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An AST unparser for Python

Project Description

An AST unparser for Python.

This is a factored out version of unparse found in the Python source distribution; under Demo/parser in Python 2 and under Tools/parser in Python 3.

Basic example:

import inspect
import ast
import astunparse

# get back the source code

# get a pretty-printed dump of the AST

This library is single-source compatible with Python 2.6 through Python 3.5. It is authored by the Python core developers; I have simply merged the Python 2.7 and the Python 3.5 source and test suites, and added a wrapper. This factoring out is to provide a library implementation that supports both versions.

Added to this is a pretty-printing dump utility function.

The test suite both runs specific tests and also roundtrips much of the standard library.

Extensions and Alternatives

Similar projects include:

None of these roundtrip much of the standard library and fail several of the basic tests in the test_unparse test suite.

This library uses mature and core maintained code instead of trying to patch existing libraries. The unparse and the test_unparse modules are under the PSF license.

Extensions include:

  • typed-astunparse: extends astunparse to support type annotations.


  • unparses Python AST.
  • pretty-prints AST.


Here’s the recent changes to AST Unparser.

1.5.0 - 2017-02-05

  • Python 3.6 compatibility
  • bugfix: correct argparser option type

1.4.0 - 2016-06-24

  • Support for the async keyword
  • Support for unparsing “Interactive” and “Expression” nodes

1.3.0 - 2016-01-17

  • Python 3.5 compatibility

1.2.0 - 2014-04-03

  • Python 2.6 through 3.4 compatibility
  • A new function dump is added to return a pretty-printed version of the AST. It’s also available when running python -m astunparse as the --dump argument.

1.1.0 - 2014-04-01

  • unparse will return the source code for an AST. It is pretty feature-complete, and round-trips the stdlib, and is compatible with Python 2.7 and Python 3.4.

    Running python -m astunparse will print the round-tripped source for any python files given as argument.

Release History

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