GenericEval.h

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/*
 * GenericEval.h
 *
 * Template for a generic shell-oriented evaluator
 * Copyright (c) 2008, 2013, 2014 Linas Vepstas <linas@linas.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License v3 as
 * published by the Free Software Foundation and including the exceptions
 * at http://opencog.org/wiki/Licenses
 *
 * This program 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 Affero General Public License
 * along with this program; if not, write to:
 * Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef _OPENCOG_GENERIC_EVAL_H
#define _OPENCOG_GENERIC_EVAL_H

#include <string>

namespace opencog {
class GenericEval
{
    protected:
        std::string _input_line;
        bool _pending_input;
        bool _caught_error;

    public:
        GenericEval(void) :
            _input_line(""),
            _pending_input(false),
            _caught_error(false) {}
        virtual ~GenericEval() {}

        virtual bool input_pending()
        {
            return _pending_input;
        }

        virtual void clear_pending()
        {
            _input_line = "";
            _pending_input = false;
            _caught_error = false;
        }

        virtual bool eval_error(void)
        {
            return _caught_error;
        }

        virtual void begin_eval() = 0;
        virtual void eval_expr(const std::string&) = 0;
        virtual std::string poll_result() = 0;
};

}

#endif // _OPENCOG_GENERIC_EVAL_H