ES|QL Language library

The general idea of this package is to provide comprehensive ES|QL functionality including low-level parsing, building, traversal, pretty-printing, manipulation features on top of a custom compact AST representation, and advanced language features such as validation, autocomplete, hover, and signature help.

Contents of the package

Core AST Functionality

At the lowest level, the package provides a parser that converts ES|QL text into an AST representation. Or, you can use the Builder class to construct the AST manually:

• parser — Contains text to ES|QL AST parsing code
• ast/builder — Contains the Builder class for AST node construction

The Traversal API lets you walk the AST. The Walker class is simple to use, while the mutate utilities provide more powerful manipulation capabilities:

• ast/walker — Contains the ES|QL AST Walker utility
• ast/mutate — Contains code for traversing and mutating the AST

The Pretty-printing API lets you format the AST to text:

• pretty_print — Contains code for formatting AST to text

Language Features

Advanced ES|QL language features including editor support:

• language — Validation, autocomplete, hover, and signature help
  • language/validation — ES|QL query validation logic
  • language/autocomplete — Autocomplete and suggestion services
  • language/hover — Hover information providers
  • language/signature_help — Function signature assistance
  • language/inline_suggestions — Inline suggestion features

Commands and Query Building

The Commands registry allows you to register and manage ES|QL commands:

• commands/registry — Provides a centralized system for managing and interacting with ES|QL commands

The Composer API provides a high-level, secure, and developer-friendly way to build ES|QL queries:

• composer — ES|QL query composer with secure parameter handling and fluent API

Demo

Much of the functionality of this package is demonstrated in the demo UI. You can run it in Storybook, using the following command:

yarn storybook esql_ast_inspector

Alternatively, you can start Kibana with Example Plugins enabled, using:

yarn start --run-examples

Then navigate to the ES|QL AST Inspector plugin in the Kibana UI.

Keeping ES|QL AST library up to date

In general when operating on changes here use the yarn kbn watch in a terminal window to make sure changes are correctly compiled.