* General Public License for more details.
*/
+#define DBG_EVAL 1
#include "ao_lisp.h"
-
-#if 0
-#define DBG(...) printf(__VA_ARGS__)
-#define DBG_CONS(a) ao_lisp_cons_print(ao_lisp_cons_poly(a))
-#define DBG_POLY(a) ao_lisp_poly_print(a)
-#define OFFSET(a) ((a) ? (int) ((uint8_t *) a - ao_lisp_pool) : -1)
-#else
-#define DBG(...)
-#define DBG_CONS(a)
-#define DBG_POLY(a)
-#endif
-
-struct ao_lisp_stack {
- ao_poly next;
- ao_poly actuals;
- ao_poly formals;
- ao_poly frame;
- ao_poly cond;
-};
-
-static struct ao_lisp_stack *
-ao_lisp_poly_stack(ao_poly p)
-{
- return ao_lisp_ref(p);
-}
-
-static ao_poly
-ao_lisp_stack_poly(struct ao_lisp_stack *stack)
-{
- return ao_lisp_poly(stack, AO_LISP_OTHER);
-}
+#include <assert.h>
static int
stack_size(void *addr)
{
struct ao_lisp_stack *stack = addr;
for (;;) {
- ao_lisp_poly_mark(stack->actuals);
- ao_lisp_poly_mark(stack->formals);
- ao_lisp_poly_mark(stack->frame);
- ao_lisp_poly_mark(stack->cond);
- stack = ao_lisp_poly_stack(stack->next);
+ ao_lisp_poly_mark(stack->sexprs, 0);
+ ao_lisp_poly_mark(stack->values, 0);
+ /* no need to mark values_tail */
+ ao_lisp_poly_mark(stack->frame, 0);
+ ao_lisp_poly_mark(stack->macro_frame, 0);
+ stack = ao_lisp_poly_stack(stack->prev);
if (ao_lisp_mark_memory(stack, sizeof (struct ao_lisp_stack)))
break;
}
}
+static const struct ao_lisp_type ao_lisp_stack_type;
+
static void
stack_move(void *addr)
{
struct ao_lisp_stack *stack = addr;
- for (;;) {
- struct ao_lisp_stack *next;
- stack->actuals = ao_lisp_poly_move(stack->actuals);
- stack->formals = ao_lisp_poly_move(stack->formals);
- stack->frame = ao_lisp_poly_move(stack->frame);
- stack->cond = ao_lisp_poly_move(stack->cond);
- next = ao_lisp_ref(stack->next);
- next = ao_lisp_move_memory(next, sizeof (struct ao_lisp_stack));
- stack->next = ao_lisp_stack_poly(next);
- stack = next;
+ while (stack) {
+ void *prev;
+ int ret;
+ (void) ao_lisp_poly_move(&stack->sexprs, 0);
+ (void) ao_lisp_poly_move(&stack->values, 0);
+ (void) ao_lisp_poly_move(&stack->values_tail, 0);
+ (void) ao_lisp_poly_move(&stack->frame, 0);
+ (void) ao_lisp_poly_move(&stack->macro_frame, 0);
+ prev = ao_lisp_poly_stack(stack->prev);
+ ret = ao_lisp_move(&ao_lisp_stack_type, &prev);
+ if (prev != ao_lisp_poly_stack(stack->prev))
+ stack->prev = ao_lisp_stack_poly(prev);
+ if (ret)
+ break;
+ stack = ao_lisp_poly_stack(stack->prev);
}
}
.move = stack_move
};
-
-static struct ao_lisp_stack *stack;
-static struct ao_lisp_cons *actuals;
-static struct ao_lisp_cons *formals;
-static struct ao_lisp_cons *formals_tail;
-static struct ao_lisp_cons *cond;
-struct ao_lisp_frame *next_frame;
-static uint8_t been_here;
+struct ao_lisp_stack *ao_lisp_stack;
+ao_poly ao_lisp_v;
ao_poly
ao_lisp_set_cond(struct ao_lisp_cons *c)
{
- cond = c;
+ ao_lisp_stack->state = eval_cond;
+ ao_lisp_stack->sexprs = ao_lisp_cons_poly(c);
return AO_LISP_NIL;
}
+static void
+ao_lisp_stack_reset(struct ao_lisp_stack *stack)
+{
+ stack->state = eval_sexpr;
+ stack->macro = 0;
+ stack->sexprs = AO_LISP_NIL;
+ stack->values = AO_LISP_NIL;
+ stack->values_tail = AO_LISP_NIL;
+}
+
+static void
+ao_lisp_frames_dump(void)
+{
+ struct ao_lisp_stack *s;
+ DBGI(".. current frame: "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ for (s = ao_lisp_stack; s; s = ao_lisp_poly_stack(s->prev)) {
