Python parser for Python-like language

Question

I'm looking to write a Python import filter or preprocessor for source files that are essentially Python with extra language elements. The goal is to read the source file, parse it to an abstract syntax tree, apply some transforms in order to implement the new parts of the language, and write valid Python source which can then be consumed by CPython. I want to write this thing in Python and am looking for the best parser for the task.

The parser built in to Python is not appropriate because it requires the source files be actual Python, which these will not be. There are tons of parsers (or parser generators) that will work with Python, but it's hard to tell which is the best for my needs without a whole bunch of research.

In summary, my requirements are:

1. Parser is written in Python or has Python bindings.
2. Comes with a Python grammar that I can tweak, or can easily consume a tweakable Python grammar available elsewhere (such as http://docs.python.org/reference/grammar.html).
3. Can re-serialize the AST after transforming it.
4. Should not be too horrific to work with API-wise.

Any suggestions?

Answer 1

I would recommend that you check out my library: https://github.com/erezsh/lark

It can parse ALL context-free grammars, automatically builds an AST (with line & column numbers), and accepts the grammar in EBNF format, which is considered the standard.

It can easily parse a language like Python, and it can do so faster than any other parsing library written in Python.

In fact, there's already an example python grammar and parser