ast-grep

ast-grep

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ast-grep run --pattern 'console.log($ARG)' --lang javascript .        # simple pattern
ast-grep scan --inline-rules "<yaml>" <path>                          # relational/composite rule, no temp file
ast-grep scan --rule /path/rule.yml <path>                            # complex rule from file
echo '<code>' | ast-grep scan --inline-rules "<yaml>" --stdin         # test a rule on a snippet before scanning the codebase
ast-grep run --pattern '<code>' --lang <lang> --debug-query=<style>   # cst = target's full tree (find correct `kind`), ast = named nodes only, pattern = how ast-grep parsed your pattern

Gotchas:

Relational rules (inside, has) stop at the first non-matching node unless you add stopBy: end — always add it for deep traversal:

has:
  pattern: await $EXPR
  stopBy: end

Escape metavariables in shell: \$VAR inside double quotes, or single-quote the pattern.
Start with a plain pattern; add kind and relational rules only when the pattern alone over- or under-matches. Compose with all/any/not.

Full YAML rule syntax: references/rule-reference.md.

Outline (ast-grep ≥ 0.44, alpha)

Map structure before reading full files — top-level items (functions, classes, imports, exports) and their members, syntax-only, no indexing.

ast-grep outline <file>                                        # local items + member digest
ast-grep outline <dir> --items exports                         # public surface of a directory
ast-grep outline <file> --match Parser --type class --view expanded   # zoom into one symbol, with line numbers
ast-grep outline <dir> --items imports --view signatures       # dependency map

--items structure|exports|imports|all; --view names|signatures|digest|expanded in increasing detail. Defaults: file → structure/digest, directory → exports/names.
--match <regex> and --type class,enum,... filter top-level items only, never members; --pub-members restricts member views to public members.
--json[=stream] for structured output — stream emits one object per file, pipes to jq.

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Outline (ast-grep ≥ 0.44, alpha)