Railroad diagram for Python grammar

Question

I am looking for a way to get better grasp on the Python grammar. My experience is that a railroad diagram for the grammar may be helpful.

Python documentation contains the grammar in a text form:

https://docs.python.org/3/reference/grammar.html

But that is not very easy to digest for someone who is just starting with software engineering.

Anybody has a good beginners material?

There is a Railroad Diagram Generator that I might be able to use, but I was not able to find an EBNF syntax for the Python grammar, that would be accepted by that generator. A link to such a grammar would be very helpful as well.

Answer 1

To convert the Python grammar found at, e.g., https://docs.python.org/3/reference/grammar.html, to EBNF, you basically need to do three things:

1. Replace all #... comments with /*...*/ (or just delete them)
2. Use ::= instead of : for defining production rules
3. Use (...)? to indicate optional elements instead of [...].

For example, instead of

# The function statement
funcdef: 'def' NAME parameters ['->' test] ':' suite

you would use

/* The function statement */
funcdef ::= 'def' NAME parameters ('->' test)? ':' suite