cpplint/cpplint.py

#!/usr/bin/python2.4
#
# cpplint.py is Copyright (C) 2009 Google Inc.
#
# It is free software; you can redistribute it and/or modify it under the
# terms of either:
#
# a) the GNU General Public License as published by the Free Software
# Foundation; either version 1, or (at your option) any later version, or
#
# b) the "Artistic License".

# Here are some issues that I've had people identify in my code during reviews,
# that I think are possible to flag automatically in a lint tool.  If these were
# caught by lint, it would save time both for myself and that of my reviewers.
# Most likely, some of these are beyond the scope of the current lint framework,
# but I think it is valuable to retain these wish-list items even if they cannot
# be immediately implemented.
#
#  Suggestions
#  -----------
#  - Check for no 'explicit' for multi-arg ctor
#  - Check for boolean assign RHS in parens
#  - Check for ctor initializer-list colon position and spacing
#  - Check that if there's a ctor, there should be a dtor
#  - Check accessors that return non-pointer member variables are
#    declared const
#  - Check accessors that return non-const pointer member vars are
#    *not* declared const
#  - Check for using public includes for testing
#  - Check for spaces between brackets in one-line inline method
#  - Check for no assert()
#  - Check for spaces surrounding operators
#  - Check for 0 in pointer context (should be NULL)
#  - Check for 0 in char context (should be '\0')
#  - Check for camel-case method name conventions for methods
#    that are not simple inline getters and setters
#  - Check that base classes have virtual destructors
#    put "  // namespace" after } that closes a namespace, with
#    namespace's name after 'namespace' if it is named.
#  - Do not indent namespace contents
#  - Avoid inlining non-trivial constructors in header files
#    include base/basictypes.h if DISALLOW_EVIL_CONSTRUCTORS is used
#  - Check for old-school (void) cast for call-sites of functions
#    ignored return value
#  - Check gUnit usage of anonymous namespace
#  - Check for class declaration order (typedefs, consts, enums,
#    ctor(s?), dtor, friend declarations, methods, member vars)
#

"""Does google-lint on c++ files.

The goal of this script is to identify places in the code that *may*
be in non-compliance with google style.  It does not attempt to fix
up these problems -- the point is to educate.  It does also not
attempt to find all problems, or to ensure that everything it does
find is legitimately a problem.

In particular, we can get very confused by /* and // inside strings!
We do a small hack, which is to ignore //'s with "'s after them on the
same line, but it is far from perfect (in either direction).
"""

import codecs
import getopt
import math  # for log
import os
import re
import sre_compile
import string
import sys
import unicodedata


_USAGE = """
Syntax: cpplint.py [--verbose=#] [--output=vs7] [--filter=-x,+y,...]
        <file> [file] ...

  The style guidelines this tries to follow are those in
    http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml

  Every problem is given a confidence score from 1-5, with 5 meaning we are
  certain of the problem, and 1 meaning it could be a legitimate construct.
  This will miss some errors, and is not a substitute for a code review.

  To prevent specific lines from being linted, add a '// NOLINT' comment to the
  end of the line.

  The files passed in will be linted; at least one file must be provided.
  Linted extensions are .cc, .cpp, and .h.  Other file types will be ignored.

  Flags:

    output=vs7
      By default, the output is formatted to ease emacs parsing.  Visual Studio
      compatible output (vs7) may also be used.  Other formats are unsupported.

    verbose=#
      Specify a number 0-5 to restrict errors to certain verbosity levels.

    filter=-x,+y,...
      Specify a comma-separated list of category-filters to apply: only
      error messages whose category names pass the filters will be printed.
      (Category names are printed with the message and look like
      "[whitespace/indent]".)  Filters are evaluated left to right.
      "-FOO" and "FOO" means "do not print categories that start with FOO".
      "+FOO" means "do print categories that start with FOO".

      Examples: --filter=-whitespace,+whitespace/braces
                --filter=whitespace,runtime/printf,+runtime/printf_format
                --filter=-,+build/include_what_you_use

      To see a list of all the categories used in cpplint, pass no arg:
         --filter=
"""

# We categorize each error message we print.  Here are the categories.
# We want an explicit list so we can list them all in cpplint --filter=.
# If you add a new error message with a new category, add it to the list
# here!  cpplint_unittest.py should tell you if you forget to do this.
# \ used for clearer layout -- pylint: disable-msg=C6013
_ERROR_CATEGORIES = '''\
  build/class
  build/deprecated
  build/endif_comment
  build/forward_decl
  build/header_guard
  build/include
  build/include_order
  build/include_what_you_use
  build/namespaces
  build/printf_format
  build/storage_class
  legal/copyright
  readability/braces
  readability/casting
  readability/check
  readability/constructors
  readability/fn_size
  readability/function
  readability/multiline_comment
  readability/multiline_string
  readability/streams
  readability/todo
  readability/utf8
  runtime/arrays
  runtime/casting
  runtime/explicit
  runtime/int
  runtime/init
  runtime/memset
  runtime/printf
  runtime/printf_format
  runtime/references
  runtime/rtti
  runtime/sizeof
  runtime/string
  runtime/threadsafe_fn
  runtime/virtual
  whitespace/blank_line
  whitespace/braces
  whitespace/comma
  whitespace/comments
  whitespace/end_of_line
  whitespace/ending_newline
  whitespace/indent
  whitespace/labels
  whitespace/line_length
  whitespace/newline
  whitespace/operators
  whitespace/parens
  whitespace/semicolon
  whitespace/tab
  whitespace/todo
'''

# We used to check for high-bit characters, but after much discussion we
# decided those were OK, as long as they were in UTF-8 and didn't represent
# hard-coded international strings, which belong in a seperate i18n file.

# Headers that we consider STL headers.
_STL_HEADERS = frozenset([
    'algobase.h', 'algorithm', 'alloc.h', 'bitset', 'deque', 'exception',
    'function.h', 'functional', 'hash_map', 'hash_map.h', 'hash_set',
    'hash_set.h', 'iterator', 'list', 'list.h', 'map', 'memory', 'pair.h',
    'pthread_alloc', 'queue', 'set', 'set.h', 'sstream', 'stack',
    'stl_alloc.h', 'stl_relops.h', 'type_traits.h',
    'utility', 'vector', 'vector.h',
    ])


# Non-STL C++ system headers.
_CPP_HEADERS = frozenset([
    'algo.h', 'builtinbuf.h', 'bvector.h', 'cassert', 'cctype',
    'cerrno', 'cfloat', 'ciso646', 'climits', 'clocale', 'cmath',
    'complex', 'complex.h', 'csetjmp', 'csignal', 'cstdarg', 'cstddef',
    'cstdio', 'cstdlib', 'cstring', 'ctime', 'cwchar', 'cwctype',
    'defalloc.h', 'deque.h', 'editbuf.h', 'exception', 'fstream',
    'fstream.h', 'hashtable.h', 'heap.h', 'indstream.h', 'iomanip',
    'iomanip.h', 'ios', 'iosfwd', 'iostream', 'iostream.h', 'istream.h',
    'iterator.h', 'limits', 'map.h', 'multimap.h', 'multiset.h',
    'numeric', 'ostream.h', 'parsestream.h', 'pfstream.h', 'PlotFile.h',
    'procbuf.h', 'pthread_alloc.h', 'rope', 'rope.h', 'ropeimpl.h',
    'SFile.h', 'slist', 'slist.h', 'stack.h', 'stdexcept',
    'stdiostream.h', 'streambuf.h', 'stream.h', 'strfile.h', 'string',
    'strstream', 'strstream.h', 'tempbuf.h', 'tree.h', 'typeinfo', 'valarray',
    ])


# Assertion macros.  These are defined in base/logging.h and
# testing/base/gunit.h.  Note that the _M versions need to come first
# for substring matching to work.
_CHECK_MACROS = [
    'CHECK',
    'EXPECT_TRUE_M', 'EXPECT_TRUE',
    'ASSERT_TRUE_M', 'ASSERT_TRUE',
    'EXPECT_FALSE_M', 'EXPECT_FALSE',
    'ASSERT_FALSE_M', 'ASSERT_FALSE',
    ]

# Replacement macros for CHECK/EXPECT_TRUE/EXPECT_FALSE
_CHECK_REPLACEMENT = dict([(m, {}) for m in _CHECK_MACROS])

for op, replacement in [('==', 'EQ'), ('!=', 'NE'),
                        ('>=', 'GE'), ('>', 'GT'),
                        ('<=', 'LE'), ('<', 'LT')]:
  _CHECK_REPLACEMENT['CHECK'][op] = 'CHECK_%s' % replacement
  _CHECK_REPLACEMENT['EXPECT_TRUE'][op] = 'EXPECT_%s' % replacement
  _CHECK_REPLACEMENT['ASSERT_TRUE'][op] = 'ASSERT_%s' % replacement
  _CHECK_REPLACEMENT['EXPECT_TRUE_M'][op] = 'EXPECT_%s_M' % replacement
  _CHECK_REPLACEMENT['ASSERT_TRUE_M'][op] = 'ASSERT_%s_M' % replacement

for op, inv_replacement in [('==', 'NE'), ('!=', 'EQ'),
                            ('>=', 'LT'), ('>', 'LE'),
                            ('<=', 'GT'), ('<', 'GE')]:
  _CHECK_REPLACEMENT['EXPECT_FALSE'][op] = 'EXPECT_%s' % inv_replacement
  _CHECK_REPLACEMENT['ASSERT_FALSE'][op] = 'ASSERT_%s' % inv_replacement
  _CHECK_REPLACEMENT['EXPECT_FALSE_M'][op] = 'EXPECT_%s_M' % inv_replacement
  _CHECK_REPLACEMENT['ASSERT_FALSE_M'][op] = 'ASSERT_%s_M' % inv_replacement


# These constants define types of headers for use with
# _IncludeState.CheckNextIncludeOrder().
_C_SYS_HEADER = 1
_CPP_SYS_HEADER = 2
_LIKELY_MY_HEADER = 3
_POSSIBLE_MY_HEADER = 4
_OTHER_HEADER = 5


_regexp_compile_cache = {}


def Match(pattern, s):
  """Matches the string with the pattern, caching the compiled regexp."""
  # The regexp compilation caching is inlined in both Match and Search for
  # performance reasons; factoring it out into a separate function turns out
  # to be noticeably expensive.
  if not pattern in _regexp_compile_cache:
    _regexp_compile_cache[pattern] = sre_compile.compile(pattern)
  return _regexp_compile_cache[pattern].match(s)


def Search(pattern, s):
  """Searches the string for the pattern, caching the compiled regexp."""
  if not pattern in _regexp_compile_cache:
    _regexp_compile_cache[pattern] = sre_compile.compile(pattern)
  return _regexp_compile_cache[pattern].search(s)


class _IncludeState(dict):
  """Tracks line numbers for includes, and the order in which includes appear.

  As a dict, an _IncludeState object serves as a mapping between include
  filename and line number on which that file was included.

  Call CheckNextIncludeOrder() once for each header in the file, passing
  in the type constants defined above. Calls in an illegal order will
  raise an _IncludeError with an appropriate error message.

