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..7e4217c0d2bf51e3c5e6251271581dd944e7a1a4 100755
--- a/cpplint.py
+++ b/cpplint.py
@@ -133,6 +133,38 @@ 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:
+
+      set noparent
+      filter=+filter1,-filter2,...
+      exclude_files=regex
+
+    "set noparent" option prevents cpplint from traversing directory tree
+    upwards looking for more .cfg files in parent directories. This option
+    is usually placed in the top-level project directory.
+
+    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 +714,8 @@ 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 +754,10 @@ 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 +767,14 @@ 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 +842,25 @@ 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 +5393,7 @@ 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 +5489,71 @@ def ProcessFileData(filename, file_extension, lines, error,
 
   CheckForNewlineAtEOF(filename, lines, error)
 
+def ProcessConfigOverrides(filename):
+  """ Loads the configuration files and processes the config overrides.
+
+  Args:
+    filename: The name of the file being processed by the linter.
+
+  Returns:
+    False if the current |filename| should not be processed further.
+  """
+
+  abs_filename = os.path.abspath(filename)
+  cfg_filters = []
+  keep_looking = True
+  while keep_looking:
+    abs_path, base_name = os.path.split(abs_filename)
+    if not base_name:
+        break  # Reached the root directory.

[sosa, 2014/07/28 20:28:45]

Too much indentation

+    cfg_file = os.path.join(abs_path, "CPPLINT.cfg")
+    if os.path.isfile(cfg_file):

[sosa, 2014/07/28 20:28:45]

This is very nesty. I'd consider negating these if's with continue so you don't
have to indent as much. I'll leave it up to you (this one here and the
line.strip below are a couple examples).

+      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 == 'set noparent':
+                keep_looking = False
+              elif name == 'filter':
+                cfg_filters.append(val)
+              elif name == 'exclude_files':
+                # When matching exclude_files pattern, use the base_name of
+                # the current file name or the directory name we are processing.
+                # For example, if we are checking for lint errors /foo/bar/baz
+                # and we found the .cfg file in the parent directory (/foo),
+                # then the config file's "exclude_files" filter is meant to
+                # be checked against "bar" and not "baz" or "bar/baz".
+                if base_name:
+                  pattern = re.compile(val)
+                  if pattern.match(base_name):
+                    sys.stderr.write('Ignoring "%s": file excluded by "%s". '
+                                     'File path component "%s" matches '
+                                     'pattern "%s"\n' %
+                                     (filename, cfg_file, base_name, val))
+                    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)
+        keep_looking = False
+
+    abs_filename = abs_path
+
+  # Apply all the accumulated filters in reverse order (top-level directory
+  # config options having the least priority).
+  for filter in reversed(cfg_filters):
+     _AddFilters(filter)
+
+  return True
+
 
 def ProcessFile(filename, vlevel, extra_check_functions=[]):
   """Does google-lint on a single file.
@@ -5440,6 +5570,11 @@ def ProcessFile(filename, vlevel, extra_check_functions=[]):
   """
 
   _SetVerboseLevel(vlevel)
+  _BackupFilters()
+
+  if not ProcessConfigOverrides(filename):
+    _RestoreFilters()
+    return
 
   lf_lines = []
   crlf_lines = []
@@ -5471,6 +5606,7 @@ 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 +5640,7 @@ 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):