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name: ast-grep description: Search code using Abstract Syntax Tree patterns with ast-grep. Use when finding code structures, bug patterns, or refactoring candidates that depend on syntax rather than text. allowed-tools: Bash, Read, Glob

ast-grep - Structural Code Search

ast-grep searches code by matching AST patterns, not text. This finds code based on structure regardless of formatting or variable names.

Basic Usage

ast-grep run -p 'PATTERN' -l LANGUAGE

Pattern Syntax

• $VAR - Match any single node (like a wildcard)
• $$$ - Match zero or more nodes
• Literal code matches itself

Common Patterns

Goal	Pattern	Language
Find subtraction with specific left operand	discount - $VAR	typescript
Find all useEffect with empty deps	useEffect($FN, [])	tsx
Find console.log calls	console.log($$$)	typescript
Find async functions	async function $NAME($$$) { $$$ }	typescript

Example: Finding Reversed Operands

To find where discount appears on the left side of subtraction:

ast-grep run -p 'discount - $VAR' -l typescript

This would find bugs like discount - basePrice (should be basePrice - discount).

When to Use

• Finding bug patterns based on code structure
• Locating specific API usage patterns
• Identifying refactoring candidates
• Searching for security anti-patterns