From: Eric Niebler (eric_at_[hidden])
Date: 2007-04-04 03:18:11
As discussed here recently, Boost.Proto is an expression template (ET)
framework for building domain-specific embedded languages (DSEL). The
purpose of this preliminary submission is to solicit feedback prior to a
full submission (and to buy myself a little time to polish the
docs/tests/examples :-).
<< Marketing Blurb >>
Boost.Proto eases the development of domain-specific embedded languages
(DSELs). Use Proto to define the primitives of your mini-language and
let Proto handle the operator overloading and the construction of the
expression parse tree. Immediately evaluate the expression tree by
passing it a function object. Or transform the expression tree by
defining the meta-grammar of your mini-language, decorated with an
assortment of tree transforms provided by Proto or defined by you. Then
use the meta-grammar to give your users short and readable syntax errors
for invalid expressions! An expression template library developed with
Proto is declarative and readable.
In short, Proto is a DSEL for defining DSELs.
<< Hello, World >>
Here's the required hello world example in proto. It builds an
expression template and evaluates it. (The docs have more interesting
examples.)
#include <iostream>
#include <boost/xpressive/proto/proto.hpp>
#include <boost/xpressive/proto/context.hpp>
#include <boost/typeof/std/ostream.hpp>
using namespace boost;
proto::terminal< std::ostream & >::type cout_ = { std::cout };
template< typename Expr >
void evaluate( Expr const & expr )
{
proto::default_context ctx;
proto::eval(expr, ctx);
}
int main()
{
evaluate( cout_ << "hello" << ',' << " world" );
return 0;
}
<< Documentation (such as it is) >>
http://boost-sandbox.sourceforge.net/libs/proto/doc/html/index.html
<< Download >>
proto.zip at
http://boost-consulting.com/vault/index.php?&directory=Template%20Metaprogramming
<< Requirements >>
Tested with Boost RC 1.34 and HEAD.
Feedback is most welcome.
-- Eric Niebler Boost Consulting www.boost-consulting.com