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#! /usr/bin/env python

# Fix Python source files to use the new equality test operator, i.e.,

# if x = y: ...

# is changed to

# if x == y: ...

# The script correctly tokenizes the Python program to reliably

# distinguish between assignments and equality tests.

#

# Command line arguments are files or directories to be processed.

# Directories are searched recursively for files whose name looks

# like a python module.

# Symbolic links are always ignored (except as explicit directory

# arguments). Of course, the original file is kept as a back-up

# (with a "~" attached to its name).

# It complains about binaries (files containing null bytes)

# and about files that are ostensibly not Python files: if the first

# line starts with '#!' and does not contain the string 'python'.

#

# Changes made are reported to stdout in a diff-like format.

#

# Undoubtedly you can do this using find and sed or perl, but this is

# a nice example of Python code that recurses down a directory tree

# and uses regular expressions. Also note several subtleties like

# preserving the file's mode and avoiding to even write a temp file

# when no changes are needed for a file.

#

# NB: by changing only the function fixline() you can turn this

# into a program for a different change to Python programs...

import sys

import re

import os

from stat import *

import string

err = sys.stderr.write

dbg = err

rep = sys.stdout.write

def main():

bad = 0

if not sys.argv[1:]: # No arguments

err('usage: ' + sys.argv[0] + ' file-or-directory ...\n')

sys.exit(2)

for arg in sys.argv[1:]:

if os.path.isdir(arg):

if recursedown(arg): bad = 1

elif os.path.islink(arg):

err(arg + ': will not process symbolic links\n')

bad = 1

else:

if fix(arg): bad = 1

sys.exit(bad)

ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')

def ispython(name):

return ispythonprog.match(name) >= 0

def recursedown(dirname):

dbg('recursedown(%r)\n' % (dirname,))

bad = 0

try:

names = os.listdir(dirname)

except os.error, msg:

err('%s: cannot list directory: %r\n' % (dirname, msg))

return 1

names.sort()

subdirs = []

for name in names:

if name in (os.curdir, os.pardir): continue

fullname = os.path.join(dirname, name)

if os.path.islink(fullname): pass

elif os.path.isdir(fullname):

subdirs.append(fullname)

elif ispython(name):

if fix(fullname): bad = 1

for fullname in subdirs:

if recursedown(fullname): bad = 1

return bad

def fix(filename):

## dbg('fix(%r)\n' % (dirname,))

try:

f = open(filename, 'r')

except IOError, msg:

err('%s: cannot open: %r\n' % (filename, msg))

return 1

head, tail = os.path.split(filename)

tempname = os.path.join(head, '@' + tail)

g = None

# If we find a match, we rewind the file and start over but

# now copy everything to a temp file.

lineno = 0

while 1:

line = f.readline()

if not line: break

lineno = lineno + 1

if g is None and '\0' in line:

# Check for binary files

err(filename + ': contains null bytes; not fixed\n')

f.close()

return 1

if lineno == 1 and g is None and line[:2] == '#!':

# Check for non-Python scripts

words = string.split(line[2:])

if words and re.search('[pP]ython', words[0]) < 0:

msg = filename + ': ' + words[0]

msg = msg + ' script; not fixed\n'

err(msg)

f.close()

return 1

while line[-2:] == '\\\n':

nextline = f.readline()

if not nextline: break

line = line + nextline

lineno = lineno + 1

newline = fixline(line)

if newline != line:

if g is None:

try:

g = open(tempname, 'w')

except IOError, msg:

f.close()

err('%s: cannot create: %r\n' % (tempname, msg))

return 1

f.seek(0)

lineno = 0

rep(filename + ':\n')

continue # restart from the beginning

rep(repr(lineno) + '\n')

rep('< ' + line)

rep('> ' + newline)

if g is not None:

g.write(newline)

# End of file

f.close()

if not g: return 0 # No changes

# Finishing touch -- move files

# First copy the file's mode to the temp file

try:

statbuf = os.stat(filename)

os.chmod(tempname, statbuf[ST_MODE] & 07777)

except os.error, msg:

err('%s: warning: chmod failed (%r)\n' % (tempname, msg))

# Then make a backup of the original file as filename~

try:

os.rename(filename, filename + '~')

except os.error, msg:

err('%s: warning: backup failed (%r)\n' % (filename, msg))

# Now move the temp file to the original file

try:

os.rename(tempname, filename)

except os.error, msg:

err('%s: rename failed (%r)\n' % (filename, msg))

return 1

# Return succes

return 0

from tokenize import tokenprog

match = {'if':':', 'elif':':', 'while':':', 'return':'\n', \

'(':')', '[':']', '{':'}', '`':'`'}

def fixline(line):

# Quick check for easy case

if '=' not in line: return line

i, n = 0, len(line)

stack = []

while i < n:

j = tokenprog.match(line, i)

if j < 0:

# A bad token; forget about the rest of this line

print '(Syntax error:)'

print line,

return line

a, b = tokenprog.regs[3] # Location of the token proper

token = line[a:b]

i = i+j

if stack and token == stack[-1]:

del stack[-1]

elif match.has_key(token):

stack.append(match[token])

elif token == '=' and stack:

line = line[:a] + '==' + line[b:]

i, n = a + len('=='), len(line)

elif token == '==' and not stack:

print '(Warning: \'==\' at top level:)'

print line,

return line

if __name__ == "__main__":

main()