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� & �d�# � �T � d Z ddlmZ G d� de� Z eddddd� ZdZej ZeZd Zdd l � dd l � dd l� ddlm Z mZ dd l� dd l� ddlmZ dd l� ddlmZ dd lmZmZmZ ddlmZ ddlmZmZ d e� vreZd e� vreZd e� vreZeeez z Zg d�Zy)a pyparsing module - Classes and methods to define and execute parsing grammars ============================================================================= 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. With pyparsing, you don't need to learn a new syntax for defining grammars or matching expressions - the parsing module provides a library of classes that you use to construct the grammar directly in Python. Here is a program to parse "Hello, World!" (or any greeting of the form ``"<salutation>, <addressee>!"``), built up using :class:`Word`, :class:`Literal`, and :class:`And` elements (the :meth:`'+'<ParserElement.__add__>` operators create :class:`And` expressions, and the strings are auto-converted to :class:`Literal` expressions):: from pyparsing import Word, alphas # define grammar of a greeting greet = Word(alphas) + "," + Word(alphas) + "!" hello = "Hello, World!" print(hello, "->", greet.parse_string(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 :class:`'+'<And>`, :class:`'|'<MatchFirst>`, :class:`'^'<Or>` and :class:`'&'<Each>` operators. The :class:`ParseResults` object returned from :class:`ParserElement.parse_string` 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 Getting Started - ----------------- Visit the classes :class:`ParserElement` and :class:`ParseResults` to see the base classes that most other pyparsing classes inherit from. Use the docstrings for examples of how to: - construct literal match expressions from :class:`Literal` and :class:`CaselessLiteral` classes - construct character word-group expressions using the :class:`Word` class - see how to create repetitive expressions using :class:`ZeroOrMore` and :class:`OneOrMore` classes - use :class:`'+'<And>`, :class:`'|'<MatchFirst>`, :class:`'^'<Or>`, and :class:`'&'<Each>` operators to combine simple expressions into more complex ones - associate names with your parsed results using :class:`ParserElement.set_results_name` - access the parsed data, which is returned as a :class:`ParseResults` object - find some helpful expression short-cuts like :class:`DelimitedList` and :class:`one_of` - find more useful common expressions in the :class:`pyparsing_common` namespace class � )� NamedTuplec �\ � e Zd ZU eed<