parso 0.5.0

A Python Parser

Parso is a Python parser that supports error recovery and round-trip parsing for different Python versions (in multiple Python versions). Parso is also able to list multiple syntax errors in your python file.

Parso has been battle-tested by jedi. It was pulled out of jedi to be useful for other projects as well.

Parso consists of a small API to parse Python and analyse the syntax tree.

A simple example:

>>> import parso
>>> module = parso.parse('hello + 1', version="3.6")
>>> expr = module.children[0]
>>> expr
PythonNode(arith_expr, [<Name: hello@1,0>, <Operator: +>, <Number: 1>])
>>> print(expr.get_code())
hello + 1
>>> name = expr.children[0]
>>> name
<Name: hello@1,0>
>>> name.end_pos
(1, 5)
>>> expr.end_pos
(1, 9)

To list multiple issues:

>>> grammar = parso.load_grammar()
>>> module = grammar.parse('foo +\nbar\ncontinue')
>>> error1, error2 = grammar.iter_errors(module)
>>> error1.message
'SyntaxError: invalid syntax'
>>> error2.message
"SyntaxError: 'continue' not properly in loop"

Resources

• Testing
• PyPI
• Docs
• Uses semantic versioning

Installation

pip install parso

Future

• There will be better support for refactoring and comments. Stay tuned.
• There’s a WIP PEP8 validator. It’s however not in a good shape, yet.

Known Issues

• async/await are already used as keywords in Python3.6.
• from __future__ import print_function is not ignored.

Acknowledgements

• Guido van Rossum (@gvanrossum) for creating the parser generator pgen2 (originally used in lib2to3).
• Salome Schneider for the extremely awesome parso logo.

Changelog

0.5.0 (2019-06-20)

• Breaking Change comp_for is now called sync_comp_for for all Python versions to be compatible with the Python 3.8 Grammar
• Added .pyi stubs for a lot of the parso API
• Small FileIO changes

0.4.0 (2019-04-05)

• Python 3.8 support
• FileIO support, it’s now possible to use abstract file IO, support is alpha

0.3.4 (2018-02-13)

• Fix an f-string tokenizer error

0.3.3 (2018-02-06)

• Fix async errors in the diff parser
• A fix in iter_errors
• This is a very small bugfix release

0.3.2 (2018-01-24)

• 20+ bugfixes in the diff parser and 3 in the tokenizer
• A fuzzer for the diff parser, to give confidence that the diff parser is in a good shape.
• Some bugfixes for f-string

0.3.1 (2018-07-09)

• Bugfixes in the diff parser and keyword-only arguments

0.3.0 (2018-06-30)

• Rewrote the pgen2 parser generator.

0.2.1 (2018-05-21)

• A bugfix for the diff parser.
• Grammar files can now be loaded from a specific path.

0.2.0 (2018-04-15)

• f-strings are now parsed as a part of the normal Python grammar. This makes it way easier to deal with them.

0.1.1 (2017-11-05)

• Fixed a few bugs in the caching layer
• Added support for Python 3.7

0.1.0 (2017-09-04)

• Pulling the library out of Jedi. Some APIs will definitely change.