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      1 #!/usr/bin/env python
      2 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
      3 # Use of this source code is governed by a BSD-style license that can be
      4 # found in the LICENSE file.
      5 
      6 """Given a filename as an argument, sort the #include/#imports in that file.
      7 
      8 Shows a diff and prompts for confirmation before doing the deed.
      9 Works great with tools/git/for-all-touched-files.py.
     10 """
     11 
     12 import optparse
     13 import os
     14 import sys
     15 
     16 
     17 def YesNo(prompt):
     18   """Prompts with a yes/no question, returns True if yes."""
     19   print prompt,
     20   sys.stdout.flush()
     21   # http://code.activestate.com/recipes/134892/
     22   if sys.platform == 'win32':
     23     import msvcrt
     24     ch = msvcrt.getch()
     25   else:
     26     import termios
     27     import tty
     28     fd = sys.stdin.fileno()
     29     old_settings = termios.tcgetattr(fd)
     30     ch = 'n'
     31     try:
     32       tty.setraw(sys.stdin.fileno())
     33       ch = sys.stdin.read(1)
     34     finally:
     35       termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
     36   print ch
     37   return ch in ('Y', 'y')
     38 
     39 
     40 def IncludeCompareKey(line):
     41   """Sorting comparator key used for comparing two #include lines.
     42   Returns the filename without the #include/#import/import prefix.
     43   """
     44   for prefix in ('#include ', '#import ', 'import '):
     45     if line.startswith(prefix):
     46       line = line[len(prefix):]
     47       break
     48 
     49   # The win32 api has all sorts of implicit include order dependencies :-/
     50   # Give a few headers special sort keys that make sure they appear before all
     51   # other headers.
     52   if line.startswith('<windows.h>'):  # Must be before e.g. shellapi.h
     53     return '0'
     54   if line.startswith('<atlbase.h>'):  # Must be before atlapp.h.
     55     return '1' + line
     56   if line.startswith('<ole2.h>'):  # Must be before e.g. intshcut.h
     57     return '1' + line
     58   if line.startswith('<unknwn.h>'):  # Must be before e.g. intshcut.h
     59     return '1' + line
     60 
     61   # C++ system headers should come after C system headers.
     62   if line.startswith('<'):
     63     if line.find('.h>') != -1:
     64       return '2' + line.lower()
     65     else:
     66       return '3' + line.lower()
     67 
     68   return '4' + line
     69 
     70 
     71 def IsInclude(line):
     72   """Returns True if the line is an #include/#import/import line."""
     73   return any([line.startswith('#include '), line.startswith('#import '),
     74               line.startswith('import ')])
     75 
     76 
     77 def SortHeader(infile, outfile):
     78   """Sorts the headers in infile, writing the sorted file to outfile."""
     79   for line in infile:
     80     if IsInclude(line):
     81       headerblock = []
     82       while IsInclude(line):
     83         infile_ended_on_include_line = False
     84         headerblock.append(line)
     85         # Ensure we don't die due to trying to read beyond the end of the file.
     86         try:
     87           line = infile.next()
     88         except StopIteration:
     89           infile_ended_on_include_line = True
     90           break
     91       for header in sorted(headerblock, key=IncludeCompareKey):
     92         outfile.write(header)
     93       if infile_ended_on_include_line:
     94         # We already wrote the last line above; exit to ensure it isn't written
     95         # again.
     96         return
     97       # Intentionally fall through, to write the line that caused
     98       # the above while loop to exit.
     99     outfile.write(line)
    100 
    101 
    102 def FixFileWithConfirmFunction(filename, confirm_function,
    103                                perform_safety_checks):
    104   """Creates a fixed version of the file, invokes |confirm_function|
    105   to decide whether to use the new file, and cleans up.
    106 
    107   |confirm_function| takes two parameters, the original filename and
    108   the fixed-up filename, and returns True to use the fixed-up file,
    109   false to not use it.
    110 
    111   If |perform_safety_checks| is True, then the function checks whether it is
    112   unsafe to reorder headers in this file and skips the reorder with a warning
    113   message in that case.
    114   """
    115   if perform_safety_checks and IsUnsafeToReorderHeaders(filename):
    116     print ('Not reordering headers in %s as the script thinks that the '
    117            'order of headers in this file is semantically significant.'
    118            % (filename))
    119     return
    120   fixfilename = filename + '.new'
    121   infile = open(filename, 'rb')
    122   outfile = open(fixfilename, 'wb')
    123   SortHeader(infile, outfile)
    124   infile.close()
    125   outfile.close()  # Important so the below diff gets the updated contents.
    126 
    127   try:
    128     if confirm_function(filename, fixfilename):
    129       if sys.platform == 'win32':
    130         os.unlink(filename)
    131       os.rename(fixfilename, filename)
    132   finally:
    133     try:
    134       os.remove(fixfilename)
    135     except OSError:
    136       # If the file isn't there, we don't care.
    137       pass
    138 
    139 
    140 def DiffAndConfirm(filename, should_confirm, perform_safety_checks):
    141   """Shows a diff of what the tool would change the file named
    142   filename to.  Shows a confirmation prompt if should_confirm is true.
    143   Saves the resulting file if should_confirm is false or the user
    144   answers Y to the confirmation prompt.
    145   """
    146   def ConfirmFunction(filename, fixfilename):
    147     diff = os.system('diff -u %s %s' % (filename, fixfilename))
    148     if sys.platform != 'win32':
    149       diff >>= 8
    150     if diff == 0:  # Check exit code.
    151       print '%s: no change' % filename
    152       return False
    153 
    154     return (not should_confirm or YesNo('Use new file (y/N)?'))
    155 
    156   FixFileWithConfirmFunction(filename, ConfirmFunction, perform_safety_checks)
    157 
    158 def IsUnsafeToReorderHeaders(filename):
    159   # *_message_generator.cc is almost certainly a file that generates IPC
    160   # definitions. Changes in include order in these files can result in them not
    161   # building correctly.
    162   if filename.find("message_generator.cc") != -1:
    163     return True
    164   return False
    165 
    166 def main():
    167   parser = optparse.OptionParser(usage='%prog filename1 filename2 ...')
    168   parser.add_option('-f', '--force', action='store_false', default=True,
    169                     dest='should_confirm',
    170                     help='Turn off confirmation prompt.')
    171   parser.add_option('--no_safety_checks',
    172                     action='store_false', default=True,
    173                     dest='perform_safety_checks',
    174                     help='Do not perform the safety checks via which this '
    175                     'script refuses to operate on files for which it thinks '
    176                     'the include ordering is semantically significant.')
    177   opts, filenames = parser.parse_args()
    178 
    179   if len(filenames) < 1:
    180     parser.print_help()
    181     return 1
    182 
    183   for filename in filenames:
    184     DiffAndConfirm(filename, opts.should_confirm, opts.perform_safety_checks)
    185 
    186 
    187 if __name__ == '__main__':
    188   sys.exit(main())
    189