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 prefix.
  43   """
  44   for prefix in ('#include ', '#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('<unknwn.h>'):  # Must be before e.g. intshcut.h
  57     return '1' + line
  58
  59   # C++ system headers should come after C system headers.
  60   if line.startswith('<'):
  61     if line.find('.h>') != -1:
  62       return '2' + line.lower()
  63     else:
  64       return '3' + line.lower()
  65
  66   return '4' + line
  67
  68
  69 def IsInclude(line):
  70   """Returns True if the line is an #include/#import line."""
  71   return line.startswith('#include ') or line.startswith('#import ')
  72
  73
  74 def SortHeader(infile, outfile):
  75   """Sorts the headers in infile, writing the sorted file to outfile."""
  76   for line in infile:
  77     if IsInclude(line):
  78       headerblock = []
  79       while IsInclude(line):
  80         infile_ended_on_include_line = False
  81         headerblock.append(line)
  82         # Ensure we don't die due to trying to read beyond the end of the file.
  83         try:
  84           line = infile.next()
  85         except StopIteration:
  86           infile_ended_on_include_line = True
  87           break
  88       for header in sorted(headerblock, key=IncludeCompareKey):
  89         outfile.write(header)
  90       if infile_ended_on_include_line:
  91         # We already wrote the last line above; exit to ensure it isn't written
  92         # again.
  93         return
  94       # Intentionally fall through, to write the line that caused
  95       # the above while loop to exit.
  96     outfile.write(line)
  97
  98
  99 def FixFileWithConfirmFunction(filename, confirm_function,
 100                                perform_safety_checks):
 101   """Creates a fixed version of the file, invokes |confirm_function|
 102   to decide whether to use the new file, and cleans up.
 103
 104   |confirm_function| takes two parameters, the original filename and
 105   the fixed-up filename, and returns True to use the fixed-up file,
 106   false to not use it.
 107
 108   If |perform_safety_checks| is True, then the function checks whether it is
 109   unsafe to reorder headers in this file and skips the reorder with a warning
 110   message in that case.
 111   """
 112   if perform_safety_checks and IsUnsafeToReorderHeaders(filename):
 113     print ('Not reordering headers in %s as the script thinks that the '
 114            'order of headers in this file is semantically significant.'
 115            % (filename))
 116     return
 117   fixfilename = filename + '.new'
 118   infile = open(filename, 'rb')
 119   outfile = open(fixfilename, 'wb')
 120   SortHeader(infile, outfile)
 121   infile.close()
 122   outfile.close()  # Important so the below diff gets the updated contents.
 123
 124   try:
 125     if confirm_function(filename, fixfilename):
 126       if sys.platform == 'win32':
 127         os.unlink(filename)
 128       os.rename(fixfilename, filename)
 129   finally:
 130     try:
 131       os.remove(fixfilename)
 132     except OSError:
 133       # If the file isn't there, we don't care.
 134       pass
 135
 136
 137 def DiffAndConfirm(filename, should_confirm, perform_safety_checks):
 138   """Shows a diff of what the tool would change the file named
 139   filename to.  Shows a confirmation prompt if should_confirm is true.
 140   Saves the resulting file if should_confirm is false or the user
 141   answers Y to the confirmation prompt.
 142   """
 143   def ConfirmFunction(filename, fixfilename):
 144     diff = os.system('diff -u %s %s' % (filename, fixfilename))
 145     if sys.platform != 'win32':
 146       diff >>= 8
 147     if diff == 0:  # Check exit code.
 148       print '%s: no change' % filename
 149       return False
 150
 151     return (not should_confirm or YesNo('Use new file (y/N)?'))
 152
 153   FixFileWithConfirmFunction(filename, ConfirmFunction, perform_safety_checks)
 154
 155 def IsUnsafeToReorderHeaders(filename):
 156   # *_message_generator.cc is almost certainly a file that generates IPC
 157   # definitions. Changes in include order in these files can result in them not
 158   # building correctly.
 159   if filename.find("message_generator.cc") != -1:
 160     return True
 161   return False
 162
 163 def main():
 164   parser = optparse.OptionParser(usage='%prog filename1 filename2 ...')
 165   parser.add_option('-f', '--force', action='store_false', default=True,
 166                     dest='should_confirm',
 167                     help='Turn off confirmation prompt.')
 168   parser.add_option('--no_safety_checks',
 169                     action='store_false', default=True,
 170                     dest='perform_safety_checks',
 171                     help='Do not perform the safety checks via which this '
 172                     'script refuses to operate on files for which it thinks '
 173                     'the include ordering is semantically significant.')
 174   opts, filenames = parser.parse_args()
 175
 176   if len(filenames) < 1:
 177     parser.print_help()
 178     return 1
 179
 180   for filename in filenames:
 181     DiffAndConfirm(filename, opts.should_confirm, opts.perform_safety_checks)
 182
 183
 184 if __name__ == '__main__':
 185   sys.exit(main())