depot_tools: modify cpplint.py to allow CPPLINT.cfg overrides

cpplint.py

Index: cpplint.py
diff --git a/cpplint.py b/cpplint.py
index 92384dc37181f6e982d0e6f74afe93d393c5de19..65e2b4259217663e6c50ad2d4e700aec80938419 100755
--- a/cpplint.py
+++ b/cpplint.py
@@ -133,6 +133,33 @@ Syntax: cpplint.py [--verbose=#] [--output=vs7] [--filter=-x,+y,...]
 
       Examples:
         --extensions=hpp,cpp
+
+    cpplint.py supports per-directory configurations specified in CPPLINT.cfg
+    files. CPPLINT.cfg file can contain a number of key=value pairs.
+    Currently the following options are supported:
+
+      filter=+filter1,-filter2,...
+      exclude_files=regex
+
+    The "filter" option is similar in function to --filter flag. It specifies
+    message filters in addition to the |_DEFAULT_FILTERS| and those specified
+    through --filter command-line flag.
+
+    "exclude_files" allows to specify a regular expression to be matched against
+    a file name. If the expression matches, the file is skipped and not run
+    through liner.
+
+    CPPLINT.cfg has an effect on files in the same directory and all
+    sub-directories, unless overridden by a nested configuration file.
+
+      Example file:
+        filter=-build/include_order,+build/include_alpha
+        exclude_files=.*\.cc
+
+    The above example disables build/include_order warning and enables
+    build/include_alpha as well as excludes all .cc from being
+    processed by linter, in the current directory (where the .cfg
+    file is located) and all sub-directories.
 """
 
 # We categorize each error message we print.  Here are the categories.
@@ -682,6 +709,8 @@ class _CppLintState(object):
     self.error_count = 0    # global count of reported errors
     # filters to apply when emitting error messages
     self.filters = _DEFAULT_FILTERS[:]
+    # backup of filter list. Used to restore the state after each file.
+    self._filters_backup = self.filters[:]
     self.counting = 'total'  # In what way are we counting errors?
     self.errors_by_category = {}  # string to int dict storing error counts
 
@@ -720,6 +749,10 @@ class _CppLintState(object):
     """
     # Default filters always have less priority than the flag ones.
     self.filters = _DEFAULT_FILTERS[:]
+    self.AddFilters(filters)
+
+  def AddFilters(self, filters):
+    """ Adds more filters to the existing list of error-message filters. """
     for filt in filters.split(','):
       clean_filt = filt.strip()
       if clean_filt:
@@ -729,6 +762,14 @@ class _CppLintState(object):
         raise ValueError('Every filter in --filters must start with + or -'
                          ' (%s does not)' % filt)
 
+  def BackupFilters(self):
+    """ Saves the current filter list to backup storage."""
+    self._filters_backup = self.filters[:]
+
+  def RestoreFilters(self):
+    """ Restores filters previously backed up."""
+    self.filters = self._filters_backup[:]
+
   def ResetErrorCounts(self):
     """Sets the module's error statistic back to zero."""
     self.error_count = 0
@@ -796,6 +837,25 @@ def _SetFilters(filters):
   """
   _cpplint_state.SetFilters(filters)
 
+def _AddFilters(filters):
+  """Adds more filter overrides.
+ 
+  Unlike _SetFilters, this function does not reset the current list of filters
+  available.
+
+  Args:
+    filters: A string of comma-separated filters (eg "whitespace/indent").
+             Each filter should start with + or -; else we die.
+  """
+  _cpplint_state.AddFilters(filters)
+
+def _BackupFilters():
+  """ Saves the current filter list to backup storage."""
+  _cpplint_state.BackupFilters()
+
+def _RestoreFilters():
+  """ Restores filters previously backed up."""
+  _cpplint_state.RestoreFilters()
 
 class _FunctionState(object):
   """Tracks current function name and the number of lines in its body."""
@@ -5328,7 +5388,7 @@ def ProcessLine(filename, file_extension, clean_lines, line,
   CheckDefaultLambdaCaptures(filename, clean_lines, line, error)
   for check_fn in extra_check_functions:
     check_fn(filename, clean_lines, line, error)
-	
+
 def FlagCxx11Features(filename, clean_lines, linenum, error):
   """Flag those c++11 features that we only allow in certain places.
 
