tools/sort-headers.py

   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())