Code Symbols Skill
Use ast-grep (sg) for structural code search based on tree-sitter parsing. Works with 31 languages.
Important: Clojure is NOT supported. Use the clj-symbols skill for Clojure code.
Prerequisites
# npm
npm install --global @ast-grep/cli
# Homebrew
brew install ast-grep
# Cargo
cargo install ast-grep --locked
Verify: ast-grep --version or sg --version
Supported Languages
| Category | Languages |
|---|---|
| Web | JavaScript, TypeScript, HTML, CSS, JSON |
| Systems | C, C++, Go, Rust |
| Scripting | Python, Ruby, PHP, Lua, Bash |
| JVM | Java, Kotlin, Scala |
| Other | Swift, Haskell, Elixir, Nix |
Not supported: Clojure, Erlang, R, MATLAB
Quick Reference
| Task | Command |
|---|---|
| Find pattern | ast-grep run --pattern 'PATTERN' --lang LANG path/ |
| Find with JSON | ast-grep run --pattern 'PATTERN' --lang LANG path/ --json |
| Rename symbol | ast-grep run --pattern 'old' --rewrite 'new' --lang LANG path/ --update-all |
Pattern Syntax
Patterns must be valid code that tree-sitter can parse.
Meta-Variables
| Syntax | Meaning | Example |
|---|---|---|
$NAME | Match single node | function $NAME() {} |
$$$ | Match zero or more nodes | function foo($$$) |
$_ | Match but don't capture | $_($$$) |
Basic Examples
# Match any function call
ast-grep run --pattern '$FUNC($$$)' --lang js path/
# Match specific function
ast-grep run --pattern 'myFunction($$$)' --lang js path/
# Match variable assignment
ast-grep run --pattern 'const $NAME = $VALUE' --lang js path/
Common Operations
Find Function Definition
# JavaScript
ast-grep run --pattern 'function $NAME($$$) { $$$ }' --lang js path/
# Python
ast-grep run --pattern 'def $NAME($$$):' --lang py path/
# Go
ast-grep run --pattern 'func $NAME($$$)' --lang go path/
Find Symbol Usages
ast-grep run --pattern 'myFunction($$$)' --lang js path/
ast-grep run --pattern '$OBJ.myMethod($$$)' --lang js path/
Rename Symbol
# Preview
ast-grep run --pattern 'oldName' --rewrite 'newName' --lang js src/
# Apply
ast-grep run --pattern 'oldName' --rewrite 'newName' --lang js src/ --update-all
# Interactive
ast-grep run --pattern 'oldName' --rewrite 'newName' --lang js src/ --interactive
JSON Output
ast-grep run --pattern '$FUNC($$$)' --lang js path/ --json
Parse with jq:
ast-grep run --pattern 'function $NAME($$$) { $$$ }' --lang js path/ --json \
| jq '.[] | {name: .metaVariables.single.NAME.text, file, line: .range.start.line}'
When to Use ast-grep vs ripgrep
| Scenario | Tool |
|---|---|
| Find by name (text pattern) | ripgrep (rg) |
| Find by structure (function, class) | ast-grep |
| Language-specific patterns | ast-grep |
| Maximum speed | ripgrep |
| Accurate symbol boundaries | ast-grep |
Additional References
- Language patterns: See references/languages.md for JS, TS, Python, Go, Rust patterns
- Editing: See references/editing.md for rewrite, rename, and YAML rules
- Workflows: See references/workflows.md for common workflows