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void display(Object *root);
void
display_pair(Object *root) {
display(root->car);
if (root->cdr->type == OBJ_TYPE_PAIR) {
printf(" ");
display_pair(root->cdr);
} else if (root->cdr->type == OBJ_TYPE_NIL) {
return;
} else {
printf(" . ");
display(root->cdr);
}
}
void
display(Object *root) {
if (root == NULL) {
return;
}
switch (root->type) {
case OBJ_TYPE_FIXNUM: {
printf("%zd", root->fixnum);
} break;
case OBJ_TYPE_BOOL: {
if (root->boolean) {
printf("true");
} else {
printf("false");
}
} break;
case OBJ_TYPE_NIL: {
printf("()");
} break;
case OBJ_TYPE_STRING: {
printf("\"%.*s\"", (int)root->string_n, root->string);
} break;
case OBJ_TYPE_SYMBOL: {
printf(":%.*s", (int)root->symbol_n, root->symbol);
} break;
case OBJ_TYPE_PAIR: {
printf("(");
display_pair(root);
printf(")");
} break;
case OBJ_TYPE_PROCEDURE: {
printf("#{procedure}");
} break;
}
}
Object *
eval(Object *root) {
switch (root->type) {
case OBJ_TYPE_FIXNUM:
case OBJ_TYPE_BOOL:
case OBJ_TYPE_NIL:
case OBJ_TYPE_STRING: {
return root;
} break;
case OBJ_TYPE_SYMBOL: {
Object *value = find_environment_symbol(root);
if (value == NULL) {
printf("error: symbol not found: `");
display(root);
printf("`\n");
return obj_nil;
}
return value;
} break;
case OBJ_TYPE_PAIR: {
if (root->car->type == OBJ_TYPE_SYMBOL) {
Object *value = find_environment_symbol(root->car);
if (value == NULL) {
printf("error: symbol not found: `");
display(root->car);
printf("`\n");
return obj_nil;
}
if (value->type == OBJ_TYPE_PROCEDURE) {
return value->proc(root->cdr);
}
}
} break;
default: {
printf("error: can't eval type %d.\n", root->type);
} break;
}
return obj_nil;
}
Object *
proc_add(Object *args) {
// Extract first parameter.
Object *car = eval(args->car);
if (car == NULL) {
fprintf(stderr, "error: not enough arguments\n");
return obj_nil;
}
if (car->type != OBJ_TYPE_FIXNUM) {
fprintf(stderr, "addition not supported for type %d\n", car->type);
return obj_nil;
}
args = args->cdr;
ssize_t tot = car->fixnum;
while (args->type == OBJ_TYPE_PAIR) {
Object *car = eval(args->car);
if (car == NULL) {
car = obj_nil;
}
if (car->type != OBJ_TYPE_FIXNUM) {
fprintf(stderr, "addition not supported for type %d\n", car->type);
return obj_nil;
}
tot += car->fixnum;
args = args->cdr;
}
return make_fixnum(tot);
}
Object *
proc_sub(Object *args) {
// Extract first parameter.
Object *car = eval(args->car);
if (car == NULL) {
fprintf(stderr, "error: not enough arguments\n");
return obj_nil;
}
if (car->type != OBJ_TYPE_FIXNUM) {
fprintf(stderr, "error: sub not supported for type %d\n", car->type);
return obj_nil;
}
args = args->cdr;
ssize_t tot = car->fixnum;
while (args->type == OBJ_TYPE_PAIR) {
car = eval(args->car);
if (car == NULL) {
car = obj_nil;
}
if (car->type != OBJ_TYPE_FIXNUM) {
fprintf(stderr, "error: sub not supported for type %d\n", car->type);
return obj_nil;
}
tot -= car->fixnum;
args = args->cdr;
}
return make_fixnum(tot);
}
Object *
proc_mul(Object *args) {
// Extract first parameter.
Object *car = eval(args->car);
if (car == NULL) {
fprintf(stderr, "error: not enough arguments\n");
return obj_nil;
}
if (car->type != OBJ_TYPE_FIXNUM) {
fprintf(stderr, "error: mult not supported for type %d\n", car->type);
return obj_nil;
}
args = args->cdr;
ssize_t tot = car->fixnum;
while (args->type == OBJ_TYPE_PAIR) {
Object *car = eval(args->car);
if (car == NULL) {
car = obj_nil;
}
if (car->type != OBJ_TYPE_FIXNUM) {
fprintf(stderr, "error: mult not supported for type %d\n", car->type);
return obj_nil;
}
tot *= car->fixnum;
args = args->cdr;
}
return make_fixnum(tot);
}
Object *
proc_div(Object *args) {
// Extract first parameter.
Object *car = eval(args->car);
if (car == NULL) {
fprintf(stderr, "error: not enough arguments\n");
return obj_nil;
}
args = args->cdr;
ssize_t tot = car->fixnum;
while (args->type == OBJ_TYPE_PAIR) {
Object *car = eval(args->car);
if (car == NULL) {
car = obj_nil;
}
if (car->type != OBJ_TYPE_FIXNUM) {
fprintf(stderr, "error: div not supported for type %d\n", car->type);
return obj_nil;
}
if (car->fixnum == 0) {
fprintf(stderr, "error: division by zero\n");
return obj_nil;
}
tot /= car->fixnum;
args = args->cdr;
}
return make_fixnum(tot);
}
Object *
proc_display(Object *args) {
if (args == NULL) {
return obj_nil;
}
if (args->type == OBJ_TYPE_PAIR) {
display(eval(args->car));
}
return obj_nil;
}
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