2 * Copyright © 2016 Keith Packard <keithp@keithp.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
19 const struct ao_lisp_type ao_lisp_stack_type;
22 stack_size(void *addr)
25 return sizeof (struct ao_lisp_stack);
29 stack_mark(void *addr)
31 struct ao_lisp_stack *stack = addr;
33 ao_lisp_poly_mark(stack->sexprs, 0);
34 ao_lisp_poly_mark(stack->values, 0);
35 /* no need to mark values_tail */
36 ao_lisp_poly_mark(stack->frame, 0);
37 ao_lisp_poly_mark(stack->list, 0);
38 stack = ao_lisp_poly_stack(stack->prev);
39 if (ao_lisp_mark_memory(&ao_lisp_stack_type, stack))
45 stack_move(void *addr)
47 struct ao_lisp_stack *stack = addr;
50 struct ao_lisp_stack *prev;
52 (void) ao_lisp_poly_move(&stack->sexprs, 0);
53 (void) ao_lisp_poly_move(&stack->values, 0);
54 (void) ao_lisp_poly_move(&stack->values_tail, 0);
55 (void) ao_lisp_poly_move(&stack->frame, 0);
56 (void) ao_lisp_poly_move(&stack->list, 0);
57 prev = ao_lisp_poly_stack(stack->prev);
60 ret = ao_lisp_move_memory(&ao_lisp_stack_type, (void **) &prev);
61 if (prev != ao_lisp_poly_stack(stack->prev))
62 stack->prev = ao_lisp_stack_poly(prev);
69 const struct ao_lisp_type ao_lisp_stack_type = {
76 struct ao_lisp_stack *ao_lisp_stack;
79 struct ao_lisp_stack *ao_lisp_stack_free_list;
82 ao_lisp_set_cond(struct ao_lisp_cons *c)
84 ao_lisp_stack->state = eval_cond;
85 ao_lisp_stack->sexprs = ao_lisp_cons_poly(c);
90 ao_lisp_stack_reset(struct ao_lisp_stack *stack)
92 stack->state = eval_sexpr;
93 stack->sexprs = AO_LISP_NIL;
94 stack->values = AO_LISP_NIL;
95 stack->values_tail = AO_LISP_NIL;
100 ao_lisp_stack_push(void)
102 struct ao_lisp_stack *stack;
103 if (ao_lisp_stack_free_list) {
104 stack = ao_lisp_stack_free_list;
105 ao_lisp_stack_free_list = ao_lisp_poly_stack(stack->prev);
107 stack = ao_lisp_alloc(sizeof (struct ao_lisp_stack));
111 stack->prev = ao_lisp_stack_poly(ao_lisp_stack);
112 stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
113 stack->list = AO_LISP_NIL;
114 ao_lisp_stack = stack;
115 ao_lisp_stack_reset(stack);
116 DBGI("stack push\n");
123 ao_lisp_stack_pop(void)
129 prev = ao_lisp_stack->prev;
130 ao_lisp_stack->prev = ao_lisp_stack_poly(ao_lisp_stack_free_list);
131 ao_lisp_stack_free_list = ao_lisp_stack;
133 ao_lisp_stack = ao_lisp_poly_stack(prev);
135 ao_lisp_frame_current = ao_lisp_poly_frame(ao_lisp_stack->frame);
137 ao_lisp_frame_current = NULL;
144 ao_lisp_stack_clear(void)
146 ao_lisp_stack = NULL;
147 ao_lisp_frame_current = NULL;
148 ao_lisp_v = AO_LISP_NIL;
152 func_type(ao_poly func)
154 if (func == AO_LISP_NIL)
155 return ao_lisp_error(AO_LISP_INVALID, "func is nil");
156 switch (ao_lisp_poly_type(func)) {
157 case AO_LISP_BUILTIN:
158 return ao_lisp_poly_builtin(func)->args & AO_LISP_FUNC_MASK;
160 return ao_lisp_poly_lambda(func)->args;
162 ao_lisp_error(AO_LISP_INVALID, "not a func");
168 * Flattened eval to avoid stack issues
172 * Evaluate an s-expression
174 * For a list, evaluate all of the elements and
175 * then execute the resulting function call.
