cpplint.py

    if _cpplint_state.output_format == 'vs7':
      sys.stderr.write('%s(%s):  %s  [%s] [%d]\n' % (
          filename, linenum, message, category, confidence))
    elif _cpplint_state.output_format == 'eclipse':
      sys.stderr.write('%s:%s: warning: %s  [%s] [%d]\n' % (
          filename, linenum, message, category, confidence))
    else:
      sys.stderr.write('%s:%s:  %s  [%s] [%d]\n' % (
          filename, linenum, message, category, confidence))


# Matches standard C++ escape sequences per 2.13.2.3 of the C++ standard.
_RE_PATTERN_CLEANSE_LINE_ESCAPES = re.compile(
    r'\\([abfnrtv?"\\\']|\d+|x[0-9a-fA-F]+)')
# Matches strings.  Escape codes should already be removed by ESCAPES.
_RE_PATTERN_CLEANSE_LINE_DOUBLE_QUOTES = re.compile(r'"[^"]*"')
# Matches characters.  Escape codes should already be removed by ESCAPES.
_RE_PATTERN_CLEANSE_LINE_SINGLE_QUOTES = re.compile(r"'.'")
# Matches multi-line C++ comments.
# This RE is a little bit more complicated than one might expect, because we
# have to take care of space removals tools so we can handle comments inside
# statements better.
# The current rule is: We only clear spaces from both sides when we're at the
# end of the line. Otherwise, we try to remove spaces from the right side,
# if this doesn't work we try on left side but only if there's a non-character
# on the right.
_RE_PATTERN_CLEANSE_LINE_C_COMMENTS = re.compile(
    r"""(\s*/\*.*\*/\s*$|
            /\*.*\*/\s+|
         \s+/\*.*\*/(?=\W)|
            /\*.*\*/)""", re.VERBOSE)


def IsCppString(line):
  """Does line terminate so, that the next symbol is in string constant.

  This function does not consider single-line nor multi-line comments.

  Args:
    line: is a partial line of code starting from the 0..n.

  Returns:
    True, if next character appended to 'line' is inside a
    string constant.
  """

  line = line.replace(r'\\', 'XX')  # after this, \\" does not match to \"
  return ((line.count('"') - line.count(r'\"') - line.count("'\"'")) & 1) == 1


def CleanseRawStrings(raw_lines):
  """Removes C++11 raw strings from lines.

    Before:
      static const char kData[] = R"(
          multi-line string
          )";

    After:
      static const char kData[] = ""
          (replaced by blank line)
          "";

  Args:
    raw_lines: list of raw lines.

  Returns:
    list of lines with C++11 raw strings replaced by empty strings.
  """

  delimiter = None
  lines_without_raw_strings = []
  for line in raw_lines:
    if delimiter:
      # Inside a raw string, look for the end
      end = line.find(delimiter)
      if end >= 0:
        # Found the end of the string, match leading space for this
        # line and resume copying the original lines, and also insert
        # a "" on the last line.
        leading_space = Match(r'^(\s*)\S', line)
        line = leading_space.group(1) + '""' + line[end + len(delimiter):]
        delimiter = None
      else:
        # Haven't found the end yet, append a blank line.
        line = ''

    else:
      # Look for beginning of a raw string.
      # See 2.14.15 [lex.string] for syntax.
      matched = Match(r'^(.*)\b(?:R|u8R|uR|UR|LR)"([^\s\\()]*)\((.*)$', line)
      if matched:
        delimiter = ')' + matched.group(2) + '"'

        end = matched.group(3).find(delimiter)
        if end >= 0:
          # Raw string ended on same line
          line = (matched.group(1) + '""' +
                  matched.group(3)[end + len(delimiter):])
          delimiter = None
        else:
          # Start of a multi-line raw string
          line = matched.group(1) + '""'

    lines_without_raw_strings.append(line)

