#! /usr/bin/env python

# Perform massive identifier substitution on C source files.
# This actually tokenizes the files (to some extent) so it can
# avoid making substitutions inside strings or comments.
# Inside strings, substitutions are never made; inside comments,
# it is a user option (off by default).
#
# The substitutions are read from one or more files whose lines,
# when not empty, after stripping comments starting with #,
# must contain exactly two words separated by whitespace: the
# old identifier and its replacement.
#
# The option -r reverses the sense of the substitutions (this may be
# useful to undo a particular substitution).
#
# If the old identifier is prefixed with a '*' (with no intervening
# whitespace), then it will not be substituted inside comments.
#
# Command line arguments are files or directories to be processed.
# Directories are searched recursively for files whose name looks
# like a C file (ends in .h or .c).  The special filename '-' means
# operate in filter mode: read stdin, write stdout.
#
# Symbolic links are always ignored (except as explicit directory
# arguments).
#
# The original files are kept as back-up with a "~" suffix.
#
# Changes made are reported to stdout in a diff-like format.
#
# NB: by changing only the function fixline() you can turn this
# into a program for different changes to C source files; by
# changing the function wanted() you can make a different selection of
# files.

import sys
import re
import os
from stat import *
import getopt

err = sys.stderr.write
dbg = err
rep = sys.stdout.write

def usage():
   progname = sys.argv[0]
   err('Usage: ' + progname +
             ' [-c] [-r] [-s file] ... file-or-directory ...\n')
   err('\n')
   err('-c           : substitute inside comments\n')
   err('-r           : reverse direction for following -s options\n')
   err('-s substfile : add a file of substitutions\n')
   err('\n')
   err('Each non-empty non-comment line in a substitution file must\n')
   err('contain exactly two words: an identifier and its replacement.\n')
   err('Comments start with a # character and end at end of line.\n')
   err('If an identifier is preceded with a *, it is not substituted\n')
   err('inside a comment even when -c is specified.\n')

def main():
   try:
       opts, args = getopt.getopt(sys.argv[1:], 'crs:')
   except getopt.error, msg:
       err('Options error: ' + str(msg) + '\n')
       usage()
       sys.exit(2)
   bad = 0
   if not args: # No arguments
       usage()
       sys.exit(2)
   for opt, arg in opts:
       if opt == '-c':
           setdocomments()
       if opt == '-r':
           setreverse()
       if opt == '-s':
           addsubst(arg)
   for arg in args:
       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)

# Change this regular expression to select a different set of files
Wanted = '^[a-zA-Z0-9_]+\.[ch]$'
def wanted(name):
   return re.match(Wanted, name) >= 0

def recursedown(dirname):
   dbg('recursedown(%r)\n' % (dirname,))
   bad = 0
   try:
       names = os.listdir(dirname)
   except os.error, msg:
       err(dirname + ': cannot list directory: ' + str(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 wanted(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,))
   if filename == '-':
       # Filter mode
       f = sys.stdin
       g = sys.stdout
   else:
       # File replacement mode
       try:
           f = open(filename, 'r')
       except IOError, msg:
           err(filename + ': cannot open: ' + str(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
   initfixline()
   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: '+
                       str(msg)+'\n')
                   return 1
               f.seek(0)
               lineno = 0
               initfixline()
               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
   if filename == '-': return 0 # Done in filter mode
   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 (' + str(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 (' + str(msg) + ')\n')
   # Now move the temp file to the original file
   try:
       os.rename(tempname, filename)
   except os.error, msg:
       err(filename + ': rename failed (' + str(msg) + ')\n')
       return 1
   # Return succes
   return 0

# Tokenizing ANSI C (partly)

Identifier = '\(struct \)?[a-zA-Z_][a-zA-Z0-9_]+'
String = '"\([^\n\\"]\|\\\\.\)*"'
Char = '\'\([^\n\\\']\|\\\\.\)*\''
CommentStart = '/\*'
CommentEnd = '\*/'

Hexnumber = '0[xX][0-9a-fA-F]*[uUlL]*'
Octnumber = '0[0-7]*[uUlL]*'
Decnumber = '[1-9][0-9]*[uUlL]*'
Intnumber = Hexnumber + '\|' + Octnumber + '\|' + Decnumber
Exponent = '[eE][-+]?[0-9]+'
Pointfloat = '\([0-9]+\.[0-9]*\|\.[0-9]+\)\(' + Exponent + '\)?'
Expfloat = '[0-9]+' + Exponent
Floatnumber = Pointfloat + '\|' + Expfloat
Number = Floatnumber + '\|' + Intnumber

# Anything else is an operator -- don't list this explicitly because of '/*'

OutsideComment = (Identifier, Number, String, Char, CommentStart)
OutsideCommentPattern = '(' + '|'.join(OutsideComment) + ')'
OutsideCommentProgram = re.compile(OutsideCommentPattern)

InsideComment = (Identifier, Number, CommentEnd)
InsideCommentPattern = '(' + '|'.join(InsideComment) + ')'
InsideCommentProgram = re.compile(InsideCommentPattern)

def initfixline():
   global Program
   Program = OutsideCommentProgram

def fixline(line):
   global Program
##  print '-->', repr(line)
   i = 0
   while i < len(line):
       i = Program.search(line, i)
       if i < 0: break
       found = Program.group(0)
##      if Program is InsideCommentProgram: print '...',
##      else: print '   ',
##      print found
       if len(found) == 2:
           if found == '/*':
               Program = InsideCommentProgram
           elif found == '*/':
               Program = OutsideCommentProgram
       n = len(found)
       if Dict.has_key(found):
           subst = Dict[found]
           if Program is InsideCommentProgram:
               if not Docomments:
                   print 'Found in comment:', found
                   i = i + n
                   continue
               if NotInComment.has_key(found):
##                  print 'Ignored in comment:',
##                  print found, '-->', subst
##                  print 'Line:', line,
                   subst = found
##              else:
##                  print 'Substituting in comment:',
##                  print found, '-->', subst
##                  print 'Line:', line,
           line = line[:i] + subst + line[i+n:]
           n = len(subst)
       i = i + n
   return line

Docomments = 0
def setdocomments():
   global Docomments
   Docomments = 1

Reverse = 0
def setreverse():
   global Reverse
   Reverse = (not Reverse)

Dict = {}
NotInComment = {}
def addsubst(substfile):
   try:
       fp = open(substfile, 'r')
   except IOError, msg:
       err(substfile + ': cannot read substfile: ' + str(msg) + '\n')
       sys.exit(1)
   lineno = 0
   while 1:
       line = fp.readline()
       if not line: break
       lineno = lineno + 1
       try:
           i = line.index('#')
       except ValueError:
           i = -1          # Happens to delete trailing \n
       words = line[:i].split()
       if not words: continue
       if len(words) == 3 and words[0] == 'struct':
           words[:2] = [words[0] + ' ' + words[1]]
       elif len(words) <> 2:
           err(substfile + '%s:%r: warning: bad line: %r' % (substfile, lineno, line))
           continue
       if Reverse:
           [value, key] = words
       else:
           [key, value] = words
       if value[0] == '*':
           value = value[1:]
       if key[0] == '*':
           key = key[1:]
           NotInComment[key] = value
       if Dict.has_key(key):
           err('%s:%r: warning: overriding: %r %r\n' % (substfile, lineno, key, value))
           err('%s:%r: warning: previous: %r\n' % (substfile, lineno, Dict[key]))
       Dict[key] = value
   fp.close()

if __name__ == '__main__':
   main()