[issue44177] Unable to get the else while parsing through AST module

[Bikram Singh Mehra]

New submission from Bikram Singh Mehra :

Hi Team,

I was parsing python file using AST module but ran into a situation where the 
else statement is not found in the parsed data.

-
Module used is: ast
-

In the parsed data I can see "if" followed by "elif" but the "else" part I am 
not able to see.

Sample code used:
-
sample_data = """
if num > 0:
print("Positive number")
elif num == 0:
print("Zero")
else:
print("Negative number")
"""
-

tree = ast.parse(sample_data )

The above code provide me below data in ast.dump(tree)

Module(body=[If(test=Compare(left=Name(id='num', ctx=Load()), ops=[Gt()], 
comparators=[Constant(value=0, kind=None)]), 
body=[Expr(value=Call(func=Name(id='print', ctx=Load()), 
args=[Constant(value='Positive number', kind=None)], keywords=[]))], 
orelse=[If(test=Compare(left=Name(id='num', ctx=Load()), ops=[Eq()], 
comparators=[Constant(value=0, kind=None)]), 
body=[Expr(value=Call(func=Name(id='print', ctx=Load()), 
args=[Constant(value='Zero', kind=None)], keywords=[]))], 
orelse=[Expr(value=Call(func=Name(id='print', ctx=Load()), 
args=[Constant(value='Negative number', kind=None)], keywords=[]))])])], 
type_ignores=[])

While I was traversing through this tree I can't see else in the structure 
because it is subpart of orelse i.e. inside elif part.


Doc referred is : https://docs.python.org/3/library/ast.html
 

Thanks and Best Regards,
Bikram

--
components: Parser
messages: 393941
nosy: bikrammehra97, lys.nikolaou, pablogsal
priority: normal
severity: normal
status: open
title: Unable to get the else while parsing through AST module
type: enhancement
versions: Python 3.7

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[issue44177] Unable to get the else while parsing through AST module

[Bikram Singh Mehra]

Bikram Singh Mehra  added the comment:

Hi Eric,

Thanks for the quick response here,

I have gone through your suggestion but following that I am able to print the 
else node data i.e. "print("Negative number")" but unable to get the lineno of 
that else child node.

Could you please confirm if there is a way in AST where I can get the lineno of 
the else child node.

Thanks and Best Regards,
Bikram

--

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[issue44177] Unable to get the else while parsing through AST module

[Bikram Singh Mehra]

Bikram Singh Mehra  added the comment:

Hi Eric,

I have tried the action plan suggested by you in your last comment, but below 
are my logs and still I am unable to get lineno for else statement.


The respective line no for each line are below 


1 
2 if num > 0:
3 print("Positive number")
4 elif num == 0:
5 print("Zero")
6 else:
7 print("Negative number")



>The re-formatted dump is as below and doesn't have lineno for else statement

Module(body=[If(test=Compare(left=Name(id='num', ctx=Load(), lineno=2, 
col_offset=3, end_lineno=2, end_col_offset=6), 
 ops=[Gt()], 
comparators=[Constant(value=0, kind=None, lineno=2, col_offset=9, end_lineno=2, 
end_col_offset=10)], lineno=2, col_offset=3, end_lineno=2, end_col_offset=10), 
 body=[Expr(value=Call(func=Name(id='print', 
ctx=Load(), lineno=3, col_offset=4, end_lineno=3, end_col_offset=9),
   args=[Constant(value='Positive 
number', kind=None, lineno=3, col_offset=10, end_lineno=3, 

end_col_offset=27)], 

keywords=[], lineno=3, col_offset=4, end_lineno=3, end_col_offset=28), 
lineno=3, col_offset=4, 
end_lineno=3, end_col_offset=28)], 
orelse=[If(test=Compare(left=Name(id='num', 
ctx=Load(), lineno=4, col_offset=5, end_lineno=4, end_col_offset=8),

 ops=[Eq()], 

 comparators=[Constant(value=0, kind=None, lineno=4, col_offset=12, 
end_lineno=4, 

 end_col_offset=13)], lineno=4, col_offset=5, end_lineno=4, end_col_offset=13), 

body=[Expr(value=Call(func=Name(id='print', ctx=Load(), lineno=5, col_offset=4, 
end_lineno=5, end_col_offset=9), 

args=[Constant(value='Zero', kind=None, lineno=5, 
col_offset=10, end_lineno=5, 

end_col_offset=16)], 

keywords=[], lineno=5, col_offset=4, end_lineno=5, 
end_col_offset=17), lineno=5, col_offset=4, end_lineno=5, end_col_offset=17)], 

orelse=[Expr(value=Call(func=Name(id='print', ctx=Load(), lineno=7, 
col_offset=4, end_lineno=7, end_col_offset=9), 

args=[Constant(value='Negative number', kind=None, lineno=7, 
col_offset=10, end_lineno=7, end_col_offset=27)], 

keywords=[], lineno=7, col_offset=4, end_lineno=7, 
end_col_offset=28), 

lineno=7, col_offset=4, end_lineno=7, end_col_offset=28)], 
lineno=4, col_offset=0, end_lineno=7,

end_col_offset=28)], 
lineno=2, col_offset=0, 
end_lineno=7, end_col_offset=28)], type_ignores=[])




> If we use tree to get the lineno then its giving as below 
tree.body[0].orelse[0].orelse[0].lineno
7



Here the lineno 7 denotes to the body of else statement not the else lineno.


Could you please help me out where you can show the respective line no of else 
statement i.e. 6 in above example.

Thanks and Best Regards,
Bikram

--
resolution: works for me -> 
status: closed -> open

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