  """
  # self._section will move monotonically through this set. If it ever
  # needs to move backwards, CheckNextIncludeOrder will raise an error.
  _INITIAL_SECTION = 0
  _MY_H_SECTION = 1
  _C_SECTION = 2
  _CPP_SECTION = 3
  _OTHER_H_SECTION = 4

  _TYPE_NAMES = {
      _C_SYS_HEADER: 'C system header',
      _CPP_SYS_HEADER: 'C++ system header',
      _LIKELY_MY_HEADER: 'header this file implements',
      _POSSIBLE_MY_HEADER: 'header this file may implement',
      _OTHER_HEADER: 'other header',
      }
  _SECTION_NAMES = {
      _INITIAL_SECTION: "... nothing. (This can't be an error.)",
      _MY_H_SECTION: 'a header this file implements',
      _C_SECTION: 'C system header',
      _CPP_SECTION: 'C++ system header',
      _OTHER_H_SECTION: 'other header',
      }

  def __init__(self):
    dict.__init__(self)
    self._section = self._INITIAL_SECTION

  def CheckNextIncludeOrder(self, header_type):
    """Returns a non-empty error message if the next header is out of order.

    This function also updates the internal state to be ready to check
    the next include.

    Args:
      header_type: One of the _XXX_HEADER constants defined above.

    Returns:
      The empty string if the header is in the right order, or an
      error message describing what's wrong.

    """
    error_message = ('Found %s after %s' %
                     (self._TYPE_NAMES[header_type],
                      self._SECTION_NAMES[self._section]))

    if header_type == _C_SYS_HEADER:
      if self._section <= self._C_SECTION:
        self._section = self._C_SECTION
      else:
        return error_message
    elif header_type == _CPP_SYS_HEADER:
      if self._section <= self._CPP_SECTION:
        self._section = self._CPP_SECTION
      else:
        return error_message
    elif header_type == _LIKELY_MY_HEADER:
      if self._section <= self._MY_H_SECTION:
        self._section = self._MY_H_SECTION
      else:
        self._section = self._OTHER_H_SECTION
    elif header_type == _POSSIBLE_MY_HEADER:
      if self._section <= self._MY_H_SECTION:
        self._section = self._MY_H_SECTION
      else:
        # This will always be the fallback because we're not sure
        # enough that the header is associated with this file.
        self._section = self._OTHER_H_SECTION
    else:
      assert header_type == _OTHER_HEADER
      self._section = self._OTHER_H_SECTION

    return ''


class _CppLintState(object):
  """Maintains module-wide state.."""

  def __init__(self):
    self.verbose_level = 1  # global setting.
    self.error_count = 0    # global count of reported errors
    self.filters = []       # filters to apply when emitting error messages

    # output format:
    # "emacs" - format that emacs can parse (default)
    # "vs7" - format that Microsoft Visual Studio 7 can parse
    self.output_format = 'emacs'

  def SetOutputFormat(self, output_format):
    """Sets the output format for errors."""
    self.output_format = output_format

  def SetVerboseLevel(self, level):
    """Sets the module's verbosity, and returns the previous setting."""
    last_verbose_level = self.verbose_level
    self.verbose_level = level
    return last_verbose_level

  def SetFilters(self, filters):
    """Sets the error-message filters.

    These filters are applied when deciding whether to emit a given
    error message.

    Args:
      filters: A string of comma-separated filters (eg "+whitespace/indent").
               Each filter should start with + or -; else we die.

    Raises:
      ValueError: The comma-separated filters did not all start with '+' or '-'.
                  E.g. "-,+whitespace,-whitespace/indent,whitespace/badfilter"
    """
    if not filters:
      self.filters = []
    else:
      self.filters = filters.split(',')
    for filt in self.filters:
      if not (filt.startswith('+') or filt.startswith('-')):
        raise ValueError('Every filter in --filters must start with + or -'
                         ' (%s does not)' % filt)

  def ResetErrorCount(self):
    """Sets the module's error statistic back to zero."""
    self.error_count = 0

  def IncrementErrorCount(self):
    """Bumps the module's error statistic."""
    self.error_count += 1


_cpplint_state = _CppLintState()


def _OutputFormat():
  """Gets the module's output format."""
  return _cpplint_state.output_format


def _SetOutputFormat(output_format):
  """Sets the module's output format."""
  _cpplint_state.SetOutputFormat(output_format)


def _VerboseLevel():
  """Returns the module's verbosity setting."""
  return _cpplint_state.verbose_level


def _SetVerboseLevel(level):
  """Sets the module's verbosity, and returns the previous setting."""
  return _cpplint_state.SetVerboseLevel(level)


def _Filters():
  """Returns the module's list of output filters, as a list."""
  return _cpplint_state.filters


def _SetFilters(filters):
  """Sets the module's error-message filters.

  These filters are applied when deciding whether to emit a given
  error message.

  Args:
    filters: A string of comma-separated filters (eg "whitespace/indent").
             Each filter should start with + or -; else we die.
  """
  _cpplint_state.SetFilters(filters)


class _FunctionState(object):
  """Tracks current function name and the number of lines in its body."""

  _NORMAL_TRIGGER = 250  # for --v=0, 500 for --v=1, etc.
  _TEST_TRIGGER = 400    # about 50% more than _NORMAL_TRIGGER.

  def __init__(self):
    self.in_a_function = False
    self.lines_in_function = 0
    self.current_function = ''

  def Begin(self, function_name):
    """Start analyzing function body.

    Args:
      function_name: The name of the function being tracked.
    """
    self.in_a_function = True
    self.lines_in_function = 0
    self.current_function = function_name

  def Count(self):
    """Count line in current function body."""
    if self.in_a_function:
      self.lines_in_function += 1

  def Check(self, error, filename, linenum):
    """Report if too many lines in function body.

    Args:
      error: The function to call with any errors found.
      filename: The name of the current file.
      linenum: The number of the line to check.
    """
    if Match(r'T(EST|est)', self.current_function):
      base_trigger = self._TEST_TRIGGER
    else:
      base_trigger = self._NORMAL_TRIGGER
    trigger = base_trigger * 2**_VerboseLevel()

    if self.lines_in_function > trigger:
      error_level = int(math.log(self.lines_in_function / base_trigger, 2))
      # 50 => 0, 100 => 1, 200 => 2, 400 => 3, 800 => 4, 1600 => 5, ...
      if error_level > 5:
        error_level = 5
      error(filename, linenum, 'readability/fn_size', error_level,
            'Small and focused functions are preferred:'
            ' %s has %d non-comment lines'
            ' (error triggered by exceeding %d lines).'  % (
                self.current_function, self.lines_in_function, trigger))

  def End(self):
    """Stop analizing function body."""
    self.in_a_function = False


class _IncludeError(Exception):
  """Indicates a problem with the include order in a file."""
  pass


class FileInfo:
  """Provides utility functions for filenames.

  FileInfo provides easy access to the components of a file's path
  relative to the project root.
  """

  def __init__(self, filename):
    self._filename = filename

  def FullName(self):
    """Make Windows paths like Unix."""
    return os.path.abspath(self._filename).replace('\\', '/')

  def RepositoryName(self):
    """FullName after removing the local path to the repository.

    If we have a real absolute path name here we can try to do something smart:
    detecting the root of the checkout and truncating /path/to/checkout from
    the name so that we get header guards that don't include things like
    "C:\Documents and Settings\..." or "/home/username/..." in them and thus
    people on different computers who have checked the source out to different
    locations won't see bogus errors.
    """
    fullname = self.FullName()

    if os.path.exists(fullname):
      project_dir = os.path.dirname(fullname)

      if os.path.exists(os.path.join(project_dir, ".svn")):
        # If there's a .svn file in the current directory, we recursively look
        # up the directory tree for the top of the SVN checkout
        root_dir = project_dir
        one_up_dir = os.path.dirname(root_dir)
        while os.path.exists(os.path.join(one_up_dir, ".svn")):
          root_dir = os.path.dirname(root_dir)
          one_up_dir = os.path.dirname(one_up_dir)

        prefix = os.path.commonprefix([root_dir, project_dir])
        return fullname[len(prefix) + 1:]

      # Not SVN? Try to find a git top level directory by searching up from the
      # current path.
      root_dir = os.path.dirname(fullname)
      while (root_dir != os.path.dirname(root_dir) and
             not os.path.exists(os.path.join(root_dir, ".git"))):
        root_dir = os.path.dirname(root_dir)
        if os.path.exists(os.path.join(root_dir, ".git")):
          prefix = os.path.commonprefix([root_dir, project_dir])
          return fullname[len(prefix) + 1:]

    # Don't know what to do; header guard warnings may be wrong...
    return fullname

  def Split(self):
    """Splits the file into the directory, basename, and extension.

    For 'chrome/browser/browser.cc', Split() would
    return ('chrome/browser', 'browser', '.cc')

    Returns:
      A tuple of (directory, basename, extension).
    """

    googlename = self.RepositoryName()
    project, rest = os.path.split(googlename)
    return (project,) + os.path.splitext(rest)

  def BaseName(self):
    """File base name - text after the final slash, before the final period."""
    return self.Split()[1]

  def Extension(self):
    """File extension - text following the final period."""
    return self.Split()[2]

  def NoExtension(self):
    """File has no source file extension."""
    return '/'.join(self.Split()[0:2])

  def IsSource(self):
    """File has a source file extension."""
    return self.Extension()[1:] in ('c', 'cc', 'cpp', 'cxx')


def _ShouldPrintError(category, confidence):
  """Returns true iff confidence >= verbose, and category passes filter."""
  # There are two ways we might decide not to print an error message:
  # the verbosity level isn't high enough, or the filters filter it out.
  if confidence < _cpplint_state.verbose_level:
    return False

  is_filtered = False
  for one_filter in _Filters():
    if one_filter.startswith('-'):
      if category.startswith(one_filter[1:]):
        is_filtered = True
    elif one_filter.startswith('+'):
      if category.startswith(one_filter[1:]):
        is_filtered = False
    else:
      assert False  # should have been checked for in SetFilter.
  if is_filtered:
    return False

  return True


def Error(filename, linenum, category, confidence, message):
  """Logs the fact we've found a lint error.

  We log where the error was found, and also our confidence in the error,
  that is, how certain we are this is a legitimate style regression, and
  not a misidentification or a use that's sometimes justified.

  Args:
    filename: The name of the file containing the error.
    linenum: The number of the line containing the error.
    category: A string used to describe the "category" this bug
      falls under: "whitespace", say, or "runtime".  Categories
      may have a hierarchy separated by slashes: "whitespace/indent".
    confidence: A number from 1-5 representing a confidence score for
      the error, with 5 meaning that we are certain of the problem,
      and 1 meaning that it could be a legitimate construct.
    message: The error message.
  """
  # There are two ways we might decide not to print an error message:
  # the verbosity level isn't high enough, or the filters filter it out.
  if _ShouldPrintError(category, confidence):
    _cpplint_state.IncrementErrorCount()
    if _cpplint_state.output_format == 'vs7':
      sys.stderr.write('%s(%s):  %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 esequences 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 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]
  # 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 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)
    for linenum in range(len(lines)):
      self.lines.append(CleanseComments(lines[linenum]))
      elided = self._CollapseStrings(lines[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 CloseExpression(clean_lines, linenum, pos):
  """If input points to ( or { or [, finds the position that closes it.

