Re: [boost] [local] Help for the Alternatives section

Subject: Re: [boost] [local] Help for the Alternatives section
From: Lorenzo Caminiti (lorcaminiti_at_[hidden])
Date: 2011-05-06 22:59:22

On Fri, May 6, 2011 at 2:07 PM, Lorenzo Caminiti <lorcaminiti_at_[hidden]> wrote:
> On Fri, May 6, 2011 at 1:32 PM, Jeffrey Lee Hellrung, Jr.
> <jeffrey.hellrung_at_[hidden]> wrote:
>> Would "const bind(int)& x" work?

It think yes :) I should be able to support the syntax (also with
optional leading const and optional &):

bind& x // deduced type (with Boost.Typeof)
bind(int)& x // specify type (no Boost.Typeof)

More in general "[const] bind [(type)] [&] name" where "[t]" indicates
that token t is optional.

The basic internal preprocessor tools for that should be:

#include <boost/local/aux_/preprocessor/keyword/bind.hpp>
#include <boost/preprocessor.hpp>
#include <boost/preprocessor/detail/is_unary.hpp>

#define IS_BIND_TYPED_(tokens) \
    BOOST_PP_IS_UNARY(BOOST_LOCAL_AUX_PP_KEYWORD_BIND_REMOVE_FRONT(tokens))

#define IS_BIND_TYPED(tokens) \
    BOOST_PP_IIF(BOOST_LOCAL_AUX_PP_KEYWORD_IS_BIND_FRONT(tokens), \
        IS_BIND_TYPED_ \
    , \
        0 BOOST_PP_TUPLE_EAT(1) \
    )(tokens)

#define BIND_TYPED_EXPR_bind(type) \
    type

#define BIND_TYPED_EXPR_(tokens) \
    BOOST_PP_CAT(BIND_TYPED_EXPR_, tokens)

#define BIND_TYPED_EXPR(tokens) \
    BOOST_PP_IIF(IS_BIND_TYPED(tokens), \
        BIND_TYPED_EXPR_ \
    , \
        tokens BOOST_PP_TUPLE_EAT(1) \
    )(tokens)

#define BIND_TYPED_REMOVE_FRONT_bind(tokens) /* must expand to nothing */

#define BIND_TYPED_REMOVE_FRONT_(tokens) \
    BOOST_PP_CAT(BIND_TYPED_REMOVE_FRONT_, tokens)

#define BIND_TYPED_REMOVE_FRONT(tokens) \
    BOOST_PP_IIF(IS_BIND_TYPED(tokens), \
        BIND_TYPED_REMOVE_FRONT_ \
    , \
        tokens BOOST_PP_TUPLE_EAT(1) \
    )(tokens)

-----
IS_BIND_TYPED( int& x ) // 0
IS_BIND_TYPED( bind& x ) // 0
IS_BIND_TYPED( bind(double)& x ) // 1
-----
BIND_TYPED_EXPR( int& x ) // int& x
BIND_TYPED_EXPR( bind& x ) // bind& x
BIND_TYPED_EXPR( bind(double)& x ) // double& x
-----
BIND_TYPED_REMOVE_FRONT( int& x ) // int& x
BIND_TYPED_REMOVE_FRONT( bind& x ) // bind& x
BIND_TYPED_REMOVE_FRONT( bind(double)& x ) // &x
-----

-- 
Lorenzo