ast-grep 0.39 is Here

ast-grep 0.39 is out! This release includes new languages support, better file config and esquery style.

Esquery Style Kind

ast-grep now supports ESQuery style kind in the kind field of the rule configuration. This allows you to write more concise rule in ast-grep. Under the hood, it is equivalent to relational rules like has.

ESQuery is a library for querying the AST using a CSS style selector system.

For example, you can write a rule to match all identifier nodes that are direct children of call_expression nodes like this:

kind: call_expression > identifier

This is equivalent to the following relational rule:

kind: identifier
inside:
  kind: call_expression

Currently, ast-grep's ESQuery style kind only supports the following selectors:

• node kind: identifier
• >: direct child selectors
• : descendant selector
• +: next sibling selector
• ~: following sibling selector

The corresponding relational rules are:

direct child

kind: call_expression > identifier
# is equivalent to
kind: identifier
inside:
  kind: call_expression

direct child

kind: call_expression identifier
# is equivalent to
kind: identifier
inside:
  kind: call_expression
  stopBy: end  # note the stopBy

next sibling

kind: decorator + method_definition
# is equivalent to
kind: method_definition
follows:
  kind: decorator

next sibling

kind: decorator ~ method_definition
# is equivalent to
kind: method_definition
follows:
  kind: decorator
  stopBy: end  # note the stopBy

If you want to use more ESQuery selectors, please file your use cases in this ast-grep issue.

New Languages Support

ast-grep 0.39 adds support for the following languages:

• Nix a domain-specific, purely functional, lazily evaluated, dynamically typed programming languages for Nixpkgs and NixOS.
• Solidity A statically-typed curly-braces programming language designed for developing smart contracts that run on Ethereum. ($ETH bull run incoming? 🐂)

file in rule config is relative to the project config file

Previously, the files section appears to be treated as relative to the current working directory from which ast-grep was invoked rather than the dir containing the sgconfig.yml file.

This has been changed in 0.39, so now the files section is relative to the project config file.

NAPI-RS version bump!

NAPI-RS recently released its version 3. ast-grep followed the release and the result is amazing. ThreadSafeFunction's implementation complexity is greatly reduced.

Though this does not impact ast-grep-napi users' experience or code. This section is a tribute to NAPI-RS and its creator, Brooklyn.

Next Steps

Thanks for reading! If you are interested in the new features, please try them out and let us know your feedback.