Added an extensible set() for header extensions

Using flag name to --headers as it makes more sense
Added the extensions option to the CPPLINT.cfg option file

Author: Marco Massenzio

cpplint.py

@@ -61,6 +61,7 @@
 Syntax: cpplint.py [--verbose=#] [--output=vs7] [--filter=-x,+y,...]
                    [--counting=total|toplevel|detailed] [--root=subdir]
                    [--linelength=digits]
+                   [--headers=ext1,ext2]
         <file> [file] ...
 
   The style guidelines this tries to follow are those in
@@ -139,6 +140,13 @@
       Examples:
         --extensions=hpp,cpp
 
+    headers=extension,extension,...
+      The allowed header extensions that cpplint will consider to be header files
+      (by default, only .h files will be assumed to be headers)
+
+      Examples:
+        --headers=h,hpp
+
     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:
@@ -519,6 +527,12 @@ def u(x):
     itervalues = dict.values
     iteritems = dict.items
 
+# Files with any of these extensions are considered to be
+# header files (and will undergo different style checks).
+# This set can be extended by using the --headers
+# option (also supported in CPPLINT.cfg)
+_header_extensions = set(['h'])
+
 def ParseNolintSuppressions(filename, raw_line, linenum, error):
   """Updates the global list of error-suppressions.
 
@@ -1798,21 +1812,22 @@ def CheckHeaderFileIncluded(filename, include_state, error):
     return
 
   fileinfo = FileInfo(filename)
-  headerfile = filename[0:len(filename) - 2] + 'h'
-  if not os.path.exists(headerfile):
-    return
-  headername = FileInfo(headerfile).RepositoryName()
-  first_include = 0
-  for section_list in include_state.include_list:
-    for f in section_list:
-      if headername in f[0] or f[0] in headername:
-        return
-      if not first_include:
-        first_include = f[1]
+  for ext in _header_extensions:
+      headerfile = filename[0:len(filename) - 2] + ext
+      if not os.path.exists(headerfile):
+        continue
+      headername = FileInfo(headerfile).RepositoryName()
+      first_include = None
+      for section_list in include_state.include_list:
+        for f in section_list:
+          if headername in f[0] or f[0] in headername:
+            return
+          if not first_include:
+            first_include = f[1]
 
-  error(filename, first_include, 'build/include', 5,
-        '%s should include its header file %s' % (fileinfo.RepositoryName(),
-                                                  headername))
+      error(filename, first_include, 'build/include', 5,
+            '%s should include its header file %s' % (fileinfo.RepositoryName(),
+                                                      headername))
 
 
 def CheckForBadCharacters(filename, lines, error):
@@ -4453,7 +4468,7 @@ def CheckStyle(filename, clean_lines, linenum, file_extension, nesting_state,
 
   # Check if the line is a header guard.
   is_header_guard = False
-  if file_extension == 'h':
+  if file_extension in _header_extensions:
     cppvar = GetHeaderGuardCPPVariable(filename)
     if (line.startswith('#ifndef %s' % cppvar) or
         line.startswith('#define %s' % cppvar) or
@@ -4825,7 +4840,7 @@ def CheckLanguage(filename, clean_lines, linenum, file_extension,
   CheckGlobalStatic(filename, clean_lines, linenum, error)
   CheckPrintf(filename, clean_lines, linenum, error)
 
-  if file_extension == 'h':
+  if file_extension in _header_extensions:
     # TODO(unknown): check that 1-arg constructors are explicit.
     #                How to tell it's a constructor?
     #                (handled in CheckForNonStandardConstructs for now)
@@ -4932,7 +4947,7 @@ def CheckLanguage(filename, clean_lines, linenum, file_extension,
   # 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'
+  if (file_extension in _header_extensions
       and Search(r'\bnamespace\s*{', line)
       and line[-1] != '\\'):
     error(filename, linenum, 'build/namespaces', 4,
@@ -6048,7 +6063,7 @@ def ProcessFileData(filename, file_extension, lines, error,
   RemoveMultiLineComments(filename, lines, error)
   clean_lines = CleansedLines(lines)
 
-  if file_extension == 'h':
+  if file_extension in _header_extensions:
     CheckForHeaderGuard(filename, clean_lines, error)
 
   for line in range(clean_lines.NumLines()):
@@ -6128,6 +6143,15 @@ def ProcessConfigOverrides(filename):
                 _line_length = int(val)
             except ValueError:
                 sys.stderr.write('Line length must be numeric.')
+          elif name == 'extensions':
+              global _valid_extensions
+              try:
+                  extensions = [ext.strip() for ext in val.split(',')]
+                  _valid_extensions = _valid_extensions.union(set(extensions))
+              except ValueError:
+                  sys.stderr.write('Extensions should be a comma-separated list of values;'
+                                   'for example: extensions=hpp,cpp\n'
+                                   'This could not be parsed: "%s"' % (values,))
           else:
             sys.stderr.write(
                 'Invalid configuration option (%s) in file %s\n' %
@@ -6274,7 +6298,8 @@ def ParseArguments(args):
                                                  'filter=',
                                                  'root=',
                                                  'linelength=',
-                                                 'extensions='])
+                                                 'extensions=',
+                                                 'headers='])
   except getopt.GetoptError:
     PrintUsage('Invalid arguments.')
 
@@ -6315,6 +6340,12 @@ def ParseArguments(args):
           _valid_extensions = set(val.split(','))
       except ValueError:
           PrintUsage('Extensions must be comma seperated list.')
+    elif opt == '--headers':
+      global _header_extensions
+      try:
+          _header_extensions = set(val.split(','))
+      except ValueError:
+          PrintUsage('Extensions must be comma seperated list.')
 
   if not filenames:
     PrintUsage('No files were specified.')