+ DBGI(".. stack frame: "); DBG_POLY(s->frame); DBG("\n");
+ DBGI(".. macro frame: "); DBG_POLY(s->frame); DBG("\n");
+ }
+}
+
static int
ao_lisp_stack_push(void)
{
- struct ao_lisp_stack *n = ao_lisp_alloc(sizeof (struct ao_lisp_stack));
- if (!n)
+ DBGI("stack push\n");
+ DBG_IN();
+ struct ao_lisp_stack *stack = ao_lisp_alloc(sizeof (struct ao_lisp_stack));
+ if (!stack)
return 0;
- n->next = ao_lisp_stack_poly(stack);
- n->actuals = ao_lisp_cons_poly(actuals);
- n->formals = ao_lisp_cons_poly(formals);
- n->cond = ao_lisp_cons_poly(cond);
- n->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
- DBG("push frame %d\n", OFFSET(ao_lisp_frame_current));
- stack = n;
+ stack->prev = ao_lisp_stack_poly(ao_lisp_stack);
+ stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
+ stack->list = AO_LISP_NIL;
+ ao_lisp_stack = stack;
+ ao_lisp_stack_reset(stack);
+ ao_lisp_frames_dump();
return 1;
}
static void
ao_lisp_stack_pop(void)
{
- actuals = ao_lisp_poly_cons(stack->actuals);
- formals = ao_lisp_poly_cons(stack->formals);
- cond = ao_lisp_poly_cons(stack->cond);
- ao_lisp_frame_current = ao_lisp_poly_frame(stack->frame);
- DBG("pop frame %d\n", OFFSET(ao_lisp_frame_current));
- formals_tail = 0;
-
- /* Recompute the tail of the formals list */
- if (formals) {
- struct ao_lisp_cons *formal;
- for (formal = formals; formal->cdr != AO_LISP_NIL; formal = ao_lisp_poly_cons(formal->cdr));
- formals_tail = formal;
- }
- stack = ao_lisp_poly_stack(stack->next);
+ if (!ao_lisp_stack)
+ return;
+ ao_lisp_frame_current = ao_lisp_poly_frame(ao_lisp_stack->frame);
+ ao_lisp_stack = ao_lisp_poly_stack(ao_lisp_stack->prev);
+ DBG_OUT();
+ DBGI("stack pop\n");
+ ao_lisp_frames_dump();
}
static void
ao_lisp_stack_clear(void)
{
- stack = 0;
- actuals = formals = formals_tail = 0;
- cond = 0;
- ao_lisp_frame_current = 0;
+ ao_lisp_stack = NULL;
+ ao_lisp_frame_current = NULL;
+ ao_lisp_v = AO_LISP_NIL;
}
-
-static ao_poly
+static int
func_type(ao_poly func)
{
- struct ao_lisp_cons *cons;
- struct ao_lisp_cons *args;
- int f;
-
- DBG("func type "); DBG_POLY(func); DBG("\n");
if (func == AO_LISP_NIL)
return ao_lisp_error(AO_LISP_INVALID, "func is nil");
- if (ao_lisp_poly_type(func) != AO_LISP_CONS)
- return ao_lisp_error(AO_LISP_INVALID, "func is not list");
- cons = ao_lisp_poly_cons(func);
- if (!ao_lisp_check_argc(_ao_lisp_atom_lambda, cons, 3, 3))
- return AO_LISP_NIL;
- if (!ao_lisp_check_argt(_ao_lisp_atom_lambda, cons, 0, AO_LISP_ATOM, 0))
- return AO_LISP_NIL;
- if (!ao_lisp_check_argt(_ao_lisp_atom_lambda, cons, 1, AO_LISP_CONS, 1))
- return AO_LISP_NIL;
- args = ao_lisp_poly_cons(ao_lisp_arg(cons, 1));
- f = 0;
- while (args) {
- if (ao_lisp_poly_type(args->car) != AO_LISP_ATOM) {
- return ao_lisp_error(ao_lisp_arg(cons, 0), "formal %d is not an atom", f);
- }
- args = ao_lisp_poly_cons(args->cdr);
- f++;
+ switch (ao_lisp_poly_type(func)) {
+ case AO_LISP_BUILTIN:
+ return ao_lisp_poly_builtin(func)->args;
+ case AO_LISP_LAMBDA:
+ return ao_lisp_poly_lambda(func)->args;
+ default:
+ ao_lisp_error(AO_LISP_INVALID, "not a func");
+ return -1;
}
- return ao_lisp_arg(cons, 0);
}
-static int
-ao_lisp_cons_length(struct ao_lisp_cons *cons)
-{
- int len = 0;
- while (cons) {
- len++;
- cons = ao_lisp_poly_cons(cons->cdr);
- }
- return len;
-}
-