  If lines[linenum][pos] points to a '(' or '{' or '[', finds the 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 = '}'

  num_open = line.count(startchar) - line.count(endchar)
  while linenum < clean_lines.NumLines() and num_open > 0:
    linenum += 1
    line = clean_lines.elided[linenum]
    num_open += line.count(startchar) - line.count(endchar)
  # OK, now find the endchar that actually got us back to even
  endpos = len(line)
  while num_open >= 0:
    endpos = line.rfind(')', 0, endpos)
    num_open -= 1                 # chopped off another )
  return (line, linenum, endpos + 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.

  """

  fileinfo = FileInfo(filename)
  return re.sub(r'[-./\s]', '_', fileinfo.RepositoryName()).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 or not define or ifndef != define:
    error(filename, 0, 'build/header_guard', 5,
          'No #ifndef 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

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

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

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


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

  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).')


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.  They\'re '
          'ugly and unnecessary, and you should use 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('),
    ('readdir(', 'readdir_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-msg=C6403
    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.')


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

  def __init__(self, name, linenum):
    self.name = name
    self.linenum = linenum
    self.seen_open_brace = False
    self.is_derived = False
    self.virtual_method_linenumber = None
    self.has_virtual_destructor = False
    self.brace_depth = 0


class _ClassState(object):
  """Holds the current state of the parse relating to class declarations.

  It maintains a stack of _ClassInfos representing the parser's guess
  as to the current nesting of class declarations. The innermost class
  is at the top (back) of the stack. Typically, the stack will either
  be empty or have exactly one entry.
  """

  def __init__(self):
    self.classinfo_stack = []

  def CheckFinished(self, filename, error):
    """Checks that all classes have been completely parsed.

    Call this when all lines in a file have been processed.
    Args:
      filename: The name of the current file.
      error: The function to call with any errors found.
    """
    if self.classinfo_stack:
      # Note: This test can result in false positives if #ifdef constructs
      # get in the way of brace matching. See the testBuildClass test in
      # cpplint_unittest.py for an example of this.
      error(filename, self.classinfo_stack[0].linenum, 'build/class', 5,
            'Failed to find complete declaration of class %s' %
            self.classinfo_stack[0].name)


def CheckForNonStandardConstructs(filename, clean_lines, linenum,
                                  class_state, error):
  """Logs an error if we see certain non-ANSI constructs ignored by gcc-2.

  Complain about several constructs which gcc-2 accepts, but which are
  not standard C++.  Warning about these in lint is one way to ease the
  transition to new compilers.
  - put storage class first (e.g. "static const" instead of "const static").
  - "%lld" instead of %qd" in printf-type functions.
  - "%1$d" is non-standard in printf-type functions.
  - "\%" is an undefined character escape sequence.
  - text after #endif is not allowed.
  - invalid inner-style forward declaration.
  - >? and <? operators, and their >?= and <?= cousins.
  - classes with virtual methods need virtual destructors (compiler warning
    available, but not turned on yet.)

  Additionally, check for constructor/destructor style violations as it
  is very convenient to do so while checking for gcc-2 compliance.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    class_state: A _ClassState instance which maintains information about
                 the current stack of nested class declarations being parsed.
    error: A callable to which errors are reported, which takes 4 arguments:
           filename, line number, error level, and message
  """

  # Remove comments from the line, but leave in strings for now.
  line = clean_lines.lines[linenum]

  if Search(r'printf\s*\(.*".*%[-+ ]?\d*q', line):
    error(filename, linenum, 'runtime/printf_format', 3,
          '%q in format strings is deprecated.  Use %ll instead.')

  if Search(r'printf\s*\(.*".*%\d+\$', line):
    error(filename, linenum, 'runtime/printf_format', 2,
          '%N$ formats are unconventional.  Try rewriting to avoid them.')

  # Remove escaped backslashes before looking for undefined escapes.
  line = line.replace('\\\\', '')

  if Search(r'("|\').*\\(%|\[|\(|{)', line):
    error(filename, linenum, 'build/printf_format', 3,
          '%, [, (, and { are undefined character escapes.  Unescape them.')

  # For the rest, work with both comments and strings removed.
  line = clean_lines.elided[linenum]

  if Search(r'\b(const|volatile|void|char|short|int|long'
            r'|float|double|signed|unsigned'
            r'|schar|u?int8|u?int16|u?int32|u?int64)'
            r'\s+(auto|register|static|extern|typedef)\b',
            line):
    error(filename, linenum, 'build/storage_class', 5,
          'Storage class (static, extern, typedef, etc) should be first.')

  if Match(r'\s*#\s*endif\s*[^/\s]+', line):
    error(filename, linenum, 'build/endif_comment', 5,
          'Uncommented text after #endif is non-standard.  Use a comment.')

  if Match(r'\s*class\s+(\w+\s*::\s*)+\w+\s*;', line):
    error(filename, linenum, 'build/forward_decl', 5,
          'Inner-style forward declarations are invalid.  Remove this line.')

  if Search(r'(\w+|[+-]?\d+(\.\d*)?)\s*(<|>)\?=?\s*(\w+|[+-]?\d+)(\.\d*)?',
            line):
    error(filename, linenum, 'build/deprecated', 3,
          '>? and <? (max and min) operators are non-standard and deprecated.')

  # Track class entry and exit, and attempt to find cases within the
  # class declaration that don't meet the C++ style
  # guidelines. Tracking is very dependent on the code matching Google
  # style guidelines, but it seems to perform well enough in testing
  # to be a worthwhile addition to the checks.
  classinfo_stack = class_state.classinfo_stack
  # Look for a class declaration
  class_decl_match = Match(
      r'\s*(template\s*<[\w\s<>,:]*>\s*)?(class|struct)\s+(\w+(::\w+)*)', line)
  if class_decl_match:
    classinfo_stack.append(_ClassInfo(class_decl_match.group(3), linenum))

  # Everything else in this function uses the top of the stack if it's
  # not empty.
  if not classinfo_stack:
    return

  classinfo = classinfo_stack[-1]

  # If the opening brace hasn't been seen look for it and also
  # parent class declarations.
  if not classinfo.seen_open_brace:
    # If the line has a ';' in it, assume it's a forward declaration or
    # a single-line class declaration, which we won't process.
    if line.find(';') != -1:
      classinfo_stack.pop()
      return
    classinfo.seen_open_brace = (line.find('{') != -1)
    # Look for a bare ':'
    if Search('(^|[^:]):($|[^:])', line):
      classinfo.is_derived = True
    if not classinfo.seen_open_brace:
      return  # Everything else in this function is for after open brace

  # The class may have been declared with namespace or classname qualifiers.
  # The constructor and destructor will not have those qualifiers.
  base_classname = classinfo.name.split('::')[-1]

  # Look for single-argument constructors that aren't marked explicit.
  # Technically a valid construct, but against style.
  args = Match(r'(?<!explicit)\s+%s\s*\(([^,()]+)\)'
               % re.escape(base_classname),
               line)
  if (args and
      args.group(1) != 'void' and
      not Match(r'(const\s+)?%s\s*&' % re.escape(base_classname),
                args.group(1).strip())):
    error(filename, linenum, 'runtime/explicit', 5,
          'Single-argument constructors should be marked explicit.')

  # Look for methods declared virtual.
  if Search(r'\bvirtual\b', line):
    classinfo.virtual_method_linenumber = linenum
    # Only look for a destructor declaration on the same line. It would
    # be extremely unlikely for the destructor declaration to occupy
    # more than one line.
    if Search(r'~%s\s*\(' % base_classname, line):
      classinfo.has_virtual_destructor = True

  # Look for class end.
  brace_depth = classinfo.brace_depth
  brace_depth = brace_depth + line.count('{') - line.count('}')
  if brace_depth <= 0:
    classinfo = classinfo_stack.pop()
    # Try to detect missing virtual destructor declarations.
    # For now, only warn if a non-derived class with virtual methods lacks
    # a virtual destructor. This is to make it less likely that people will
    # declare derived virtual destructors without declaring the base
    # destructor virtual.
    if ((classinfo.virtual_method_linenumber is not None) and
        (not classinfo.has_virtual_destructor) and
        (not classinfo.is_derived)):  # Only warn for base classes
      error(filename, classinfo.linenum, 'runtime/virtual', 4,
            'The class %s probably needs a virtual destructor due to '
            'having virtual method(s), one declared at line %d.'
            % (classinfo.name, classinfo.virtual_method_linenumber))
  else:
    classinfo.brace_depth = brace_depth


def CheckSpacingForFunctionCall(filename, line, linenum, error):
  """Checks for the correctness of various spacing around function calls.

  Args:
    filename: The name of the current file.
    line: The text of the line to check.
    linenum: The number of the line to check.
    error: The function to call with any errors found.
  """

  # Since function calls often occur inside if/for/while/switch
  # expressions - which have their own, more liberal conventions - we
  # first see if we should be looking inside such an expression for a
  # function call, to which we can apply more strict standards.
  fncall = line    # if there's no control flow construct, look at whole line
  for pattern in (r'\bif\s*\((.*)\)\s*{',
                  r'\bfor\s*\((.*)\)\s*{',
                  r'\bwhile\s*\((.*)\)\s*[{;]',
                  r'\bswitch\s*\((.*)\)\s*{'):
    match = Search(pattern, line)
    if match:
      fncall = match.group(1)    # look inside the parens for function calls
      break

  # Except in if/for/while/switch, there should never be space
  # immediately inside parens (eg "f( 3, 4 )").  We make an exception
  # for nested parens ( (a+b) + c ).  Likewise, there should never be
  # a space before a ( when it's a function argument.  I assume it's a
  # function argument when the char before the whitespace is legal in
  # a function name (alnum + _) and we're not starting a macro. Also ignore
  # pointers and references to arrays and functions coz they're too tricky:
  # we use a very simple way to recognize these:
  # " (something)(maybe-something)" or
  # " (something)(maybe-something," or
  # " (something)[something]"
  # Note that we assume the contents of [] to be short enough that
  # they'll never need to wrap.
  if (  # Ignore control structures.
      not Search(r'\b(if|for|while|switch|return|delete)\b', fncall) and
      # Ignore pointers/references to functions.
      not Search(r' \([^)]+\)\([^)]*(\)|,$)', fncall) and
      # Ignore pointers/references to arrays.
      not Search(r' \([^)]+\)\[[^\]]+\]', fncall)):
    if Search(r'\w\s*\(\s', fncall):      # a ( used for a fn call
      error(filename, linenum, 'whitespace/parens', 4,
            'Extra space after ( in function call')
    elif Search(r'\(\s+[^(]', fncall):
      error(filename, linenum, 'whitespace/parens', 2,
            'Extra space after (')
    if (Search(r'\w\s+\(', fncall) and
        not Search(r'#\s*define|typedef', fncall)):
      error(filename, linenum, 'whitespace/parens', 4,
            'Extra space before ( in function call')
    # If the ) is followed only by a newline or a { + newline, assume it's
    # part of a control statement (if/while/etc), and don't complain
    if Search(r'[^)]\s+\)\s*[^{\s]', fncall):
      error(filename, linenum, 'whitespace/parens', 2,
            'Extra space before )')


def IsBlankLine(line):
  """Returns true if the given line is blank.

