[−][src]Trait rusty_leveldb::LdbIterator

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) { ... }
}

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

fn advance(&mut self) -> bool

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).

fn current(&self, key: &mut Vec<u8>, val: &mut Vec<u8>) -> bool

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

fn seek(&mut self, key: &[u8])

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.

fn reset(&mut self)

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

fn valid(&self) -> bool

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

fn prev(&mut self) -> bool

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.

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Provided methods

fn next(&mut self) -> Option<(Vec<u8>, Vec<u8>)>

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 {}.

fn seek_to_first(&mut self)

seek_to_first seeks to the first element.

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Implementations on Foreign Types

impl LdbIterator for Box<dyn LdbIterator>[src]

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Implementors

impl LdbIterator for DBIterator[src]

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