  # TODO(unknown): if delimiter is not None here, we might want to
  # emit a warning for unterminated string.
  return lines_without_raw_strings


def FindNextMultiLineCommentStart(lines, lineix):
  """Find the beginning marker for a multiline comment."""
  while lineix < len(lines):
    if lines[lineix].strip().startswith('/*'):
      # Only return this marker if the comment goes beyond this line
      if lines[lineix].strip().find('*/', 2) < 0:
        return lineix
    lineix += 1
  return len(lines)


def FindNextMultiLineCommentEnd(lines, lineix):
  """We are inside a comment, find the end marker."""
  while lineix < len(lines):
    if lines[lineix].strip().endswith('*/'):
      return lineix
    lineix += 1
  return len(lines)


def RemoveMultiLineCommentsFromRange(lines, begin, end):
  """Clears a range of lines for multi-line comments."""
  # Having // dummy comments makes the lines non-empty, so we will not get
  # unnecessary blank line warnings later in the code.
  for i in range(begin, end):
    lines[i] = '// dummy'


def RemoveMultiLineComments(filename, lines, error):
  """Removes multiline (c-style) comments from lines."""
  lineix = 0
  while lineix < len(lines):
    lineix_begin = FindNextMultiLineCommentStart(lines, lineix)
    if lineix_begin >= len(lines):
      return
    lineix_end = FindNextMultiLineCommentEnd(lines, lineix_begin)
    if lineix_end >= len(lines):
      error(filename, lineix_begin + 1, 'readability/multiline_comment', 5,
            'Could not find end of multi-line comment')
      return
    RemoveMultiLineCommentsFromRange(lines, lineix_begin, lineix_end + 1)
    lineix = lineix_end + 1


def CleanseComments(line):
  """Removes //-comments and single-line C-style /* */ comments.

  Args:
    line: A line of C++ source.

  Returns:
    The line with single-line comments removed.
  """
  commentpos = line.find('//')
  if commentpos != -1 and not IsCppString(line[:commentpos]):
    line = line[:commentpos].rstrip()
  # get rid of /* ... */
  return _RE_PATTERN_CLEANSE_LINE_C_COMMENTS.sub('', line)


class CleansedLines(object):
  """Holds 3 copies of all lines with different preprocessing applied to them.

  1) elided member contains lines without strings and comments,
  2) lines member contains lines without comments, and
  3) raw_lines member contains all the lines without processing.
  All these three members are of <type 'list'>, and of the same length.
  """

  def __init__(self, lines):
    self.elided = []
    self.lines = []
    self.raw_lines = lines
    self.num_lines = len(lines)
    self.lines_without_raw_strings = CleanseRawStrings(lines)
    for linenum in range(len(self.lines_without_raw_strings)):
      self.lines.append(CleanseComments(
          self.lines_without_raw_strings[linenum]))
      elided = self._CollapseStrings(self.lines_without_raw_strings[linenum])
      self.elided.append(CleanseComments(elided))

  def NumLines(self):
    """Returns the number of lines represented."""
    return self.num_lines

  @staticmethod
  def _CollapseStrings(elided):
    """Collapses strings and chars on a line to simple "" or '' blocks.

    We nix strings first so we're not fooled by text like '"http://"'

    Args:
      elided: The line being processed.

    Returns:
      The line with collapsed strings.
    """
    if not _RE_PATTERN_INCLUDE.match(elided):
      # Remove escaped characters first to make quote/single quote collapsing
      # basic.  Things that look like escaped characters shouldn't occur
      # outside of strings and chars.
      elided = _RE_PATTERN_CLEANSE_LINE_ESCAPES.sub('', elided)
      elided = _RE_PATTERN_CLEANSE_LINE_SINGLE_QUOTES.sub("''", elided)
      elided = _RE_PATTERN_CLEANSE_LINE_DOUBLE_QUOTES.sub('""', elided)
    return elided


def FindEndOfExpressionInLine(line, startpos, depth, startchar, endchar):
  """Find the position just after the matching endchar.

  Args:
    line: a CleansedLines line.
    startpos: start searching at this position.
    depth: nesting level at startpos.
    startchar: expression opening character.
    endchar: expression closing character.

  Returns:
    On finding matching endchar: (index just after matching endchar, 0)
    Otherwise: (-1, new depth at end of this line)
  """
  for i in xrange(startpos, len(line)):
    if line[i] == startchar:
      depth += 1
    elif line[i] == endchar:
      depth -= 1
      if depth == 0:
        return (i + 1, 0)
  return (-1, depth)


def CloseExpression(clean_lines, linenum, pos):
  """If input points to ( or { or [ or <, finds the position that closes it.

  If lines[linenum][pos] points to a '(' or '{' or '[' or '<', finds the
  linenum/pos that correspond to the closing of the expression.

  Args:
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    pos: A position on the line.

