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/*
* Copyright © 2016 Keith Packard <keithp@keithp.com>
*
* 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; version 2 of the License.
*
* 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 "ao_lisp.h"
int
lambda_size(void *addr)
{
(void) addr;
return sizeof (struct ao_lisp_lambda);
}
void
lambda_mark(void *addr)
{
struct ao_lisp_lambda *lambda = addr;
ao_lisp_poly_mark(lambda->code, 0);
ao_lisp_poly_mark(lambda->frame, 0);
}
void
lambda_move(void *addr)
{
struct ao_lisp_lambda *lambda = addr;
ao_lisp_poly_move(&lambda->code, 0);
ao_lisp_poly_move(&lambda->frame, 0);
}
const struct ao_lisp_type ao_lisp_lambda_type = {
.size = lambda_size,
.mark = lambda_mark,
.move = lambda_move,
.name = "lambda",
};
void
ao_lisp_lambda_write(ao_poly poly)
{
struct ao_lisp_lambda *lambda = ao_lisp_poly_lambda(poly);
struct ao_lisp_cons *cons = ao_lisp_poly_cons(lambda->code);
printf("(");
printf("%s", ao_lisp_args_name(lambda->args));
while (cons) {
printf(" ");
ao_lisp_poly_write(cons->car);
cons = ao_lisp_poly_cons(cons->cdr);
}
printf(")");
}
ao_poly
ao_lisp_lambda_alloc(struct ao_lisp_cons *code, int args)
{
struct ao_lisp_lambda *lambda;
ao_poly formal;
struct ao_lisp_cons *cons;
formal = ao_lisp_arg(code, 0);
while (formal != AO_LISP_NIL) {
switch (ao_lisp_poly_type(formal)) {
case AO_LISP_CONS:
cons = ao_lisp_poly_cons(formal);
if (ao_lisp_poly_type(cons->car) != AO_LISP_ATOM)
return ao_lisp_error(AO_LISP_INVALID, "formal %p is not atom", cons->car);
formal = cons->cdr;
break;
case AO_LISP_ATOM:
formal = AO_LISP_NIL;
break;
default:
return ao_lisp_error(AO_LISP_INVALID, "formal %p is not atom", formal);
}
}
ao_lisp_cons_stash(0, code);
lambda = ao_lisp_alloc(sizeof (struct ao_lisp_lambda));
code = ao_lisp_cons_fetch(0);
if (!lambda)
return AO_LISP_NIL;
lambda->type = AO_LISP_LAMBDA;
lambda->args = args;
lambda->code = ao_lisp_cons_poly(code);
lambda->frame = ao_lisp_frame_mark(ao_lisp_frame_current);
DBGI("build frame: "); DBG_POLY(lambda->frame); DBG("\n");
DBG_STACK();
return ao_lisp_lambda_poly(lambda);
}
ao_poly
ao_lisp_do_lambda(struct ao_lisp_cons *cons)
{
return ao_lisp_lambda_alloc(cons, AO_LISP_FUNC_LAMBDA);
}
ao_poly
ao_lisp_do_nlambda(struct ao_lisp_cons *cons)
{
return ao_lisp_lambda_alloc(cons, AO_LISP_FUNC_NLAMBDA);
}
ao_poly
ao_lisp_do_macro(struct ao_lisp_cons *cons)
{
return ao_lisp_lambda_alloc(cons, AO_LISP_FUNC_MACRO);
}
ao_poly
ao_lisp_lambda_eval(void)
{
struct ao_lisp_lambda *lambda = ao_lisp_poly_lambda(ao_lisp_v);
struct ao_lisp_cons *cons = ao_lisp_poly_cons(ao_lisp_stack->values);
struct ao_lisp_cons *code = ao_lisp_poly_cons(lambda->code);
ao_poly formals;
struct ao_lisp_frame *next_frame;
int args_wanted;
ao_poly varargs = AO_LISP_NIL;
int args_provided;
int f;
struct ao_lisp_cons *vals;
DBGI("lambda "); DBG_POLY(ao_lisp_lambda_poly(lambda)); DBG("\n");
args_wanted = 0;
for (formals = ao_lisp_arg(code, 0);
ao_lisp_is_pair(formals);
formals = ao_lisp_poly_cons(formals)->cdr)
++args_wanted;
if (formals != AO_LISP_NIL) {
if (ao_lisp_poly_type(formals) != AO_LISP_ATOM)
return ao_lisp_error(AO_LISP_INVALID, "bad lambda form");
varargs = formals;
}
/* Create a frame to hold the variables
*/
args_provided = ao_lisp_cons_length(cons) - 1;
if (varargs == AO_LISP_NIL) {
if (args_wanted != args_provided)
return ao_lisp_error(AO_LISP_INVALID, "need %d args, got %d", args_wanted, args_provided);
} else {
if (args_provided < args_wanted)
return ao_lisp_error(AO_LISP_INVALID, "need at least %d args, got %d", args_wanted, args_provided);
}
ao_lisp_poly_stash(1, varargs);
next_frame = ao_lisp_frame_new(args_wanted + (varargs != AO_LISP_NIL));
varargs = ao_lisp_poly_fetch(1);
if (!next_frame)
return AO_LISP_NIL;
/* Re-fetch all of the values in case something moved */
lambda = ao_lisp_poly_lambda(ao_lisp_v);
cons = ao_lisp_poly_cons(ao_lisp_stack->values);
code = ao_lisp_poly_cons(lambda->code);
formals = ao_lisp_arg(code, 0);
vals = ao_lisp_poly_cons(cons->cdr);
next_frame->prev = lambda->frame;
ao_lisp_frame_current = next_frame;
ao_lisp_stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
for (f = 0; f < args_wanted; f++) {
struct ao_lisp_cons *arg = ao_lisp_poly_cons(formals);
DBGI("bind "); DBG_POLY(arg->car); DBG(" = "); DBG_POLY(vals->car); DBG("\n");
ao_lisp_frame_bind(next_frame, f, arg->car, vals->car);
formals = arg->cdr;
vals = ao_lisp_poly_cons(vals->cdr);
}
if (varargs) {
DBGI("bind "); DBG_POLY(varargs); DBG(" = "); DBG_POLY(ao_lisp_cons_poly(vals)); DBG("\n");
/*
* Bind the rest of the arguments to the final parameter
*/
ao_lisp_frame_bind(next_frame, f, varargs, ao_lisp_cons_poly(vals));
} else {
/*
* Mark the cons cells from the actuals as freed for immediate re-use, unless
* the actuals point into the source function (nlambdas and macros), or if the
* stack containing them was copied as a part of a continuation
*/
if (lambda->args == AO_LISP_FUNC_LAMBDA && !ao_lisp_stack_marked(ao_lisp_stack)) {
ao_lisp_stack->values = AO_LISP_NIL;
ao_lisp_cons_free(cons);
}
}
DBGI("eval frame: "); DBG_POLY(ao_lisp_frame_poly(next_frame)); DBG("\n");
DBG_STACK();
DBGI("eval code: "); DBG_POLY(code->cdr); DBG("\n");
return code->cdr;
}
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