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https://github.com/scylladb/scylladb.git
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190d1b20bf
Since all function overload selection is done by prepare_expression(), we no longer need to implement the assignment_testable interface, so drop it. Since there's now just one implementation of assignment_testable, we can drop it and replace it by the implementation (expressions), but that is left for later.
102 lines
2.3 KiB
C++
102 lines
2.3 KiB
C++
/*
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* Copyright (C) 2015-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 "cql3/selection/selection.hh"
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#include "cql3/selection/selector.hh"
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namespace cql3 {
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namespace selection {
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class simple_selector_factory : public selector::factory {
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private:
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const sstring _column_name;
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const uint32_t _idx;
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data_type _type;
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public:
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simple_selector_factory(const sstring& column_name, uint32_t idx, data_type type)
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: _column_name(std::move(column_name))
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, _idx(idx)
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, _type(type)
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{ }
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virtual bool is_simple_selector_factory() const override {
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return true;
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}
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virtual sstring column_name() const override {
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return _column_name;
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}
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virtual data_type get_return_type() const override {
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return _type;
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}
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virtual ::shared_ptr<selector> new_instance() const override;
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};
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class simple_selector : public selector {
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private:
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const sstring _column_name;
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const uint32_t _idx;
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data_type _type;
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managed_bytes_opt _current;
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bool _first; ///< Whether the next row we receive is the first in its group.
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public:
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static ::shared_ptr<factory> new_factory(const sstring& column_name, uint32_t idx, data_type type) {
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return ::make_shared<simple_selector_factory>(column_name, idx, type);
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}
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simple_selector(const sstring& column_name, uint32_t idx, data_type type)
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: _column_name(std::move(column_name))
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, _idx(idx)
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, _type(type)
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, _first(true)
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{ }
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virtual void add_input(result_set_builder& rs) override {
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// GROUP BY calls add_input() repeatedly without reset() in between, and it expects the
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// output to be the first value encountered:
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// https://cassandra.apache.org/doc/latest/cql/dml.html#grouping-results
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if (_first) {
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// TODO: can we steal it?
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_current = (*rs.current)[_idx];
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_first = false;
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}
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}
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virtual managed_bytes_opt get_output() override {
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return std::move(_current);
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}
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virtual void reset() override {
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_current = {};
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_first = true;
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}
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virtual data_type get_type() const override {
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return _type;
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}
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#if 0
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@Override
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public String toString()
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{
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return columnName;
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}
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#endif
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};
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}
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}
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