  We consider a line to be blank if the line is empty or consists of
  only white spaces.

  Args:
    line: A line of a string.

  Returns:
    True, if the given line is blank.
  """
  return not line or line.isspace()


def CheckForFunctionLengths(filename, clean_lines, linenum,
                            function_state, error):
  """Reports for long function bodies.

  For an overview why this is done, see:
  http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Write_Short_Functions

  Uses a simplistic algorithm assuming other style guidelines
  (especially spacing) are followed.
  Only checks unindented functions, so class members are unchecked.
  Trivial bodies are unchecked, so constructors with huge initializer lists
  may be missed.
  Blank/comment lines are not counted so as to avoid encouraging the removal
  of vertical space and commments just to get through a lint check.
  NOLINT *on the last line of a function* disables this check.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    function_state: Current function name and lines in body so far.
    error: The function to call with any errors found.
  """
  lines = clean_lines.lines
  line = lines[linenum]
  raw = clean_lines.raw_lines
  raw_line = raw[linenum]
  joined_line = ''

  starting_func = False
  regexp = r'(\w(\w|::|\*|\&|\s)*)\('  # decls * & space::name( ...
  match_result = Match(regexp, line)
  if match_result:
    # If the name is all caps and underscores, figure it's a macro and
    # ignore it, unless it's TEST or TEST_F.
    function_name = match_result.group(1).split()[-1]
    if function_name == 'TEST' or function_name == 'TEST_F' or (
        not Match(r'[A-Z_]+$', function_name)):
      starting_func = True

  if starting_func:
    body_found = False
    for start_linenum in xrange(linenum, clean_lines.NumLines()):
      start_line = lines[start_linenum]
      joined_line += ' ' + start_line.lstrip()
      if Search(r'(;|})', start_line):  # Declarations and trivial functions
        body_found = True
        break                              # ... ignore
      elif Search(r'{', start_line):
        body_found = True
        function = Search(r'((\w|:)*)\(', line).group(1)
        if Match(r'TEST', function):    # Handle TEST... macros
          parameter_regexp = Search(r'(\(.*\))', joined_line)
          if parameter_regexp:             # Ignore bad syntax
            function += parameter_regexp.group(1)
        else:
          function += '()'
        function_state.Begin(function)
        break
    if not body_found:
      # No body for the function (or evidence of a non-function) was found.
      error(filename, linenum, 'readability/fn_size', 5,
            'Lint failed to find start of function body.')
  elif Match(r'^\}\s*$', line):  # function end
    if not Search(r'\bNOLINT\b', raw_line):
      function_state.Check(error, filename, linenum)
    function_state.End()
  elif not Match(r'^\s*$', line):
    function_state.Count()  # Count non-blank/non-comment lines.


_RE_PATTERN_TODO = re.compile(r'^//(\s*)TODO(\(.+?\))?:?(\s|$)?')


def CheckComment(comment, filename, linenum, error):
  """Checks for common mistakes in TODO comments.

  Args:
    comment: The text of the comment from the line in question.
    filename: The name of the current file.
    linenum: The number of the line to check.
    error: The function to call with any errors found.
  """
  match = _RE_PATTERN_TODO.match(comment)
  if match:
    # One whitespace is correct; zero whitespace is handled elsewhere.
    leading_whitespace = match.group(1)
    if len(leading_whitespace) > 1:
      error(filename, linenum, 'whitespace/todo', 2,
            'Too many spaces before TODO')

    username = match.group(2)
    if not username:
      error(filename, linenum, 'readability/todo', 2,
            'Missing username in TODO; it should look like '
            '"// TODO(my_username): Stuff."')

    middle_whitespace = match.group(3)
    # Comparisons made explicit for correctness -- pylint: disable-msg=C6403
    if middle_whitespace != ' ' and middle_whitespace != '':
      error(filename, linenum, 'whitespace/todo', 2,
            'TODO(my_username) should be followed by a space')


def CheckSpacing(filename, clean_lines, linenum, error):
  """Checks for the correctness of various spacing issues in the code.

  Things we check for: spaces around operators, spaces after
  if/for/while/switch, no spaces around parens in function calls, two
  spaces between code and comment, don't start a block with a blank
  line, don't end a function with a blank line, don't have too many
  blank lines in a row.

  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.
  """

  raw = clean_lines.raw_lines
  line = raw[linenum]

  # Before nixing comments, check if the line is blank for no good
  # reason.  This includes the first line after a block is opened, and
  # blank lines at the end of a function (ie, right before a line like '}'
  if IsBlankLine(line):
    elided = clean_lines.elided
    prev_line = elided[linenum - 1]
    prevbrace = prev_line.rfind('{')
    # TODO(unknown): Don't complain if line before blank line, and line after,
    #                both start with alnums and are indented the same amount.
    #                This ignores whitespace at the start of a namespace block
    #                because those are not usually indented.
    if (prevbrace != -1 and prev_line[prevbrace:].find('}') == -1
        and prev_line[:prevbrace].find('namespace') == -1):
      # OK, we have a blank line at the start of a code block.  Before we
      # complain, we check if it is an exception to the rule: The previous
      # non-empty line has the paramters of a function header that are indented
      # 4 spaces (because they did not fit in a 80 column line when placed on
      # the same line as the function name).  We also check for the case where
      # the previous line is indented 6 spaces, which may happen when the
      # initializers of a constructor do not fit into a 80 column line.
      exception = False
      if Match(r' {6}\w', prev_line):  # Initializer list?
        # We are looking for the opening column of initializer list, which
        # should be indented 4 spaces to cause 6 space indentation afterwards.
        search_position = linenum-2
        while (search_position >= 0
               and Match(r' {6}\w', elided[search_position])):
          search_position -= 1
        exception = (search_position >= 0
                     and elided[search_position][:5] == '    :')
      else:
        # Search for the function arguments or an initializer list.  We use a
        # simple heuristic here: If the line is indented 4 spaces; and we have a
        # closing paren, without the opening paren, followed by an opening brace
        # or colon (for initializer lists) we assume that it is the last line of
        # a function header.  If we have a colon indented 4 spaces, it is an
        # initializer list.
        exception = (Match(r' {4}\w[^\(]*\)\s*(const\s*)?(\{\s*$|:)',
                           prev_line)
                     or Match(r' {4}:', prev_line))

      if not exception:
        error(filename, linenum, 'whitespace/blank_line', 2,
              'Blank line at the start of a code block.  Is this needed?')
    # This doesn't ignore whitespace at the end of a namespace block
    # because that is too hard without pairing open/close braces;
    # however, a special exception is made for namespace closing
    # brackets which have a comment containing "namespace".
    #
    # Also, ignore blank lines at the end of a block in a long if-else
    # chain, like this:
    #   if (condition1) {
    #     // Something followed by a blank line
    #
    #   } else if (condition2) {
    #     // Something else
    #   }
    if linenum + 1 < clean_lines.NumLines():
      next_line = raw[linenum + 1]
      if (next_line
          and Match(r'\s*}', next_line)
          and next_line.find('namespace') == -1
          and next_line.find('} else ') == -1):
        error(filename, linenum, 'whitespace/blank_line', 3,
              'Blank line at the end of a code block.  Is this needed?')

  # Next, we complain if there's a comment too near the text
  commentpos = line.find('//')
  if commentpos != -1:
    # Check if the // may be in quotes.  If so, ignore it
    # Comparisons made explicit for clarity -- pylint: disable-msg=C6403
    if (line.count('"', 0, commentpos) -
        line.count('\\"', 0, commentpos)) % 2 == 0:   # not in quotes
      # Allow one space for new scopes, two spaces otherwise:
      if (not Match(r'^\s*{ //', line) and
          ((commentpos >= 1 and
            line[commentpos-1] not in string.whitespace) or
           (commentpos >= 2 and
            line[commentpos-2] not in string.whitespace))):
        error(filename, linenum, 'whitespace/comments', 2,
              'At least two spaces is best between code and comments')
      # There should always be a space between the // and the comment
      commentend = commentpos + 2
      if commentend < len(line) and not line[commentend] == ' ':
        # but some lines are exceptions -- e.g. if they're big
        # comment delimiters like:
        # //----------------------------------------------------------
        match = Search(r'[=/-]{4,}\s*$', line[commentend:])
        if not match:
          error(filename, linenum, 'whitespace/comments', 4,
                'Should have a space between // and comment')
      CheckComment(line[commentpos:], filename, linenum, error)

  line = clean_lines.elided[linenum]  # get rid of comments and strings

  # Don't try to do spacing checks for operator methods
  line = re.sub(r'operator(==|!=|<|<<|<=|>=|>>|>)\(', 'operator\(', line)

  # We allow no-spaces around = within an if: "if ( (a=Foo()) == 0 )".
  # Otherwise not.  Note we only check for non-spaces on *both* sides;
  # sometimes people put non-spaces on one side when aligning ='s among
  # many lines (not that this is behavior that I approve of...)
  if Search(r'[\w.]=[\w.]', line) and not Search(r'\b(if|while) ', line):
    error(filename, linenum, 'whitespace/operators', 4,
          'Missing spaces around =')

  # It's ok not to have spaces around binary operators like + - * /, but if
  # there's too little whitespace, we get concerned.  It's hard to tell,
  # though, so we punt on this one for now.  TODO.

  # You should always have whitespace around binary operators.
  # Alas, we can't test < or > because they're legitimately used sans spaces
  # (a->b, vector<int> a).  The only time we can tell is a < with no >, and
  # only if it's not template params list spilling into the next line.
  match = Search(r'[^<>=!\s](==|!=|<=|>=)[^<>=!\s]', line)
  if not match:
    # Note that while it seems that the '<[^<]*' term in the following
    # regexp could be simplified to '<.*', which would indeed match
    # the same class of strings, the [^<] means that searching for the
    # regexp takes linear rather than quadratic time.
    if not Search(r'<[^<]*,\s*$', line):  # template params spill
      match = Search(r'[^<>=!\s](<)[^<>=!\s]([^>]|->)*$', line)
  if match:
    error(filename, linenum, 'whitespace/operators', 3,
          'Missing spaces around %s' % match.group(1))
  # We allow no-spaces around << and >> when used like this: 10<<20, but
  # not otherwise (particularly, not when used as streams)
  match = Search(r'[^0-9\s](<<|>>)[^0-9\s]', line)
  if match:
    error(filename, linenum, 'whitespace/operators', 3,
          'Missing spaces around %s' % match.group(1))

  # There shouldn't be space around unary operators
  match = Search(r'(!\s|~\s|[\s]--[\s;]|[\s]\+\+[\s;])', line)
  if match:
    error(filename, linenum, 'whitespace/operators', 4,
          'Extra space for operator %s' % match.group(1))

  # A pet peeve of mine: no spaces after an if, while, switch, or for
  match = Search(r' (if\(|for\(|while\(|switch\()', line)
  if match:
    error(filename, linenum, 'whitespace/parens', 5,
          'Missing space before ( in %s' % match.group(1))

