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https://github.com/gristlabs/asttokens

Annotate Python AST trees with source text and token information
https://github.com/gristlabs/asttokens

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Annotate Python AST trees with source text and token information

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README 

        
ASTTokens

=========



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.. Start of user-guide



The ``asttokens`` module annotates Python abstract syntax trees (ASTs) with the positions of tokens

and text in the source code that generated them.



It makes it possible for tools that work with logical AST nodes to find the particular text that

resulted in those nodes, for example for automated refactoring or highlighting.



Installation

------------

asttokens is available on PyPI: https://pypi.python.org/pypi/asttokens/::



    pip install asttokens



The code is on GitHub: https://github.com/gristlabs/asttokens.



The API Reference is here: http://asttokens.readthedocs.io/en/latest/api-index.html.



Usage

-----

ASTTokens works with both Python2 and Python3.



ASTTokens can annotate both trees built by `ast `_,

AND those built by `astroid `_.



Here's an example:



.. code-block:: python



    import asttokens, ast

    source = "Robot('blue').walk(steps=10*n)"

    atok = asttokens.ASTTokens(source, parse=True)



Once the tree has been marked, nodes get ``.first_token``, ``.last_token`` attributes, and

the ``ASTTokens`` object offers helpful methods:



.. code-block:: python



    attr_node = next(n for n in ast.walk(atok.tree) if isinstance(n, ast.Attribute))

    print(atok.get_text(attr_node))

    start, end = attr_node.last_token.startpos, attr_node.last_token.endpos

    print(atok.text[:start] + 'RUN' + atok.text[end:])



Which produces this output:



.. code-block:: text



    Robot('blue').walk

    Robot('blue').RUN(steps=10*n)



The ``ASTTokens`` object also offers methods to walk and search the list of tokens that make up

the code (or a particular AST node), which is more useful and powerful than dealing with the text

directly.



Contribute

----------



To contribute:



1. Fork this repository, and clone your fork.

2. Install the package with test dependencies (ideally in a virtualenv) with::



    pip install -e '.[test]'



3. Run tests in your current interpreter with the command ``pytest`` or ``python -m pytest``.

4. Run tests across all supported interpreters with the ``tox`` command. You will need to have the interpreters installed separately. We recommend ``pyenv`` for that. Use ``tox -p auto`` to run the tests in parallel.

5. By default certain tests which take a very long time to run are skipped, but they are run in CI.

   These are marked using the ``pytest`` marker ``slow`` and can be run on their own with ``pytest -m slow`` or as part of the full suite with ``pytest -m ''``.