  Returns:
    A tuple (line, linenum, pos) pointer *past* the closing brace, or
    (line, len(lines), -1) if we never find a close.  Note we ignore
    strings and comments when matching; and the line we return is the
    'cleansed' line at linenum.
  """

  line = clean_lines.elided[linenum]
  startchar = line[pos]
  if startchar not in '({[<':
    return (line, clean_lines.NumLines(), -1)
  if startchar == '(': endchar = ')'
  if startchar == '[': endchar = ']'
  if startchar == '{': endchar = '}'
  if startchar == '<': endchar = '>'

  # Check first line
  (end_pos, num_open) = FindEndOfExpressionInLine(
      line, pos, 0, startchar, endchar)
  if end_pos > -1:
    return (line, linenum, end_pos)

  # Continue scanning forward
  while linenum < clean_lines.NumLines() - 1:
    linenum += 1
    line = clean_lines.elided[linenum]
    (end_pos, num_open) = FindEndOfExpressionInLine(
        line, 0, num_open, startchar, endchar)
    if end_pos > -1:
      return (line, linenum, end_pos)

  # Did not find endchar before end of file, give up
  return (line, clean_lines.NumLines(), -1)


def FindStartOfExpressionInLine(line, endpos, depth, startchar, endchar):
  """Find position at the matching startchar.

  This is almost the reverse of FindEndOfExpressionInLine, but note
  that the input position and returned position differs by 1.

  Args:
    line: a CleansedLines line.
    endpos: start searching at this position.
    depth: nesting level at endpos.
    startchar: expression opening character.
    endchar: expression closing character.

  Returns:
    On finding matching startchar: (index at matching startchar, 0)
    Otherwise: (-1, new depth at beginning of this line)
  """
  for i in xrange(endpos, -1, -1):
    if line[i] == endchar:
      depth += 1
    elif line[i] == startchar:
      depth -= 1
      if depth == 0:
        return (i, 0)
  return (-1, depth)


def ReverseCloseExpression(clean_lines, linenum, pos):
  """If input points to ) or } or ] or >, finds the position that opens it.

  If lines[linenum][pos] points to a ')' or '}' or ']' or '>', finds the
  linenum/pos that correspond to the opening of the expression.

  Args:
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    pos: A position on the line.

  Returns:
    A tuple (line, linenum, pos) pointer *at* the opening brace, or
    (line, 0, -1) if we never find the matching opening brace.  Note
    we ignore strings and comments when matching; and the line we
    return is the 'cleansed' line at linenum.
  """
  line = clean_lines.elided[linenum]
  endchar = line[pos]
  if endchar not in ')}]>':
    return (line, 0, -1)
  if endchar == ')': startchar = '('
  if endchar == ']': startchar = '['
  if endchar == '}': startchar = '{'
  if endchar == '>': startchar = '<'

  # Check last line
  (start_pos, num_open) = FindStartOfExpressionInLine(
      line, pos, 0, startchar, endchar)
  if start_pos > -1:
    return (line, linenum, start_pos)

  # Continue scanning backward
  while linenum > 0:
    linenum -= 1
    line = clean_lines.elided[linenum]
    (start_pos, num_open) = FindStartOfExpressionInLine(
        line, len(line) - 1, num_open, startchar, endchar)
    if start_pos > -1:
      return (line, linenum, start_pos)

  # Did not find startchar before beginning of file, give up
  return (line, 0, -1)


def CheckForCopyright(filename, lines, error):
  """Logs an error if no Copyright message appears at the top of the file."""

  # We'll say it should occur by line 10. Don't forget there's a
  # dummy line at the front.
  for line in xrange(1, min(len(lines), 11)):
    if re.search(r'Copyright', lines[line], re.I): break
  else:                       # means no copyright line was found
    error(filename, 0, 'legal/copyright', 5,
          'No copyright message found.  '
          'You should have a line: "Copyright [year] <Copyright Owner>"')


def GetHeaderGuardCPPVariable(filename):
  """Returns the CPP variable that should be used as a header guard.

  Args:
    filename: The name of a C++ header file.

  Returns:
    The CPP variable that should be used as a header guard in the
    named file.