177 * Each element of the list is evaluated in
178 * a clean stack context.
180 * The current stack state is set to 'formal' so that
181 * when the evaluation is complete, the value
182 * will get appended to the values list.
184 * For other types, compute the value directly.
188 ao_lisp_eval_sexpr(void)
190 DBGI("sexpr: "); DBG_POLY(ao_lisp_v); DBG("\n");
191 switch (ao_lisp_poly_type(ao_lisp_v)) {
193 if (ao_lisp_v == AO_LISP_NIL) {
194 if (!ao_lisp_stack->values) {
196 * empty list evaluates to empty list
198 ao_lisp_v = AO_LISP_NIL;
199 ao_lisp_stack->state = eval_val;
202 * done with arguments, go execute it
204 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->values)->car;
205 ao_lisp_stack->state = eval_exec;
208 if (!ao_lisp_stack->values)
209 ao_lisp_stack->list = ao_lisp_v;
211 * Evaluate another argument and then switch
212 * to 'formal' to add the value to the values
215 ao_lisp_stack->sexprs = ao_lisp_v;
216 ao_lisp_stack->state = eval_formal;
217 if (!ao_lisp_stack_push())
220 * push will reset the state to 'sexpr', which
221 * will evaluate the expression
223 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
227 DBGI("..frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
228 ao_lisp_v = ao_lisp_atom_get(ao_lisp_v);
232 case AO_LISP_BUILTIN:
234 ao_lisp_stack->state = eval_val;
237 DBGI(".. result "); DBG_POLY(ao_lisp_v); DBG("\n");
242 * A value has been computed.
244 * If the value was computed from a macro,
245 * then we want to reset the current context
246 * to evaluate the macro result again.
248 * If not a macro, then pop the stack.
249 * If the stack is empty, we're done.
250 * Otherwise, the stack will contain
255 ao_lisp_eval_val(void)
257 DBGI("val: "); DBG_POLY(ao_lisp_v); DBG("\n");
259 * Value computed, pop the stack
260 * to figure out what to do with the value
263 DBGI("..state %d\n", ao_lisp_stack ? ao_lisp_stack->state : -1);
268 * A formal has been computed.
270 * If this is the first formal, then check to see if we've got a
271 * lamda/lexpr or macro/nlambda.
273 * For lambda/lexpr, go compute another formal. This will terminate
274 * when the sexpr state sees nil.
276 * For macro/nlambda, we're done, so move the sexprs into the values
279 * Macros have an additional step of saving a stack frame holding the
280 * macro value execution context, which then gets the result of the
285 ao_lisp_eval_formal(void)
288 struct ao_lisp_stack *prev;
290 DBGI("formal: "); DBG_POLY(ao_lisp_v); DBG("\n");
292 /* Check what kind of function we've got */
293 if (!ao_lisp_stack->values) {
294 switch (func_type(ao_lisp_v)) {
295 case AO_LISP_FUNC_LAMBDA:
296 case AO_LISP_FUNC_LEXPR:
297 DBGI(".. lambda or lexpr\n");
299 case AO_LISP_FUNC_MACRO:
300 /* Evaluate the result once more */
301 ao_lisp_stack->state = eval_sexpr;
302 if (!ao_lisp_stack_push())
305 /* After the function returns, take that
306 * value and re-evaluate it
308 prev = ao_lisp_poly_stack(ao_lisp_stack->prev);
309 ao_lisp_stack->state = eval_sexpr;
310 ao_lisp_stack->sexprs = prev->sexprs;
311 prev->sexprs = AO_LISP_NIL;
313 DBGI(".. start macro\n");
314 DBGI(".. sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
315 DBGI(".. values "); DBG_POLY(ao_lisp_stack->values); DBG("\n");
318 /* fall through ... */
319 case AO_LISP_FUNC_NLAMBDA:
320 DBGI(".. nlambda or macro\n");
322 /* use the raw sexprs as values */
323 ao_lisp_stack->values = ao_lisp_stack->sexprs;
324 ao_lisp_stack->values_tail = AO_LISP_NIL;
325 ao_lisp_stack->state = eval_exec;
327 /* ready to execute now */
334 /* Append formal to list of values */
335 formal = ao_lisp_cons_poly(ao_lisp_cons_cons(ao_lisp_v, NULL));
339 if (ao_lisp_stack->values_tail)
340 ao_lisp_poly_cons(ao_lisp_stack->values_tail)->cdr = formal;
342 ao_lisp_stack->values = formal;
343 ao_lisp_stack->values_tail = formal;
345 DBGI(".. values "); DBG_POLY(ao_lisp_stack->values); DBG("\n");
348 * Step to the next argument, if this is last, then
349 * 'sexpr' will end up switching to 'exec'
351 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
353 ao_lisp_stack->state = eval_sexpr;
355 DBGI(".. "); DBG_POLY(ao_lisp_v); DBG("\n");
360 * Start executing a function call
362 * Most builtins are easy, just call the function.
