[TransWarp] fmtparse - recursive grammar

[alexander smishlajev]

Phillip J. Eby wrote:
> 
> I found a simpler way to fix the issue, and have checked it in.

thank you.

we found that Rule and Epsilon classes haven't got the third argument to 
getOpening().  this breaks Repeat() without explicit separator.

the following example parses simple function-like boolean expressions. 
if there is something wrong with it, i would appreciate your comments.

=== cut ===
from peak.util.fmtparse import *

class Expression(Alternatives):

     alternatives = []

     def __init__(self, *alternatives):
         if alternatives:
             super(Expression, self).__init__(*alternatives)

class Function(Tuple):

     syntax = ()

     def __init__(self, *__args, **__kw):
         if not __args:
             __args = self.syntax
         super(Function, self).__init__(*__args, **__kw)

class Comparison(Function):

     syntax = (
         ExtractString(Alternatives(
             "eq", "neq", "lt", "le", "gt", "ge"
         )), "(", Tuple(ExtractString(), ",", ExtractString()), ")",
     )

class AndOr(Function):

     syntax = (
         ExtractString(Alternatives("and", "or")),
         "(", Repeat(Expression(), separator=",", minCt=2), ")",
     )

Expression.alternatives = (Comparison(), AndOr())

query = Named("query", Expression())

def test():
     print parse("eq(a,1)", query)
     print parse("and(eq(a,1),lt(b,2))", query)
     print parse("or(and(lt(a,1),gt(b,2)))", query)
     print parse("or(and(lt(a,1),gt(b,2)),eq(c,3),neq(d,4))", query)

if __name__ == "__main__":
     test()
=== cut ===

thanks again,
alex.