  # For if/for/while/switch, the left and right parens should be
  # consistent about how many spaces are inside the parens, and
  # there should either be zero or one spaces inside the parens.
  # We don't want: "if ( foo)" or "if ( foo   )".
  # Exception: "for ( ; foo; bar)" is allowed.
  match = Search(r'\b(if|for|while|switch)\s*'
                 r'\(([ ]*)(.).*[^ ]+([ ]*)\)\s*{\s*$',
                 line)
  if match:
    if len(match.group(2)) != len(match.group(4)):
      if not (match.group(3) == ';' and
              len(match.group(2)) == 1 + len(match.group(4))):
        error(filename, linenum, 'whitespace/parens', 5,
              'Mismatching spaces inside () in %s' % match.group(1))
    if not len(match.group(2)) in [0, 1]:
      error(filename, linenum, 'whitespace/parens', 5,
            'Should have zero or one spaces inside ( and ) in %s' %
            match.group(1))

  # You should always have a space after a comma (either as fn arg or operator)
  if Search(r',[^\s]', line):
    error(filename, linenum, 'whitespace/comma', 3,
          'Missing space after ,')

  # Next we will look for issues with function calls.
  CheckSpacingForFunctionCall(filename, line, linenum, error)

  # Except after an opening paren, you should have spaces before your braces.
  # And since you should never have braces at the beginning of a line, this is
  # an easy test.
  if Search(r'[^ (]{', line):
    error(filename, linenum, 'whitespace/braces', 5,
          'Missing space before {')

  # Make sure '} else {' has spaces.
  if Search(r'}else', line):
    error(filename, linenum, 'whitespace/braces', 5,
          'Missing space before else')

  # You shouldn't have spaces before your brackets, except maybe after
  # 'delete []' or 'new char * []'.
  if Search(r'\w\s+\[', line) and not Search(r'delete\s+\[', line):
    error(filename, linenum, 'whitespace/braces', 5,
          'Extra space before [')

  # You shouldn't have a space before a semicolon at the end of the line.
  # There's a special case for "for" since the style guide allows space before
  # the semicolon there.
  if Search(r':\s*;\s*$', line):
    error(filename, linenum, 'whitespace/semicolon', 5,
          'Semicolon defining empty statement. Use { } instead.')
  elif Search(r'^\s*;\s*$', line):
    error(filename, linenum, 'whitespace/semicolon', 5,
          'Line contains only semicolon. If this should be an empty statement, '
          'use { } instead.')
  elif (Search(r'\s+;\s*$', line) and
        not Search(r'\bfor\b', line)):
    error(filename, linenum, 'whitespace/semicolon', 5,
          'Extra space before last semicolon. If this should be an empty '
          'statement, use { } instead.')


def GetPreviousNonBlankLine(clean_lines, linenum):
  """Return the most recent non-blank line and its line number.

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

  Returns:
    A tuple with two elements.  The first element is the contents of the last
    non-blank line before the current line, or the empty string if this is the
    first non-blank line.  The second is the line number of that line, or -1
    if this is the first non-blank line.
  """

  prevlinenum = linenum - 1
  while prevlinenum >= 0:
    prevline = clean_lines.elided[prevlinenum]
    if not IsBlankLine(prevline):     # if not a blank line...
      return (prevline, prevlinenum)
    prevlinenum -= 1
  return ('', -1)


def CheckBraces(filename, clean_lines, linenum, error):
  """Looks for misplaced braces (e.g. at the end of 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]        # get rid of comments and strings

  if Match(r'\s*{\s*$', line):
    # We allow an open brace to start a line in the case where someone
    # is using braces in a block to explicitly create a new scope,
    # which is commonly used to control the lifetime of
    # stack-allocated variables.  We don't detect this perfectly: we
    # just don't complain if the last non-whitespace character on the
    # previous non-blank line is ';', ':', '{', or '}'.
    prevline = GetPreviousNonBlankLine(clean_lines, linenum)[0]
    if not Search(r'[;:}{]\s*$', prevline):
      error(filename, linenum, 'whitespace/braces', 4,
            '{ should almost always be at the end of the previous line')

  # An else clause should be on the same line as the preceding closing brace.
  if Match(r'\s*else\s*', line):
    prevline = GetPreviousNonBlankLine(clean_lines, linenum)[0]
    if Match(r'\s*}\s*$', prevline):
      error(filename, linenum, 'whitespace/newline', 4,
            'An else should appear on the same line as the preceding }')

  # If braces come on one side of an else, they should be on both.
  # However, we have to worry about "else if" that spans multiple lines!
  if Search(r'}\s*else[^{]*$', line) or Match(r'[^}]*else\s*{', line):
    if Search(r'}\s*else if([^{]*)$', line):       # could be multi-line if
      # find the ( after the if
      pos = line.find('else if')
      pos = line.find('(', pos)
      if pos > 0:
        (endline, _, endpos) = CloseExpression(clean_lines, linenum, pos)
        if endline[endpos:].find('{') == -1:    # must be brace after if
          error(filename, linenum, 'readability/braces', 5,
                'If an else has a brace on one side, it should have it on both')
    else:            # common case: else not followed by a multi-line if
      error(filename, linenum, 'readability/braces', 5,
            'If an else has a brace on one side, it should have it on both')

  # Likewise, an else should never have the else clause on the same line
  if Search(r'\belse [^\s{]', line) and not Search(r'\belse if\b', line):
    error(filename, linenum, 'whitespace/newline', 4,
          'Else clause should never be on same line as else (use 2 lines)')

  # In the same way, a do/while should never be on one line
  if Match(r'\s*do [^\s{]', line):
    error(filename, linenum, 'whitespace/newline', 4,
          'do/while clauses should not be on a single line')

  # Braces shouldn't be followed by a ; unless they're defining a struct
  # or initializing an array.
  # We can't tell in general, but we can for some common cases.
  prevlinenum = linenum
  while True:
    (prevline, prevlinenum) = GetPreviousNonBlankLine(clean_lines, prevlinenum)
    if Match(r'\s+{.*}\s*;', line) and not prevline.count(';'):
      line = prevline + line
    else:
      break
  if (Search(r'{.*}\s*;', line) and
      line.count('{') == line.count('}') and
      not Search(r'struct|class|enum|\s*=\s*{', line)):
    error(filename, linenum, 'readability/braces', 4,
          "You don't need a ; after a }")


def ReplaceableCheck(operator, macro, line):
  """Determine whether a basic CHECK can be replaced with a more specific one.

  For example suggest using CHECK_EQ instead of CHECK(a == b) and
  similarly for CHECK_GE, CHECK_GT, CHECK_LE, CHECK_LT, CHECK_NE.

  Args:
    operator: The C++ operator used in the CHECK.
    macro: The CHECK or EXPECT macro being called.
    line: The current source line.

  Returns:
    True if the CHECK can be replaced with a more specific one.
  """

  # This matches decimal and hex integers, strings, and chars (in that order).
  match_constant = r'([-+]?(\d+|0[xX][0-9a-fA-F]+)[lLuU]{0,3}|".*"|\'.*\')'

  # Expression to match two sides of the operator with something that
  # looks like a literal, since CHECK(x == iterator) won't compile.
  # This means we can't catch all the cases where a more specific
  # CHECK is possible, but it's less annoying than dealing with
  # extraneous warnings.
  match_this = (r'\s*' + macro + r'\((\s*' +
                match_constant + r'\s*' + operator + r'[^<>].*|'
                r'.*[^<>]' + operator + r'\s*' + match_constant +
                r'\s*\))')

  # Don't complain about CHECK(x == NULL) or similar because
  # CHECK_EQ(x, NULL) won't compile (requires a cast).
  # Also, don't complain about more complex boolean expressions
  # involving && or || such as CHECK(a == b || c == d).
  return Match(match_this, line) and not Search(r'NULL|&&|\|\|', line)


def CheckCheck(filename, clean_lines, linenum, error):
  """Checks the use of CHECK and EXPECT macros.

  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.
  """

  # Decide the set of replacement macros that should be suggested
  raw_lines = clean_lines.raw_lines
  current_macro = ''
  for macro in _CHECK_MACROS:
    if raw_lines[linenum].find(macro) >= 0:
      current_macro = macro
      break
  if not current_macro:
    # Don't waste time here if line doesn't contain 'CHECK' or 'EXPECT'
    return

  line = clean_lines.elided[linenum]        # get rid of comments and strings

  # Encourage replacing plain CHECKs with CHECK_EQ/CHECK_NE/etc.
  for operator in ['==', '!=', '>=', '>', '<=', '<']:
    if ReplaceableCheck(operator, current_macro, line):
      error(filename, linenum, 'readability/check', 2,
            'Consider using %s instead of %s(a %s b)' % (
                _CHECK_REPLACEMENT[current_macro][operator],
                current_macro, operator))
      break


def GetLineWidth(line):
  """Determines the width of the line in column positions.

  Args:
    line: A string, which may be a Unicode string.

  Returns:
    The width of the line in column positions, accounting for Unicode
    combining characters and wide characters.
  """
  if isinstance(line, unicode):
    width = 0
    for c in unicodedata.normalize('NFC', line):
      if unicodedata.east_asian_width(c) in ('W', 'F'):
        width += 2
      elif not unicodedata.combining(c):
        width += 1
    return width
  else:
    return len(line)


def CheckStyle(filename, clean_lines, linenum, file_extension, error):
  """Checks rules from the 'C++ style rules' section of cppguide.html.

  Most of these rules are hard to test (naming, comment style), but we
  do what we can.  In particular we check for 2-space indents, line lengths,
  tab usage, spaces inside code, etc.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    file_extension: The extension (without the dot) of the filename.
    error: The function to call with any errors found.
  """

  raw_lines = clean_lines.raw_lines
  line = raw_lines[linenum]

  if line.find('\t') != -1:
    error(filename, linenum, 'whitespace/tab', 1,
          'Tab found; better to use spaces')

  # One or three blank spaces at the beginning of the line is weird; it's
  # hard to reconcile that with 2-space indents.
  # NOTE: here are the conditions rob pike used for his tests.  Mine aren't
  # as sophisticated, but it may be worth becoming so:  RLENGTH==initial_spaces
  # if(RLENGTH > 20) complain = 0;
  # if(match($0, " +(error|private|public|protected):")) complain = 0;
  # if(match(prev, "&& *$")) complain = 0;
  # if(match(prev, "\\|\\| *$")) complain = 0;
  # if(match(prev, "[\",=><] *$")) complain = 0;
  # if(match($0, " <<")) complain = 0;
  # if(match(prev, " +for \\(")) complain = 0;
  # if(prevodd && match(prevprev, " +for \\(")) complain = 0;
  initial_spaces = 0
  cleansed_line = clean_lines.elided[linenum]
  while initial_spaces < len(line) and line[initial_spaces] == ' ':
    initial_spaces += 1
  if line and line[-1].isspace():
    error(filename, linenum, 'whitespace/end_of_line', 4,
          'Line ends in whitespace.  Consider deleting these extra spaces.')
  # There are certain situations we allow one space, notably for labels
  elif ((initial_spaces == 1 or initial_spaces == 3) and
        not Match(r'\s*\w+\s*:\s*$', cleansed_line)):
    error(filename, linenum, 'whitespace/indent', 3,
          'Weird number of spaces at line-start.  '
          'Are you using a 2-space indent?')
  # Labels should always be indented at least one space.
  elif not initial_spaces and line[:2] != '//' and Search(r'[^:]:\s*$',
                                                          line):
    error(filename, linenum, 'whitespace/labels', 4,
          'Labels should always be indented at least one space.  '
          'If this is a member-initializer list in a constructor, '
          'the colon should be on the line after the definition header.')