-static ao_poly
-ao_lisp_lambda(struct ao_lisp_cons *cons)
-{
- ao_poly type;
- struct ao_lisp_cons *lambda;
- struct ao_lisp_cons *args;
- int args_wanted;
- int args_provided;
-
- lambda = ao_lisp_poly_cons(ao_lisp_arg(cons, 0));
- DBG("lambda "); DBG_CONS(lambda); DBG("\n");
- type = ao_lisp_arg(lambda, 0);
- args = ao_lisp_poly_cons(ao_lisp_arg(lambda, 1));
+/*
+ * Flattened eval to avoid stack issues
+ */
- args_wanted = ao_lisp_cons_length(args);
+/*
+ * Evaluate an s-expression
+ *
+ * For a list, evaluate all of the elements and
+ * then execute the resulting function call.
+ *
+ * Each element of the list is evaluated in
+ * a clean stack context.
+ *
+ * The current stack state is set to 'formal' so that
+ * when the evaluation is complete, the value
+ * will get appended to the values list.
+ *
+ * For other types, compute the value directly.
+ */
- /* Create a frame to hold the variables
- */
- if (type == _ao_lisp_atom_lambda)
- args_provided = ao_lisp_cons_length(cons) - 1;
- else
- args_provided = 1;
- if (args_wanted != args_provided)
- return ao_lisp_error(AO_LISP_INVALID, "need %d args, not %d", args_wanted, args_provided);
- next_frame = ao_lisp_frame_new(args_wanted, 0);
- DBG("new frame %d\n", OFFSET(next_frame));
- switch (type) {
- case _ao_lisp_atom_lambda: {
- int f;
- struct ao_lisp_cons *vals = ao_lisp_poly_cons(cons->cdr);
-
- for (f = 0; f < args_wanted; f++) {
- next_frame->vals[f].atom = args->car;
- next_frame->vals[f].val = vals->car;
- args = ao_lisp_poly_cons(args->cdr);
- vals = ao_lisp_poly_cons(vals->cdr);
+static int
+ao_lisp_eval_sexpr(void)
+{
+ DBGI("sexpr: "); DBG_POLY(ao_lisp_v); DBG("\n");
+ switch (ao_lisp_poly_type(ao_lisp_v)) {
+ case AO_LISP_CONS:
+ if (ao_lisp_v == AO_LISP_NIL) {
+ if (!ao_lisp_stack->values) {
+ /*
+ * empty list evaluates to empty list
+ */
+ ao_lisp_v = AO_LISP_NIL;
+ ao_lisp_stack->state = eval_val;
+ } else {
+ /*
+ * done with arguments, go execute it
+ */
+ ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->values)->car;
+ ao_lisp_stack->state = eval_exec;
+ }
+ } else {
+ if (!ao_lisp_stack->values)
+ ao_lisp_stack->list = ao_lisp_v;
+ /*
+ * Evaluate another argument and then switch
+ * to 'formal' to add the value to the values
+ * list
+ */
+ ao_lisp_stack->sexprs = ao_lisp_v;
+ ao_lisp_stack->state = eval_formal;
+ if (!ao_lisp_stack_push())
+ return 0;
+ /*
+ * push will reset the state to 'sexpr', which
+ * will evaluate the expression
+ */
+ ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
}
break;
- }
- case _ao_lisp_atom_lexpr:
- case _ao_lisp_atom_nlambda:
- next_frame->vals[0].atom = args->car;
- next_frame->vals[0].val = cons->cdr;
- break;
- case _ao_lisp_atom_macro:
- next_frame->vals[0].atom = args->car;
- next_frame->vals[0].val = ao_lisp_cons_poly(cons);
+ case AO_LISP_ATOM:
+ DBGI("..frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ ao_lisp_v = ao_lisp_atom_get(ao_lisp_v);
+ /* fall through */
+ case AO_LISP_INT:
+ case AO_LISP_STRING:
+ case AO_LISP_BUILTIN:
+ case AO_LISP_LAMBDA:
+ ao_lisp_stack->state = eval_val;
break;
}
- return ao_lisp_arg(lambda, 2);
+ DBGI(".. result "); DBG_POLY(ao_lisp_v); DBG("\n");
+ return 1;
}
-ao_poly
-ao_lisp_eval(ao_poly v)
-{
- struct ao_lisp_cons *formal;
- int cons = 0;
+/*
+ * A value has been computed.
