Create the Next Generation of depot_tools. Eh.

depot_tools/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.
+_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.
+    """
+    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:
+  """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 google3
+  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)
+    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
+    # Don't look too far for the function body. Lint might be mistaken about
+    # whether it's a function definition.
+    for start_linenum in xrange(linenum,
+                                min(linenum+100, 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:
+      # 50 lines after finding a line deemed to start a function
+      # definition, no body for the function was found. A macro
+      # invocation with no terminating semicolon could trigger this.
+      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)
+    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
+    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.
+  if not line.startswith('#include') and not is_header_guard:
+    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', 'sort', 'swap'):
+  # 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 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()