Literals empty list causes IndexError

[wnissen]

If i set:

literals = []

I get:

Traceback (most recent call last):
File "Translator.py", line 379, in
lexer = lex(outputText)
File "Translator.py", line 105, in lex
lexer = lex.lex(reflags=re.VERBOSE, module=LexerPassThrough)
File "ply/lex.py", line 920, in lex
IndexError: list index out of range

Below is a suggested possible patch.

*** lex.py.old  Wed Dec 21 10:44:55 2011
--- lex.py  Wed Dec 21 10:45:28 2011
***************
*** 917,923 ****

      # Get literals specification
      if isinstance(linfo.literals,(list,tuple)):
!         lexobj.lexliterals = type(linfo.literals[0])().join(linfo.literals)
      else:
          lexobj.lexliterals = linfo.literals

--- 917,926 ----

      # Get literals specification
      if isinstance(linfo.literals,(list,tuple)):
!         if linfo.literals:
!             lexobj.lexliterals = type(linfo.literals[0])().join(linfo.literals)
!         else:
!             lexobj.lexliterals = ""
      else:
          lexobj.lexliterals = linfo.literals

I could also see calling iter(linfo.literals) , which would be more Pythonic than an explicit check for list/tuple, but that's maybe going too far.

[dabeaz]

Fixed in PLY-3.5 (in progress).

[wnissen]

Thanks! Ply was exactly what I needed to write a robust quickie translator.