Cull violations against a patch set of git from a complete cpplint result file

cull_violation.py

#!/usr/bin/python

import sys, os
from sys import argv
from unidiff import PatchSet
import subprocess

def parse_log_line(line):
	"""
	parse a line from the cpplint results with --output=vs7
	"""
	if ":" not in line:
		return None
	file_lineno = line.split(":")[0]
	if "(" not in file_lineno:
		return None
	(file, lineno) = file_lineno.split("(")
	file = file.replace("\\", "/")  # for Windows
	lineno = lineno[:-1]
	try:
		lineno = int(lineno)
	except:
		return None
	return (file, lineno)

def cull_violations(inputFile, outputFile, diff):
	cull_list = []
	with open(inputFile) as input:
		patch_files = PatchSet(diff, encoding='utf-8')
		for line in input:
			parsedLine = parse_log_line(line)
			if parsedLine is None:
				continue
			for patch in patch_files:
				if patch.path != parsedLine[0]:
					continue
				for p in patch:
					for l in p.target_lines():
						if l.is_context or l.is_removed:
							continue
						if l.is_added and l.target_line_no != parsedLine[1]:
							continue
						cull_list.append(line)
		
		with open(outputFile, 'w') as out:
			if len(cull_list) == 0:
				return 0
			for line in cull_list:
				out.write(line)
	return 1

if __name__ == "__main__":
	if len(argv) < 3:
		print("Usage: %s {input log file} {output log file} <diff file>" % argv[0])
		sys.exit(1)
	if len(argv) != 4:
		diff = subprocess.check_output("git format-patch -1 --stdout HEAD", shell=True)
	else:
		with open(argv[3]) as f:
			diff = f.read()
	ret = cull_violations(argv[1], argv[2], diff)
	sys.exit(ret)