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 IsInclude(line):
  20   """Returns True if the line is an #include/#import/import line."""
  21   return any([line.startswith('#include '), line.startswith('#import '),
  22               line.startswith('import ')])
  23
  24
  25 def IncludeCompareKey(line, for_blink):
  26   """Sorting comparator key used for comparing two #include lines.
  27
  28   Returns an integer, optionally followed by a string. The integer is used
  29   for coarse sorting of different categories of headers, and the string is
  30   used for fine sorting of headers within categeries.
  31   """
  32   for prefix in ('#include ', '#import ', 'import '):
  33     if line.startswith(prefix):
  34       line = line[len(prefix):]
  35       break
  36
  37   if for_blink:
  38     # Blink likes to have its "config.h" include first.
  39     if line.startswith('"config.h"'):
  40       return '0'
  41
  42     # Blink sorts system headers after others. This is handled by sorting
  43     # alphabetically so no need to do anything tricky.
  44     return '1' + line
  45
  46   # The win32 api has all sorts of implicit include order dependencies :-/
  47   # Give a few headers special sort keys that make sure they appear before all
  48   # other headers.
  49   if line.startswith('<windows.h>'):  # Must be before e.g. shellapi.h
  50     return '0'
  51   if line.startswith('<atlbase.h>'):  # Must be before atlapp.h.
  52     return '1' + line
  53   if line.startswith('<ole2.h>'):  # Must be before e.g. intshcut.h
  54     return '1' + line
  55   if line.startswith('<unknwn.h>'):  # Must be before e.g. intshcut.h
  56     return '1' + line
  57
  58   # C++ system headers should come after C system headers.
  59   if line.startswith('<'):
  60     if line.find('.h>') != -1:
  61       return '2' + line.lower()
  62     else:
  63       return '3' + line.lower()
  64
  65   return '4' + line
  66
  67
  68 def SortHeader(infile, outfile, for_blink):
  69   """Sorts the headers in infile, writing the sorted file to outfile."""
  70   def CompareKey(line):
  71     return IncludeCompareKey(line, for_blink)
  72
  73   for line in infile:
  74     if IsInclude(line):
  75       headerblock = []
  76       while IsInclude(line):
  77         infile_ended_on_include_line = False
  78         headerblock.append(line)
  79         # Ensure we don't die due to trying to read beyond the end of the file.
  80         try:
  81           line = infile.next()
  82         except StopIteration:
  83           infile_ended_on_include_line = True
  84           break
  85       for header in sorted(headerblock, key=CompareKey):
  86         outfile.write(header)
  87       if infile_ended_on_include_line:
  88         # We already wrote the last line above; exit to ensure it isn't written
  89         # again.
  90         return
  91       # Intentionally fall through, to write the line that caused
  92       # the above while loop to exit.
  93     outfile.write(line)
  94
  95
  96 def FixFileWithConfirmFunction(filename, confirm_function,
  97                                perform_safety_checks, for_blink=False):
  98   """Creates a fixed version of the file, invokes |confirm_function|
  99   to decide whether to use the new file, and cleans up.
 100
 101   |confirm_function| takes two parameters, the original filename and
 102   the fixed-up filename, and returns True to use the fixed-up file,
 103   false to not use it.
 104
 105   If |perform_safety_checks| is True, then the function checks whether it is
 106   unsafe to reorder headers in this file and skips the reorder with a warning
 107   message in that case.
 108   """
 109   if perform_safety_checks and IsUnsafeToReorderHeaders(filename):
 110     print ('Not reordering headers in %s as the script thinks that the '
 111            'order of headers in this file is semantically significant.'
 112            % (filename))
 113     return
 114   fixfilename = filename + '.new'
 115   infile = open(filename, 'rb')
 116   outfile = open(fixfilename, 'wb')
 117   SortHeader(infile, outfile, for_blink)
 118   infile.close()
 119   outfile.close()  # Important so the below diff gets the updated contents.
 120
 121   try:
 122     if confirm_function(filename, fixfilename):
 123       if sys.platform == 'win32':
 124         os.unlink(filename)
 125       os.rename(fixfilename, filename)
 126   finally:
 127     try:
 128       os.remove(fixfilename)
 129     except OSError:
 130       # If the file isn't there, we don't care.
 131       pass
 132
 133
 134 def DiffAndConfirm(filename, should_confirm, perform_safety_checks, for_blink):
 135   """Shows a diff of what the tool would change the file named
 136   filename to.  Shows a confirmation prompt if should_confirm is true.
 137   Saves the resulting file if should_confirm is false or the user
 138   answers Y to the confirmation prompt.
 139   """
 140   def ConfirmFunction(filename, fixfilename):
 141     diff = os.system('diff -u %s %s' % (filename, fixfilename))
 142     if sys.platform != 'win32':
 143       diff >>= 8
 144     if diff == 0:  # Check exit code.
 145       print '%s: no change' % filename
 146       return False
 147
 148     return (not should_confirm or YesNo('Use new file (y/N)?'))
 149
 150   FixFileWithConfirmFunction(filename, ConfirmFunction, perform_safety_checks,
 151                              for_blink)
 152
 153 def IsUnsafeToReorderHeaders(filename):
 154   # *_message_generator.cc is almost certainly a file that generates IPC
 155   # definitions. Changes in include order in these files can result in them not
 156   # building correctly.
 157   if filename.find("message_generator.cc") != -1:
 158     return True
 159   return False
 160
 161 def main():
 162   parser = optparse.OptionParser(usage='%prog filename1 filename2 ...')
 163   parser.add_option('-f', '--force', action='store_false', default=True,
 164                     dest='should_confirm',
 165                     help='Turn off confirmation prompt.')
 166   parser.add_option('--no_safety_checks',
 167                     action='store_false', default=True,
 168                     dest='perform_safety_checks',
 169                     help='Do not perform the safety checks via which this '
 170                     'script refuses to operate on files for which it thinks '
 171                     'the include ordering is semantically significant.')
 172   parser.add_option('--for_blink', action='store_true', default=False,
 173                     dest='for_blink', help='Whether the blink header sorting '
 174                     'rules should be applied.')
 175   opts, filenames = parser.parse_args()
 176
 177   if len(filenames) < 1:
 178     parser.print_help()
 179     return 1
 180
 181   for filename in filenames:
 182     DiffAndConfirm(filename, opts.should_confirm, opts.perform_safety_checks,
 183                    opts.for_blink)
 184
 185
 186 if __name__ == '__main__':
 187   sys.exit(main())