Re: [Boost-users] [Proto]: How to use complex grammars in a domain/extension

On 20/09/10 19:59, Roland Bock wrote:

Hi,

I am trying to create a DSEL with Boost.Proto, which (among other things) should allow expressions like

i == j + 3 && t != "foo"

and want to prevent disallowed operators to be generated by Proto.

Please consider the code below.

// ----------------------------------------------------------------------- #include

using namespace boost;

typedef proto::terminal<int>::type terminal;

struct addition: proto::or_ < terminal, proto::plus

...

{};

struct equation: proto::equal_to {};

struct condition: proto::or_ < equation, proto::logical_and

...

{};

In my_domain, I can replace condition by addition, which allows i + i, but then the == operator is still missing (and the &&, too, probably).

i+i doesn't match your grammar at all. an equation is addition == addition which is not matchable by i+i if equation was: struct equation: proto::or_< addition, proto::equal_to > {}; then it'll work.