@@ -5424,6 +5484,83 @@ def ProcessFileData(filename, file_extension, lines, error,
 
   CheckForNewlineAtEOF(filename, lines, error)
 
+def GetConfigOverrideFiles(filename):
+  """ Looks for CPPLINT.cfg files in the directory containing |filename| and

[sosa, 2014/07/23 20:25:42]

docstring issue

[Alex Vakulenko (Google), 2014/07/23 20:44:32]

Done.

+  its parents and returns a list of configuration files found.
+
+  Args:
+    filename: The name of the file being processed by the linter.
+  """
+
+  cfg_override_files = []
+  abs_path = os.path.abspath(os.path.dirname(filename))
+
+  while True:
+    file = os.path.join(abs_path, "CPPLINT.cfg")
+    if os.path.isfile(file):
+      cfg_override_files.append(file)
+    parent = os.path.dirname(abs_path)
+    if parent == abs_path:
+      break
+    abs_path = parent
+
+  return reversed(cfg_override_files)
+
+def ProcessConfigFile(cfg_file, filename):
+  """ Loads the configuration file and processes the config overrides.
+
+  Args:
+    cfg_file: config file to process
+    filename: The name of the file being processed by the linter.
+
+  Returns:
+    false if the current |filename| should not be processed further.
+  """
+
+  try:
+    with open(cfg_file) as file_handle:
+      for line in file_handle:
+        line, _, _ = line.partition('#')  # Remove comments.
+        if line.strip():
+          name, _, val = line.partition('=')
+          name = name.strip()
+          val = val.strip()
+          if name == 'filter':
+            _AddFilters(val)
+          elif name == 'exclude_files':
+            pattern = re.compile(val)
+            if pattern.match(filename):
+              sys.stderr.write('Ignoring %s; file excluded by (%s)\n' %
+                               (filename, cfg_file))
+              return False
+          else:
+            sys.stderr.write('Invalid configuration option (%s) in file %s\n' %
+                             (name, cfg_file))
+
+  except IOError:
+    sys.stderr.write(
+        "Skipping config file '%s': Can't open for reading\n" % cfg_file)
+    _RestoreFilters()
+    return True
+
+  return True
+
+
+def ProcessConfigOverrides(cfg_override_files, filename):
+  """ Loads the configuration files and processes the config overrides.
+
+  Args:
+    cfg_override_files: list of cfg files to process
+    filename: The name of the file being processed by the linter.
+
+  Returns:
+    false if the current |filename| should not be processed further.
+  """
+  for cfg_file in cfg_override_files:
+    if not ProcessConfigFile(cfg_file, filename):
+      return False
+
+  return True
 
 def ProcessFile(filename, vlevel, extra_check_functions=[]):
   """Does google-lint on a single file.
@@ -5440,6 +5577,12 @@ def ProcessFile(filename, vlevel, extra_check_functions=[]):
   """
 
   _SetVerboseLevel(vlevel)
+  _BackupFilters()
+
+  cfg_override_files = GetConfigOverrideFiles(filename)
+  if not ProcessConfigOverrides(cfg_override_files, filename):
+    _RestoreFilters()
+    return
 
   lf_lines = []
   crlf_lines = []
@@ -5471,6 +5614,7 @@ def ProcessFile(filename, vlevel, extra_check_functions=[]):
   except IOError:
     sys.stderr.write(
         "Skipping input '%s': Can't open for reading\n" % filename)
+    _RestoreFilters()
     return
 
   # Note, if no dot is found, this will give the entire filename as the ext.
@@ -5504,6 +5648,7 @@ def ProcessFile(filename, vlevel, extra_check_functions=[]):
               'Unexpected \\r (^M) found; better to use only \\n')
 
   sys.stderr.write('Done processing %s\n' % filename)
+  _RestoreFilters()
 
 
 def PrintUsage(message):