Breaking up Strings correctly:

[Adam Atlas]

On Apr 9, 8:19 am, "Michael Yanowitz" <m.yanow... at kearfott.com> wrote:
> Hello:
>
>    I have been searching for an easy solution, and hopefully one
> has already been written, so I don't want to reinvent the wheel:

Pyparsing is indeed a fine package, but if Paul gets to plug his
module, then so do I! :)

I have a package called ZestyParser... a lot of it is inspired by
Pyparsing, actually, but I'm going in a different direction in many
areas. (One major goal is to be crazily dynamic and flexible on the
inside. And it hasn't failed me thus far; I've used it to easily parse
grammars that would make lex and yacc scream in horror.)

Here's how I'd do it...

from ZestyParser import *
from ZestyParser.Helpers import *

varName = Token(r'\$(\w+)', group=1)
varVal = QuoteHelper() | Int
sp = Skip(Token(r'\s*'))
comparison = sp.pad(varName + CompositeToken([RawToken(sym) for sym in
('=','<','>','>=','<=','!=')]) + varVal)
#Maybe I should "borrow" PyParsing's OneOf idea :)

expr = ExpressionHelper((
    comparison,
    (RawToken('(') + Only(_top_) + RawToken(')')),
    oper('NOT', ops=UNARY),
    oper('AND'),
    oper('OR'),
))

Now you can scan for `expr` and get a return value like [[['IP', '=',
'127.1.2.3'], ['AX', '<', 15]], [['IP', '=', '127.1.2.4'], ['AY', '!
=', 0]]] (for the example you gave).

Note that this example uses several features that won't be available
until the next release, but it's coming soon. So Michael, though you'd
still be able to parse this with the current version, the code
wouldn't look as nice as this or the Pyparsing version. Maybe just add
it to your watchlist. :)

- Adam