Re: [boost] [ANN] Xpressive 2.0 pre

From: Matias Capeletto (matias.capeletto_at_[hidden])
Date: 2007-06-01 18:35:32

On 6/1/07, Eric Niebler <eric_at_[hidden]> wrote:
> It's a poorly kept secret that I've been adding new features to
> Xpressive on CVS HEAD for a while now. So here are the features already
> implemented (documentation forthcoming) for Xpressive 2.0:
>
> << Semantic Actions >>
>
> Specify code to execute when parts of a regex match, a-la Spirit's
> semantic actions. Eg.: if you want to parse a string of name/value pairs
> into a std::map, you might:
>
>      std::map<std::string, int> result;
>      std::string str("aaa=>1 bbb=>23 ccc=>456");
>
>      // Like "(\\w+)=>(\\d+)":
>      sregex pair = ( (s1= +_w) >> "=>" >> (s2= +_d) )
>                    [ ref(result)[s1] = as<int>(s2) ];
>      sregex rx = pair >> *(+_s >> pair);
>
>      if(regex_match(str, rx))
>      {
>          assert(result["aaa"] == 1);
>          assert(result["bbb"] == 23);
>          assert(result["ccc"] == 456);
>      }
>
> The actions are placed on a queue and executed in order only when the
> regex match succeeds.

Neat! Great work Eric!

I want to use this with my bimaps (I will add a section Bimap and
Boost.Xpressive to my Bimap and Boost.? docs) but I do not know the
correct approach.
Because bimaps have other constraints than maps, I can not provide
operator[] for insertion. I have to use the usual insert.

This works as you said: (operator[] is provided for this bimap
because list_of collection type does not impose additional
constraints)

----------------------------------------------------------------------------
typedef bimap< std::string, list_of< int > > bm_type;
bm_type bm;

std::string str("aaa=>1 bbb=>23 ccc=>456");
sregex pair = ( (s1= +_w) >> "=>" >> (s2= +_d) )
   [ xp::ref(bm.left)[ s1 ] = as<int>(s2) ];
----------------------------------------------------------------------------

But when operator[] is not present I have tried to use insert
but failed.
Being able to parse a file is a nice addition to bimap docs.
I know I have to wait to your docs but I want to know now :)
Can you help me?

Regards
Matias