pasta: Python AST Augmentation
This is still a work-in-progress; there is much more to do. Existing functionality may not be perfect.
Enable python source code refactoring through AST modifications.
Sample use cases:
- Facilitate moving or renaming python modules by rewriting import statements.
- Refactor code to enforce a certain style, such as reordering function definitions.
- Safely migrate code from one API to another.
- Symmetry: Given any input source, it should hold that
pasta.dump(pasta.parse(src)) == src.
- Mutability: Any changes made in the AST are reflected in the code generated from it.
- Standardization: The syntax tree parsed by pasta will not introduce new nodes or structure that the user must learn.
Python Version Support
2.7 and up to
pasta depends on
import pasta tree = pasta.parse(source_code) # ... Augment contents of tree ... source_code = pasta.dump(tree)
Pasta includes some common augmentations out-of-the-box. These can be used as building blocks for more complex refactoring actions.
There will be more of these basic augmentations added over time. Stay tuned!
Rename an imported name
Rewrites references to an imported name, module or package. For some more
# Rewrite references from one module to another rename.rename_external(tree, 'pkg.subpkg.module', 'pkg.other_module') # Rewrite references from one package to another rename.rename_external(tree, 'pkg.subpkg', 'pkg.other_pkg') # Rewrite references to an imported name in another module rename.rename_external(tree, 'pkg.module.Query', 'pkg.module.ExecuteQuery')
Known issues and limitations
Changing the indentation level of a block of code is not supported. This is not an issue for renames, but would cause problems for refactors like extracting a method.
pastaworks under the assumption that the python version that the code is written for and the version used to run pasta are the same. This is because pasta relies on
Some python features are not fully supported, including
globaland python3 language features including PEP-498.
This project uses
facilitate testing and packaging.
# Run all tests python setup.py test # Run a single test suite python setup.py test -s pasta.base.annotate_test.suite
This is not an official Google product.