AgentSkillsCN

ast-grep

借助 ast-grep（sg）这一具备语法感知能力的工具，使代理能够执行结构化代码搜索与重写任务——该工具可在多种编程语言中实现精准的模式匹配与重构操作。

SKILL.md
--- frontmatter
name: ast-grep
description:
  Enables the agent to perform structural code search and rewrite tasks using
  ast-grep (sg), a syntax-aware tool for accurate pattern matching and
  refactoring across multiple programming languages.
license: MIT

ast-grep (sg) Utility Skill

Overview

The agent has access to ast-grep (command: sg), a structural code search and rewrite tool based on syntactic pattern matching. It enables precise, language-aware codebase queries and transformations.

When to Use

  • •Searching for code patterns across files/languages accurately
  • •Refactoring code safely using structural matches instead of regex
  • •Finding complex syntactic constructs (e.g. function calls with specific parameters)
  • •Replacing code patterns with templates
  • •Analyzing code structure without false positives from text-based search

Usage

Important: patterns should be wrapped in single quotes not double quotes to avoid variable expansion (patterns use the $ symbol).

Search

sh
sg run -p <pattern> -l <language>

Example: Find all console.log calls in JavaScript

sh
sg run -p 'console.log($ARGS)' -l js

Rewrite

sh
sg run -p <pattern> --rewrite <template> -l <language>

Example: Replace console.log with logger.info

sh
sg run -p 'console.log($ARGS)' --rewrite 'logger.info($ARGS)' -l js

Pattern Syntax

  • •Syntax Requirements: Pattern code must be valid and parseable by tree-sitter. Provide sufficient context if parsing fails.
  • •Metavariables: Start with $ (e.g., $VAR, $_) to match a single AST node.
  • •Multi Metavariables: Use $$$ (or $$$NAME) to match zero or more AST nodes (e.g., arguments, statements).
  • •Capturing Rules:
    • •Reusing a metavariable (e.g., $A == $A) ensures identical nodes match.
    • •Prefix with _ (e.g., $_FUNC) for non-capturing matches (optimizes performance).
    • •Use $$VAR to capture unnamed AST nodes.

Use sg --help for more info.