+ *
+ * If the value was computed from a macro,
+ * then we want to reset the current context
+ * to evaluate the macro result again.
+ *
+ * If not a macro, then pop the stack.
+ * If the stack is empty, we're done.
+ * Otherwise, the stack will contain
+ * the next state.
+ */
- if (!been_here) {
- been_here = 1;
- ao_lisp_root_add(&ao_lisp_stack_type, &stack);
- ao_lisp_root_add(&ao_lisp_cons_type, &actuals);
- ao_lisp_root_add(&ao_lisp_cons_type, &formals);
- ao_lisp_root_add(&ao_lisp_cons_type, &formals_tail);
+static int
+ao_lisp_eval_val(void)
+{
+ DBGI("val: "); DBG_POLY(ao_lisp_v); DBG("\n");
+ if (ao_lisp_stack->macro) {
+ DBGI("..macro %d\n", ao_lisp_stack->macro);
+ DBGI("..current frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ DBGI("..saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+ DBGI("..macro frame "); DBG_POLY(ao_lisp_stack->macro_frame); DBG("\n");
+ DBGI("..sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+ DBGI("..values "); DBG_POLY(ao_lisp_stack->values); DBG("\n");
+ /*
+ * Re-use the current stack to evaluate
+ * the value from the macro
+ */
+ ao_lisp_stack->state = eval_sexpr;
+// assert(ao_lisp_stack->frame == ao_lisp_stack->macro_frame);
+ ao_lisp_frame_current = ao_lisp_poly_frame(ao_lisp_stack->macro_frame);
+ ao_lisp_stack->frame = ao_lisp_stack->macro_frame;
+ ao_lisp_stack->macro = 0;
+ ao_lisp_stack->macro_frame = AO_LISP_NIL;
+ ao_lisp_stack->sexprs = AO_LISP_NIL;
+ ao_lisp_stack->values = AO_LISP_NIL;
+ ao_lisp_stack->values_tail = AO_LISP_NIL;
+ } else {
+ /*
+ * Value computed, pop the stack
+ * to figure out what to do with the value
+ */
+ ao_lisp_stack_pop();
}
- stack = 0;
- actuals = 0;
- formals = 0;
- formals_tail = 0;
- cond = 0;
- for (;;) {
+ DBGI("..state %d\n", ao_lisp_stack ? ao_lisp_stack->state : -1);
+ return 1;
+}
- restart:
- if (cond) {
- if (cond->car == AO_LISP_NIL) {
- cond = AO_LISP_NIL;
- v = AO_LISP_NIL;
- } else {
- if (ao_lisp_poly_type(cond->car) != AO_LISP_CONS) {
- ao_lisp_error(AO_LISP_INVALID, "malformed cond");
- goto bail;
- }
- v = ao_lisp_poly_cons(cond->car)->car;
- }
- }
+/*
+ * A formal has been computed.
+ *
+ * If this is the first formal, then
+ * check to see if we've got a lamda/lexpr or
+ * macro/nlambda.
+ *
+ * For lambda/lexpr, go compute another formal.
+ * This will terminate when the sexpr state
+ * sees nil.
+ *
+ * For macro/nlambda, we're done, so move the
+ * sexprs into the values and go execute it.
