Trait sstable::SSIterator

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pub trait SSIterator {
    // Required methods
    fn advance(&mut self) -> bool;
    fn current(&self, key: &mut Vec<u8>, val: &mut Vec<u8>) -> bool;
    fn current_key(&self) -> Option<&[u8]>;
    fn seek(&mut self, key: &[u8]);
    fn reset(&mut self);
    fn valid(&self) -> bool;
    fn prev(&mut self) -> bool;

    // Provided methods
    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 supporting some additional functionality.

Note: Implementing types are expected to hold !valid() before the first call to advance(), and after advance() has returned false for the first time.

test_util::test_iterator_properties() verifies that all properties hold for a given implementation.

Required Methods§

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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).

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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()).

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fn current_key(&self) -> Option<&[u8]>

Return a reference to the key of the current item (i.e. the item most recently returned by next()).

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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.

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fn reset(&mut self)

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

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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.

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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.

Provided Methods§

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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: SSIterator> Iterator<Item=Vec<u8>> for T {}.

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fn seek_to_first(&mut self)

seek_to_first seeks to the first element.

Trait Implementations§

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impl Iterator for dyn SSIterator

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type Item = (Vec<u8, Global>, Vec<u8, Global>)

The type of the elements being iterated over.
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fn next(&mut self) -> Option<Self::Item>

Advances the iterator and returns the next value. Read more
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fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator. Read more
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fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize>

🔬This is a nightly-only experimental API. (iter_advance_by)
Advances the iterator by n elements. Read more
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fn nth(&mut self, n: usize) -> Option<Self::Item>

Returns the nth element of the iterator. Read more
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impl SSIterator for Box<dyn SSIterator>

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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).
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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()).
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fn current_key(&self) -> Option<&[u8]>

Return a reference to the key of the current item (i.e. the item most recently returned by next()).
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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.
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fn reset(&mut self)

Resets the iterator to be !valid(), i.e. positioned before the first element.
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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.
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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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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: SSIterator> Iterator<Item=Vec<u8>> for T {}.
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fn seek_to_first(&mut self)

seek_to_first seeks to the first element.

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impl SSIterator for Box<dyn SSIterator>

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fn advance(&mut self) -> bool

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

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fn current_key(&self) -> Option<&[u8]>

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

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fn reset(&mut self)

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fn valid(&self) -> bool

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fn prev(&mut self) -> bool

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