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ast-grep(sg) is a CLI tool for code structural search, lint, and rewriting.

ast-grep is anabstract syntax tree based tool to search code by pattern code. Think of it as your old-friendgrep, but matching AST nodes instead of text.You can write patterns as if you are writing ordinary code. It will match all code that has the same syntactical structure.You can use$ sign + upper case letters as awildcard, e.g.$MATCH, to match any single AST node. Think of it asregular expression dot., except it is not textual.

Try theonline playground for a taste!

See more screenshots on thewebsite.

You can install it fromnpm,pip,cargo,cargo-binstall,homebrew,scoop orMacPorts!

npm install --global @ast-grep/clipip install ast-grep-clibrew install ast-grep

cargo install ast-grep --lockedcargo binstall ast-grep# install via scoop, thank @brian6932scoop install main/ast-grep# install via MacPortssudo port install ast-grep# try ast-grep in nix-shellnix-shell -p ast-grep

Or you can build ast-grep from source. You need to install rustup, clone the repository and then

cargo install --path ./crates/cli --locked

Packages are available on other platforms too.

ast-grep has following form.

sg --pattern 'var code = $PATTERN' --rewrite 'let code = new $PATTERN' --lang ts

• Rewrite code in null coalescing operator

sg -p'$A && $A()' -l ts -r'$A?.()'

• RewriteZodios

sg -p'new Zodios($URL,  $CONF as const,)' -l ts -r'new Zodios($URL, $CONF)' -i

• Implement eslint rule using YAML.

If you find ast-grep interesting and useful for your work, pleasebuy me a coffeeso I can spend more time on the project!

ast-grep's core is an algorithm to search and replace code based on abstract syntax tree produced by tree-sitter.It can help you to do lightweight static analysis and massive scale code manipulation in an intuitive way.

Key highlights:

• An intuitive pattern to find and replace AST.ast-grep's pattern looks like ordinary code you would write every day (you could say the pattern is isomorphic to code).

• jQuery like API for AST traversal and manipulation.

• YAML configuration to write new linting rules or code modification.

• Written in compiled language, with tree-sitter based parsing and utilizing multiple cores.

• Beautiful command line interface :)

ast-grep's vision is to democratize abstract syntax tree magic and to liberate one from cumbersome AST programming!

• If you are an open-source library author, ast-grep can help your library users adopt breaking changes more easily.
• if you are a tech lead in your team, ast-grep can help you enforce code best practice tailored to your business need.
• If you are a security researcher, ast-grep can help you write rules much faster.