RegExp find and replace string in all matching files and subdirectories (recursive)

replace.py

#------------------------------------------------------------------------------
# Filename: replace.py
# Purpose:  RegExp find and replace string in all matching files and current subdirectories (recursive)
# Usage:	python FindAndReplace.py "[Old Regexp]" "[New String]" 
#				[File Filters(ex/default: ".c,.cc,.h"")] [Working Directory]
# Requirement: Files must be text (non-binary) and not very large.
# WARNING:  This script will OVERWRITE files matching [File Filters]. 
#		    All occurrences of [Old Regexp] will be replaced with [New String]. 
#           Make sure you really, really want to do this!!!
#------------------------------------------------------------------------------

import os
import sys
import traceback
import re

def usage():
	print('Usage: python FindAndReplace.py [Old RegExp] [New String] ' \
		  '[File Filters (default: ".c,.cc,.h")] [Working Directory (default: ".")]')

def replaceStringInFile(fileName, oldStringRegexp, newString):

	if not(os.path.isfile(fileName) and os.access(fileName, os.W_OK)):
		print("WARNING: Skipping... File does not exist or and is not writeable:" + fileName)
		return False

	j = 0
	with open(fileName, 'r') as f:
		i = 0
		newlines = []
		for line in f.readlines():
			i = len(re.findall(oldStringRegexp, line))
			if (i > 0) :
			    j = j + i
			    line = re.sub(oldStringRegexp, newString, line)
			newlines.append(line)

	# Write changes to same file
	if (j > 0) :
		print((" Found %d matches in " % j) + fileName)
		try:
			with open(fileName, 'w') as f:
				for line in newlines:
					f.write(line)
		except:
			print('ERROR: Cannot open/access existing file for writing: ' + fileName)
			return false

	return (j > 0)

def main():
	try:
		DEFAULT_PATH = '.'

		if len(sys.argv) < 3:
			usage()
			# old/new string required parameters, exit if not supplied
			sys.exit(-1)
		else:
			oldString = sys.argv[1]
			newString = sys.argv[2]

		if len(sys.argv) < 4:
			patterns = ['.c', '.cc', '.h']
		else:
			stringFilter = sys.argv[3]
			patterns = stringFilter.split(',')

		if len(sys.argv) < 5:
			path = DEFAULT_PATH
		else:
			path = sys.argv[4]

		oldStringRe = re.compile(oldString, re.IGNORECASE | re.VERBOSE)
		newString = newString.decode('string_escape')
		
		print('') 
		print('Old RegExp   : ' + oldStringRe.pattern) 
		print('New String   : ' + newString)
		print('File Filters : ' + ', '.join(patterns))
		print('Directory    : ' + path)

		if not os.path.exists(path):
			raise Exception("Selected path does not exist: " + path)
			
		# Walks through directory structure looking for files matching patterns
		matchingFileList = \
			[os.path.join(dp, f) \
				for dp, dn, filenames in os.walk(path) \
					for f in filenames \
						if os.path.splitext(f)[1] in patterns]

		print('Files found matching patterns: ' + str(len(matchingFileList)))
		fileCount = 0
		filesReplaced = 0
		
		for currentFile in matchingFileList:
		
			fileCount+=1
			fileReplaced = replaceStringInFile(currentFile, oldStringRe, newString)
			if fileReplaced:
				filesReplaced+=1

		print("Total Files Searched         : " + str(fileCount))
		print("Total Files Replaced/Updated : " + str(filesReplaced))
	
	except Exception as err:
		print(traceback.format_exception_only(type(err), err)[0].rstrip())
		sys.exit(-1)

if __name__ == '__main__':
	main()