use antlr4 python runtime with python 2.6

Question

Is it possible to use the antlr4 python runtime with python 2.6 or is the minimun required version python 2.7? I want to use it on CentOS 6.3 that comes with python 2.6.6. If it is not possible, is it known what features of python 2.7 that is used?

Answer 1

Finally I can answer this myself. It is not possible to use antlr4-python2 runtime on centos6.3 (that has python 2.6.6), I have installed it and tried this example. The result is as follows:

[lg@localhost py]$ python test.py data.txt 
Traceback (most recent call last):
  File "test.py", line 15, in <module>
    main(sys.argv)
  File "test.py", line 10, in main
    tree = parser.r()
  File "/home/lg/antlr/py/HelloParser.py", line 74, in r
    self.enterRule(localctx, 0, self.RULE_r)
  File "/usr/lib/python2.6/site-packages/antlr4/Parser.py", line 367, in enterRule
    self._ctx.start = self._input.LT(1)
  File "/usr/lib/python2.6/site-packages/antlr4/CommonTokenStream.py", line 85, in LT
    self.lazyInit()
  File "/usr/lib/python2.6/site-packages/antlr4/BufferedTokenStream.py", line 209, in lazyInit
    self.setup()
  File "/usr/lib/python2.6/site-packages/antlr4/BufferedTokenStream.py", line 212, in setup
    self.sync(0)
  File "/usr/lib/python2.6/site-packages/antlr4/BufferedTokenStream.py", line 134, in sync
    fetched = self.fetch(n)
  File "/usr/lib/python2.6/site-packages/antlr4/BufferedTokenStream.py", line 146, in fetch
    t = self.tokenSource.nextToken()
  File "/usr/lib/python2.6/site-packages/antlr4/Lexer.py", line 131, in nextToken
    tokenStartMarker = self._input.mark()
AttributeError: 'builtin_function_or_method' object has no attribute 'mark'
[lg@localhost py]$ 

Answer 2

The example you used was badly written. input is the name of a built-in Python function. Give the Lexer a FileStream and it might work.