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typedef enum ObjectType {
OBJ_TYPE_FIXNUM,
OBJ_TYPE_BOOL,
OBJ_TYPE_NIL,
OBJ_TYPE_SYMBOL,
OBJ_TYPE_STRING,
OBJ_TYPE_PAIR,
OBJ_TYPE_PROCEDURE,
OBJ_TYPE_ERR,
} ObjectType;
typedef struct Object {
ObjectType type;
union {
// OBJ_TYPE_FIXNUM
ssize_t fixnum;
// OBJ_TYPE_STRING
struct {
char *string;
size_t string_n;
};
// OBJ_TYPE_PAIR
struct {
struct Object *car;
struct Object *cdr;
};
// OBJ_TYPE_SYMBOL
struct {
char *symbol;
size_t symbol_n;
};
// OBJ_TYPE_PROCEDURE
struct Object *(*proc)(struct Object *args);
};
} Object;
//
// Singletons.
//
static Object *obj_nil;
static Object *obj_true;
static Object *obj_false;
static Object *obj_err;
//
// Constructors.
//
Object *
alloc_object(ObjectType type) {
Object *obj = malloc(sizeof(Object));
obj->type = type;
return obj;
}
Object *
make_fixnum(ssize_t num) {
Object *obj = alloc_object(OBJ_TYPE_FIXNUM);
obj->fixnum = num;
return obj;
}
Object *
make_procedure(Object *(*proc)(struct Object *args)) {
Object *obj = alloc_object(OBJ_TYPE_PROCEDURE);
obj->proc = proc;
return obj;
}
Object *
make_pair(Object *car, Object *cdr) {
Object *obj = alloc_object(OBJ_TYPE_PAIR);
obj->car = car;
obj->cdr = cdr;
return obj;
}
Object *
make_symbol(StringView sv) {
Object *obj = alloc_object(OBJ_TYPE_SYMBOL);
obj->symbol = malloc(sizeof(char) * sv.n);
memcpy(obj->symbol, sv.start, sv.n);
obj->symbol_n = sv.n;
return obj;
}
Object *
make_string(void) {
Object *obj = alloc_object(OBJ_TYPE_STRING);
obj->string = NULL;
obj->string_n = 0;
return obj;
}
void
append_string(Object *obj, const StringView sv) {
assert(obj != NULL);
assert(obj->type == OBJ_TYPE_STRING);
if (sv.n == 0) {
return;
}
obj->string = realloc(obj->string, (obj->string_n + sv.n) * sizeof(char));
memcpy(obj->string + obj->string_n, sv.start, sv.n);
obj->string_n += sv.n;
}
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