C++/boost Style Indenter

This indenter (initially) was designed to help code typing in a boost::mpl style (i.e. w/ leading comma in formatted parameters list). One may read rationale of such approach in the "C++ Template Metaprogramming: Concepts, Tools, and Techniques from Boost and Beyond" by David Abrahams and Aleksey Gurtovoy. It is really easy to miss a comma when "calling" templates and it would leads to really complicated compile errors. This technique helps to visually control syntax in a stricter way.

Example:

typedef typename boost::mpl::eval_if<
    boost::is_same<iter, boost::mpl::end<types_map>::type>
  , boost::mpl::int_<-1>
  , boost::mpl::distance<boost::mpl::begin<types_map>::type, iter>
  >::type type;

In practice I've noticed that this style can be used to format long function calls or even for statements. Actually everything that can be split into several lines could be formatted that way. And yes, it is convenient to have a delimiter (comma, semicolon, whatever) as leading character to make it visually noticeable.

// Inheritance list formatting
struct sample
  : public base_1
  , public base_2
  , ...
  , public base_N
{
    // Parameter list formatting
    void foo(
        const std::string& param_1                      ///< A string parameter
      , double param_2                                  ///< A double parameter
      , ...
      , const some_type& param_N                        ///< An user defined type parameter
      )
    {
        //
        for (
            auto first = std::begin(param_1)
          , last = std::end(param_1)
          ; it != last
          ; ++it
          )
        {
            auto val = check_some_condition()
              ? get_then_value()
              : get_else_value()
              ;
        }
    }
};

It looks unusual for awhile :) but later it become "normal" and easily to read and edit :) Really! When you want to add one more parameter to a function declaration or change order it will takes less typing comparing to "traditional" way :) (especially if you have some help from editor, like moving current line or selected block up/down by hotkey or having indenter like this :)

Features

• support for boost-like formatting style everywhere is possible
• align inline comments to 60th position after typing ‘’//'
• turn'///'into'/// 'or'///< 'depending on comment placement
• take care of inline comments whenENTERpressed on a commented line (before, middle or after comment start)
• turn'/*'or'/**'into multiline (doxygen style) comment
• auto continue multiline comment onENTER
• indent preprocessor directives according nesting level of#if/#endif
• take care about backslashes alignment in preprocessor macro definitions
• append a space after comma or some keywords (likeif,for,while, etc...) oroperator<<`
• align access modifiers

TODO

Initially it was designed as typing helper and nowadays it lacks of align functionality (it's capable to align only few basic constructs). But I have plans to add some logic here to better align source code keeping C++/boost style in mind.