#! /usr/bin/env python

# This script is obsolete -- it is kept for historical purposes only.
#
# Fix Python source files to use the new class definition syntax, i.e.,
# the syntax used in Python versions before 0.9.8:
#       class C() = base(), base(), ...: ...
# is changed to the current syntax:
#       class C(base, base, ...): ...
#
# The script uses heuristics to find class definitions that usually
# work but occasionally can fail; carefully check the output!
#
# 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 re
import os
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: ' + 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' % (filename,))
   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
       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

# This expression doesn't catch *all* class definition headers,
# but it's pretty darn close.
classexpr = '^([ \t]*class +[a-zA-Z0-9_]+) *( *) *((=.*)?):'
classprog = re.compile(classexpr)

# Expressions for finding base class expressions.
baseexpr = '^ *(.*) *( *) *$'
baseprog = re.compile(baseexpr)

def fixline(line):
   if classprog.match(line) < 0: # No 'class' keyword -- no change
       return line

   (a0, b0), (a1, b1), (a2, b2) = classprog.regs[:3]
   # a0, b0 = Whole match (up to ':')
   # a1, b1 = First subexpression (up to classname)
   # a2, b2 = Second subexpression (=.*)
   head = line[:b1]
   tail = line[b0:] # Unmatched rest of line

   if a2 == b2: # No base classes -- easy case
       return head + ':' + tail

   # Get rid of leading '='
   basepart = line[a2+1:b2]

   # Extract list of base expressions
   bases = basepart.split(',')

   # Strip trailing '()' from each base expression
   for i in range(len(bases)):
       if baseprog.match(bases[i]) >= 0:
           x1, y1 = baseprog.regs[1]
           bases[i] = bases[i][x1:y1]

   # Join the bases back again and build the new line
   basepart = ', '.join(bases)

   return head + '(' + basepart + '):' + tail

if __name__ == '__main__':
   main()