sql-autocomplete-parsers

SQL Autocomplete Parsers

A tool that provides autocompletion for various sql dialects.

Parser theory

In order to parse any language, you need a lexer (tokenizer) and a parser (ast builder)

Resources to research:

• Bison grammar specification: https://www.gnu.org/software/bison/manual/html_node/Rules-Syntax.html
• Playlist with the explanation on how parser and lexer work together: https://www.youtube.com/playlist?list=PLIrl0f9NJZy4oOOAVPU6MyRdFjJFGtceu

How everything works

1. Autocomplete parser source code for different {dialect} are defined in src/parsing/parsers/{dialect} directories.
2. Lexer configuration is specified in src/parsing/parsers/{dialect}/jison/sql.jisonlex file.
3. SQL grammar is specified in src/parsing/parsers/{dialect}/jison/**/*.jison. It is placed in multiple files for easier understanding. Test files *.test.json are placed nearby. Jison is basically bison, but for javascript.
4. src/parsing/parsers/{dialect}/jison/structure.json specifies paths to a lexer, and to all the grammar files.
5. Parser extension (basically the autocomplete features) is specified in src/parsing/parsers/{dialect}/parser-extension.js.
6. src/generator/main.js concatenates all the jison files into a single big jison file, and runs the jison tool with the specified lexer, then wires everything up with the parser-extension.js, generating src/parsing/parsers/{dialect}/{dialect}AutocompleteParser.js.
7. The generated file is in plain javascript, so we create a convenient typescript wrapper in src/parsing/index.ts with all the types and functions. Our users should include this file in their own projects.

Main scripts

• npm run generate - Generate parsers
• npm run test - Run tests

Contributing

• When adding a new file, just add Yandex copyright header
• When editing a file that has not Yandex copyright, add Yandex copyright header underneath the existent copyright from Cloudera, and update changed files list in NOTICE.txt at the bottom
• Delete and move files freely

Yandex copyright:

// Please note that the code below is the modified code distributed on the terms, mentioned below.
// The copyright for the changes belongs to YANDEX LLC.
//
// Copyright 2023 YANDEX LLC
//
// Licensed under the Apache License, Version 2.0 (the "License")
// You may not use this file except in compliance with the License.
// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under
// the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.

Changelog

1.22.0 (2023-09-05)

Features

• actualise clickhouse data types (#82) (e16505a)