  """

  # Restores original filename in case that cpplint is invoked from Emacs's
  # flymake.
  filename = re.sub(r'_flymake\.h$', '.h', filename)
  filename = re.sub(r'/\.flymake/([^/]*)$', r'/\1', filename)

  fileinfo = FileInfo(filename)
  file_path_from_root = fileinfo.RepositoryName()
  if _root:
    file_path_from_root = re.sub('^' + _root + os.sep, '', file_path_from_root)
  return re.sub(r'[-./\s]', '_', file_path_from_root).upper() + '_'


def CheckForHeaderGuard(filename, lines, error):
  """Checks that the file contains a header guard.

  Logs an error if no #ifndef header guard is present.  For other
  headers, checks that the full pathname is used.

  Args:
    filename: The name of the C++ header file.
    lines: An array of strings, each representing a line of the file.
    error: The function to call with any errors found.
  """

  cppvar = GetHeaderGuardCPPVariable(filename)

  ifndef = None
  ifndef_linenum = 0
  define = None
  endif = None
  endif_linenum = 0
  for linenum, line in enumerate(lines):
    linesplit = line.split()
    if len(linesplit) >= 2:
      # find the first occurrence of #ifndef and #define, save arg
      if not ifndef and linesplit[0] == '#ifndef':
        # set ifndef to the header guard presented on the #ifndef line.
        ifndef = linesplit[1]
        ifndef_linenum = linenum
      if not define and linesplit[0] == '#define':
        define = linesplit[1]
    # find the last occurrence of #endif, save entire line
    if line.startswith('#endif'):
      endif = line
      endif_linenum = linenum

  if not ifndef:
    error(filename, 0, 'build/header_guard', 5,
          'No #ifndef header guard found, suggested CPP variable is: %s' %
          cppvar)
    return

  if not define:
    error(filename, 0, 'build/header_guard', 5,
          'No #define header guard found, suggested CPP variable is: %s' %
          cppvar)
    return

  # The guard should be PATH_FILE_H_, but we also allow PATH_FILE_H__
  # for backward compatibility.
  if ifndef != cppvar:
    error_level = 0
    if ifndef != cppvar + '_':
      error_level = 5

    ParseNolintSuppressions(filename, lines[ifndef_linenum], ifndef_linenum,
                            error)
    error(filename, ifndef_linenum, 'build/header_guard', error_level,
          '#ifndef header guard has wrong style, please use: %s' % cppvar)

  if define != ifndef:
    error(filename, 0, 'build/header_guard', 5,
          '#ifndef and #define don\'t match, suggested CPP variable is: %s' %
          cppvar)
    return

  if endif != ('#endif  // %s' % cppvar):
    error_level = 0
    if endif != ('#endif  // %s' % (cppvar + '_')):
      error_level = 5

    ParseNolintSuppressions(filename, lines[endif_linenum], endif_linenum,
                            error)
    error(filename, endif_linenum, 'build/header_guard', error_level,
          '#endif line should be "#endif  // %s"' % cppvar)


def CheckForBadCharacters(filename, lines, error):
  """Logs an error for each line containing bad characters.

  Two kinds of bad characters:

  1. Unicode replacement characters: These indicate that either the file
  contained invalid UTF-8 (likely) or Unicode replacement characters (which
  it shouldn't).  Note that it's possible for this to throw off line
  numbering if the invalid UTF-8 occurred adjacent to a newline.

  2. NUL bytes.  These are problematic for some tools.

  Args:
    filename: The name of the current file.
    lines: An array of strings, each representing a line of the file.
    error: The function to call with any errors found.
  """
  for linenum, line in enumerate(lines):
    if u'\ufffd' in line:
      error(filename, linenum, 'readability/utf8', 5,
            'Line contains invalid UTF-8 (or Unicode replacement character).')
    if '\0' in line:
      error(filename, linenum, 'readability/nul', 5, 'Line contains NUL byte.')


def CheckForNewlineAtEOF(filename, lines, error):
  """Logs an error if there is no newline char at the end of the file.

  Args:
    filename: The name of the current file.
    lines: An array of strings, each representing a line of the file.
    error: The function to call with any errors found.
  """

  # The array lines() was created by adding two newlines to the
  # original file (go figure), then splitting on \n.
  # To verify that the file ends in \n, we just have to make sure the
  # last-but-two element of lines() exists and is empty.
  if len(lines) < 3 or lines[-2]:
    error(filename, len(lines) - 2, 'whitespace/ending_newline', 5,
          'Could not find a newline character at the end of the file.')


def CheckForMultilineCommentsAndStrings(filename, clean_lines, linenum, error):
  """Logs an error if we see /* ... */ or "..." that extend past one line.

