Skip to main content

Python bindings to the Tree-sitter parsing library

Project description


Build Status Build status

This module provides Python bindings to the tree-sitter parsing library.


This package currently only works with Python 3. There are no library dependencies.

pip3 install tree_sitter



First you'll need a Tree-sitter language implementation for each language that you want to parse. You can clone some of the existing language repos or create your own:

git clone
git clone
git clone

Use the Language.build_library method to compile these into a library that's usable from Python. This function will return immediately if the library has already been compiled since the last time its source code was modified:

from tree_sitter import Language, Parser

  # Store the library in the `build` directory

  # Include one or more languages

Load the languages into your app as Language objects:

GO_LANGUAGE = Language('build/', 'go')
JS_LANGUAGE = Language('build/', 'javascript')
PY_LANGUAGE = Language('build/', 'python')

Basic Parsing

Create a Parser and configure it to use one of the languages:

parser = Parser()

Parse some source code:

tree = parser.parse(bytes("""
def foo():
    if bar:
""", "utf8"))

Inspect the resulting Tree:

root_node = tree.root_node
assert root_node.type == 'module'
assert root_node.start_point == (1, 0)
assert root_node.end_point == (3, 13)

function_node = root_node.children[0]
assert function_node.type == 'function_definition'
assert function_node.child_by_field_name('name').type == 'identifier'

function_name_node = function_node.children[1]
assert function_name_node.type == 'identifier'
assert function_name_node.start_point == (1, 4)
assert function_name_node.end_point == (1, 7)

assert root_node.sexp() == "(module "
    "(function_definition "
        "name: (identifier) "
        "parameters: (parameters) "
        "body: (block "
            "(if_statement "
                "condition: (identifier) "
                "consequence: (block "
                    "(expression_statement (call "
                        "function: (identifier) "
                        "arguments: (argument_list))))))))"

Walking Syntax Trees

If you need to traverse a large number of nodes efficiently, you can use a TreeCursor:

cursor = tree.walk()

assert cursor.node.type == 'module'

assert cursor.goto_first_child()
assert cursor.node.type == 'function_definition'

assert cursor.goto_first_child()
assert cursor.node.type == 'def'

# Returns `False` because the `def` node has no children
assert not cursor.goto_first_child()

assert cursor.goto_next_sibling()
assert cursor.node.type == 'identifier'

assert cursor.goto_next_sibling()
assert cursor.node.type == 'parameters'

assert cursor.goto_parent()
assert cursor.node.type == 'function_definition'


When a source file is edited, you can edit the syntax tree to keep it in sync with the source:

    new_end_byte=5 + 2,
    start_point=(0, 5),
    old_end_point=(0, 5),
    new_end_point=(0, 5 + 2),

Then, when you're ready to incorporate the changes into a new syntax tree, you can call Parser.parse again, but pass in the old tree:

new_tree = parser.parse(new_source, tree)

This will run much faster than if you were parsing from scratch.


You can search for patterns in a syntax tree using a tree query:

query = PY_LANGUAGE.query("""
  name: (identifier) @function.def)

  function: (identifier)

captures = query.captures(tree.root_node)
assert len(captures) == 2
assert captures[0][0] == function_name_node
assert captures[0][1] == "function.def"

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

tree_sitter-0.1.0.tar.gz (93.5 kB view hashes)

Uploaded source

Built Distribution

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring Fastly Fastly CDN Google Google Object Storage and Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page