combinators.c

/* combinators.c
 *
 * Builtin combinator functions (S, K, ...)
 *
 * $Id$ */

/* lsh, an implementation of the ssh protocol
 *
 * Copyright (C) 1998 Niels Möller
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "command.h"
#include "werror.h"
#include "xalloc.h"

#include <assert.h>

#include "combinators.c.x"

/* Combinators */

/* Ix == x */
DEFINE_COMMAND(command_I)
     (struct command *s UNUSED,
      struct lsh_object *a,
      struct command_continuation *c,
      struct exception_handler *e UNUSED)
{
  COMMAND_RETURN(c, a);
}


/* ((K x) y) == x */
DEFINE_COMMAND2(command_K)
     (struct command_2 *s UNUSED,
      struct lsh_object *x,
      struct lsh_object *y UNUSED,
      struct command_continuation *c,
      struct exception_handler *e UNUSED)
{
  COMMAND_RETURN(c, x);
}
      

/* ((S f) g) x == (f x)(g x) */

/* Receives the value of (f x) */
/* GABA:
   (class
     (name command_S_continuation)
     (super command_frame)
     (vars
       (g object command)
       (x object lsh_object)))
*/

static void
do_command_S_continuation(struct command_continuation *c,
			  struct lsh_object *value)
{
  CAST(command_S_continuation, self, c);
  CAST_SUBTYPE(command, op, value);
  COMMAND_CALL(self->g, self->x,
	       make_apply(op, self->super.up, self->super.e),
	       self->super.e);
}

static struct command_continuation *
make_command_S_continuation(struct command *g,
			    struct lsh_object *x,
			    struct command_continuation *up,
			    struct exception_handler *e)
{
  NEW(command_S_continuation, c);
  c->g = g;
  c->x = x;
  c->super.up = up;
  c->super.e = e;
  c->super.super.c = do_command_S_continuation;

  return &c->super.super;
}

DEFINE_COMMAND3(command_S)
     (struct lsh_object *f,
      struct lsh_object *g,
      struct lsh_object *x,
      struct command_continuation *c,
      struct exception_handler *e)
{
  CAST_SUBTYPE(command, cf, f);
  CAST_SUBTYPE(command, cg, g);

  COMMAND_CALL(cf, x,
	       make_command_S_continuation(cg, x, c, e),
	       e);
}

/* S' k f g x == k (f x) (g x) */

DEFINE_COMMAND4(command_Sp)
     (struct lsh_object *k,
      struct lsh_object *f,
      struct lsh_object *g,
      struct lsh_object *x,
      struct command_continuation *c,
      struct exception_handler *e)
{
  CAST_SUBTYPE(command, ck, k);
  CAST_SUBTYPE(command, cf, f);
  CAST_SUBTYPE(command, cg, g);

  trace("command_Sp\n");
  
  COMMAND_CALL(cf, x,
	       make_apply(ck,
			  make_command_S_continuation(cg,
						      x, c, e),
			  e),
	       e);
}


/* B f g x == f (g x) */
DEFINE_COMMAND3(command_B)
     (struct lsh_object *f,
      struct lsh_object *g,
      struct lsh_object *x,
      struct command_continuation *c,
      struct exception_handler *e)
{
  CAST_SUBTYPE(command, cf, f);
  CAST_SUBTYPE(command, cg, g);

  trace("command_B, f = %xi, cf = %xi, g = %xi, cg = %xi\n",
        f, cf, g, cg);
  
  COMMAND_CALL(cg, x,
	       make_apply(cf, c, e), e);
}


/* B' k f g x == k (f (g x)) */
DEFINE_COMMAND4(command_Bp)
     (struct lsh_object *k,
      struct lsh_object *f,
      struct lsh_object *g,
      struct lsh_object *x,
      struct command_continuation *c,
      struct exception_handler *e)
{
  CAST_SUBTYPE(command, ck, k);
  CAST_SUBTYPE(command, cf, f);
  CAST_SUBTYPE(command, cg, g);

  trace("command_Bp\n");

  COMMAND_CALL(cg, x,
	       make_apply(cf,
			  make_apply(ck, c, e), e),
	       e);
}


/* ((C f) y) x == (f x) y  */

/* GABA:
   (class
     (name command_C_continuation)
     (super command_frame)
     (vars
       (y object lsh_object)))
*/

static void
do_command_C_continuation(struct command_continuation *c,
			  struct lsh_object *value)
{
  CAST(command_C_continuation, self, c);
  CAST_SUBTYPE(command, op, value);
  
  COMMAND_CALL(op, self->y, self->super.up, self->super.e);
}

static struct command_continuation *
make_command_C_continuation(struct lsh_object *y,
			    struct command_continuation *up,
			    struct exception_handler *e)
{
  NEW(command_C_continuation, c);
  c->y = y;
  c->super.up = up;
  c->super.e = e;
  c->super.super.c = do_command_C_continuation;
  
  return &c->super.super;
}

DEFINE_COMMAND3(command_C)
     (struct lsh_object *f,
      struct lsh_object *y,
      struct lsh_object *x,
      struct command_continuation *c,
      struct exception_handler *e)
{
  CAST_SUBTYPE(command, cf, f);

  trace("command_C\n");

  COMMAND_CALL(cf, x,
	       make_command_C_continuation(y, c, e),
	       e);
}


/* C' k f y x == k (f x) y */
DEFINE_COMMAND4(command_Cp)
     (struct lsh_object *k,
      struct lsh_object *f,
      struct lsh_object *y,
      struct lsh_object *x,
      struct command_continuation *c,
      struct exception_handler *e)
{
  CAST_SUBTYPE(command, ck, k);
  CAST_SUBTYPE(command, cf, f);

  trace("command_Cp\n");

#if 0
  werror("command_Cp: k: %t, f: %t, y: %t, x: %t\n",
	 k, f, y, x);
#endif
  
  COMMAND_CALL(cf, x,
	       make_apply(ck,
			  make_command_C_continuation(y, c, e), e),
	       e);
}