src/evaluator.cpp

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/******************************************************************************
* MODULE     : evaluator.cpp
* DESCRIPTION: Abstract evaluators for symbolic expressions
* COPYRIGHT  : (C) 2006  Joris van der Hoeven
*******************************************************************************
* This software falls under the GNU general public license and comes WITHOUT
* ANY WARRANTY WHATSOEVER. See the file $TEXMACS_PATH/LICENSE for more details.
* If you don't have this file, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
******************************************************************************/

#include <basix/evaluator.hpp>
#include <basix/glue.hpp>
namespace mmx {

/******************************************************************************
* Default evaluation methods do not do much...
******************************************************************************/

void* evaluator_rep::get_internal_data () const {
  return NULL; }
void evaluator_rep::set (const generic& var, const generic& val) const {
  (void) var; (void) val; }
void evaluator_rep::reset (const generic& var) const {
  (void) var; }
void evaluator_rep::overload
  (const generic& var, const generic& val, nat pen) const {
    (void) var; (void) val; (void) pen; }
bool evaluator_rep::contains (const generic& var) const {
  (void) var; return false; }
generic evaluator_rep::get (const generic& var) const {
  return var; }
bool evaluator_rep::get (const generic& var, generic& val) const {
  (void) var; (void) val; return false; }

generic evaluator_rep::eval (const generic& x) const {
  return x; }
generic evaluator_rep::construct (const generic& x) const {
  return x; }
generic evaluator_rep::apply (const generic& fun) const {
  return gen (fun); }
generic evaluator_rep::apply (const generic& fun, const generic& x1) const {
  return gen (fun, x1); }
generic evaluator_rep::apply (const generic& fun,
                              const generic& x1, const generic& x2) const {
  return gen (fun, x1, x2); }
generic evaluator_rep::apply (const generic& fun,
                              const vector<generic>& v) const {
  return gen (fun, v); }

/******************************************************************************
* Current evaluator management
******************************************************************************/

bool ev_lock= false;
evaluator current_ev;
list<evaluator> stack_ev;

void
select_evaluator (const evaluator& ev) {
  //assert (!ev_lock);
  //ev_lock= true;
  //{
  /*
    if (N(stack_ev) < 6)
    mmout << "[" << N (stack_ev)
    << ":" << inside (current_ev)
    << "+" << inside (ev)
    << "]" << flush_now;
  */
  stack_ev  = cons (current_ev, stack_ev);
  current_ev= ev;
  //}
  //ev_lock= false;
}

void
restore_evaluator () {
  //assert (!ev_lock);
  //ev_lock= true;
  //{
  ASSERT (!is_nil (stack_ev), "empty evaluator stack");
  /*
    if (N(stack_ev) < 6)
    mmout << "[" << N (stack_ev)-1
    << ":" << inside (current_ev)
    << "-" << inside (car (stack_ev))
    << "]" << flush_now;
  */
  evaluator aux_ev= current_ev; // only destroy current_ev on exit
  current_ev= read_car (stack_ev);
  stack_ev  = read_cdr (stack_ev);
  //}
  //ev_lock= false;
}

} // namespace mmx

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