+ */
- /* Build stack frames for each list */
- while (ao_lisp_poly_type(v) == AO_LISP_CONS) {
- if (v == AO_LISP_NIL)
- break;
+static int
+ao_lisp_eval_formal(void)
+{
+ ao_poly formal;
+
+ DBGI("formal: "); DBG_POLY(ao_lisp_v); DBG("\n");
- /* Push existing bits on the stack */
- if (cons++)
- if (!ao_lisp_stack_push())
- goto bail;
+ /* Check what kind of function we've got */
+ if (!ao_lisp_stack->values) {
+ switch (func_type(ao_lisp_v)) {
+ case AO_LISP_FUNC_LAMBDA:
+ case AO_LISP_FUNC_LEXPR:
+ DBGI(".. lambda or lexpr\n");
+ break;
+ case AO_LISP_FUNC_MACRO:
+ ao_lisp_stack->macro = 1;
+ DBGI(".. macro %d\n", ao_lisp_stack->macro);
+ DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+ ao_lisp_stack->macro_frame = ao_lisp_stack->frame;
+ /* fall through ... */
+ case AO_LISP_FUNC_NLAMBDA:
+ DBGI(".. nlambda or macro\n");
+ ao_lisp_stack->values = ao_lisp_stack->sexprs;
+ ao_lisp_stack->values_tail = AO_LISP_NIL;
+ ao_lisp_stack->state = eval_exec;
+ return 1;
+ case -1:
+ return 0;
+ }
+ }
- actuals = ao_lisp_poly_cons(v);
- formals = NULL;
- formals_tail = NULL;
- cond = NULL;
+ /* Append formal to list of values */
+ formal = ao_lisp_cons_poly(ao_lisp_cons_cons(ao_lisp_v, NULL));
+ if (!formal)
+ return 0;
- v = actuals->car;
+ if (ao_lisp_stack->values_tail)
+ ao_lisp_poly_cons(ao_lisp_stack->values_tail)->cdr = formal;
+ else
+ ao_lisp_stack->values = formal;
+ ao_lisp_stack->values_tail = formal;
-// DBG("start: stack"); DBG_CONS(stack); DBG("\n");
-// DBG("start: actuals"); DBG_CONS(actuals); DBG("\n");
-// DBG("start: formals"); DBG_CONS(formals); DBG("\n");
- }
+ DBGI(".. values "); DBG_POLY(ao_lisp_stack->values); DBG("\n");
- /* Evaluate primitive types */
+ /*
+ * Step to the next argument, if this is last, then
+ * 'sexpr' will end up switching to 'exec'
+ */
+ ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
- DBG ("actual: "); DBG_POLY(v); DBG("\n");
+ ao_lisp_stack->state = eval_sexpr;
- switch (ao_lisp_poly_type(v)) {
- case AO_LISP_INT:
- case AO_LISP_STRING:
- break;
- case AO_LISP_ATOM:
- v = ao_lisp_atom_get(v);
- break;
- }
+ DBGI(".. "); DBG_POLY(ao_lisp_v); DBG("\n");
+ return 1;
+}
- while (cons) {
- DBG("add formal: "); DBG_POLY(v); DBG("\n");
+/*
+ * Start executing a function call
+ *
+ * Most builtins are easy, just call the function.
+ * 'cond' is magic; it sticks the list of clauses
+ * in 'sexprs' and switches to 'cond' state. That
+ * bit of magic is done in ao_lisp_set_cond.
+ *
+ * Lambdas build a new frame to hold the locals and
+ * then re-use the current stack context to evaluate
+ * the s-expression from the lambda.
