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
74 lines
1.5 KiB
C++
74 lines
1.5 KiB
C++
/*
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* Copyright (C) 2016-present ScyllaDB
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*
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* Modified by ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: (AGPL-3.0-or-later and Apache-2.0)
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*/
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#pragma once
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#include <string_view>
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#include <functional>
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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 auth {
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///
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/// A type-safe wrapper for the name of a logged-in user, or a nameless (anonymous) user.
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///
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class authenticated_user final {
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public:
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///
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/// An anonymous user has no name.
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///
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std::optional<sstring> name{};
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///
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/// An anonymous user.
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///
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authenticated_user() = default;
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explicit authenticated_user(std::string_view name);
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friend bool operator==(const authenticated_user&, const authenticated_user&) noexcept = default;
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};
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const authenticated_user& anonymous_user() noexcept;
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inline bool is_anonymous(const authenticated_user& u) noexcept {
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return u == anonymous_user();
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}
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}
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///
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/// The user name, or "anonymous".
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///
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template <>
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struct fmt::formatter<auth::authenticated_user> : fmt::formatter<std::string_view> {
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template <typename FormatContext>
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auto format(const auth::authenticated_user& u, FormatContext& ctx) const {
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if (u.name) {
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return fmt::format_to(ctx.out(), "{}", *u.name);
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} else {
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return fmt::format_to(ctx.out(), "{}", "anonymous");
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}
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}
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};
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namespace std {
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template <>
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struct hash<auth::authenticated_user> final {
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size_t operator()(const auth::authenticated_user &u) const {
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return std::hash<std::optional<sstring>>()(u.name);
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}
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};
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}
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