  # Check if the line is a header guard.
  is_header_guard = False
  if file_extension == 'h':
    cppvar = GetHeaderGuardCPPVariable(filename)
    if (line.startswith('#ifndef %s' % cppvar) or
        line.startswith('#define %s' % cppvar) or
        line.startswith('#endif  // %s' % cppvar)):
      is_header_guard = True
  # #include lines and header guards can be long, since there's no clean way to
  # split them.
  #
  # URLs can be long too.  It's possible to split these, but it makes them
  # harder to cut&paste.
  if (not line.startswith('#include') and not is_header_guard and
      not Match(r'^\s*//\s*http(s?)://\S*$', line)):
    line_width = GetLineWidth(line)
    if line_width > 100:
      error(filename, linenum, 'whitespace/line_length', 4,
            'Lines should very rarely be longer than 100 characters')
    elif line_width > 80:
      error(filename, linenum, 'whitespace/line_length', 2,
            'Lines should be <= 80 characters long')

  if (cleansed_line.count(';') > 1 and
      # for loops are allowed two ;'s (and may run over two lines).
      cleansed_line.find('for') == -1 and
      (GetPreviousNonBlankLine(clean_lines, linenum)[0].find('for') == -1 or
       GetPreviousNonBlankLine(clean_lines, linenum)[0].find(';') != -1) and
      # It's ok to have many commands in a switch case that fits in 1 line
      not ((cleansed_line.find('case ') != -1 or
            cleansed_line.find('default:') != -1) and
           cleansed_line.find('break;') != -1)):
    error(filename, linenum, 'whitespace/newline', 4,
          'More than one command on the same line')

  # Some more style checks
  CheckBraces(filename, clean_lines, linenum, error)
  CheckSpacing(filename, clean_lines, linenum, error)
  CheckCheck(filename, clean_lines, linenum, error)


_RE_PATTERN_INCLUDE_NEW_STYLE = re.compile(r'#include +"[^/]+\.h"')
_RE_PATTERN_INCLUDE = re.compile(r'^\s*#\s*include\s*([<"])([^>"]*)[>"].*$')
# Matches the first component of a filename delimited by -s and _s. That is:
#  _RE_FIRST_COMPONENT.match('foo').group(0) == 'foo'
#  _RE_FIRST_COMPONENT.match('foo.cc').group(0) == 'foo'
#  _RE_FIRST_COMPONENT.match('foo-bar_baz.cc').group(0) == 'foo'
#  _RE_FIRST_COMPONENT.match('foo_bar-baz.cc').group(0) == 'foo'
_RE_FIRST_COMPONENT = re.compile(r'^[^-_.]+')


def _DropCommonSuffixes(filename):
  """Drops common suffixes like _test.cc or -inl.h from filename.

  For example:
    >>> _DropCommonSuffixes('foo/foo-inl.h')
    'foo/foo'
    >>> _DropCommonSuffixes('foo/bar/foo.cc')
    'foo/bar/foo'
    >>> _DropCommonSuffixes('foo/foo_internal.h')
    'foo/foo'
    >>> _DropCommonSuffixes('foo/foo_unusualinternal.h')
    'foo/foo_unusualinternal'

  Args:
    filename: The input filename.

  Returns:
    The filename with the common suffix removed.
  """
  for suffix in ('test.cc', 'regtest.cc', 'unittest.cc',
                 'inl.h', 'impl.h', 'internal.h'):
    if (filename.endswith(suffix) and len(filename) > len(suffix) and
        filename[-len(suffix) - 1] in ('-', '_')):
      return filename[:-len(suffix) - 1]
  return os.path.splitext(filename)[0]


def _IsTestFilename(filename):
  """Determines if the given filename has a suffix that identifies it as a test.

  Args:
    filename: The input filename.

  Returns:
    True if 'filename' looks like a test, False otherwise.
  """
  if (filename.endswith('_test.cc') or
      filename.endswith('_unittest.cc') or
      filename.endswith('_regtest.cc')):
    return True
  else:
    return False


def _ClassifyInclude(fileinfo, include, is_system):
  """Figures out what kind of header 'include' is.

  Args:
    fileinfo: The current file cpplint is running over. A FileInfo instance.
    include: The path to a #included file.
    is_system: True if the #include used <> rather than "".

  Returns:
    One of the _XXX_HEADER constants.

  For example:
    >>> _ClassifyInclude(FileInfo('foo/foo.cc'), 'stdio.h', True)
    _C_SYS_HEADER
    >>> _ClassifyInclude(FileInfo('foo/foo.cc'), 'string', True)
    _CPP_SYS_HEADER
    >>> _ClassifyInclude(FileInfo('foo/foo.cc'), 'foo/foo.h', False)
    _LIKELY_MY_HEADER
    >>> _ClassifyInclude(FileInfo('foo/foo_unknown_extension.cc'),
    ...                  'bar/foo_other_ext.h', False)
    _POSSIBLE_MY_HEADER
    >>> _ClassifyInclude(FileInfo('foo/foo.cc'), 'foo/bar.h', False)
    _OTHER_HEADER
  """
  # This is a list of all standard c++ header files, except
  # those already checked for above.
  is_stl_h = include in _STL_HEADERS
  is_cpp_h = is_stl_h or include in _CPP_HEADERS

  if is_system:
    if is_cpp_h:
      return _CPP_SYS_HEADER
    else:
      return _C_SYS_HEADER

  # If the target file and the include we're checking share a
  # basename when we drop common extensions, and the include
  # lives in . , then it's likely to be owned by the target file.
  target_dir, target_base = (
      os.path.split(_DropCommonSuffixes(fileinfo.RepositoryName())))
  include_dir, include_base = os.path.split(_DropCommonSuffixes(include))
  if target_base == include_base and (
      include_dir == target_dir or
      include_dir == os.path.normpath(target_dir + '/../public')):
    return _LIKELY_MY_HEADER

  # If the target and include share some initial basename
  # component, it's possible the target is implementing the
  # include, so it's allowed to be first, but we'll never
  # complain if it's not there.
  target_first_component = _RE_FIRST_COMPONENT.match(target_base)
  include_first_component = _RE_FIRST_COMPONENT.match(include_base)
  if (target_first_component and include_first_component and
      target_first_component.group(0) ==
      include_first_component.group(0)):
    return _POSSIBLE_MY_HEADER

  return _OTHER_HEADER



def CheckLanguage(filename, clean_lines, linenum, file_extension, include_state,
                  error):
  """Checks rules from the 'C++ language rules' section of cppguide.html.

  Some of these rules are hard to test (function overloading, using
  uint32 inappropriately), but we do the best we can.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    linenum: The number of the line to check.
    file_extension: The extension (without the dot) of the filename.
    include_state: An _IncludeState instance in which the headers are inserted.
    error: The function to call with any errors found.
  """
  fileinfo = FileInfo(filename)

  # get rid of comments
  comment_elided_line = clean_lines.lines[linenum]

  # "include" should use the new style "foo/bar.h" instead of just "bar.h"
  if _RE_PATTERN_INCLUDE_NEW_STYLE.search(comment_elided_line):
    error(filename, linenum, 'build/include', 4,
          'Include the directory when naming .h files')

  # we shouldn't include a file more than once. actually, there are a
  # handful of instances where doing so is okay, but in general it's
  # not.
  match = _RE_PATTERN_INCLUDE.search(comment_elided_line)
  if match:
    include = match.group(2)
    is_system = (match.group(1) == '<')
    if include in include_state:
      error(filename, linenum, 'build/include', 4,
            '"%s" already included at %s:%s' %
            (include, filename, include_state[include]))
    else:
      include_state[include] = linenum

      # We want to ensure that headers appear in the right order:
      # 1) for foo.cc, foo.h  (preferred location)
      # 2) c system files
      # 3) cpp system files
      # 4) for foo.cc, foo.h  (deprecated location)
      # 5) other google headers
      #
      # We classify each include statement as one of those 5 types
      # using a number of techniques. The include_state object keeps
      # track of the highest type seen, and complains if we see a
      # lower type after that.
      error_message = include_state.CheckNextIncludeOrder(
          _ClassifyInclude(fileinfo, include, is_system))
      if error_message:
        error(filename, linenum, 'build/include_order', 4,
              '%s. Should be: %s.h, c system, c++ system, other.' %
              (error_message, fileinfo.BaseName()))

  # If the line is empty or consists of entirely a comment, no need to
  # check it.
  line = clean_lines.elided[linenum]
  if not line:
    return

  # Create an extended_line, which is the concatenation of the current and
  # next lines, for more effective checking of code that may span more than one
  # line.
  if linenum + 1 < clean_lines.NumLines():
    extended_line = line + clean_lines.elided[linenum + 1]
  else:
    extended_line = line

  # Make Windows paths like Unix.
  fullname = os.path.abspath(filename).replace('\\', '/')

  # TODO(unknown): figure out if they're using default arguments in fn proto.

  # Look for any of the stream classes that are part of standard C++.
  match = _RE_PATTERN_INCLUDE.match(line)
  if match:
    include = match.group(2)
    if Match(r'(f|ind|io|i|o|parse|pf|stdio|str|)?stream$', include):
      # Many unit tests use cout, so we exempt them.
      if not _IsTestFilename(filename):
        error(filename, linenum, 'readability/streams', 3,
              'Streams are highly discouraged.')

  # Check for non-const references in functions.  This is tricky because &
  # is also used to take the address of something.  We allow <> for templates,
  # (ignoring whatever is between the braces) and : for classes.
  # These are complicated re's.  They try to capture the following:
  # paren (for fn-prototype start), typename, &, varname.  For the const
  # version, we're willing for const to be before typename or after
  # Don't check the implemention on same line.
  fnline = line.split('{', 1)[0]
  if (len(re.findall(r'\([^()]*\b(?:[\w:]|<[^()]*>)+(\s?&|&\s?)\w+', fnline)) >
      len(re.findall(r'\([^()]*\bconst\s+(?:typename\s+)?(?:struct\s+)?'
                     r'(?:[\w:]|<[^()]*>)+(\s?&|&\s?)\w+', fnline)) +
      len(re.findall(r'\([^()]*\b(?:[\w:]|<[^()]*>)+\s+const(\s?&|&\s?)[\w]+',
                     fnline))):

    # We allow non-const references in a few standard places, like functions
    # called "swap()" or iostream operators like "<<" or ">>".
    if not Search(
        r'(swap|Swap|operator[<>][<>])\s*\(\s*(?:[\w:]|<.*>)+\s*&',
        fnline):
      error(filename, linenum, 'runtime/references', 2,
            'Is this a non-const reference? '
            'If so, make const or use a pointer.')

