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