Trait rusty_leveldb::LdbIterator

source · [−]
pub trait LdbIterator {
    fn advance(&mut self) -> bool;
    fn current(&self, key: &mut Vec<u8>, val: &mut Vec<u8>) -> bool;
    fn seek(&mut self, key: &[u8]);
    fn reset(&mut self);
    fn valid(&self) -> bool;
    fn prev(&mut self) -> bool;

    fn next(&mut self) -> Option<(Vec<u8>, Vec<u8>)> { ... }
    fn seek_to_first(&mut self) { ... }
}
Expand description

An extension of the standard Iterator trait that supports some methods necessary for LevelDB. This works because the iterators used are stateful and keep the last returned element.

Note: Implementing types are expected to hold !valid() before the first call to advance().

test_util::test_iterator_properties() verifies that all properties hold.

Required Methods

Advances the position of the iterator by one element (which can be retrieved using current(). If no more elements are available, advance() returns false, and the iterator becomes invalid (i.e. as if reset() had been called).

Return the current item (i.e. the item most recently returned by next()).

Seek the iterator to key or the next bigger key. If the seek is invalid (past last element, or before first element), the iterator is reset() and not valid.

Resets the iterator to be !valid(), i.e. positioned before the first element.

Returns true if the iterator is not positioned before the first or after the last element, i.e. if current() would succeed.

Go to the previous item; if the iterator is moved beyond the first element, prev() returns false and it will be !valid(). This is inefficient for most iterator implementations.

Provided Methods

next is like Iterator::next(). It’s implemented here because Rust disallows implementing a foreign trait for any type, thus we can’t do impl<T: LdbIterator> Iterator<Item=Vec<u8>> for T {}.

seek_to_first seeks to the first element.

Trait Implementations

Advances the position of the iterator by one element (which can be retrieved using current(). If no more elements are available, advance() returns false, and the iterator becomes invalid (i.e. as if reset() had been called). Read more
Return the current item (i.e. the item most recently returned by next()).
Seek the iterator to key or the next bigger key. If the seek is invalid (past last element, or before first element), the iterator is reset() and not valid. Read more
Resets the iterator to be !valid(), i.e. positioned before the first element.
Returns true if the iterator is not positioned before the first or after the last element, i.e. if current() would succeed. Read more
Go to the previous item; if the iterator is moved beyond the first element, prev() returns false and it will be !valid(). This is inefficient for most iterator implementations. Read more
next is like Iterator::next(). It’s implemented here because Rust disallows implementing a foreign trait for any type, thus we can’t do impl<T: LdbIterator> Iterator<Item=Vec<u8>> for T {}. Read more
seek_to_first seeks to the first element.

Implementations on Foreign Types

Implementors