  /* ... */ comments are legit inside macros, for one line.
  Otherwise, we prefer // comments, so it's ok to warn about the
  other.  Likewise, it's ok for strings to extend across multiple
  lines, as long as a line continuation character (backslash)
  terminates each line. Although not currently prohibited by the C++
  style guide, it's ugly and unnecessary. We don't do well with either
  in this lint program, so we warn about both.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    error: The function to call with any errors found.
  """
  line = clean_lines.elided[linenum]

  # Remove all \\ (escaped backslashes) from the line. They are OK, and the
  # second (escaped) slash may trigger later \" detection erroneously.
  line = line.replace('\\\\', '')

  if line.count('/*') > line.count('*/'):
    error(filename, linenum, 'readability/multiline_comment', 5,
          'Complex multi-line /*...*/-style comment found. '
          'Lint may give bogus warnings.  '
          'Consider replacing these with //-style comments, '
          'with #if 0...#endif, '
          'or with more clearly structured multi-line comments.')

  if (line.count('"') - line.count('\\"')) % 2:
    error(filename, linenum, 'readability/multiline_string', 5,
          'Multi-line string ("...") found.  This lint script doesn\'t '
          'do well with such strings, and may give bogus warnings.  '
          'Use C++11 raw strings or concatenation instead.')


threading_list = (
    ('asctime(', 'asctime_r('),
    ('ctime(', 'ctime_r('),
    ('getgrgid(', 'getgrgid_r('),
    ('getgrnam(', 'getgrnam_r('),
    ('getlogin(', 'getlogin_r('),
    ('getpwnam(', 'getpwnam_r('),
    ('getpwuid(', 'getpwuid_r('),
    ('gmtime(', 'gmtime_r('),
    ('localtime(', 'localtime_r('),
    ('rand(', 'rand_r('),
    ('strtok(', 'strtok_r('),
    ('ttyname(', 'ttyname_r('),
    )


def CheckPosixThreading(filename, clean_lines, linenum, error):
  """Checks for calls to thread-unsafe functions.

  Much code has been originally written without consideration of
  multi-threading. Also, engineers are relying on their old experience;
  they have learned posix before threading extensions were added. These
  tests guide the engineers to use thread-safe functions (when using
  posix directly).

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    error: The function to call with any errors found.
  """
  line = clean_lines.elided[linenum]
  for single_thread_function, multithread_safe_function in threading_list:
    ix = line.find(single_thread_function)
    # Comparisons made explicit for clarity -- pylint: disable=g-explicit-bool-comparison
    if ix >= 0 and (ix == 0 or (not line[ix - 1].isalnum() and
                                line[ix - 1] not in ('_', '.', '>'))):
      error(filename, linenum, 'runtime/threadsafe_fn', 2,
            'Consider using ' + multithread_safe_function +
            '...) instead of ' + single_thread_function +
            '...) for improved thread safety.')


def CheckVlogArguments(filename, clean_lines, linenum, error):
  """Checks that VLOG() is only used for defining a logging level.

  For example, VLOG(2) is correct. VLOG(INFO), VLOG(WARNING), VLOG(ERROR), and
  VLOG(FATAL) are not.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    error: The function to call with any errors found.
  """
  line = clean_lines.elided[linenum]
  if Search(r'\bVLOG\((INFO|ERROR|WARNING|DFATAL|FATAL)\)', line):
    error(filename, linenum, 'runtime/vlog', 5,
          'VLOG() should be used with numeric verbosity level.  '
          'Use LOG() if you want symbolic severity levels.')


# Matches invalid increment: *count++, which moves pointer instead of
# incrementing a value.
_RE_PATTERN_INVALID_INCREMENT = re.compile(
    r'^\s*\*\w+(\+\+|--);')


def CheckInvalidIncrement(filename, clean_lines, linenum, error):
  """Checks for invalid increment *count++.

