Struct mz_persist_client::fetch::Cursor

pub(crate) struct Cursor {
    idx: usize,
}

A pointer into a particular encoded part, with methods for fetching an update and scanning forward to the next. It is an error to use the same cursor for distinct parts.

We avoid implementing copy to make it hard to accidentally duplicate a cursor. However, clone is very cheap.

Fields

idx: usize

Implementations

impl Cursor

pub fn get<'a, T: Timestamp + Lattice + Codec64>( &self, encoded: &'a EncodedPart<T>, ) -> Option<(&'a [u8], &'a [u8], T, [u8; 8])>

Get the tuple at the specified pair of indices. If there is no such tuple, either because we are out of range or because this tuple has been filtered out, this returns None.

pub fn peek<'a, T: Timestamp + Lattice + Codec64>( &mut self, part: &'a EncodedPart<T>, ) -> Option<(&'a [u8], &'a [u8], T, [u8; 8])>

A cursor points to a particular update in the backing part data. If the update it points to is not valid, advance it to the next valid update if there is one, and return the pointed-to data.

pub fn pop<'a, T: Timestamp + Lattice + Codec64>( &mut self, part: &'a EncodedPart<T>, ) -> Option<((&'a [u8], &'a [u8], T, [u8; 8]), usize)>

Similar to peek, but advance the cursor just past the end of the most recent update. Returns the update and the (part_idx, idx) that is was popped at.

pub fn is_exhausted<T: Timestamp + Codec64>( &self, part: &EncodedPart<T>, ) -> bool

Returns true if the cursor is past the end of the part data.

pub fn advance<T: Timestamp + Codec64>(&mut self, part: &EncodedPart<T>)

Advance the cursor just past the end of the most recent update, if there is one.

Trait Implementations

impl Clone for Cursor

fn clone(&self) -> Cursor

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Cursor

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Cursor

fn default() -> Cursor

Returns the “default value” for a type.