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#! /ufs/guido/bin/sgi/python
#! /usr/local/python
# Fix Python source files to use the new equality test operator,
# i.e.,
# if x == y: ...
# instead of
# if x = y: ...
#
# 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).
#
# 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 regex
import posix
import path
from stat import *
err = sys.stderr.write
dbg = err
rep = sys.stdout.write
def main():
bad = 0
if not sys.argv[1:]: # No arguments
err('usage: ' + argv[0] + ' file-or-directory ...\n')
sys.exit(2)
for arg in sys.argv[1:]:
if path.isdir(arg):
if recursedown(arg): bad = 1
elif path.islink(arg):
err(arg + ': will not process symbolic links\n')
bad = 1
else:
if fix(arg): bad = 1
sys.exit(bad)
ispythonprog = regex.compile('^[a-zA-Z0-9_]+\.py$')
def ispython(name):
return ispythonprog.match(name) >= 0
def recursedown(dirname):
dbg('recursedown(' + `dirname` + ')\n')
bad = 0
try:
names = posix.listdir(dirname)
except posix.error, msg:
err(dirname + ': cannot list directory: ' + `msg` + '\n')
return 1
names.sort()
subdirs = []
for name in names:
if name in ('.', '..'): continue
fullname = path.join(dirname, name)
if path.islink(fullname): pass
elif 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(' + `filename` + ')\n')
try:
f = open(filename, 'r')
except IOError, msg:
err(filename + ': cannot open: ' + `msg` + '\n')
return 1
head, tail = path.split(filename)
tempname = 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
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(tempname+': cannot create: '+\
`msg`+'\n')
return 1
f.seek(0)
lineno = 0
rep(filename + ':\n')
continue # restart from the beginning
rep(`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 = posix.stat(filename)
posix.chmod(tempname, statbuf[ST_MODE] & 07777)
except posix.error, msg:
err(tempname + ': warning: chmod failed (' + `msg` + ')\n')
# Then make a backup of the original file as filename~
try:
posix.rename(filename, filename + '~')
except posix.error, msg:
err(filename + ': warning: backup failed (' + `msg` + ')\n')
# Now move the temp file to the original file
try:
posix.rename(tempname, filename)
except posix.error, msg:
err(filename + ': rename failed (' + `msg` + ')\n')
return 1
# Return succes
return 0
PAT1 = '\<\(if\|elif\|while\)\>[\0-\377]*[^<>!=]\(=\)[^=][\0-\377]*[^[]:[^]]'
# \2 \3
PAT2 = '\<return\>[\0-\377]*[^<>!=]\(=\)[^=]'
# \4
PAT = '^[ \t]*\(' + PAT1 + '\|' + PAT2 + '\)'
# \1
prog = regex.compile(PAT)
def fixline(line):
while prog.match(line) >= 0:
regs = prog.regs
if regs[3] == (-1, -1):
a, b = regs[4]
else:
a, b = regs[3]
if not 0 < a < b < len(line):
dbg('Weird: ' + line)
break
line = line[:a] + '==' + line[b:]
return line
main()
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