ast-grep

What is ast-grep?

ast-grep searches source code by its abstract syntax tree rather than by text alone. Write a pattern resembling the code you want to find, capture variable parts with metavariables, and use the matches to inspect or rewrite a codebase. This suits repetitive API migrations and project-specific code checks where whitespace differences make a plain-text search less useful.

The command-line tool supports interactive rewrite review and YAML rules for repeatable linting. The publisher's quick start demonstrates replacing repeated property checks with optional chaining in TypeScript; its homepage also shows scan-based diagnostics. These are publisher examples, not tests performed for this entry.

The linked 0.51.0 archive targets 64-bit x86 Windows with MSVC; ARM64 and 32-bit Windows archives are separate release assets. The sources reviewed do not establish a minimum Windows version. The screenshot is the publisher's terminal demonstration with macOS-style window chrome, illustrating the cross-platform command-line workflow rather than a Windows installation.

Structural matching is not full semantic analysis. The publisher explicitly excludes type information, scope analysis, control-flow analysis and data-flow analysis. Patterns also need parseable code or an explicit context and selector, so a fragment that looks right as text can still require adjustment before it matches the intended syntax node.

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