  For example following function:
  void increment_counter(int* count) {
    *count++;
  }
  is invalid, because it effectively does count++, moving pointer, and should
  be replaced with ++*count, (*count)++ or *count += 1.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    error: The function to call with any errors found.
  """
  line = clean_lines.elided[linenum]
  if _RE_PATTERN_INVALID_INCREMENT.match(line):
    error(filename, linenum, 'runtime/invalid_increment', 5,
          'Changing pointer instead of value (or unused value of operator*).')


class _BlockInfo(object):
  """Stores information about a generic block of code."""

  def __init__(self, seen_open_brace):
    self.seen_open_brace = seen_open_brace
    self.open_parentheses = 0
    self.inline_asm = _NO_ASM

  def CheckBegin(self, filename, clean_lines, linenum, error):
    """Run checks that applies to text up to the opening brace.

    This is mostly for checking the text after the class identifier
    and the "{", usually where the base class is specified.  For other
    blocks, there isn't much to check, so we always pass.

    Args:
      filename: The name of the current file.
      clean_lines: A CleansedLines instance containing the file.
      linenum: The number of the line to check.
      error: The function to call with any errors found.
    """
    pass

  def CheckEnd(self, filename, clean_lines, linenum, error):
    """Run checks that applies to text after the closing brace.

    This is mostly used for checking end of namespace comments.

    Args:
      filename: The name of the current file.
      clean_lines: A CleansedLines instance containing the file.
      linenum: The number of the line to check.
      error: The function to call with any errors found.
    """
    pass


class _ClassInfo(_BlockInfo):
  """Stores information about a class."""

  def __init__(self, name, class_or_struct, clean_lines, linenum):
    _BlockInfo.__init__(self, False)
    self.name = name
    self.starting_linenum = linenum
    self.is_derived = False
    if class_or_struct == 'struct':
      self.access = 'public'
      self.is_struct = True
    else:
      self.access = 'private'
      self.is_struct = False

    # Remember initial indentation level for this class.  Using raw_lines here
    # instead of elided to account for leading comments.
    initial_indent = Match(r'^( *)\S', clean_lines.raw_lines[linenum])
    if initial_indent:
      self.class_indent = len(initial_indent.group(1))
    else:
      self.class_indent = 0

    # Try to find the end of the class.  This will be confused by things like:
    #   class A {
    #   } *x = { ...
    #
    # But it's still good enough for CheckSectionSpacing.
    self.last_line = 0
    depth = 0
    for i in range(linenum, clean_lines.NumLines()):
      line = clean_lines.elided[i]
      depth += line.count('{') - line.count('}')
      if not depth:
        self.last_line = i
        break

  def CheckBegin(self, filename, clean_lines, linenum, error):
    # Look for a bare ':'
    if Search('(^|[^:]):($|[^:])', clean_lines.elided[linenum]):
      self.is_derived = True

  def CheckEnd(self, filename, clean_lines, linenum, error):
    # Check that closing brace is aligned with beginning of the class.
    # Only do this if the closing brace is indented by only whitespaces.
    # This means we will not check single-line class definitions.
    indent = Match(r'^( *)\}', clean_lines.elided[linenum])
    if indent and len(indent.group(1)) != self.class_indent:
      if self.is_struct:
        parent = 'struct ' + self.name
      else:
        parent = 'class ' + self.name
      error(filename, linenum, 'whitespace/indent', 3,
            'Closing brace should be aligned with beginning of %s' % parent)


class _NamespaceInfo(_BlockInfo):
  """Stores information about a namespace."""

  def __init__(self, name, linenum):
    _BlockInfo.__init__(self, False)
    self.name = name or ''
    self.starting_linenum = linenum

  def CheckEnd(self, filename, clean_lines, linenum, error):
    """Check end of namespace comments."""
    line = clean_lines.raw_lines[linenum]

    # Check how many lines is enclosed in this namespace.  Don't issue
    # warning for missing namespace comments if there aren't enough
    # lines.  However, do apply checks if there is already an end of
    # namespace comment and it's incorrect.
    #
    # TODO(unknown): We always want to check end of namespace comments
    # if a namespace is large, but sometimes we also want to apply the
    # check if a short namespace contained nontrivial things (something
    # other than forward declarations).  There is currently no logic on
    # deciding what these nontrivial things are, so this check is
    # triggered by namespace size only, which works most of the time.
    if (linenum - self.starting_linenum < 10
        and not Match(r'};*\s*(//|/\*).*\bnamespace\b', line)):
      return

