int s_dstr::find(s_dstr needle)
{
	assert(needle.len > 0);
	if(needle.len > len) { return - 1; }
	for(int haystack_i = 0; haystack_i < len; haystack_i++)
	{
		b8 all_match = true;
		for(int needle_i = 0; needle_i < needle.len; needle_i++)
		{
			char haystack_c = data[haystack_i + needle_i];
			char needle_c = needle.data[needle_i];
			if(haystack_c != needle_c)
			{
				all_match = false;
			}
		}
		if(all_match)
		{
			return haystack_i;
		}
	}
	return -1;
}