Trait CursorIterator

pub trait CursorIterator: Iterator {
    // Required methods
    fn valid(&self) -> bool;
    fn current(&self) -> Option<Self::Item>;
    fn prev(&mut self) -> Option<Self::Item>;
}

A CursorIterator provides access to the entries of some sorted collection, and can move its current position in either direction.

Conceptually, it is circular, and its initial position is before the first entry and after the last entry. As such, it is not a FusedIterator, as continuing to call next() at the end of iteration wraps around to the start. (Note that if the collection is empty, then the iterator will remain at that phantom position.)

Implementations may or may not be threadsafe. Even if an implementation is threadsafe, newly-added entries may or may not be seen immediately by other threads.

Forwards iteration should be preferred over backwards iteration.

Required Methods

fn valid(&self) -> bool

Determine whether the iterator is currently at any value in the collection. If the iterator is invalid, then it is conceptually one position before the first entry and one position after the last entry. (Or, there may be no entries.)

current() will be Some if and only if the iterator is valid.

fn current(&self) -> Option<Self::Item>

Get the current value the iterator is at, if the iterator is valid.

fn prev(&mut self) -> Option<Self::Item>

Move the iterator one position back, and return the entry at that position. Returns None if the iterator was at the first entry.

Implementors