Demo/scripts/eqfix.py

   1 #! /usr/bin/env python
   2
   3 # Fix Python source files to use the new equality test operator, i.e.,
   4 #       if x = y: ...
   5 # is changed to
   6 #       if x == y: ...
   7 # The script correctly tokenizes the Python program to reliably
   8 # distinguish between assignments and equality tests.
   9 #
  10 # Command line arguments are files or directories to be processed.
  11 # Directories are searched recursively for files whose name looks
  12 # like a python module.
  13 # Symbolic links are always ignored (except as explicit directory
  14 # arguments).  Of course, the original file is kept as a back-up
  15 # (with a "~" attached to its name).
  16 # It complains about binaries (files containing null bytes)
  17 # and about files that are ostensibly not Python files: if the first
  18 # line starts with '#!' and does not contain the string 'python'.
  19 #
  20 # Changes made are reported to stdout in a diff-like format.
  21 #
  22 # Undoubtedly you can do this using find and sed or perl, but this is
  23 # a nice example of Python code that recurses down a directory tree
  24 # and uses regular expressions.  Also note several subtleties like
  25 # preserving the file's mode and avoiding to even write a temp file
  26 # when no changes are needed for a file.
  27 #
  28 # NB: by changing only the function fixline() you can turn this
  29 # into a program for a different change to Python programs...
  30
  31 import sys
  32 import re
  33 import os
  34 from stat import *
  35 import string
  36
  37 err = sys.stderr.write
  38 dbg = err
  39 rep = sys.stdout.write
  40
  41 def main():
  42     bad = 0
  43     if not sys.argv[1:]: # No arguments
  44         err('usage: ' + sys.argv[0] + ' file-or-directory ...\n')
  45         sys.exit(2)
  46     for arg in sys.argv[1:]:
  47         if os.path.isdir(arg):
  48             if recursedown(arg): bad = 1
  49         elif os.path.islink(arg):
  50             err(arg + ': will not process symbolic links\n')
  51             bad = 1
  52         else:
  53             if fix(arg): bad = 1
  54     sys.exit(bad)
  55
  56 ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')
  57 def ispython(name):
  58     return ispythonprog.match(name) >= 0
  59
  60 def recursedown(dirname):
  61     dbg('recursedown(%r)\n' % (dirname,))
  62     bad = 0
  63     try:
  64         names = os.listdir(dirname)
  65     except os.error, msg:
  66         err('%s: cannot list directory: %r\n' % (dirname, msg))
  67         return 1
  68     names.sort()
  69     subdirs = []
  70     for name in names:
  71         if name in (os.curdir, os.pardir): continue
  72         fullname = os.path.join(dirname, name)
  73         if os.path.islink(fullname): pass
  74         elif os.path.isdir(fullname):
  75             subdirs.append(fullname)
  76         elif ispython(name):
  77             if fix(fullname): bad = 1
  78     for fullname in subdirs:
  79         if recursedown(fullname): bad = 1
  80     return bad
  81
  82 def fix(filename):
  83 ##      dbg('fix(%r)\n' % (dirname,))
  84     try:
  85         f = open(filename, 'r')
  86     except IOError, msg:
  87         err('%s: cannot open: %r\n' % (filename, msg))
  88         return 1
  89     head, tail = os.path.split(filename)
  90     tempname = os.path.join(head, '@' + tail)
  91     g = None
  92     # If we find a match, we rewind the file and start over but
  93     # now copy everything to a temp file.
  94     lineno = 0
  95     while 1:
  96         line = f.readline()
  97         if not line: break
  98         lineno = lineno + 1
  99         if g is None and '\0' in line:
 100             # Check for binary files
 101             err(filename + ': contains null bytes; not fixed\n')
 102             f.close()
 103             return 1
 104         if lineno == 1 and g is None and line[:2] == '#!':
 105             # Check for non-Python scripts
 106             words = string.split(line[2:])
 107             if words and re.search('[pP]ython', words[0]) < 0:
 108                 msg = filename + ': ' + words[0]
 109                 msg = msg + ' script; not fixed\n'
 110                 err(msg)
 111                 f.close()
 112                 return 1
 113         while line[-2:] == '\\\n':
 114             nextline = f.readline()
 115             if not nextline: break
 116             line = line + nextline
 117             lineno = lineno + 1
 118         newline = fixline(line)
 119         if newline != line:
 120             if g is None:
 121                 try:
 122                     g = open(tempname, 'w')
 123                 except IOError, msg:
 124                     f.close()
 125                     err('%s: cannot create: %r\n' % (tempname, msg))
 126                     return 1
 127                 f.seek(0)
 128                 lineno = 0
 129                 rep(filename + ':\n')
 130                 continue # restart from the beginning
 131             rep(repr(lineno) + '\n')
 132             rep('< ' + line)
 133             rep('> ' + newline)
 134         if g is not None:
 135             g.write(newline)
 136
 137     # End of file
 138     f.close()
 139     if not g: return 0 # No changes
 140
 141     # Finishing touch -- move files
 142
 143     # First copy the file's mode to the temp file
 144     try:
 145         statbuf = os.stat(filename)
 146         os.chmod(tempname, statbuf[ST_MODE] & 07777)
 147     except os.error, msg:
 148         err('%s: warning: chmod failed (%r)\n' % (tempname, msg))
 149     # Then make a backup of the original file as filename~
 150     try:
 151         os.rename(filename, filename + '~')
 152     except os.error, msg:
 153         err('%s: warning: backup failed (%r)\n' % (filename, msg))
 154     # Now move the temp file to the original file
 155     try:
 156         os.rename(tempname, filename)
 157     except os.error, msg:
 158         err('%s: rename failed (%r)\n' % (filename, msg))
 159         return 1
 160     # Return succes
 161     return 0
 162
 163
 164 from tokenize import tokenprog
 165
 166 match = {'if':':', 'elif':':', 'while':':', 'return':'\n', \
 167          '(':')', '[':']', '{':'}', '`':'`'}
 168
 169 def fixline(line):
 170     # Quick check for easy case
 171     if '=' not in line: return line
 172
 173     i, n = 0, len(line)
 174     stack = []
 175     while i < n:
 176         j = tokenprog.match(line, i)
 177         if j < 0:
 178             # A bad token; forget about the rest of this line
 179             print '(Syntax error:)'
 180             print line,
 181             return line
 182         a, b = tokenprog.regs[3] # Location of the token proper
 183         token = line[a:b]
 184         i = i+j
 185         if stack and token == stack[-1]:
 186             del stack[-1]
 187         elif match.has_key(token):
 188             stack.append(match[token])
 189         elif token == '=' and stack:
 190             line = line[:a] + '==' + line[b:]
 191             i, n = a + len('=='), len(line)
 192         elif token == '==' and not stack:
 193             print '(Warning: \'==\' at top level:)'
 194             print line,
 195     return line
 196
 197 if __name__ == "__main__":
 198     main()