text: #!/usr/bin/env python
  # vim:fenc=utf-8:shiftwidth=2
  
  # Copyright 2018 the V8 project authors. All rights reserved.
  # Use of this source code is governed by a BSD-style license that can be
  # found in the LICENSE file.
  
  """Check that each header can be included in isolation.
  
  For each header we generate one .cc file which only includes this one header.
  All these .cc files are then added to a sources.gni file which is included in
  BUILD.gn. Just compile to check whether there are any violations to the rule
  that each header must be includable in isolation.
  """
  
  # for py2/py3 compatibility
  from __future__ import print_function
  
  import argparse
  import os
  import os.path
  import re
  import sys
  
  # TODO(clemensb): Extend to tests.
  DEFAULT_INPUT = ['base', 'src']
  DEFAULT_GN_FILE = 'BUILD.gn'
  MY_DIR = os.path.dirname(os.path.realpath(__file__))
  V8_DIR = os.path.dirname(MY_DIR)
  OUT_DIR = os.path.join(V8_DIR, 'check-header-includes')
  AUTO_EXCLUDE = [
    # flag-definitions.h needs a mode set for being included.
    'src/flags/flag-definitions.h',
  ]
  AUTO_EXCLUDE_PATTERNS = [
    'src/base/atomicops_internals_.*',
    # TODO(petermarshall): Enable once Perfetto is built by default.
    'src/libplatform/tracing/perfetto*',
  ] + [
    # platform-specific headers
    '\\b{}\\b'.format(p) for p in
      ('win', 'win32', 'ia32', 'x64', 'arm', 'arm64', 'mips', 'mips64', 's390',
       'ppc')]
  
  args = None
  def parse_args():
    global args
    parser = argparse.ArgumentParser()
    parser.add_argument('-i', '--input', type=str, action='append',
                        help='Headers or directories to check (directories '
                             'are scanned for headers recursively); default: ' +
                             ','.join(DEFAULT_INPUT))
    parser.add_argument('-x', '--exclude', type=str, action='append',
                        help='Add an exclude pattern (regex)')
    parser.add_argument('-v', '--verbose', action='store_true',
                        help='Be verbose')
    args = parser.parse_args()
    args.exclude = (args.exclude or []) + AUTO_EXCLUDE_PATTERNS
    args.exclude += ['^' + re.escape(x) + '$' for x in AUTO_EXCLUDE]
    if not args.input:
      args.input=DEFAULT_INPUT
  
  
  def printv(line):
    if args.verbose:
      print(line)
  
  
  def find_all_headers():
    printv('Searching for headers...')
    header_files = []
    exclude_patterns = [re.compile(x) for x in args.exclude]
    def add_recursively(filename):
      full_name = os.path.join(V8_DIR, filename)
      if not os.path.exists(full_name):
        sys.exit('File does not exist: {}'.format(full_name))
      if os.path.isdir(full_name):
        for subfile in os.listdir(full_name):
          full_name = os.path.join(filename, subfile)
          printv('Scanning {}'.format(full_name))
          add_recursively(full_name)
      elif filename.endswith('.h'):
        printv('--> Found header file {}'.format(filename))
        for p in exclude_patterns:
          if p.search(filename):
            printv('--> EXCLUDED (matches {})'.format(p.pattern))
            return
        header_files.append(filename)
  
    for filename in args.input:
      add_recursively(filename)
  
    return header_files
  
  
  def get_cc_file_name(header):
    split = os.path.split(header)
    header_dir = os.path.relpath(split[0], V8_DIR)
    # Prefix with the directory name, to avoid collisions in the object files.
    prefix = header_dir.replace(os.path.sep, '-')
    cc_file_name = 'test-include-' + prefix + '-' + split[1][:-1] + 'cc'
    return os.path.join(OUT_DIR, cc_file_name)
  
  
  def create_including_cc_files(header_files):
    comment = 'check including this header in isolation'
    for header in header_files:
      cc_file_name = get_cc_file_name(header)
      rel_cc_file_name = os.path.relpath(cc_file_name, V8_DIR)
      content = '#include "{}"  // {}\n'.format(header, comment)
      if os.path.exists(cc_file_name):
        with open(cc_file_name) as cc_file:
          if cc_file.read() == content:
            printv('File {} is up to date'.format(rel_cc_file_name))
            continue
      printv('Creating file {}'.format(rel_cc_file_name))
      with open(cc_file_name, 'w') as cc_file:
        cc_file.write(content)
  
  
  def generate_gni(header_files):
    gni_file = os.path.join(OUT_DIR, 'sources.gni')
    printv('Generating file "{}"'.format(os.path.relpath(gni_file, V8_DIR)))
    with open(gni_file, 'w') as gn:
      gn.write("""\
  # Copyright 2018 The Chromium Authors. All rights reserved.
  # Use of this source code is governed by a BSD-style license that can be
  # found in the LICENSE file.
  
  # This list is filled automatically by tools/check_header_includes.py.
  check_header_includes_sources = [
  """);
      for header in header_files:
        cc_file_name = get_cc_file_name(header)
        gn.write('    "{}",\n'.format(os.path.relpath(cc_file_name, V8_DIR)))
      gn.write(']\n')
  
  
  def main():
    parse_args()
    header_files = find_all_headers()
    if not os.path.exists(OUT_DIR):
      os.mkdir(OUT_DIR)
    create_including_cc_files(header_files)
    generate_gni(header_files)
  
  if __name__ == '__main__':
    main()
  