+ */
- /* We've processed the first element of the list, go check
- * what kind of function we've got
- */
- if (formals == NULL) {
- if (ao_lisp_poly_type(v) == AO_LISP_BUILTIN) {
- struct ao_lisp_builtin *b = ao_lisp_poly_builtin(v);
- switch (b->args) {
- case AO_LISP_NLAMBDA:
- formals = actuals;
- goto eval;
-
- case AO_LISP_MACRO:
- v = ao_lisp_func(b)(ao_lisp_poly_cons(actuals->cdr));
- DBG("macro "); DBG_POLY(ao_lisp_cons_poly(actuals));
- DBG(" -> "); DBG_POLY(v);
- DBG("\n");
- if (ao_lisp_poly_type(v) != AO_LISP_CONS) {
- ao_lisp_error(AO_LISP_INVALID, "macro didn't return list");
- goto bail;
- }
- /* Reset frame to the new list */
- actuals = ao_lisp_poly_cons(v);
- v = actuals->car;
- goto restart;
- }
- } else {
- switch (func_type(v)) {
- case _ao_lisp_atom_lambda:
- case _ao_lisp_atom_lexpr:
- break;
- case _ao_lisp_atom_nlambda:
- formals = actuals;
- goto eval;
- case _ao_lisp_atom_macro:
- break;
- default:
- ao_lisp_error(AO_LISP_INVALID, "operator is not a function");
- goto bail;
- }
- }
- }
+static int
+ao_lisp_eval_exec(void)
+{
+ ao_poly v;
+ DBGI("exec: "); DBG_POLY(ao_lisp_v); DBG(" values "); DBG_POLY(ao_lisp_stack->values); DBG ("\n");
+ ao_lisp_stack->sexprs = AO_LISP_NIL;
+ switch (ao_lisp_poly_type(ao_lisp_v)) {
+ case AO_LISP_BUILTIN:
+ ao_lisp_stack->state = eval_val;
+ v = ao_lisp_func(ao_lisp_poly_builtin(ao_lisp_v)) (
+ ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->values)->cdr));
+ DBG_DO(if (!ao_lisp_exception && ao_lisp_poly_builtin(ao_lisp_v)->func == builtin_set) {
+ struct ao_lisp_cons *cons = ao_lisp_poly_cons(ao_lisp_stack->values);
+ ao_poly atom = ao_lisp_arg(cons, 1);
+ ao_poly val = ao_lisp_arg(cons, 2);
+ DBGI("set "); DBG_POLY(atom); DBG(" = "); DBG_POLY(val); DBG("\n");
+ });
+ ao_lisp_v = v;
+ DBGI(".. result "); DBG_POLY(ao_lisp_v); DBG ("\n");
+ DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ break;
+ case AO_LISP_LAMBDA:
+ ao_lisp_stack->state = eval_sexpr;
+ DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ ao_lisp_v = ao_lisp_lambda_eval(ao_lisp_poly_lambda(ao_lisp_v),
+ ao_lisp_poly_cons(ao_lisp_stack->values));
+ DBGI(".. sexpr "); DBG_POLY(ao_lisp_v); DBG("\n");
+ DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ break;
+ }
+ ao_lisp_stack->values = AO_LISP_NIL;
+ ao_lisp_stack->values_tail = AO_LISP_NIL;
+ return 1;
+}
- formal = ao_lisp_cons_cons(v, NULL);
- if (formals_tail)
- formals_tail->cdr = ao_lisp_cons_poly(formal);
- else
- formals = formal;
- formals_tail = formal;
- actuals = ao_lisp_poly_cons(actuals->cdr);
-
- DBG("formals: ");
- DBG_CONS(formals);
- DBG("\n");
- DBG("actuals: ");
- DBG_CONS(actuals);
- DBG("\n");
-
- /* Process all of the arguments */
- if (actuals) {
- v = actuals->car;
- break;
- }
+static int
+ao_lisp_eval_lambda_done(void)
+{
+ DBGI("lambda_done: "); DBG_POLY(ao_lisp_v); DBG("\n");
+ DBG_STACK();
+ return 1;
+}
- v = formals->car;
+/*
+ * Start evaluating the next cond clause
+ *
+ * If the list of clauses is empty, then
+ * the result of the cond is nil.
+ *
+ * Otherwise, set the current stack state to 'cond_test' and create a
+ * new stack context to evaluate the test s-expression. Once that's
+ * complete, we'll land in 'cond_test' to finish the clause.
+ */
+static int
+ao_lisp_eval_cond(void)
+{
+ DBGI("cond: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+ DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+ if (!ao_lisp_stack->sexprs) {
+ ao_lisp_v = AO_LISP_NIL;
+ ao_lisp_stack->state = eval_val;
+ } else {
+ ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
+ if (!ao_lisp_v || ao_lisp_poly_type(ao_lisp_v) != AO_LISP_CONS) {
+ ao_lisp_error(AO_LISP_INVALID, "invalid cond clause");
+ return 0;
+ }
+ ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
+ ao_lisp_stack->state = eval_cond_test;
+ if (!ao_lisp_stack_push())
+ return 0;
+ ao_lisp_stack->state = eval_sexpr;
+ }
+ return 1;
+}
- eval:
+/*
+ * Finish a cond clause.
