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    <p>I highly recommend <strong><a href="http://pyparsing.wikispaces.com/" rel="nofollow">pyparsing</a></strong>:</p> <blockquote> <p>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.</p> <p>The Python representation of the grammar is quite <strong>readable</strong>, owing to the <strong>self-explanatory class names</strong>, and the use of '+', '|' and '^' operator definitions. The parsed results returned from parseString() <strong>can be accessed as a nested list, a dictionary, or an object with named attributes</strong>.</p> </blockquote> <p><strong>Sample code</strong> (Hello world from the pyparsing docs):</p> <pre><code>from pyparsing import Word, alphas greet = Word( alphas ) + "," + Word( alphas ) + "!" # &lt;-- grammar defined here hello = "Hello, World!" print (hello, "-&gt;", greet.parseString( hello )) </code></pre> <p><strong>Output:</strong></p> <pre><code>Hello, World! -&gt; ['Hello', ',', 'World', '!'] </code></pre> <p><em><strong>Edit:</em></strong> Here's a solution to your sample language:</p> <pre><code>from pyparsing import * import json identifier = Word(alphas + nums + "_") expression = identifier("lhs") + Suppress("=") + identifier("rhs") struct_vals = delimitedList(Group(expression | identifier)) structure = Group(identifier + nestedExpr(opener="{", closer="}", content=struct_vals("vals"))) grammar = delimitedList(structure) my_string = "something{name1, name2, opt1=2, opt2=text}, something_else{name3, opt1=58}" parse_result = grammar.parseString(my_string) result_list = parse_result.asList() def list_to_dict(l): d = {} for struct in l: d[struct[0]] = {} for ident in struct[1]: if len(ident) == 2: d[struct[0]][ident[0]] = ident[1] elif len(ident) == 1: d[struct[0]][ident[0]] = None return d print json.dumps(list_to_dict(result_list), indent=2) </code></pre> <p><strong>Output:</strong> (pretty printed as JSON)</p> <pre><code>{ "something_else": { "opt1": "58", "name3": null }, "something": { "opt1": "2", "opt2": "text", "name2": null, "name1": null } } </code></pre> <p>Use the <a href="http://pythonhosted.org/pyparsing/" rel="nofollow">pyparsing API</a> as your guide to exploring the functionality of pyparsing and understanding the nuances of my solution. I've found that the quickest way to master this library is trying it out on some simple languages you think up yourself.</p>
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    1. COThanks butch. This looks extremely promising. The example you provided is also very helpful, but I am having a hard time seeing how to define "nested levels", such as the ones in my mini-language (i.e. the items inside vs outside the `{}`)
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    2. COAdded a solution to your sample language. Let me know if you have any questions about specific pyparsing functions or classes used in my solution.
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    3. COThanks so much. To the best of your knowledge, are there any grammars that can be expressed with [**ply**](http://www.dabeaz.com/ply/) that cannot be expressed with **pyparsing**? If not, are there any limitations of pyparsing in relation to ply?
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