# Basics

Utility functions and classes.

ripple/basic should contain no dependencies on other modules.

# Choosing a rippled container.

- `std::vector`
  - For ordered containers with most insertions or erases at the end.

- `std::deque`
  - For ordered containers with most insertions or erases at the start or end.

- `std::list`
  - For ordered containers with inserts and erases to the middle.
  - For containers with iterators stable over insert and erase.
  - Generally slower and bigger than `std::vector` or `std::deque` except for
    those cases.

- `std::set`
  - For sorted containers.

- `xrpl::hash_set`
  - Where inserts and contains need to be O(1).
  - For "small" sets, `std::set` might be faster and smaller.

- `xrpl::hardened_hash_set`
  - For data sets where the key could be manipulated by an attacker
    in an attempt to mount an algorithmic complexity attack: see
    http://en.wikipedia.org/wiki/Algorithmic_complexity_attack

The following container is deprecated

- `std::unordered_set`
- Use `xrpl::hash_set` instead, which uses a better hashing algorithm.
- Or use `xrpl::hardened_hash_set` to prevent algorithmic complexity attacks.
