[Feature] Added Override for indent spaces

Added the ability to override the default 2 spaces per indent to allow for flexibility for the end user to allow for something other than the default.

cpplint/cpplint.py

@@ -142,6 +142,13 @@ Syntax: cpplint.py [--verbose=#] [--output=vs7] [--filter=-x,+y,...]
         --headers=hpp,hxx
         --headers=hpp
 
+    indentspaces=digits
+      This is the allowed number of spaces used for each indent level at the 
+      beginning of a line of code. The default value is 2 spaces.
+
+      Examples:
+        --indentspaces=4
+
     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:
@@ -152,6 +159,7 @@ Syntax: cpplint.py [--verbose=#] [--output=vs7] [--filter=-x,+y,...]
       linelength=80
       root=subdir
       headers=x,y,...
+      indentspaces=2
 
     "set noparent" option prevents cpplint from traversing directory tree
     upwards looking for more .cfg files in parent directories. This option
@@ -552,6 +560,10 @@ _valid_extensions = set(['cc', 'h', 'cpp', 'cu', 'cuh'])
 # This is set by --headers flag.
 _hpp_headers = set(['h'])
 
+# The allowed number of indent spaces for each level of indentation
+# This is set by --indentspaces flag.
+_indent_spaces = 2
+
 # {str, bool}: a map from error categories to booleans which indicate if the
 # category should be suppressed for every line.
 _global_error_suppressions = {}
@@ -4312,6 +4324,7 @@ def CheckStyle(filename, clean_lines, linenum, file_extension, nesting_state,
            Match(r'^\s*""', line))):
     error(filename, linenum, 'whitespace/indent', 3,
           'Weird number of spaces at line-start.  '
+          'Are you using a %d-space indent?' % (_indent_spaces))
 
   if line and line[-1].isspace():
     error(filename, linenum, 'whitespace/end_of_line', 4,
@@ -5951,6 +5964,12 @@ def ProcessConfigOverrides(filename):
             _root = val
           elif name == 'headers':
             ProcessHppHeadersOption(val)
+          elif name == 'indentspaces':
+            global _indent_spaces
+            try:
+                _indent_spaces = int(val)
+            except ValueError:
+                sys.stderr.write('Indent spaces must be numeric.')
           else:
             sys.stderr.write(
                 'Invalid configuration option (%s) in file %s\n' %
@@ -6097,7 +6116,8 @@ def ParseArguments(args):
                                                  'root=',
                                                  'linelength=',
                                                  'extensions=',
-                                                 'headers='])
+                                                 'headers=',
+                                                 'indentspaces'])
   except getopt.GetoptError:
     PrintUsage('Invalid arguments.')
 
@@ -6140,6 +6160,12 @@ def ParseArguments(args):
           PrintUsage('Extensions must be comma seperated list.')
     elif opt == '--headers':
       ProcessHppHeadersOption(val)
+    elif opt == '--indentspaces':
+      global _indent_spaces
+      try:
+          _indent_spaces = int(val)
+      except ValueError:
+          PrintUsage('Indent spaces must be digits.')
 
   if not filenames:
     PrintUsage('No files were specified.')