void global_env_extend(Obj *key, Obj *val) {
assert(global_env);
Obj *existing_binding = env_lookup_binding(global_env, key);
if(existing_binding->car) {
existing_binding->cdr = val;
} else {
env_extend(global_env, key, val);
}
}
void global_env_extend(Process *process, Obj *key, Obj *val) {
assert(process->global_env);
Obj *existing_binding = env_lookup_binding(process, process->global_env, key);
if(existing_binding->car) {
existing_binding->cdr = val;
}
else {
env_extend(process->global_env, key, val);
}
}
Obj *env_assoc(Process *process, Obj *env, Obj *key, Obj *value) {
Obj *pair = env_lookup_binding(process, env, key);
if(pair && pair->car && pair->cdr) {
pair->cdr = value;
}
else {
//printf("Pair not found, will add new key.\n");
Obj *new_pair = obj_new_cons(key, value);
Obj *new_cons = obj_new_cons(new_pair, env->bindings);
env->bindings = new_cons;
}
return env;
}
Obj *env_lookup_binding(Process *process, Obj *env, Obj *symbol) {
Obj *p = env->bindings;
while(p && p->car) {
Obj *pair = p->car;
if(obj_eq(process, pair->car, symbol)) {
return pair;
}
else {
p = p->cdr;
}
}
if(env->parent) {
return env_lookup_binding(process, env->parent, symbol);
}
else {
return nil;
}
}
// returns NULL if not done yet
Obj *bytecode_eval_internal(Process *process, Obj *bytecodeObj, int steps) {
Obj *literal, *function, *lookup, *result, *bindings, *let_env, *binding;
int arg_count, i, bindings_index, body_index;
for(int step = 0; step < steps; step++) {
if(eval_error) {
return nil;
}
Obj **literals_array = process->frames[process->frame].bytecodeObj->bytecode_literals->array;
char *bytecode = process->frames[process->frame].bytecodeObj->bytecode;
int p = process->frames[process->frame].p;
char c = bytecode[p];
//printf("frame = %d, c = %c\n", frame, c);
switch(c) {
case 'l':
i = bytecode[p + 1] - 65;
literal = literals_array[i];
//printf("Pushing literal "); obj_print_cout(literal); printf("\n");
stack_push(process, literal);
process->frames[process->frame].p += 2;
break;
case 'd':
i = bytecode[p + 1] - 65;
literal = literals_array[i];
result = env_extend(process->global_env, literal, stack_pop(process));
stack_push(process, result->cdr);
process->frames[process->frame].p += 2;
break;
case 'n':
if(is_true(stack_pop(process))) {
stack_push(process, lisp_false);
} else {
stack_push(process, lisp_true);
}
process->frames[process->frame].p += 1;
break;
case 'r':
i = bytecode[p + 1] - 65;
literal = literals_array[i];
binding = env_lookup_binding(process, process->frames[process->frame].env, literal);
if(binding->car) {
//printf("binding: %s\n", obj_to_string(process, binding)->s);
binding->cdr = stack_pop(process);
stack_push(process, binding->cdr);
} else {
eval_error = obj_new_string("reset! can't find variable to reset: ");
obj_string_mut_append(eval_error, obj_to_string(process, literal)->s);
return nil;
}
process->frames[process->frame].p += 2;
break;
case 't':
//printf("entering let\n");
//shadow_stack_push(process, let_env);
bindings_index = bytecode[p + 1] - 65;
body_index = bytecode[p + 2] - 65;
bindings = literals_array[bindings_index];
//printf("bindings: %s\n", obj_to_string(process, bindings)->s);
let_env = obj_new_environment(process->frames[process->frame].env);
for(int i = 0; i < bindings->count; i++) {
env_extend(let_env, bindings->array[i], stack_pop(process));
}
process->frames[process->frame].p += 3;
process->frames[process->frame + 1].p = 0;
process->frames[process->frame + 1].bytecodeObj = literals_array[body_index];
process->frames[process->frame + 1].env = let_env;
process->frame++;
//printf("will now execute: %s\n", obj_to_string(process, process->frames[process->frame].bytecodeObj)->s);
break;
case 'y':
i = bytecode[p + 1] - 65;
literal = literals_array[i];
//printf("Looking up literal "); obj_print_cout(literal); printf("\n");
lookup = env_lookup(process, process->frames[process->frame].env, literal);
if(!lookup) {
set_error_return_nil("Failed to lookup ", literal);
}
stack_push(process, lookup);
process->frames[process->frame].p += 2;
break;
case 'i':
i = bytecode[p + 1] - 65;
if(is_true(stack_pop(process))) {
process->frames[process->frame].p = 0;
process->frames[process->frame].bytecodeObj = literals_array[i];
process->frames[process->frame].env = process->frames[process->frame - 1].env;
}
else {
process->frames[process->frame].p = 0;
process->frames[process->frame].bytecodeObj = literals_array[i + 1];
process->frames[process->frame].env = process->frames[process->frame - 1].env;
}
break;
case 'c':
function = stack_pop(process);
arg_count = bytecode[p + 1] - 65;
Obj **args = NULL;
if(arg_count > 0) {
args = malloc(sizeof(Obj*) * arg_count);
}
for(int i = 0; i < arg_count; i++) {
Obj *arg = stack_pop(process);
args[arg_count - i - 1] = arg;
//shadow_stack_push(process, arg);
}
process->frames[process->frame].p += 2;
if(function->tag == 'P') {
stack_push(process, function->primop((struct Process*)process, args, arg_count));
}
else if(function->tag == 'F') {
call_foreign_function(process, function, args, arg_count);
}
else if(function->tag == 'K') {
if(arg_count != 1) {
eval_error = obj_new_string("Args to keyword lookup must be a single arg.");
}
else if(args[0]->tag != 'E') {
eval_error = obj_new_string("Arg 0 to keyword lookup must be a dictionary: ");
obj_string_mut_append(eval_error, obj_to_string(process, args[0])->s);
}
else {
Obj *value = env_lookup(process, args[0], function);
if(value) {
stack_push(process, value);
} else {
eval_error = obj_new_string("Failed to lookup keyword '");
obj_string_mut_append(eval_error, obj_to_string(process, function)->s);
obj_string_mut_append(eval_error, "'");
obj_string_mut_append(eval_error, " in \n");
obj_string_mut_append(eval_error, obj_to_string(process, args[0])->s);
obj_string_mut_append(eval_error, "\n");
}
}
}
else if(function->tag == 'L') {
Obj *calling_env = obj_new_environment(function->env);
//printf("arg_count = %d\n", arg_count);
env_extend_with_args(process, calling_env, function, arg_count, args, true);
process->frame++;
process->frames[process->frame].p = 0;
if(function->body->tag != 'X') {
set_error_return_nil("The body of the lambda must be bytecode, ", function);
}
process->frames[process->frame].bytecodeObj = function->body;
process->frames[process->frame].env = calling_env;
//printf("Pushing new stack frame with bytecode '%s'\n", process->frames[process->frame].bytecode); // and env %s\n", process->frames[process->frame].bytecode, obj_to_string(process, calling_env)->s);
}
else {
printf("Can't handle other calling methods yet %c\n", function->tag);
obj_print_cout(function);
return nil;
}
break;
case 'q':
process->frame--;
if(process->frame < 0) {
goto done;
}
break;
default:
printf("Unhandled instruction: %c\n", c);
exit(-1);
}
}
done:;
return stack_pop(process);
}
