FWIW: This has a similiar look/feel to how sabbey wrapped dparser.
http://staff.washington.edu/sabbey/py_dparser/
Heiko Wundram wrote:
> Hi list!
>
> Not long ago I was looking for an easy to use, but powerful parser and lexer
> generating tool for Python, and to my dismay, I found quite a number of
> Python projects implementing an (LA)LR(1) parser generator, but none of them
> seemed quite finished, or even pythonic.
>
> As I required a parser generator for Python for one of my work projects, I
> set
> out to write (yet another one), and currently am at (release-)version 0.1 for
> Pyrr.ltk and ptk.
>
> An example for Pyrr.ltk and ptk usage implementing a (very) simple calculator:
>
> <<<
> # -*- coding: iso-8859-15 -*-
>
> from ltk import LexerBase, IgnoreMatch
> from ptk import ParserBase
> from operator import add, sub, mul, div
>
> class NumLexer(LexerBase):
>
> def number(self,value):
> """number -> r/[0-9]+/"""
> return float(value)
>
> def ws(self,*args):
> """ws -> r/\\s+/"""
> raise IgnoreMatch
>
> def ops(self,op):
> """addop -> /+/
> -> /-/
> mulop -> /*/
> -> r/\\//"""
> return op
>
> class NumParser(ParserBase):
> """/mulop/: left
> /addop/: left"""
> __start__ = "term"
>
> def term(self,value1,op,value2):
> """term -> term /addop/ term
> -> term /mulop/ term"""
> return {"+":add,"-":sub,"*":mul,"/":div}[op](value1,value2)
>
> def value(self,value):
> """term -> /number/"""
> return value
>
> print NumParser.parse(NumLexer.tokenize("3 + 4 - 123 / 23"))
> <<<
>
> Grammar rules and lexemes are specified in docstrings, where lines not
> matching a definition of a rule or lexeme are ignored. The resulting lexer
> and parser class is, thus, very much self-documenting, which was one of my
> biggest goals for the project.
>
> I'm currently in the process of writing documentation for both packages (and
> especially documenting the extensions to BNF-grammars that Pyrr.ptk allows,
> such as your usual RE-operators ?, *, + and {x,y}, and forward arguments, and
> documenting the stateful lexer support that Pyrr.ltk implements), but I
> thought that I'd release early and often, so that people interested in this
> project might have a look at it now to input suggestions and extensions that
> they'd like me to add to make this a fully featured Python parser generating
> toolkit which might be offered as a Python package.
>
> Anyway, the sources can be downloaded (via subversion) from:
>
> http://svn.modelnine.org/svn/Pyrr/trunk
>
> where I'll check in the documentation that I've written so far and a Python
> distutils distribution over the weekend, and make sure that I don't check in
> brocken code from now on. And, Pyrr.* is Python 2.4 only at the moment, and I
> have no plans to make it backwards-compatible, but if you're interested in
> backporting it, feel free to mail me patches.
>
> --- Heiko.
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