Crate seekable_iterator

Seekable Iterator

Traits

Provides:

• SeekableIterator, SeekableLendingIterator, and SeekablePooledIterator traits, for circular iterators that can move backwards or forwards and seek.
• PooledIterator trait, for iterators that would normally be a lending iterator, but use a buffer pool to lend out multiple items at the same time.
• CursorIterator, CursorLendingIterator, and CursorPooledIterator traits, for circular iterators that can move backwards or forwards by one element.
• Seekable trait, with all the seeking methods required by the Seekable*Iterator traits.
• Comparator trait, for comparisons done to seek.

Adapters to lender::Lender and lending_iterator::LendingIterator are provided for the lending iterator trait.

Semantics

The PooledIterator trait makes roughly the same semantic assumptions about the iterator as a normal iterator.

However, the Cursor*Iterator and Seekable*Iterator traits assume that an implementor is a circular iterator over some ordered collection; the iterator is made circular by adding a phantom element before the first element and after the last element of the ordered collection. The iterator is thus not a FusedIterator, as after iteration over the collection is completed, the iterator wraps back around to the start.

The PooledIterator and Cursor*Iterator traits do not expose any comparator that the ordered collection and iterator might be using, but the Seekable and Seekable*Iterator traits do expose it via a Comparator generic. A DefaultComparator struct is provided that can compare keys that implement Ord, using their Ord implementation.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Structs

DefaultComparator

A Comparator which uses keys’ Ord implementations.

OutOfBuffers

An error that may be returned if no buffer pools were available in a PooledIterator, instead of waiting for a buffer to become available.

Traits

Comparator

Interface for comparing keys (or entries) of a sorted collection.

CursorIterator

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

CursorLendingIterator

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

CursorPooledIterator

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

LendItem

Trait for getting the item of a lending iterator.

PooledIterator

A PooledIterator is similar to a lending iterator (which can lend one item at a time), but can make use of a buffer pool to lend out multiple items at a time.

Seekable

A trait adding seek functionality to one of the cursor iterator traits.

SeekableIterator

An Iterator with cursor methods from CursorIterator and the ability to seek from Seekable.

SeekableLendingIterator

A lending iterator with cursor methods from CursorLendingIterator and the ability to seek from Seekable.

SeekablePooledIterator

A PooledIterator with cursor methods from CursorPooledIterator and the ability to seek from Seekable.

Type Aliases

LentItem

The item of a lending iterator, with a particular lifetime.