Terry J. Reedy <tjre...@udel.edu> added the comment:
First note that 3.8.3 grammar.html is stated to be the actual grammar used by the old parser, and is a bit different from the more human readable grammar given in the reference manual. It is a bit different in 3.9 and I expect will be much more different in 3.10 with the new PEG parser. In the grammar, the CAPITALIZED_NAMES are token names returned by the tokenizer/lexer. This is a standard convention. I am pretty sure that the human readable lexing rules in lexical_analysis are not what the lexer uses. I presume the latter uses barely readable RE expressions, as does the tokenize module. Compare the float grammar in https://docs.python.org/3/reference/lexical_analysis.html#floating-point-literals to the float REs in tokenize.py. def group(*choices): return '(' + '|'.join(choices) + ')' def maybe(*choices): return group(*choices) + '?' # The above are reused for multiple REs. Exponent = r'[eE][-+]?[0-9](?:_?[0-9])*' Pointfloat = group(r'[0-9](?:_?[0-9])*\.(?:[0-9](?:_?[0-9])*)?', r'\.[0-9](?:_?[0-9])*') + maybe(Exponent) Expfloat = r'[0-9](?:_?[0-9])*' + Exponent Floatnumber = group(Pointfloat, Expfloat) Note that this is (python) code, not a text specification. You or someone else can look at what the C lexer does. But I think that the proposal should be rejected. ---------- nosy: +terry.reedy _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue40678> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
