Re: C++11/14

[Hans Aberg]

> On 19 Jan 2015, at 18:35, Akim Demaille <a...@lrde.epita.fr> wrote:
> 
>> Le 19 janv. 2015 à 14:28, Hans Aberg <haber...@telia.com> a écrit :
>> 
>> So it may suffice to have move constructors in the class variant.
> 
> Right.  With #if around them :)

I succeeded in replacing all copying with move operations in the calc++ 
example! It is a bit more:

1. In the grammar .yy file, assignments in the actions must be written $$ = 
std::move(). so it becomes
exp:
    exp "+" exp   { $$ = $1 + $3; }
  | exp "-" exp   { $$ = $1 - $3; }
  | exp "*" exp   { $$ = $1 * $3; }
  | exp "/" exp   { $$ = $1 / $3; }
  | "(" exp ")"   { $$ = std::move($2); }
  | "identifier"  { $$ = std::move(driver.variables[$1]); }
  | "number"      { $$ = std::move($1); };

2. One needs to flip in && and std::move in a number of places in 
calc++-parser.hh:

    /// Construct and fill.
    template <typename T>
    variant (const T& t)
      : yytypeid_ (&typeid (T))
    {
      YYASSERT (sizeof (T) <= S);
      new (yyas_<T> ()) T (t);
    }

    template <typename T>
    variant (T&& t)
      : yytypeid_ (&typeid (T))
    {
      YYASSERT (sizeof (T) <= S);
      new (yyas_<T> ()) T (std::move(t));
    }


// Bug: first does not have &:
  basic_symbol (typename Base::kind_type t, const Int& v, const location_type& 
l);
  basic_symbol (typename Base::kind_type t, Int&& v, const location_type& l);


    static inline
    symbol_type
    make_NUMBER (const Int& v, const location_type& l);

    static inline
    symbol_type
    make_NUMBER (Int&& v, const location_type& l);


   template <typename Base>
  calcxx_parser::basic_symbol<Base>::basic_symbol (typename Base::kind_type t, 
const Int& v, const location_type& l)
    : Base (t)
    , value (v)
    , location (l)
  {}

  template <typename Base>
  calcxx_parser::basic_symbol<Base>::basic_symbol (typename Base::kind_type t, 
Int&& v, const location_type& l)
    : Base (t)
    , value (std::move(v))
    , location (l)
  {}


  calcxx_parser::symbol_type
  calcxx_parser::make_NUMBER (const Int& v, const location_type& l)
  {
    return symbol_type (token::TOK_NUMBER, v, l);
  }

  calcxx_parser::symbol_type
  calcxx_parser::make_NUMBER (Int&& v, const location_type& l)
  {
    return symbol_type (token::TOK_NUMBER, std::move(v), l);
  }