  # Check to see if they're using an conversion function cast.
  # I just try to capture the most common basic types, though there are more.
  # Parameterless conversion functions, such as bool(), are allowed as they are
  # probably a member operator declaration or default constructor.
  match = Search(
      r'\b(int|float|double|bool|char|int32|uint32|int64|uint64)\([^)]', line)
  if match:
    # gMock methods are defined using some variant of MOCK_METHODx(name, type)
    # where type may be float(), int(string), etc.  Without context they are
    # virtually indistinguishable from int(x) casts.
    if not Match(r'^\s*MOCK_(CONST_)?METHOD\d+(_T)?\(', line):
      error(filename, linenum, 'readability/casting', 4,
            'Using deprecated casting style.  '
            'Use static_cast<%s>(...) instead' %
            match.group(1))

  CheckCStyleCast(filename, linenum, line, clean_lines.raw_lines[linenum],
                  'static_cast',
                  r'\((int|float|double|bool|char|u?int(16|32|64))\)',
                  error)
  # This doesn't catch all cases.  Consider (const char * const)"hello".
  CheckCStyleCast(filename, linenum, line, clean_lines.raw_lines[linenum],
                  'reinterpret_cast', r'\((\w+\s?\*+\s?)\)', error)

  # In addition, we look for people taking the address of a cast.  This
  # is dangerous -- casts can assign to temporaries, so the pointer doesn't
  # point where you think.
  if Search(
      r'(&\([^)]+\)[\w(])|(&(static|dynamic|reinterpret)_cast\b)', line):
    error(filename, linenum, 'runtime/casting', 4,
          ('Are you taking an address of a cast?  '
           'This is dangerous: could be a temp var.  '
           'Take the address before doing the cast, rather than after'))

  # Check for people declaring static/global STL strings at the top level.
  # This is dangerous because the C++ language does not guarantee that
  # globals with constructors are initialized before the first access.
  match = Match(
      r'((?:|static +)(?:|const +))string +([a-zA-Z0-9_:]+)\b(.*)',
      line)
  # Make sure it's not a function.
  # Function template specialization looks like: "string foo<Type>(...".
  # Class template definitions look like: "string Foo<Type>::Method(...".
  if match and not Match(r'\s*(<.*>)?(::[a-zA-Z0-9_]+)?\s*\(([^"]|$)',
                         match.group(3)):
    error(filename, linenum, 'runtime/string', 4,
          'For a static/global string constant, use a C style string instead: '
          '"%schar %s[]".' %
          (match.group(1), match.group(2)))

  # Check that we're not using RTTI outside of testing code.
  if Search(r'\bdynamic_cast<', line) and not _IsTestFilename(filename):
    error(filename, linenum, 'runtime/rtti', 5,
          'Do not use dynamic_cast<>.  If you need to cast within a class '
          "hierarchy, use static_cast<> to upcast.  Google doesn't support "
          'RTTI.')

  if Search(r'\b([A-Za-z0-9_]*_)\(\1\)', line):
    error(filename, linenum, 'runtime/init', 4,
          'You seem to be initializing a member variable with itself.')

  if file_extension == 'h':
    # TODO(unknown): check that 1-arg constructors are explicit.
    #                How to tell it's a constructor?
    #                (handled in CheckForNonStandardConstructs for now)
    # TODO(unknown): check that classes have DISALLOW_EVIL_CONSTRUCTORS
    #                (level 1 error)
    pass

  # Check if people are using the verboten C basic types.  The only exception
  # we regularly allow is "unsigned short port" for port.
  if Search(r'\bshort port\b', line):
    if not Search(r'\bunsigned short port\b', line):
      error(filename, linenum, 'runtime/int', 4,
            'Use "unsigned short" for ports, not "short"')
  else:
    match = Search(r'\b(short|long(?! +double)|long long)\b', line)
    if match:
      error(filename, linenum, 'runtime/int', 4,
            'Use int16/int64/etc, rather than the C type %s' % match.group(1))

  # When snprintf is used, the second argument shouldn't be a literal.
  match = Search(r'snprintf\s*\(([^,]*),\s*([0-9]*)\s*,', line)
  if match:
    error(filename, linenum, 'runtime/printf', 3,
          'If you can, use sizeof(%s) instead of %s as the 2nd arg '
          'to snprintf.' % (match.group(1), match.group(2)))

  # Check if some verboten C functions are being used.
  if Search(r'\bsprintf\b', line):
    error(filename, linenum, 'runtime/printf', 5,
          'Never use sprintf.  Use snprintf instead.')
  match = Search(r'\b(strcpy|strcat)\b', line)
  if match:
    error(filename, linenum, 'runtime/printf', 4,
          'Almost always, snprintf is better than %s' % match.group(1))

  if Search(r'\bsscanf\b', line):
    error(filename, linenum, 'runtime/printf', 1,
          'sscanf can be ok, but is slow and can overflow buffers.')

  # Check for suspicious usage of "if" like
  # } if (a == b) {
  if Search(r'\}\s*if\s*\(', line):
    error(filename, linenum, 'readability/braces', 4,
          'Did you mean "else if"? If not, start a new line for "if".')

  # Check for potential format string bugs like printf(foo).
  # We constrain the pattern not to pick things like DocidForPrintf(foo).
  # Not perfect but it can catch printf(foo.c_str()) and printf(foo->c_str())
  match = re.search(r'\b((?:string)?printf)\s*\(([\w.\->()]+)\)', line, re.I)
  if match:
    error(filename, linenum, 'runtime/printf', 4,
          'Potential format string bug. Do %s("%%s", %s) instead.'
          % (match.group(1), match.group(2)))

  # Check for potential memset bugs like memset(buf, sizeof(buf), 0).
  match = Search(r'memset\s*\(([^,]*),\s*([^,]*),\s*0\s*\)', line)
  if match and not Match(r"^''|-?[0-9]+|0x[0-9A-Fa-f]$", match.group(2)):
    error(filename, linenum, 'runtime/memset', 4,
          'Did you mean "memset(%s, 0, %s)"?'
          % (match.group(1), match.group(2)))

  if Search(r'\busing namespace\b', line):
    error(filename, linenum, 'build/namespaces', 5,
          'Do not use namespace using-directives.  '
          'Use using-declarations instead.')

  # Detect variable-length arrays.
  match = Match(r'\s*(.+::)?(\w+) [a-z]\w*\[(.+)];', line)
  if (match and match.group(2) != 'return' and match.group(2) != 'delete' and
      match.group(3).find(']') == -1):
    # Split the size using space and arithmetic operators as delimiters.
    # If any of the resulting tokens are not compile time constants then
    # report the error.
    tokens = re.split(r'\s|\+|\-|\*|\/|<<|>>]', match.group(3))
    is_const = True
    skip_next = False
    for tok in tokens:
      if skip_next:
        skip_next = False
        continue

      if Search(r'sizeof\(.+\)', tok): continue
      if Search(r'arraysize\(\w+\)', tok): continue

      tok = tok.lstrip('(')
      tok = tok.rstrip(')')
      if not tok: continue
      if Match(r'\d+', tok): continue
      if Match(r'0[xX][0-9a-fA-F]+', tok): continue
      if Match(r'k[A-Z0-9]\w*', tok): continue
      if Match(r'(.+::)?k[A-Z0-9]\w*', tok): continue
      if Match(r'(.+::)?[A-Z][A-Z0-9_]*', tok): continue
      # A catch all for tricky sizeof cases, including 'sizeof expression',
      # 'sizeof(*type)', 'sizeof(const type)', 'sizeof(struct StructName)'
      # requires skipping the next token becasue we split on ' ' and '*'.
      if tok.startswith('sizeof'):
        skip_next = True
        continue
      is_const = False
      break
    if not is_const:
      error(filename, linenum, 'runtime/arrays', 1,
            'Do not use variable-length arrays.  Use an appropriately named '
            "('k' followed by CamelCase) compile-time constant for the size.")

  # If DISALLOW_EVIL_CONSTRUCTORS, DISALLOW_COPY_AND_ASSIGN, or
  # DISALLOW_IMPLICIT_CONSTRUCTORS is present, then it should be the last thing
  # in the class declaration.
  match = Match(
      (r'\s*'
       r'(DISALLOW_(EVIL_CONSTRUCTORS|COPY_AND_ASSIGN|IMPLICIT_CONSTRUCTORS))'
       r'\(.*\);$'),
      line)
  if match and linenum + 1 < clean_lines.NumLines():
    next_line = clean_lines.elided[linenum + 1]
    if not Search(r'^\s*};', next_line):
      error(filename, linenum, 'readability/constructors', 3,
            match.group(1) + ' should be the last thing in the class')

  # Check for use of unnamed namespaces in header files.  Registration
  # macros are typically OK, so we allow use of "namespace {" on lines
  # that end with backslashes.
  if (file_extension == 'h'
      and Search(r'\bnamespace\s*{', line)
      and line[-1] != '\\'):
    error(filename, linenum, 'build/namespaces', 4,
          'Do not use unnamed namespaces in header files.  See '
          'http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Namespaces'
          ' for more information.')


def CheckCStyleCast(filename, linenum, line, raw_line, cast_type, pattern,
                    error):
  """Checks for a C-style cast by looking for the pattern.

  This also handles sizeof(type) warnings, due to similarity of content.

  Args:
    filename: The name of the current file.
    linenum: The number of the line to check.
    line: The line of code to check.
    raw_line: The raw line of code to check, with comments.
    cast_type: The string for the C++ cast to recommend.  This is either
      reinterpret_cast or static_cast, depending.
    pattern: The regular expression used to find C-style casts.
    error: The function to call with any errors found.
  """
  match = Search(pattern, line)
  if not match:
    return

  # e.g., sizeof(int)
  sizeof_match = Match(r'.*sizeof\s*$', line[0:match.start(1) - 1])
  if sizeof_match:
    error(filename, linenum, 'runtime/sizeof', 1,
          'Using sizeof(type).  Use sizeof(varname) instead if possible')
    return

  remainder = line[match.end(0):]

  # The close paren is for function pointers as arguments to a function.
  # eg, void foo(void (*bar)(int));
  # The semicolon check is a more basic function check; also possibly a
  # function pointer typedef.
  # eg, void foo(int); or void foo(int) const;
  # The equals check is for function pointer assignment.
  # eg, void *(*foo)(int) = ...
  #
  # Right now, this will only catch cases where there's a single argument, and
  # it's unnamed.  It should probably be expanded to check for multiple
  # arguments with some unnamed.
  function_match = Match(r'\s*(\)|=|(const)?\s*(;|\{|throw\(\)))', remainder)
  if function_match:
    if (not function_match.group(3) or
        function_match.group(3) == ';' or
        raw_line.find('/*') < 0):
      error(filename, linenum, 'readability/function', 3,
            'All parameters should be named in a function')
    return

  # At this point, all that should be left is actual casts.
  error(filename, linenum, 'readability/casting', 4,
        'Using C-style cast.  Use %s<%s>(...) instead' %
        (cast_type, match.group(1)))


