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A Python Parser

Project description

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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="3.9")
>>> 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"

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

Unreleased

0.8.0 (2020-08-05)

  • Dropped Support for Python 2.7, 3.4, 3.5
  • It’s possible to use pathlib.Path objects now in the API
  • The stubs are gone, we are now using annotations
  • namedexpr_test nodes are now a proper class called NamedExpr
  • A lot of smaller refactorings

0.7.1 (2020-07-24)

  • Fixed a couple of smaller bugs (mostly syntax error detection in Grammar.iter_errors)

This is going to be the last release that supports Python 2.7, 3.4 and 3.5.

0.7.0 (2020-04-13)

  • Fix a lot of annoying bugs in the diff parser. The fuzzer did not find issues anymore even after running it for more than 24 hours (500k tests).
  • Small grammar change: suites can now contain newlines even after a newline. This should really not matter if you don’t use error recovery. It allows for nicer error recovery.

0.6.2 (2020-02-27)

  • Bugfixes
  • Add Grammar.refactor (might still be subject to change until 0.7.0)

0.6.1 (2020-02-03)

  • Add parso.normalizer.Issue.end_pos to make it possible to know where an issue ends

0.6.0 (2020-01-26)

  • Dropped Python 2.6/Python 3.3 support
  • del_stmt names are now considered as a definition (for name.is_definition())
  • Bugfixes

0.5.2 (2019-12-15)

  • Add include_setitem to get_definition/is_definition and get_defined_names (#66)
  • Fix named expression error listing (#89, #90)
  • Fix some f-string tokenizer issues (#93)

0.5.1 (2019-07-13)

  • Fix: Some unicode identifiers were not correctly tokenized
  • Fix: Line continuations in f-strings are now working

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 (2019-02-13)

  • Fix an f-string tokenizer error

0.3.3 (2019-02-06)

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

0.3.2 (2019-01-24)

  • 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.

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