root/tlate/expr.hh

/*  This file is part of Alue, the multiprotocol Internet discussion daemon

    Copyright © 2009 Antti-Juhani Kaijanaho

    Alue is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Alue is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Alue.  If not, see <http://www.gnu.org/licenses/>.

 */

#ifndef GUARD_TLATE_EXPR_HH
#define GUARD_TLATE_EXPR_HH

#include "tlate.hh"
#include "scanner.hh"

// use as "case TLATE_EXPR_FIRST:"
#define TLATE_EXPR_FIRST scanner::ID: case scanner::LITERAL

namespace tlate
{
        class expr : public tlate
        {
        protected:
                expr(std::string fname, int line) : tlate(fname,line) {}
        public:
                typedef boost::shared_ptr<expr> ptr;

                static ptr parse(scanner &);

                virtual bool is_value_missing(overriding_structured_value::ptr
                                              env) {
                        value::const_ptr v = eval(env);
                        return !v || v->is_missing();
                }
        };
}

#endif /* GUARD_TLATE_EXPR_HH */