+++ /dev/null
-/*
- * 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, 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.
- */
-
-#define DBG_EVAL 1
-#include "ao_lisp.h"
-#include <assert.h>
-
-static int
-stack_size(void *addr)
-{
- (void) addr;
- return sizeof (struct ao_lisp_stack);
-}
-
-static void
-stack_mark(void *addr)
-{
- struct ao_lisp_stack *stack = addr;
- for (;;) {
- 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;
-
- 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);
- }
-}
-
-static const struct ao_lisp_type ao_lisp_stack_type = {
- .size = stack_size,
- .mark = stack_mark,
- .move = stack_move
-};
-
-struct ao_lisp_stack *ao_lisp_stack;
-ao_poly ao_lisp_v;
-
-ao_poly
-ao_lisp_set_cond(struct ao_lisp_cons *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)
-{
- DBGI("stack push\n");
- DBG_IN();
- struct ao_lisp_stack *stack = ao_lisp_alloc(sizeof (struct ao_lisp_stack));
- if (!stack)
- return 0;
- 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)
-{
- 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)
-{
- ao_lisp_stack = NULL;
- ao_lisp_frame_current = NULL;
- ao_lisp_v = AO_LISP_NIL;
-}
-
-static int
-func_type(ao_poly func)
-{
- if (func == AO_LISP_NIL)
- return ao_lisp_error(AO_LISP_INVALID, "func is nil");
- 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;
- }
-}
-
-/*
- * Flattened eval to avoid stack issues
- */
-
-/*
- * 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.
- */
-
-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:
- 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;
- }
- DBGI(".. result "); DBG_POLY(ao_lisp_v); DBG("\n");
- return 1;
-}
-
-/*
- * 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.
- */
-
-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();
- }
- DBGI("..state %d\n", ao_lisp_stack ? ao_lisp_stack->state : -1);
- return 1;
-}
-
-/*
- * 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.
- */
-
-static int
-ao_lisp_eval_formal(void)
-{
- ao_poly formal;
-
- DBGI("formal: "); DBG_POLY(ao_lisp_v); DBG("\n");
-
- /* 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;
- }
- }
-
- /* Append formal to list of values */
- formal = ao_lisp_cons_poly(ao_lisp_cons_cons(ao_lisp_v, NULL));
- if (!formal)
- return 0;
-
- 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;
-
- DBGI(".. values "); DBG_POLY(ao_lisp_stack->values); DBG("\n");
-
- /*
- * 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;
-
- ao_lisp_stack->state = eval_sexpr;
-
- DBGI(".. "); DBG_POLY(ao_lisp_v); DBG("\n");
- return 1;
-}
-
-/*
- * 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.
- */
-
-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;
-}
-
-static int
-ao_lisp_eval_lambda_done(void)
-{
- DBGI("lambda_done: "); DBG_POLY(ao_lisp_v); DBG("\n");
- DBG_STACK();
- return 1;
-}
-
-/*
- * 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;
-}
-
-/*
- * 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;
-}
-
-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,
-};
-
-ao_poly
-ao_lisp_eval(ao_poly _v)
-{
- static uint8_t been_here;
-
- 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 (!ao_lisp_stack_push())
- return AO_LISP_NIL;
-
- while (ao_lisp_stack) {
-// DBG_STACK();
- if (!(*evals[ao_lisp_stack->state])() || ao_lisp_exception) {
- 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;
-}
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