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https://github.com/scylladb/scylladb.git
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378556418c
Convert tri_comparators to return std::strong_ordering rather than int, to prevent confusion with less comparators. Downstream users are either also converted, or adjust the return type back to int, whichever happens to be simpler; in all cases the change it trivial.
166 lines
7.0 KiB
C++
166 lines
7.0 KiB
C++
/*
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* Copyright (C) 2019 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "query-request.hh"
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#include <optional>
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#include <variant>
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// Wraps ring_position_view so it is compatible with old-style C++: default
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// constructor, stateless comparators, yada yada.
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class compatible_ring_position_view {
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const ::schema* _schema = nullptr;
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// Optional to supply a default constructor, no more.
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std::optional<dht::ring_position_view> _rpv;
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public:
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constexpr compatible_ring_position_view() = default;
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compatible_ring_position_view(const schema& s, dht::ring_position_view rpv)
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: _schema(&s), _rpv(rpv) {
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}
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const dht::ring_position_view& position() const {
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return *_rpv;
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}
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const ::schema& schema() const {
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return *_schema;
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}
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friend std::strong_ordering tri_compare(const compatible_ring_position_view& x, const compatible_ring_position_view& y) {
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return dht::ring_position_tri_compare(*x._schema, *x._rpv, *y._rpv);
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}
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friend bool operator<(const compatible_ring_position_view& x, const compatible_ring_position_view& y) {
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return tri_compare(x, y) < 0;
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}
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friend bool operator<=(const compatible_ring_position_view& x, const compatible_ring_position_view& y) {
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return tri_compare(x, y) <= 0;
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}
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friend bool operator>(const compatible_ring_position_view& x, const compatible_ring_position_view& y) {
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return tri_compare(x, y) > 0;
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}
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friend bool operator>=(const compatible_ring_position_view& x, const compatible_ring_position_view& y) {
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return tri_compare(x, y) >= 0;
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}
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friend bool operator==(const compatible_ring_position_view& x, const compatible_ring_position_view& y) {
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return tri_compare(x, y) == 0;
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}
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friend bool operator!=(const compatible_ring_position_view& x, const compatible_ring_position_view& y) {
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return tri_compare(x, y) != 0;
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}
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};
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// Wraps ring_position so it is compatible with old-style C++: default
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// constructor, stateless comparators, yada yada.
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class compatible_ring_position {
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schema_ptr _schema;
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// Optional to supply a default constructor, no more.
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std::optional<dht::ring_position> _rp;
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public:
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constexpr compatible_ring_position() = default;
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compatible_ring_position(schema_ptr s, dht::ring_position rp)
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: _schema(std::move(s)), _rp(std::move(rp)) {
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}
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dht::ring_position_view position() const {
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return *_rp;
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}
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const ::schema& schema() const {
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return *_schema;
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}
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friend std::strong_ordering tri_compare(const compatible_ring_position& x, const compatible_ring_position& y) {
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return dht::ring_position_tri_compare(*x._schema, *x._rp, *y._rp);
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}
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friend bool operator<(const compatible_ring_position& x, const compatible_ring_position& y) {
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return tri_compare(x, y) < 0;
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}
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friend bool operator<=(const compatible_ring_position& x, const compatible_ring_position& y) {
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return tri_compare(x, y) <= 0;
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}
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friend bool operator>(const compatible_ring_position& x, const compatible_ring_position& y) {
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return tri_compare(x, y) > 0;
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}
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friend bool operator>=(const compatible_ring_position& x, const compatible_ring_position& y) {
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return tri_compare(x, y) >= 0;
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}
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friend bool operator==(const compatible_ring_position& x, const compatible_ring_position& y) {
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return tri_compare(x, y) == 0;
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}
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friend bool operator!=(const compatible_ring_position& x, const compatible_ring_position& y) {
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return tri_compare(x, y) != 0;
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}
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};
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// Wraps ring_position or ring_position_view so either is compatible with old-style C++: default
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// constructor, stateless comparators, yada yada.
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// The motivations for supporting both types are to make containers self-sufficient by not relying
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// on callers to keep ring position alive, allow lookup on containers that don't support different
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// key types, and also avoiding unnecessary copies.
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class compatible_ring_position_or_view {
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// Optional to supply a default constructor, no more.
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std::optional<std::variant<compatible_ring_position, compatible_ring_position_view>> _crp_or_view;
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public:
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constexpr compatible_ring_position_or_view() = default;
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explicit compatible_ring_position_or_view(schema_ptr s, dht::ring_position rp)
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: _crp_or_view(compatible_ring_position(std::move(s), std::move(rp))) {
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}
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explicit compatible_ring_position_or_view(const schema& s, dht::ring_position_view rpv)
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: _crp_or_view(compatible_ring_position_view(s, rpv)) {
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}
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dht::ring_position_view position() const {
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struct rpv_accessor {
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dht::ring_position_view operator()(const compatible_ring_position& crp) {
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return crp.position();
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}
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dht::ring_position_view operator()(const compatible_ring_position_view& crpv) {
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return crpv.position();
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}
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};
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return std::visit(rpv_accessor{}, *_crp_or_view);
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}
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friend std::strong_ordering tri_compare(const compatible_ring_position_or_view& x, const compatible_ring_position_or_view& y) {
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struct schema_accessor {
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const ::schema& operator()(const compatible_ring_position& crp) {
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return crp.schema();
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}
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const ::schema& operator()(const compatible_ring_position_view& crpv) {
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return crpv.schema();
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}
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};
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return dht::ring_position_tri_compare(std::visit(schema_accessor{}, *x._crp_or_view), x.position(), y.position());
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}
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friend bool operator<(const compatible_ring_position_or_view& x, const compatible_ring_position_or_view& y) {
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return tri_compare(x, y) < 0;
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}
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friend bool operator<=(const compatible_ring_position_or_view& x, const compatible_ring_position_or_view& y) {
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return tri_compare(x, y) <= 0;
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}
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friend bool operator>(const compatible_ring_position_or_view& x, const compatible_ring_position_or_view& y) {
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return tri_compare(x, y) > 0;
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}
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friend bool operator>=(const compatible_ring_position_or_view& x, const compatible_ring_position_or_view& y) {
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return tri_compare(x, y) >= 0;
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}
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friend bool operator==(const compatible_ring_position_or_view& x, const compatible_ring_position_or_view& y) {
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return tri_compare(x, y) == 0;
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}
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friend bool operator!=(const compatible_ring_position_or_view& x, const compatible_ring_position_or_view& y) {
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return tri_compare(x, y) != 0;
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}
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};
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