_HEADERS_CONTAINING_TEMPLATES = (
    ('<deque>', ('deque',)),
    ('<functional>', ('unary_function', 'binary_function',
                      'plus', 'minus', 'multiplies', 'divides', 'modulus',
                      'negate',
                      'equal_to', 'not_equal_to', 'greater', 'less',
                      'greater_equal', 'less_equal',
                      'logical_and', 'logical_or', 'logical_not',
                      'unary_negate', 'not1', 'binary_negate', 'not2',
                      'bind1st', 'bind2nd',
                      'pointer_to_unary_function',
                      'pointer_to_binary_function',
                      'ptr_fun',
                      'mem_fun_t', 'mem_fun', 'mem_fun1_t', 'mem_fun1_ref_t',
                      'mem_fun_ref_t',
                      'const_mem_fun_t', 'const_mem_fun1_t',
                      'const_mem_fun_ref_t', 'const_mem_fun1_ref_t',
                      'mem_fun_ref',
                     )),
    ('<limits>', ('numeric_limits',)),
    ('<list>', ('list',)),
    ('<map>', ('map', 'multimap',)),
    ('<memory>', ('allocator',)),
    ('<queue>', ('queue', 'priority_queue',)),
    ('<set>', ('set', 'multiset',)),
    ('<stack>', ('stack',)),
    ('<string>', ('char_traits', 'basic_string',)),
    ('<utility>', ('pair',)),
    ('<vector>', ('vector',)),

    # gcc extensions.
    # Note: std::hash is their hash, ::hash is our hash
    ('<hash_map>', ('hash_map', 'hash_multimap',)),
    ('<hash_set>', ('hash_set', 'hash_multiset',)),
    ('<slist>', ('slist',)),
    )

_HEADERS_ACCEPTED_BUT_NOT_PROMOTED = {
    # We can trust with reasonable confidence that map gives us pair<>, too.
    'pair<>': ('map', 'multimap', 'hash_map', 'hash_multimap')
}

_RE_PATTERN_STRING = re.compile(r'\bstring\b')

_re_pattern_algorithm_header = []
for _template in ('copy', 'max', 'min', 'min_element', 'sort', 'swap',
                  'transform'):
  # Match max<type>(..., ...), max(..., ...), but not foo->max, foo.max or
  # type::max().
  _re_pattern_algorithm_header.append(
      (re.compile(r'[^>.]\b' + _template + r'(<.*?>)?\([^\)]'),
       _template,
       '<algorithm>'))

_re_pattern_templates = []
for _header, _templates in _HEADERS_CONTAINING_TEMPLATES:
  for _template in _templates:
    _re_pattern_templates.append(
        (re.compile(r'(\<|\b)' + _template + r'\s*\<'),
         _template + '<>',
         _header))


def CheckForIncludeWhatYouUse(filename, clean_lines, include_state, error):
  """Reports for missing stl includes.

  This function will output warnings to make sure you are including the headers
  necessary for the stl containers and functions that you use. We only give one
  reason to include a header. For example, if you use both equal_to<> and
  less<> in a .h file, only one (the latter in the file) of these will be
  reported as a reason to include the <functional>.

  We only check headers. We do not check inside cc-files. .cc files should be
  able to depend on their respective header files for includes.  However, there
  is no simple way of producing this logic here.

  Args:
    filename: The name of the current file.
    clean_lines: A CleansedLines instance containing the file.
    include_state: An _IncludeState instance.
    error: The function to call with any errors found.
  """
  if filename.endswith('.cc'):
    return

  required = {}  # A map of header name to linenumber and the template entity.
                 # Example of required: { '<functional>': (1219, 'less<>') }

  for linenum in xrange(clean_lines.NumLines()):
    line = clean_lines.elided[linenum]
    if not line or line[0] == '#':
      continue

    # String is special -- it is a non-templatized type in STL.
    if _RE_PATTERN_STRING.search(line):
      required['<string>'] = (linenum, 'string')

    for pattern, template, header in _re_pattern_algorithm_header:
      if pattern.search(line):
        required[header] = (linenum, template)

    # The following function is just a speed up, no semantics are changed.
    if not '<' in line:  # Reduces the cpu time usage by skipping lines.
      continue

    for pattern, template, header in _re_pattern_templates:
      if pattern.search(line):
        required[header] = (linenum, template)

  # All the lines have been processed, report the errors found.
  for required_header_unstripped in required:
    template = required[required_header_unstripped][1]
    if template in _HEADERS_ACCEPTED_BUT_NOT_PROMOTED:
      headers = _HEADERS_ACCEPTED_BUT_NOT_PROMOTED[template]
      if [True for header in headers if header in include_state]:
        continue
    if required_header_unstripped.strip('<>"') not in include_state:
      error(filename, required[required_header_unstripped][0],
            'build/include_what_you_use', 4,
            'Add #include ' + required_header_unstripped + ' for ' + template)


def ProcessLine(filename, file_extension,
                clean_lines, line, include_state, function_state,
                class_state, error):
  """Processes a single line in the file.

  Args:
    filename: Filename of the file that is being processed.
    file_extension: The extension (dot not included) of the file.
    clean_lines: An array of strings, each representing a line of the file,
                 with comments stripped.
    line: Number of line being processed.
    include_state: An _IncludeState instance in which the headers are inserted.
    function_state: A _FunctionState instance which counts function lines, etc.
    class_state: A _ClassState instance which maintains information about
                 the current stack of nested class declarations being parsed.
    error: A callable to which errors are reported, which takes 4 arguments:
           filename, line number, error level, and message

  """
  raw_lines = clean_lines.raw_lines
  CheckForFunctionLengths(filename, clean_lines, line, function_state, error)
  if Search(r'\bNOLINT\b', raw_lines[line]):  # ignore nolint lines
    return
  CheckForMultilineCommentsAndStrings(filename, clean_lines, line, error)
  CheckStyle(filename, clean_lines, line, file_extension, error)
  CheckLanguage(filename, clean_lines, line, file_extension, include_state,
                error)
  CheckForNonStandardConstructs(filename, clean_lines, line,
                                class_state, error)
  CheckPosixThreading(filename, clean_lines, line, error)


def ProcessFileData(filename, file_extension, lines, error):
  """Performs lint checks and reports any errors to the given error function.

  Args:
    filename: Filename of the file that is being processed.
    file_extension: The extension (dot not included) of the file.
    lines: An array of strings, each representing a line of the file, with the
           last element being empty if the file is termined with a newline.
    error: A callable to which errors are reported, which takes 4 arguments:
  """
  lines = (['// marker so line numbers and indices both start at 1'] + lines +
           ['// marker so line numbers end in a known way'])

  include_state = _IncludeState()
  function_state = _FunctionState()
  class_state = _ClassState()

  CheckForCopyright(filename, lines, error)

  if file_extension == 'h':
    CheckForHeaderGuard(filename, lines, error)

  RemoveMultiLineComments(filename, lines, error)
  clean_lines = CleansedLines(lines)
  for line in xrange(clean_lines.NumLines()):
    ProcessLine(filename, file_extension, clean_lines, line,
                include_state, function_state, class_state, error)
  class_state.CheckFinished(filename, error)

  CheckForIncludeWhatYouUse(filename, clean_lines, include_state, error)

  # We check here rather than inside ProcessLine so that we see raw
  # lines rather than "cleaned" lines.
  CheckForUnicodeReplacementCharacters(filename, lines, error)

  CheckForNewlineAtEOF(filename, lines, error)


def ProcessFile(filename, vlevel):
  """Does google-lint on a single file.

  Args:
    filename: The name of the file to parse.

    vlevel: The level of errors to report.  Every error of confidence
    >= verbose_level will be reported.  0 is a good default.
  """

  _SetVerboseLevel(vlevel)

  try:
    # Support the UNIX convention of using "-" for stdin.  Note that
    # we are not opening the file with universal newline support
    # (which codecs doesn't support anyway), so the resulting lines do
    # contain trailing '\r' characters if we are reading a file that
    # has CRLF endings.
    # If after the split a trailing '\r' is present, it is removed
    # below. If it is not expected to be present (i.e. os.linesep !=
    # '\r\n' as in Windows), a warning is issued below if this file
    # is processed.

    if filename == '-':
      lines = codecs.StreamReaderWriter(sys.stdin,
                                        codecs.getreader('utf8'),
                                        codecs.getwriter('utf8'),
                                        'replace').read().split('\n')
    else:
      lines = codecs.open(filename, 'r', 'utf8', 'replace').read().split('\n')

    carriage_return_found = False
    # Remove trailing '\r'.
    for linenum in range(len(lines)):
      if lines[linenum].endswith('\r'):
        lines[linenum] = lines[linenum].rstrip('\r')
        carriage_return_found = True

  except IOError:
    sys.stderr.write(
        "Skipping input '%s': Can't open for reading\n" % filename)
    return

  # Note, if no dot is found, this will give the entire filename as the ext.
  file_extension = filename[filename.rfind('.') + 1:]

  # When reading from stdin, the extension is unknown, so no cpplint tests
  # should rely on the extension.
  if (filename != '-' and file_extension != 'cc' and file_extension != 'h'
      and file_extension != 'cpp'):
    sys.stderr.write('Ignoring %s; not a .cc or .h file\n' % filename)
  else:
    ProcessFileData(filename, file_extension, lines, Error)
    if carriage_return_found and os.linesep != '\r\n':
      # Use 0 for linenum since outputing only one error for potentially
      # several lines.
      Error(filename, 0, 'whitespace/newline', 1,
            'One or more unexpected \\r (^M) found;'
            'better to use only a \\n')

  sys.stderr.write('Done processing %s\n' % filename)


def PrintUsage(message):
  """Prints a brief usage string and exits, optionally with an error message.

  Args:
    message: The optional error message.
  """
  sys.stderr.write(_USAGE)
  if message:
    sys.exit('\nFATAL ERROR: ' + message)
  else:
    sys.exit(1)


def PrintCategories():
  """Prints a list of all the error-categories used by error messages.

  These are the categories used to filter messages via --filter.
  """
  sys.stderr.write(_ERROR_CATEGORIES)
  sys.exit(0)


def ParseArguments(args):
  """Parses the command line arguments.

  This may set the output format and verbosity level as side-effects.

  Args:
    args: The command line arguments:

  Returns:
    The list of filenames to lint.
  """
  try:
    (opts, filenames) = getopt.getopt(args, '', ['help', 'output=', 'verbose=',
                                                 'filter='])
  except getopt.GetoptError:
    PrintUsage('Invalid arguments.')

  verbosity = _VerboseLevel()
  output_format = _OutputFormat()
  filters = ''

  for (opt, val) in opts:
    if opt == '--help':
      PrintUsage(None)
    elif opt == '--output':
      if not val in ('emacs', 'vs7'):
        PrintUsage('The only allowed output formats are emacs and vs7.')
      output_format = val
    elif opt == '--verbose':
      verbosity = int(val)
    elif opt == '--filter':
      filters = val
      if not filters:
        PrintCategories()

  if not filenames:
    PrintUsage('No files were specified.')

  _SetOutputFormat(output_format)
  _SetVerboseLevel(verbosity)
  _SetFilters(filters)

  return filenames


def main():
  filenames = ParseArguments(sys.argv[1:])

  # Change stderr to write with replacement characters so we don't die
  # if we try to print something containing non-ASCII characters.
  sys.stderr = codecs.StreamReaderWriter(sys.stderr,
                                         codecs.getreader('utf8'),
                                         codecs.getwriter('utf8'),
                                         'replace')

  _cpplint_state.ResetErrorCount()
  for filename in filenames:
    ProcessFile(filename, _cpplint_state.verbose_level)
  sys.stderr.write('Total errors found: %d\n' % _cpplint_state.error_count)
  sys.exit(_cpplint_state.error_count > 0)


if __name__ == '__main__':
  main()