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- PyParsing -- A Python Parsing Module
- ====================================
- |Build Status|
- 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 at*
- https://en.wikipedia.org/wiki/Parsing_expression_grammar *.]*
- 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()`` 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
- at https://pyparsing-docs.readthedocs.io/en/latest/. Additional
- documentation resources and project info are listed in the online
- GitHub wiki, at https://github.com/pyparsing/pyparsing/wiki. An
- entire directory of examples is at
- https://github.com/pyparsing/pyparsing/tree/master/examples.
- License
- =======
- MIT License. See header of pyparsing.py
- History
- =======
- See CHANGES file.
- .. |Build Status| image:: https://travis-ci.org/pyparsing/pyparsing.svg?branch=master
- :target: https://travis-ci.org/pyparsing/pyparsing
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