/*
Copyright (c) 1994 - 2010, Lawrence Livermore National Security, LLC.
LLNL-CODE-425250.
All rights reserved.

This file is part of Silo. For details, see silo.llnl.gov.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the disclaimer below.
   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the disclaimer (as noted
     below) in the documentation and/or other materials provided with
     the distribution.
   * Neither the name of the LLNS/LLNL nor the names of its
     contributors may be used to endorse or promote products derived
     from this software without specific prior written permission.

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"AS  IS" AND  ANY EXPRESS  OR IMPLIED  WARRANTIES, INCLUDING,  BUT NOT
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This work was produced at Lawrence Livermore National Laboratory under
Contract No.  DE-AC52-07NA27344 with the DOE.

Neither the  United States Government nor  Lawrence Livermore National
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Any reference herein to  any specific commercial products, process, or
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*/
/*-------------------------------------------------------------------------
 *
 * Created:             cons.c
 *                      Dec  4 1996
 *                      Robb Matzke <matzke@viper.llnl.gov>
 *
 * Purpose:             The CONS class.
 *
 * Modifications:       
 *
 *-------------------------------------------------------------------------
 */
#include <assert.h>
#include <browser.h>
#define MYCLASS(X)      ((obj_cons_t*)(X))

typedef struct obj_cons_t {
   obj_pub_t    pub;
   obj_t        head, tail;
} obj_cons_t;

class_t         C_CONS;
static obj_t    cons_new (va_list);
static obj_t    cons_dest (obj_t);
static obj_t    cons_copy (obj_t, int);
static void     cons_print (obj_t, out_t*);
static obj_t    cons_eval (obj_t);
static obj_t    cons_deref(obj_t, int, obj_t*);


/*-------------------------------------------------------------------------
 * Function:    cons_class
 *
 * Purpose:     Initializes the cons cell class.
 *
 * Return:      Success:        Ptr to the cons class.
 *
 *              Failure:        NULL
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *    Lisa J. Roberts, Mon Nov 22 17:27:53 PST 1999
 *    I changed strdup to safe_strdup.
 *
 *-------------------------------------------------------------------------
 */
class_t
cons_class (void)
{
    class_t     cls = (class_t)calloc(1, sizeof(*cls));

    cls->name = safe_strdup("CONS");
    cls->newobj = cons_new;
    cls->dest = cons_dest;
    cls->copy = cons_copy;
    cls->print = cons_print;
    cls->eval = cons_eval;
    cls->feval = cons_eval;     /*same as eval*/
    cls->deref = cons_deref;
    return cls;
}


/*-------------------------------------------------------------------------
 * Function:    cons_new
 *
 * Purpose:     Creates a new CONS object with the specified head and tail.
 *
 * Return:      Success:        Ptr to the new cons object.
 *
 *              Failure:        NIL
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static obj_t
cons_new (va_list ap) {

   obj_cons_t   *self = (obj_cons_t *)calloc (1, sizeof(obj_cons_t));

   assert (self);
   self->head = va_arg (ap, obj_t);
   self->tail = va_arg (ap, obj_t);
   return (obj_t)self;
}


/*-------------------------------------------------------------------------
 * Function:    cons_dest
 *
 * Purpose:     Destroys a CONS object be destroying the head and tail.
 *
 * Return:      Success:        NIL
 *
 *              Failure:        NIL
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static obj_t
cons_dest (obj_t _self) {

   obj_cons_t   *self = MYCLASS(_self);

   obj_dest (self->head);
   obj_dest (self->tail);

   if (0==self->pub.ref) {
      self->head = self->tail = NIL;
   }
   return NIL;
}


/*-------------------------------------------------------------------------
 * Function:    cons_copy
 *
 * Purpose:     Copy constructor.
 *
 * Return:      Success:        Ptr to copy of SELF.
 *
 *              Failure:        NIL
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static obj_t
cons_copy (obj_t _self, int flag) {

   obj_t        hd=NIL, tl=NIL, ret=NIL;
   obj_cons_t   *self = MYCLASS(_self);

   assert (SHALLOW==flag);

   hd = obj_copy (self->head, SHALLOW);
   tl = obj_copy (self->tail, SHALLOW);

   if (hd!=self->head || tl!=self->tail) {
      ret = obj_new (C_CONS, hd, tl);
   } else {
      ret = _self;
   }
   return ret;
}
   

/*-------------------------------------------------------------------------
 * Function:    cons_print
 *
 * Purpose:     Prints a cons cell to the specified file.
 *
 * Return:      Void
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static void
cons_print (obj_t cur, out_t *f) {

   int          i;

   out_puts (f, "(");
   for (i=0; cur; cur=MYCLASS(cur)->tail,i++) {
      assert (C_CONS==cur->pub.cls);
      if (i) out_puts (f, " ");
      obj_print (MYCLASS(cur)->head, f);
   }
   out_puts (f, ")");
}


/*-------------------------------------------------------------------------
 * Function:    cons_eval
 *
 * Purpose:     Evaluates a list by evaluating the head in a function
 *              context and then applying the result to the rest of
 *              the arguments.
 *
 * Return:      Success:        Ptr to the result.
 *
 *              Failure:        NIL
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static obj_t
cons_eval (obj_t _self) {

   obj_cons_t   *self = MYCLASS(_self);
   obj_t        func=NIL, retval=NIL;

   /*
    * Try to evaluate this as a function.  If that doesn't work, evaluate
    * the head normally and then try to evaluate that result as a function.
    */
   func = obj_feval (self->head);
   if (!func) {
      obj_t tmp = obj_eval (self->head);
      if (tmp) {
         func = obj_feval (tmp);
         tmp = obj_dest (tmp);
      }
   }

   if (!func) {
      out_error ("expression head is not a function: ", _self);
      return NULL;
   }

   retval = obj_apply (func, self->tail);
   func = obj_dest (func);
   return retval;
}

/*---------------------------------------------------------------------------
 * Purpose:     Invokes the obj_deref() on each member of the list and
 *              returns a list of results.
 *
 * Return:      List of results or NIL
 *
 * Programmer:  Robb Matzke
 *              Wednesday, July  5, 2000
 *
 * Modifications:
 *---------------------------------------------------------------------------
 */
static obj_t
cons_deref(obj_t _self, int argc, obj_t argv[])
{
    obj_cons_t  *self = MYCLASS(_self);
    obj_t       tail=NIL, head=NIL;

    /* Dereference the head and then tail */
    head = obj_deref(self->head, argc, argv);
    if (self->tail) {
        tail = obj_deref(self->tail, argc, argv);
    }

    return obj_new(C_CONS, head, tail);
}


/*-------------------------------------------------------------------------
 * Function:    cons_head
 *
 * Purpose:     Returns the head of a cons cell.
 *
 * Return:      Success:        Ptr to the head.
 *
 *              Failure:        NIL
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
obj_t
cons_head (obj_t _self) {

   if (!_self || C_CONS!=_self->pub.cls) return NIL;
   return MYCLASS(_self)->head;
}


/*-------------------------------------------------------------------------
 * Function:    cons_tail
 *
 * Purpose:     Returns the tail of a cons cell.
 *
 * Return:      Success:        Ptr to the tail.
 *
 *              Failure:        NIL
 *
 * Programmer:  Robb Matzke
 *              matzke@viper.llnl.gov
 *              Dec  4 1996
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
obj_t
cons_tail (obj_t _self) {

   if (!_self || C_CONS!=_self->pub.cls) return NIL;
   return MYCLASS(_self)->tail;
}