    # Look for matching comment at end of namespace.
    #
    # Note that we accept C style "/* */" comments for terminating
    # namespaces, so that code that terminate namespaces inside
    # preprocessor macros can be cpplint clean.
    #
    # We also accept stuff like "// end of namespace <name>." with the
    # period at the end.
    #
    # Besides these, we don't accept anything else, otherwise we might
    # get false negatives when existing comment is a substring of the
    # expected namespace.
    if self.name:
      # Named namespace
      if not Match((r'};*\s*(//|/\*).*\bnamespace\s+' + re.escape(self.name) +
                    r'[\*/\.\\\s]*$'),
                   line):
        error(filename, linenum, 'readability/namespace', 5,
              'Namespace should be terminated with "// namespace %s"' %
              self.name)
    else:
      # Anonymous namespace
      if not Match(r'};*\s*(//|/\*).*\bnamespace[\*/\.\\\s]*$', line):
        error(filename, linenum, 'readability/namespace', 5,
              'Namespace should be terminated with "// namespace"')


class _PreprocessorInfo(object):
  """Stores checkpoints of nesting stacks when #if/#else is seen."""

  def __init__(self, stack_before_if):
    # The entire nesting stack before #if
    self.stack_before_if = stack_before_if

    # The entire nesting stack up to #else
    self.stack_before_else = []

    # Whether we have already seen #else or #elif
    self.seen_else = False


class _NestingState(object):
  """Holds states related to parsing braces."""

  def __init__(self):
    # Stack for tracking all braces.  An object is pushed whenever we
    # see a "{", and popped when we see a "}".  Only 3 types of
    # objects are possible:
    # - _ClassInfo: a class or struct.
    # - _NamespaceInfo: a namespace.
    # - _BlockInfo: some other type of block.
    self.stack = []

    # Stack of _PreprocessorInfo objects.
    self.pp_stack = []

  def SeenOpenBrace(self):
    """Check if we have seen the opening brace for the innermost block.

    Returns:
      True if we have seen the opening brace, False if the innermost
      block is still expecting an opening brace.
    """
    return (not self.stack) or self.stack[-1].seen_open_brace

  def InNamespaceBody(self):
    """Check if we are currently one level inside a namespace body.

    Returns:
      True if top of the stack is a namespace block, False otherwise.
    """
    return self.stack and isinstance(self.stack[-1], _NamespaceInfo)

  def UpdatePreprocessor(self, line):
    """Update preprocessor stack.

    We need to handle preprocessors due to classes like this:
      #ifdef SWIG
      struct ResultDetailsPageElementExtensionPoint {
      #else
      struct ResultDetailsPageElementExtensionPoint : public Extension {
      #endif

    We make the following assumptions (good enough for most files):
    - Preprocessor condition evaluates to true from #if up to first
      #else/#elif/#endif.

    - Preprocessor condition evaluates to false from #else/#elif up
      to #endif.  We still perform lint checks on these lines, but
      these do not affect nesting stack.

    Args:
      line: current line to check.
    """
    if Match(r'^\s*#\s*(if|ifdef|ifndef)\b', line):
      # Beginning of #if block, save the nesting stack here.  The saved
      # stack will allow us to restore the parsing state in the #else case.
      self.pp_stack.append(_PreprocessorInfo(copy.deepcopy(self.stack)))
    elif Match(r'^\s*#\s*(else|elif)\b', line):
      # Beginning of #else block
      if self.pp_stack:
        if not self.pp_stack[-1].seen_else:
          # This is the first #else or #elif block.  Remember the
          # whole nesting stack up to this point.  This is what we
          # keep after the #endif.
          self.pp_stack[-1].seen_else = True
          self.pp_stack[-1].stack_before_else = copy.deepcopy(self.stack)

        # Restore the stack to how it was before the #if
        self.stack = copy.deepcopy(self.pp_stack[-1].stack_before_if)
      else:
        # TODO(unknown): unexpected #else, issue warning?
        pass
    elif Match(r'^\s*#\s*endif\b', line):
      # End of #if or #else blocks.
      if self.pp_stack:
        # If we saw an #else, we will need to restore the nesting
        # stack to its former state before the #else, otherwise we
        # will just continue from where we left off.
        if self.pp_stack[-1].seen_else:
          # Here we can just use a shallow copy since we are the last
          # reference to it.
          self.stack = self.pp_stack[-1].stack_before_else
        # Drop the corresponding #if
        self.pp_stack.pop()
      else:
        # TODO(unknown): unexpected #endif, issue warning?
        pass

  def Update(self, filename, clean_lines, linenum, error):
    """Update nesting state with current line.

