treesitter-patterns

Tree-sitter Patterns Skill

Universal patterns for working with tree-sitter in any project. Covers AST parsing, query patterns, visitors, and language plugin development.

Design Principle

This skill is framework-generic. It provides universal tree-sitter patterns:

• NOT tailored to Code-Index-MCP, treesitter-chunker, or any specific project
• Covers common patterns applicable across all tree-sitter projects
• Project-specific queries go in project-specific skills

Variables

Variable	Default	Description
TREE_SITTER_DIR	tree_sitter	Directory for language parsers
QUERY_DIR	queries	Directory for .scm query files
LANGUAGES	auto	Auto-detect or list of languages

Instructions

MANDATORY - Follow the Workflow steps below in order.

1. Identify languages to parse
2. Install appropriate language parsers
3. Write queries for extraction needs
4. Handle edge cases and errors

Red Flags - STOP and Reconsider

If you're about to:

• Parse without error handling (syntax errors are common)
• Assume all files parse successfully
• Write queries without testing on sample code
• Ignore performance for large files

STOP -> Add error handling -> Test on edge cases -> Then proceed

Cookbook

Language Plugin Development

• IF: Creating a new language parser
• THEN: Read and execute ./cookbook/language-plugin.md

AST Visitor Patterns

• IF: Walking the AST to extract information
• THEN: Read and execute ./cookbook/ast-visitor.md

Query Patterns

• IF: Writing tree-sitter queries
• THEN: Read and execute ./cookbook/query-patterns.md

Quick Reference

Python Setup

import tree_sitter_python as tspython
from tree_sitter import Language, Parser

# Create parser
parser = Parser(Language(tspython.language()))

# Parse code
source = b"def hello(): pass"
tree = parser.parse(source)

# Access root node
root = tree.root_node
print(root.sexp())

Node Navigation

# Get children
for child in node.children:
    print(child.type, child.text)

# Named children only (skip punctuation)
for child in node.named_children:
    print(child.type)

# Find by type
def find_all(node, type_name):
    results = []
    if node.type == type_name:
        results.append(node)
    for child in node.children:
        results.extend(find_all(child, type_name))
    return results

functions = find_all(root, "function_definition")

Query Language