f3eade2f62
Drop the AGPL license in favor of a source-available license. See the blog post [1] for details. [1] https://www.scylladb.com/2024/12/18/why-were-moving-to-a-source-available-license/
119 lines
3.6 KiB
C++
119 lines
3.6 KiB
C++
/*
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* Copyright (C) 2018-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: (LicenseRef-ScyllaDB-Source-Available-1.0 and Apache-2.0)
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*/
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#pragma once
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#include "cql3/functions/scalar_function.hh"
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#include "cql3/functions/function_name.hh"
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#include "cql3/cql3_type.hh"
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#include "cql3/type_json.hh"
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#include "bytes_ostream.hh"
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#include "types/types.hh"
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namespace cql3 {
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namespace functions {
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/*
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* This function is used for handling 'SELECT JSON' statement.
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* 'SELECT JSON' is supposed to return a single column named '[json]'
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* with JSON representation of the query result as its value.
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* In order to achieve it, selectors from 'SELECT' are wrapped with
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* 'as_json' function, which also keeps information about underlying
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* selector names and types. This function is not registered in functions.cc,
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* because it should not be invoked directly from CQL.
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* Case-sensitive column names are wrapped in additional quotes,
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* as stated in CQL-JSON documentation.
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*/
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class as_json_function : public scalar_function {
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std::vector<sstring> _selector_names;
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std::vector<data_type> _selector_types;
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public:
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as_json_function(std::vector<sstring>&& selector_names, std::vector<data_type> selector_types)
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: _selector_names(std::move(selector_names)), _selector_types(std::move(selector_types)) {
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}
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virtual bool requires_thread() const override;
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virtual bytes_opt execute(std::span<const bytes_opt> parameters) override {
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bytes_ostream encoded_row;
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encoded_row.write("{", 1);
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for (size_t i = 0; i < _selector_names.size(); ++i) {
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if (i > 0) {
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encoded_row.write(", ", 2);
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}
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bool has_any_upper = std::ranges::any_of(_selector_names[i], [](unsigned char c) { return std::isupper(c); });
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encoded_row.write("\"", 1);
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if (has_any_upper) {
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encoded_row.write("\\\"", 2);
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}
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encoded_row.write(_selector_names[i].c_str(), _selector_names[i].size());
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if (has_any_upper) {
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encoded_row.write("\\\"", 2);
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}
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encoded_row.write("\": ", 3);
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sstring row_sstring = to_json_string(*_selector_types[i], parameters[i]);
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encoded_row.write(row_sstring.c_str(), row_sstring.size());
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}
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encoded_row.write("}", 1);
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return bytes(encoded_row.linearize());
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}
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virtual const function_name& name() const override {
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static const function_name f_name = function_name::native_function("as_json");
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return f_name;
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}
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virtual const std::vector<data_type>& arg_types() const override {
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return _selector_types;
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}
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virtual const data_type& return_type() const override {
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return utf8_type;
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}
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virtual bool is_pure() const override {
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return true;
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}
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virtual bool is_native() const override {
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return true;
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}
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virtual bool is_aggregate() const override {
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// Aggregates of aggregates are currently not supported, but JSON handles them
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return false;
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}
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virtual void print(std::ostream& os) const override {
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os << "as_json(";
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bool first = true;
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for (const sstring& selector_name: _selector_names) {
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if (first) {
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first = false;
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} else {
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os << ", ";
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}
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os << selector_name;
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}
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os << ") -> " << utf8_type->as_cql3_type().to_string();
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}
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virtual sstring column_name(const std::vector<sstring>& column_names) const override {
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return "[json]";
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}
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};
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}
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}
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