Parsing a python file to check it conforms to certain rules

Question

My mentor Barry is always kicking me for forgetting to put spaces after my commas, equals signs, and for leaving too many lines at the end of a file. I wanted to practice some python and to write a parser to check my files before presenting them to him.

#BarryParser v0.1

from re import findall, search

def comma_checker(line, lineno):
    """ Checks commas have a space after them """
    split_line =  line.split(', ')
    for string in split_line:
        found_error = findall('.*,.*', string)
        if found_error:
            print "BARRY ISSUE DETECTED: COMMA ERROR LINE: %s: %s" % (lineno, line)

def equals_checker(line, lineno):
    split_line =  line.split(' = ')
    for string in split_line:
    found_error = findall('.*==?.*', string)
    if found_error:
        print "BARRY ISSUE DETECTED: EQUALS ERROR LINE: %s: %s" % (lineno, line)

def too_many_blank_lines(lines):
    """if the last line is a new line and the line before is also a new line,
       rasises barry issue over too many blank lines
    """
    last_line = lines[len(lines)-1]
    second_to_last_line = lines[len(lines)-2]
    if last_line == "\n" and second_to_last_line == "\n":
        print "BARRY ISSUE DETECTED: TOO MANY BLANK LINES AT END OF TEXT"
    elif search('\t*\n{1}', last_line)and search('\t*\n{1}', second_to_last_line):
        print "BARRY ISSUE DETECTED: TOO MANY BLANK LINES AT END OF TEXT"
    elif search('\t*\n{1}', second_to_last_line) and last_line == "\n":
        print "BARRY ISSUE DETECTED: TOO MANY BLANK LINES AT END OF TEXT"

def main():
    file = open("test.txt")
    line_no = 0
    lines = file.readlines(100000) 
    too_many_blank_lines(lines) #CHECK FOR BLANK LINES AT END OF TEXT
    for line in lines:
        line_no +=1 
        if not line == "\n":
            if not line[:1] == "#":
                comma_checker(line, line_no) #CHECK COMMAS ARE DONE RIGHT
                equals_checker(line, line_no) #CHECK EQUALS HAVE SPACES AFTER & BEFORE

if __name__ == '__main__':
    main()

It will be parsing python files. The question being, I can't figure out how to get the equals bit to handle == and = the same way.

There are several tools that do a great job of this kind of thing for you: PyLint, PyChecker or PyFlakes?. Look at pypi.python.org/pypi/pep8 to do these tests for you, for example. — Martijn Pieters
– Martijn Pieters, Commented Sep 11, 2012 at 15:51
You can use PythonTidy. So, no need to re-invent the wheel. You use it like python PythonTidy test.py barryfile.py. — RanRag
– RanRag, Commented Sep 11, 2012 at 15:53
If this is an exercise for learning python probably your question would fit better on CodeReview — joaquin
– joaquin, Commented Sep 11, 2012 at 15:59

Hans Then · Accepted Answer · 2012-09-11 15:55:15Z

1

Have a look at the pep8 module. This checks your code for compliance against the pep8 coding standards.

See: http://www.python.org/dev/peps/pep-0008/

Here is sample output

thenh@localhost:~> pep8 *.py
1.py:11:1: W293 blank line contains whitespace
1.py:14:80: E501 line too long (81 characters)
1.py:24:1: E302 expected 2 blank lines, found 1
1.py:37:23: W291 trailing whitespace
1.py:90:27: E201 whitespace after '['
1.py:116:36: E701 multiple statements on one line (colon)
1.py:144:9: E303 too many blank lines (2)
2.py:22:1: W391 blank line at end of file
3.py:75:29: E231 missing whitespace after ','

answered Sep 11, 2012 at 15:55

Hans Then

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2 Comments

Noelkd Over a year ago

This is perfect, can just steal the things i need from here. thanks!

Hans Then Over a year ago

Good to hear that. Happy stealing.

Pierre GM · Accepted Answer · 2012-09-11 15:54:44Z

0

Use Pylint to check the program for you.

edited Sep 11, 2012 at 15:54

Pierre GM

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answered Sep 11, 2012 at 15:52

f p

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