python count keywords in a python file without counting inside quotation marks

Question

For example:

import codecs

def main():
    fileName = input("Please input a python file: ")
    file = codecs.open(fileName, encoding = "utf8")
    fornum = 0
    for line in file:
        data = line.split()
        if "for" in data:
            fornum += 1
    print("The number of for loop in", fileName, ":", fornum)

main()

There are 1 for-statement in above codes. But the program counts the 'for' inside the quotation mark which is not expected and it displays 2. How can I change the codes to make it counts the keywords(for) without counting the words inside ""? Thx

Answer 1

As mentioned in comments to propely count for loops you should parse Python file and walk through it AST. You could do it with ast module. Example code:

import ast

def main():
    fileName = input("Please input a python file: ")
    with open(fileName) as f:
        src = f.read()
        source_tree = ast.parse(src) # get AST of source file
    fornum = 0
    # and recursively walk through all AST nodes
    for n in ast.walk(source_tree):
        if n.__class__.__name__ == "For":
            fornum = fornum+1
    print("The number of for loop in ", fileName, ":", fornum)

main()