CODEWITHSUNDEEP
pythongrammarindentationply
joetde
joetde

Reputation: 1636

Parsing python with PLY, how to code the indent and dedent part

I was trying to parse the function definition for the python language with PLY. I am encountering issues related to the indentation. For instance for a for statement, I would like to be able to know when the block ends. I read the python grammar here: http://docs.python.org/2/reference/grammar.html And the grammar for this part is:

for_stmt: 'for' exprlist 'in' testlist ':' suite ['else' ':' suite]
suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT

I don't know how to describe the INDENT and DEDENT tokens with PLY. I was trying something like:

def t_indentation(t):
    r'    |\t'
    #some special treatment for the indentation.

But it seems that PLY consider that regexes with spaces match the empty string and does not build the lexer... Even if I would have managed to have the INDENT token I am not sure about the way to get the DEDENT one...

Is there a way to do that with PLY?

Upvotes: 8

Views: 3081

Answers (1)

0 _
0 _

Reputation: 11554

PLY includes in its examples one for a subset of Python to demonstrate how to handle indentation:

https://github.com/dabeaz/ply/tree/1321375e013425958ea090b55aecae0a4b7face6/example/GardenSnake

Upvotes: 3

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