eqfix.py :  » Mobile » Python-for-PalmOS » Python-1.5.2+reduced-1.0 » Demo » scripts » Python Open Source

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Python Open Source » Mobile » Python for PalmOS 
Python for PalmOS » Python 1.5.2 reduced 1.0 » Demo » scripts » eqfix.py
#! /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 regex
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 = 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 = os.listdir(dirname)
  except os.error, msg:
    err(dirname + ': cannot list directory: ' + `msg` + '\n')
    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(' + `filename` + ')\n')
  try:
    f = open(filename, 'r')
  except IOError, msg:
    err(filename + ': cannot open: ' + `msg` + '\n')
    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 regex.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(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 = os.stat(filename)
    os.chmod(tempname, statbuf[ST_MODE] & 07777)
  except os.error, msg:
    err(tempname + ': warning: chmod failed (' + `msg` + ')\n')
  # Then make a backup of the original file as filename~
  try:
    os.rename(filename, filename + '~')
  except os.error, msg:
    err(filename + ': warning: backup failed (' + `msg` + ')\n')
  # Now move the temp file to the original file
  try:
    os.rename(tempname, filename)
  except os.error, msg:
    err(filename + ': rename failed (' + `msg` + ')\n')
    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


main()
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