363 * 'cond' is magic; it sticks the list of clauses
364 * in 'sexprs' and switches to 'cond' state. That
365 * bit of magic is done in ao_lisp_set_cond.
367 * Lambdas build a new frame to hold the locals and
368 * then re-use the current stack context to evaluate
369 * the s-expression from the lambda.
373 ao_lisp_eval_exec(void)
376 struct ao_lisp_builtin *builtin;
378 DBGI("exec: "); DBG_POLY(ao_lisp_v); DBG(" values "); DBG_POLY(ao_lisp_stack->values); DBG ("\n");
379 ao_lisp_stack->sexprs = AO_LISP_NIL;
380 switch (ao_lisp_poly_type(ao_lisp_v)) {
381 case AO_LISP_BUILTIN:
382 ao_lisp_stack->state = eval_val;
383 builtin = ao_lisp_poly_builtin(ao_lisp_v);
384 v = ao_lisp_func(builtin) (
385 ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->values)->cdr));
386 DBG_DO(if (!ao_lisp_exception && ao_lisp_poly_builtin(ao_lisp_v)->func == builtin_set) {
387 struct ao_lisp_cons *cons = ao_lisp_poly_cons(ao_lisp_stack->values);
388 ao_poly atom = ao_lisp_arg(cons, 1);
389 ao_poly val = ao_lisp_arg(cons, 2);
390 DBGI("set "); DBG_POLY(atom); DBG(" = "); DBG_POLY(val); DBG("\n");
392 builtin = ao_lisp_poly_builtin(ao_lisp_v);
393 if (builtin->args & AO_LISP_FUNC_FREE_ARGS)
394 ao_lisp_cons_free(ao_lisp_poly_cons(ao_lisp_stack->values));
397 DBGI(".. result "); DBG_POLY(ao_lisp_v); DBG ("\n");
398 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
401 ao_lisp_stack->state = eval_sexpr;
402 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
403 ao_lisp_v = ao_lisp_lambda_eval();
404 DBGI(".. sexpr "); DBG_POLY(ao_lisp_v); DBG("\n");
405 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
408 ao_lisp_stack->values = AO_LISP_NIL;
409 ao_lisp_stack->values_tail = AO_LISP_NIL;
414 * Start evaluating the next cond clause
416 * If the list of clauses is empty, then
417 * the result of the cond is nil.
419 * Otherwise, set the current stack state to 'cond_test' and create a
420 * new stack context to evaluate the test s-expression. Once that's
421 * complete, we'll land in 'cond_test' to finish the clause.
424 ao_lisp_eval_cond(void)
426 DBGI("cond: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
427 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
428 DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
429 if (!ao_lisp_stack->sexprs) {
430 ao_lisp_v = AO_LISP_NIL;
431 ao_lisp_stack->state = eval_val;
433 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
434 if (!ao_lisp_v || ao_lisp_poly_type(ao_lisp_v) != AO_LISP_CONS) {
435 ao_lisp_error(AO_LISP_INVALID, "invalid cond clause");
438 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
439 ao_lisp_stack->state = eval_cond_test;
440 if (!ao_lisp_stack_push())
442 ao_lisp_stack->state = eval_sexpr;
448 * Finish a cond clause.
