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https://github.com/pyparsing/pyparsing

Python library for creating PEG parsers
https://github.com/pyparsing/pyparsing

parser-combinators parsing parsing-expression-grammar parsing-library peg-parsers python python-2 python-3 python2 python3 text-processing

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Python library for creating PEG parsers

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README 

        
PyParsing -- A Python Parsing Module

====================================



|Version| |Build Status| |Coverage| |License| |Python Versions| |Snyk Score|



Introduction

============



The pyparsing module is an alternative approach to creating and

executing simple grammars, vs. the traditional lex/yacc approach, or the

use of regular expressions. The pyparsing module provides a library of

classes that client code uses to construct the grammar directly in

Python code.



*[Since first writing this description of pyparsing in late 2003, this

technique for developing parsers has become more widespread, under the

name Parsing Expression Grammars - PEGs. See more information on PEGs*

`here `__

*.]*



Here is a program to parse ``"Hello, World!"`` (or any greeting of the form

``"salutation, addressee!"``):



.. code:: python



    from pyparsing import Word, alphas

    greet = Word(alphas) + "," + Word(alphas) + "!"

    hello = "Hello, World!"

    print(hello, "->", greet.parseString(hello))



The program outputs the following::



    Hello, World! -> ['Hello', ',', 'World', '!']



The Python representation of the grammar is quite readable, owing to the

self-explanatory class names, and the use of '+', '|' and '^' operator

definitions.



The parsed results returned from ``parseString()`` is a collection of type

``ParseResults``, which can be accessed as a

nested list, a dictionary, or an object with named attributes.



The pyparsing module handles some of the problems that are typically

vexing when writing text parsers:



- extra or missing whitespace (the above program will also handle ``"Hello,World!"``, ``"Hello , World !"``, etc.)

- quoted strings

- embedded comments



The examples directory includes a simple SQL parser, simple CORBA IDL

parser, a config file parser, a chemical formula parser, and a four-

function algebraic notation parser, among many others.



Documentation

=============



There are many examples in the online docstrings of the classes

and methods in pyparsing. You can find them compiled into `online docs `__. Additional

documentation resources and project info are listed in the online

`GitHub wiki `__. An

entire directory of examples can be found `here `__.



License

=======



MIT License. See header of the `pyparsing __init__.py `__ file.



History

=======



See `CHANGES `__ file.



.. |Build Status| image:: https://github.com/pyparsing/pyparsing/actions/workflows/ci.yml/badge.svg

   :target: https://github.com/pyparsing/pyparsing/actions/workflows/ci.yml



.. |Coverage| image:: https://codecov.io/gh/pyparsing/pyparsing/branch/master/graph/badge.svg

  :target: https://codecov.io/gh/pyparsing/pyparsing



.. |Version| image:: https://img.shields.io/pypi/v/pyparsing?style=flat-square

    :target: https://pypi.org/project/pyparsing/

    :alt: Version



.. |License| image:: https://img.shields.io/pypi/l/pyparsing.svg?style=flat-square

    :target: https://pypi.org/project/pyparsing/

    :alt: License



.. |Python Versions| image:: https://img.shields.io/pypi/pyversions/pyparsing.svg?style=flat-square

    :target: https://pypi.org/project/python-liquid/

    :alt: Python versions



.. |Snyk Score| image:: https://snyk.io//advisor/python/pyparsing/badge.svg

   :target: https://snyk.io//advisor/python/pyparsing

   :alt: pyparsing