Method: Enumerator#size

Defined in:

enumerator.c

#size ⇒ Integer, ...

Returns the size of the enumerator, or nil if it can’t be calculated lazily.

(1..100).to_a.permutation(4).size # => 94109400
loop.size # => Float::INFINITY
(1..100).drop_while.size # => nil

Returns:

• (Integer, Float::INFINITY, nil)

# File 'enumerator.c', line 1205

static VALUE
enumerator_size(VALUE obj)
{
    struct enumerator *e = enumerator_ptr(obj);
    int argc = 0;
    const VALUE *argv = NULL;
    VALUE size;

    if (e->procs) {
	struct generator *g = generator_ptr(e->obj);
	VALUE receiver = rb_check_funcall(g->obj, id_size, 0, 0);
	long i = 0;

	for (i = 0; i < RARRAY_LEN(e->procs); i++) {
	    VALUE proc = RARRAY_AREF(e->procs, i);
	    struct proc_entry *entry = proc_entry_ptr(proc);
	    lazyenum_size_func *size_fn = entry->fn->size;
	    if (!size_fn) {
		return Qnil;
	    }
	    receiver = (*size_fn)(proc, receiver);
	}
	return receiver;
    }

    if (e->size_fn) {
	return (*e->size_fn)(e->obj, e->args, obj);
    }
    if (e->args) {
	argc = (int)RARRAY_LEN(e->args);
	argv = RARRAY_CONST_PTR(e->args);
    }
    size = rb_check_funcall_kw(e->size, id_call, argc, argv, e->kw_splat);
    if (size != Qundef) return size;
    return e->size;
}