use of oneOf, but in negative way (notOneOf)

[eric_vb]

I just started to use pyparsing and stucked already in a problem.
I have following string to parse :
A keyword can be "SCR#123" or "REQUEST#123" or something else (Word(alphanums))
But if we detect "SCR" or "REQUEST" : these words must be followed by "#" and some numbers, if not then a parse exception should occur.

examples :
- "SCR"  --> wrong
- "SCR#"  --> wrong
- "SCR#1"  --> correct match
- "foo" --> correct match
- "REQ" --> correct match
- "REQUEST" --> wrong

The easy one :
SCR_REQUESTTokens = oneOf("SCR REQUEST", caseless=True) + Word("#"+nums, min=2)

I tried to use notAny, but no luck

GeneralToken = oneOf("SCR REQUEST", caseless=True)
Token = (Group(OneOrMore(~GeneralToken + SCR_REQUESTTokens))) + (Word(alphanums))

I tried also FollowedBy, but without examples, it is not easy to understand :-(

thanks,

[Paul McGuire]

eric_vb,

'~' is the same as NotAny, and I'd say you were on the right track with ~GeneralToken.  But I got confused in what was a GeneralToken vs a Token, so I tried to define your expressions with some different terminology:

data = """
- SCR  --> wrong
- SCR#  --> wrong
- SCR#1  --> correct match
- foo --> correct match
- REQ --> correct match
- REQUEST --> wrong
"""
from pyparsing import oneOf, Combine, Word, alphas, nums,line,col,Regex, Keyword

SCR_REQUESTprefix = oneOf("SCR REQUEST")
SCR_REQUESTtokens = Combine(SCR_REQUESTprefix + "#" + Word(nums))
nonSCR_REQUESTtokens = ~SCR_REQUESTprefix + Word(alphas)
# comment out next line to see difference
nonSCR_REQUESTtokens = ~SCR_REQUESTprefix + Regex(r"\b\w+\b")

ignorables = oneOf("wrong correct match")

searchGrammar = SCR_REQUESTtokens | nonSCR_REQUESTtokens
searchGrammar.ignore(ignorables)

for tokens,startLoc,endLoc in searchGrammar.scanString(data):
    print line(startLoc,data)
    print " "*(col(startLoc,data)-1)+tokens[0]
    print

prints out:

- SCR#1  --> correct match
  SCR#1

- foo --> correct match
  foo

- REQ --> correct match
  REQ

I had to cheat a little since I was just using scanString to step through the input string a character at a time looking for matches, and used a Regex with leading and trailing '\b' expressions, meaning "word break before and after".  You may or may not need this, depending on how you end up using these expressions in a larger grammar.

Anyway, I hope this gives you some leads on where to go from here, write back if you continue to struggle.

Cheers,
-- Paul