tree-hugger 0.8.0

A light-weight, Extendable, high level, universal code parser built on top of tree-sitter

tree-hugger

Mining source code repositories at scale easily. Tree-hugger is a light-weight, high level library which provides Pythonic APIs to mine recursively trough Github repositories. Tree-hugger is built on top of tree-sitter.

Covered languages:

• Python
• PHP
• Java
• JavaScript
• C++ (coming)

System Requirement: Python 3.6

Contents

1. Installation

2. Setup

3. Hello world example

4. API reference

5. Extending tree-hugger

   • Adding languages

   • Adding queries

6. Roadmap

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Installation

From pip:

pip install tree-hugger

From Source:

git clone https://github.com/autosoft-dev/tree-hugger.git

cd tree-hugger

pip install -e .

The installation process is tested in macOS Mojave, we have a separate docker binding for compiling the libraries for Linux and soon this library will be integrated in that as well

You may need to install libgit2. In case you are in mac just use brew install libgit2

Setup

Building the .so files

Please note that building the libraries has been tested under a macOS Mojave with Apple LLVM version 10.0.1 (clang-1001.0.46.4)

Please check out our Linux specific instructions here

Once this library is installed it gives you a command line utility to download and compile tree-sitter .so files with ease. As an example -

create_libs python

Here is the full usage guide of the command

usage: create_libs [-h] [-c] [-l LIB_NAME] langs [langs ...]

positional arguments:
  langs                 Give the name of languages for tree-sitter (php,
                        python, go ...)

optional arguments:
  -h, --help            show this help message and exit
  -c, --copy-to-workspace
                        Shall we copy the created libs to the present dir?
                        (default: False)
  -l LIB_NAME, --lib-name LIB_NAME
                        The name of the generated .so file

Environment variables

You can set up TS_LIB_PATH environment variable for the tree-sitter lib path and then the libary will use them automatically. Otherwise, as an alternative, you can pass it when creating any Parser object.

Hello world example

1. Generate the librairies : run the above command to generate the libraries.

   In our settings we use the -c flag to copy the generated tree-sitter library's .so file to our workspace. Once copied, we place it under a directory called tslibs (It is in the .gitignore).

   ⚠ If you are using linux,you will need to use our tree-sitter-docker image and manually copy the final .so file.

2. Setup environment variable (optional) Assuming that you have the necessary environment variable setup. The following line of code will create a PythonParser object

from tree_hugger.core import PythonParser

pp = PythonParser()

And then you can pass in any Python file that you want to analyze, like so :

pp.parse_file("tests/assets/file_with_different_functions.py")
Out[3]: True

parse_file returns True if success

And then you are free to use the methods exposed by that particular Parser object. As an example -

pp.get_all_function_names()
Out[4]:
['first_child',
 'second_child',
 'say_whee',
 'wrapper',
 'my_decorator',
 'parent']

OR

pp.get_all_function_documentations()
Out[5]:
{'parent': '"""This is the parent function\n    \n    There are other lines in the doc string\n    This is the third line\n\n    And this is the fourth\n    """',
 'first_child': "'''\n        This is first child\n        '''",
 'second_child': '"""\n        This is second child\n        """',
 'my_decorator': '"""\n    Outer decorator function\n    """',
 'say_whee': '"""\n    Hellooooooooo\n\n    This is a function with decorators\n    """'}

(Notice that, in the last call, it only returns the functions which has a documentation comment)

API reference

Language	Functions	Methods	Classes
Python	all_function_names all_function_doctrings all_function_names_and_params all_function_bodies	all_class_methods all_class_method_docstrings	all_class_names all_class_docstrings
PHP	all_function_names all_function_names_and_params all_function_bodies	all_class_methods	all_class_names
Java		all_class_methods all_method_names_and_params all_method_bodies	all_class_names
JavaScript	all_function_names all_function_names_and_params all_function_bodies	all_class_methods	all_class_names

Extending tree-hugger

Extending tree-hugger for other languages and/or more functionalities for the already provided ones, is easy.

1. Adding languages:

Parsed languages can be extended through adding a parser class from the BaseParser class. The only mandatory argument that a Parser class should pass to the parent is the language. This is a string. Such as python (lower case). Each parser class must have the options to take in the path of the tree-sitter library (.so file that we are using to parse the code) and the path to the queries yaml file, in their constructor.

The BaseParser class can do few things:

• Loading and preparing the .so file with respect to the language you just mentioned.
• Loading, preparing and parsing the query yaml file. (for the queries, we internally use an extended UserDict class)
• Providing an API to parse a file and prepare it for query. BaseParser.parse_file

It also gives you another (most likely not to be exposed outside) API _run_query_and_get_captures which lets you run any queries and return back the matched results (if any) from the parsed tree.

We use those APIs once we have called parse_file and parsed the file.

2. Adding queries:

Queries processed on source code are s-expressions, they are listed in a queries.ymlfile for each parser class. Tree-hugger gives you a way to write your queries in yaml file for each language parsed.

Query structure: A name of a query followed by the query itself. Written as an s-expression. Example:

all_function_docstrings:
        "
        (
            function_definition
            name: (identifier) @function.def
            body: (block(expression_statement(string))) @function.docstring
        )
        "

You have to follow yaml grammar while writing these queries. You can see a bit more about writng these queries in the documentation of tree-sitter.

Some example queries, that you will find in the yaml file (and their corresponding API from the PythonParser class) -

* all_function_names => get_all_function_names()

* all_function_docstrings => get_all_function_documentations()

* all_class_methods => get_all_class_method_names()

Roadmap

• Documentation: tutorial on queries writing

• Write *Parser class for other languages

Languages	Status-Finished	Author
Python	✅	Shubhadeep
PHP	✅	Clément
Java	✅	Clément
JavaScript	✅	Clément
C++	▶	Clément