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The pyparsing module is an alternative approach to creating andexecuting simple grammars, vs. the traditional lex/yacc approach, or theuse of regular expressions. The pyparsing module provides a library ofclasses that client code uses to construct the grammar directly inPython code.

Here is a program to parse “Hello, World!” (or any greeting of the form“salutation, addressee!”):

frompyparsingimportWord,alphasgreet=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 theself-explanatory class names, and the use of ‘+’, ‘|’ and ‘^’ operatordefinitions.

The parsed results returned from parseString() can be accessed as anested list, a dictionary, or an object with named attributes.

The pyparsing module handles some of the problems that are typicallyvexing when writing text parsers: - extra or missing whitespace (theabove program will also handle “Hello,World!”, “Hello , World !”, etc.)- quoted strings - embedded comments

The examples directory includes a simple SQL parser, simple CORBA IDLparser, a config file parser, a chemical formula parser, and a four-function algebraic notation parser, among many others.

MIT License. See header of pyparsing.py

See CHANGES file.