text: //  SuperTux
  //  Copyright (C) 2006 Matthias Braun <matze@braunis.de>
  //
  //  This program 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.
  //
  //  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 General Public License
  //  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  #include "lisp/list_iterator.hpp"
  #include <stdexcept>
  
  namespace lisp {
  
  ListIterator::ListIterator(const lisp::Lisp* newlisp) :
    current_item(),
    current_lisp(0),
    cur(newlisp)
  {
  }
  
  bool
  ListIterator::next()
  {
    if(cur == 0)
      return false;
  
    const lisp::Lisp* child = cur->get_car();
    if(!child)
      throw std::runtime_error("child is 0 in list entry");
    if(child->get_type() != lisp::Lisp::TYPE_CONS)
      throw std::runtime_error("Expected CONS");
    const lisp::Lisp* name = child->get_car();
    if(!name || (
         name->get_type() != lisp::Lisp::TYPE_SYMBOL
         && name->get_type() != lisp::Lisp::TYPE_STRING))
      throw std::runtime_error("Expected symbol");
    name->get(current_item);
    current_lisp = child->get_cdr();
  
    cur = cur->get_cdr();
    return true;
  }
  
  }
  
  /* EOF */
  