[Boost-users] [Spirit]Kleene star with arguments having optional attributes.

Subject: [Boost-users] [Spirit]Kleene star with arguments having optional attributes.
From: Paul Graphov (graphov_at_[hidden])
Date: 2010-11-24 05:06:27

Hello Boost Users,

I'm now building configuration file parser with Boost.Spirit.
I have a little trouble understanding how this parser builds attribute:

It was supposed to parse strings throwing 'p' letter away.

*((qi::char_ - 'p') | qi::lit('p'))

attribute of qi::lit is Unused.
attribute of (qi::char_ - 'p') is char.

so attribute of ((qi::char_ - 'p') | qi::lit('p')) should be optional<char>
that
is uninitialized optional value when matched against character 'p'

After applying Kleene star it should became vector<optional<char> >.
It seems to be compatible with string (at least it compiles). But 'p'
letters
are not thrown away.

The full example is here: http://pastebin.com/tCMw22Zy

The output of that example is:
Full parsing
Result: "abcpppdef"

Is it possible to make such a parser without using semantic actions
like [bind(&string::append, res, _1)] or something like that, which seem
to be less elegant solution.

Thanks!