#! /usr/bin/python2.7
# 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()