450 * Check the value from the test expression, if
451 * non-nil, then set up to evaluate the value expression.
453 * Otherwise, step to the next clause and go back to the 'cond'
457 ao_lisp_eval_cond_test(void)
459 DBGI("cond_test: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
460 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
461 DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
463 struct ao_lisp_cons *car = ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car);
464 struct ao_lisp_cons *c = ao_lisp_poly_cons(car->cdr);
467 ao_lisp_stack->state = eval_sexpr;
470 ao_lisp_stack->state = eval_val;
472 ao_lisp_stack->sexprs = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
473 DBGI("next cond: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
474 ao_lisp_stack->state = eval_cond;
480 * Evaluate a list of sexprs, returning the value from the last one.
482 * ao_lisp_progn records the list in stack->sexprs, so we just need to
483 * walk that list. Set ao_lisp_v to the car of the list and jump to
484 * eval_sexpr. When that's done, it will land in eval_val. For all but
485 * the last, leave a stack frame with eval_progn set so that we come
486 * back here. For the last, don't add a stack frame so that we can
490 ao_lisp_eval_progn(void)
492 DBGI("progn: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
493 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
494 DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
496 if (!ao_lisp_stack->sexprs) {
497 ao_lisp_v = AO_LISP_NIL;
498 ao_lisp_stack->state = eval_val;
500 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
501 ao_lisp_stack->sexprs = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
502 if (ao_lisp_stack->sexprs) {
503 ao_lisp_stack->state = eval_progn;
504 if (!ao_lisp_stack_push())
507 ao_lisp_stack->state = eval_sexpr;
513 * Conditionally execute a list of sexprs while the first is true
516 ao_lisp_eval_while(void)
518 DBGI("while: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
519 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
520 DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
522 if (!ao_lisp_stack->sexprs) {
523 ao_lisp_v = AO_LISP_NIL;
524 ao_lisp_stack->state = eval_val;
526 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
527 ao_lisp_stack->state = eval_while_test;
528 if (!ao_lisp_stack_push())
530 ao_lisp_stack->state = eval_sexpr;
536 * Check the while condition, terminate the loop if nil. Otherwise keep going
539 ao_lisp_eval_while_test(void)
541 DBGI("while_test: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
542 DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
543 DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
546 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
548 ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
549 ao_lisp_stack->state = eval_while;
550 if (!ao_lisp_stack_push())
554 ao_lisp_stack->state = eval_val;
558 static int (*const evals[])(void) = {
559 [eval_sexpr] = ao_lisp_eval_sexpr,
560 [eval_val] = ao_lisp_eval_val,
561 [eval_formal] = ao_lisp_eval_formal,
562 [eval_exec] = ao_lisp_eval_exec,
563 [eval_cond] = ao_lisp_eval_cond,
564 [eval_cond_test] = ao_lisp_eval_cond_test,
565 [eval_progn] = ao_lisp_eval_progn,
566 [eval_while] = ao_lisp_eval_while,
567 [eval_while_test] = ao_lisp_eval_while_test,
571 * Called at restore time to reset all execution state
575 ao_lisp_eval_clear_globals(void)
577 ao_lisp_stack = NULL;
578 ao_lisp_frame_current = NULL;
579 ao_lisp_v = AO_LISP_NIL;
583 ao_lisp_eval_restart(void)
585 return ao_lisp_stack_push();
589 ao_lisp_eval(ao_poly _v)
593 if (!ao_lisp_stack_push())
596 while (ao_lisp_stack) {
597 if (!(*evals[ao_lisp_stack->state])() || ao_lisp_exception) {
598 ao_lisp_stack_clear();
602 DBG_DO(if (ao_lisp_frame_current) {DBGI("frame left as "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");});
603 ao_lisp_frame_current = NULL;