+ *
+ * Check the value from the test expression, if
+ * non-nil, then set up to evaluate the value expression.
+ *
+ * Otherwise, step to the next clause and go back to the 'cond'
+ * state
+ */
+static int
+ao_lisp_eval_cond_test(void)
+{
+ DBGI("cond_test: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+ DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+ DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+ if (ao_lisp_v) {
+ struct ao_lisp_cons *car = ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car);
+ struct ao_lisp_cons *c = ao_lisp_poly_cons(car->cdr);
+
+ ao_lisp_stack->state = eval_val;
+ if (c) {
+ ao_lisp_v = c->car;
+ if (!ao_lisp_stack_push())
+ return 0;
+ }
+ } else {
+ ao_lisp_stack->sexprs = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
+ DBGI("next cond: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+ ao_lisp_stack->state = eval_cond;
+ }
+ return 1;
+}
- /* Evaluate the resulting list */
- if (ao_lisp_poly_type(v) == AO_LISP_BUILTIN) {
- struct ao_lisp_builtin *b = ao_lisp_poly_builtin(v);
+static int (*const evals[])(void) = {
+ [eval_sexpr] = ao_lisp_eval_sexpr,
+ [eval_val] = ao_lisp_eval_val,
+ [eval_formal] = ao_lisp_eval_formal,
+ [eval_exec] = ao_lisp_eval_exec,
+ [eval_cond] = ao_lisp_eval_cond,
+ [eval_cond_test] = ao_lisp_eval_cond_test,
+};
- v = ao_lisp_func(b) (ao_lisp_poly_cons(formals->cdr));
+ao_poly
+ao_lisp_eval(ao_poly _v)
+{
+ static uint8_t been_here;
- DBG ("eval: ");
- DBG_CONS(formals);
- DBG(" -> ");
- DBG_POLY(v);
- DBG ("\n");
- if (ao_lisp_exception)
- goto bail;
+ ao_lisp_v = _v;
+ if (!been_here) {
+ been_here = 1;
+ ao_lisp_root_add(&ao_lisp_stack_type, &ao_lisp_stack);
+ ao_lisp_root_poly_add(&ao_lisp_v);
+ }
- if (cond)
- goto restart;
- } else {
- v = ao_lisp_lambda(formals);
- if (ao_lisp_exception)
- goto bail;
- }
+ if (!ao_lisp_stack_push())
+ return AO_LISP_NIL;
- --cons;
- if (cons) {
- ao_lisp_stack_pop();
-// DBG("stack pop: stack"); DBG_CONS(stack); DBG("\n");
-// DBG("stack pop: actuals"); DBG_CONS(actuals); DBG("\n");
-// DBG("stack pop: formals"); DBG_CONS(formals); DBG("\n");
- } else {
- actuals = 0;
- formals = 0;
- formals_tail = 0;
- ao_lisp_frame_current = 0;
- }
- if (next_frame) {
- ao_lisp_frame_current = next_frame;
- DBG("next frame %d\n", OFFSET(next_frame));
- next_frame = 0;
- goto restart;
- }
- if (cond) {
- if (v) {
- v = ao_lisp_poly_cons(cond->car)->cdr;
- if (v != AO_LISP_NIL) {
- v = ao_lisp_poly_cons(v)->car;
- goto restart;
- }
- } else {
- cond = ao_lisp_poly_cons(cond->cdr);
- goto restart;
- }
- }
+ while (ao_lisp_stack) {
+// DBG_STACK();
+ if (!(*evals[ao_lisp_stack->state])() || ao_lisp_exception) {
+ ao_lisp_stack_clear();
+ return AO_LISP_NIL;
}
- if (!cons)
- break;
}
- DBG("leaving frame at %d\n", OFFSET(ao_lisp_frame_current));
- return v;
-bail:
- ao_lisp_stack_clear();
- return AO_LISP_NIL;
+ DBG_DO(if (ao_lisp_frame_current) {DBGI("frame left as "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");});
+ ao_lisp_frame_current = NULL;
+ return ao_lisp_v;
}
projects / fw / altos / blobdiff