    Args:
      filename: The name of the current file.
      clean_lines: A CleansedLines instance containing the file.
      linenum: The number of the line to check.
      error: The function to call with any errors found.
    """
    line = clean_lines.elided[linenum]

    # Update pp_stack first
    self.UpdatePreprocessor(line)

    # Count parentheses.  This is to avoid adding struct arguments to
    # the nesting stack.
    if self.stack:
      inner_block = self.stack[-1]
      depth_change = line.count('(') - line.count(')')
      inner_block.open_parentheses += depth_change

      # Also check if we are starting or ending an inline assembly block.
      if inner_block.inline_asm in (_NO_ASM, _END_ASM):
        if (depth_change != 0 and
            inner_block.open_parentheses == 1 and
            _MATCH_ASM.match(line)):
          # Enter assembly block
          inner_block.inline_asm = _INSIDE_ASM
        else:
          # Not entering assembly block.  If previous line was _END_ASM,
          # we will now shift to _NO_ASM state.
          inner_block.inline_asm = _NO_ASM
      elif (inner_block.inline_asm == _INSIDE_ASM and
            inner_block.open_parentheses == 0):
        # Exit assembly block
        inner_block.inline_asm = _END_ASM

    # Consume namespace declaration at the beginning of the line.  Do
    # this in a loop so that we catch same line declarations like this:
    #   namespace proto2 { namespace bridge { class MessageSet; } }
    while True:
      # Match start of namespace.  The "\b\s*" below catches namespace
      # declarations even if it weren't followed by a whitespace, this
      # is so that we don't confuse our namespace checker.  The
      # missing spaces will be flagged by CheckSpacing.
      namespace_decl_match = Match(r'^\s*namespace\b\s*([:\w]+)?(.*)$', line)
      if not namespace_decl_match:
        break

      new_namespace = _NamespaceInfo(namespace_decl_match.group(1), linenum)
      self.stack.append(new_namespace)

      line = namespace_decl_match.group(2)
      if line.find('{') != -1:
        new_namespace.seen_open_brace = True
        line = line[line.find('{') + 1:]

    # Look for a class declaration in whatever is left of the line
    # after parsing namespaces.  The regexp accounts for decorated classes
    # such as in:
    #   class LOCKABLE API Object {
    #   };
    #
    # Templates with class arguments may confuse the parser, for example:
    #   template <class T
    #             class Comparator = less<T>,
    #             class Vector = vector<T> >
    #   class HeapQueue {
    #
    # Because this parser has no nesting state about templates, by the
    # time it saw "class Comparator", it may think that it's a new class.
    # Nested templates have a similar problem:
    #   template <
    #       typename ExportedType,
    #       typename TupleType,
    #       template <typename, typename> class ImplTemplate>
    #
    # To avoid these cases, we ignore classes that are followed by '=' or '>'
    class_decl_match = Match(
        r'\s*(template\s*<[\w\s<>,:]*>\s*)?'
        r'(class|struct)\s+([A-Z_]+\s+)*(\w+(?:::\w+)*)'
        r'(([^=>]|<[^<>]*>|<[^<>]*<[^<>]*>\s*>)*)$', line)
    if (class_decl_match and
        (not self.stack or self.stack[-1].open_parentheses == 0)):
      self.stack.append(_ClassInfo(
          class_decl_match.group(4), class_decl_match.group(2),
          clean_lines, linenum))
      line = class_decl_match.group(5)

    # If we have not yet seen the opening brace for the innermost block,
    # run checks here.
    if not self.SeenOpenBrace():
      self.stack[-1].CheckBegin(filename, clean_lines, linenum, error)

    # Update access control if we are inside a class/struct
    if self.stack and isinstance(self.stack[-1], _ClassInfo):
      classinfo = self.stack[-1]
      access_match = Match(
          r'^(.*)\b(public|private|protected|signals)(\s+(?:slots\s*)?)?'
          r':(?:[^:]|$)',
          line)
      if access_match:
        classinfo.access = access_match.group(2)

        # Check that access keywords are indented +1 space.  Skip this
        # check if the keywords are not preceded by whitespaces.
        indent = access_match.group(1)
        if (len(indent) != classinfo.class_indent + 1 and