Does ignoring comments work in Python 3.2? about ply HOT 9 CLOSED

The calc grammar is not going to accept an input of "//comment" because it does not recognize an empty input---there has to be an expression. If you want the grammar to accept empty input, then there has to be a grammar rule for it (otherwise a syntax error will occur).

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Is the comment supposed to consume the trailing newline character or not? If so, maybe the regex needs to include it. For example r'#.*\n'

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Yep, you are right, with \n of course (or excluding \n): r"""[#][^\n]*"""
But the result remains the same - the same Stacktrace.

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The p_error() function is called with an argument of None when there's a syntax error involving the end of file. The traceback message is being caused by not checking for this. See ply/example/calc/calc.py for an example.

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Still does not ignore the comments and calls p_error instead. The same if provide ' ' as input. Also tried with t_ignore_comment = r'//.*' instead of defining new function -- the same result: it does not ignore comments and pure spaces (wo numbers) and treat them as syntax errors.

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I think I found the workaround/reason. Consider the example of calc.py after adding t_ignore_comment = r'//.*':
it parses: "1+2", "1+2\n//comment", "//comment\n1+2" (that is, as expected it Ply ignores the comments and parses the expression)

But Ply cannot parse "//comment", that is the sentence without an expression in it.
Not a major issue, therefore.
Thanks.

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After adding empty rule it works now! Thanks!

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@5nizza For multilinea comments how can I do it? I have this but it does not work
t_ignore_multi_comment = r'/*(.|\r|\n)?*[\n]?/'

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@5nizza For multilinea comments how can I do it? I have this but it does not work
t_ignore_multi_comment = r'/(.|\r|\n)_?[\n]_?/'

r'(/\*(.|\n)*?\*/)|(//.*)'
@Joshua195

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