
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bool enabled() const {
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return _enabled;
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}
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std::map<sstring, sstring> to_map() const;
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sstring to_sstring() const;
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static caching_options get_disabled_caching_options();
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static caching_options from_map(const std::map<sstring, sstring>& map);
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static caching_options from_sstring(const sstring& str);
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bool operator==(const caching_options& other) const = default;
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};
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